The Importance of Lumbar Lordosis
Sofitel Melbourne on Collins | 15 -17 April 201122SPINESOCIETY OFAUSTRALIA
The Spine Society of Australia 22nd Annual Scientific Meeting 2011
In conjunction with the
Australian Orthopaedic Association
Continuing Orthopaedic Education
(AOA COE) | 13 - 15 April 2011
This Conference has been awarded
16 points - Category 1,
in the Australian Orthopaedic
Association CPD program and
15 credit points - Category 4 :
Maintenance of Clinical Knowledge
and Skills in the Royal Australasian
College of Surgeons CPD Program
Handbook COVER & AD PAGES_Layout 1 4/04/11 6:23 PM Page 1
ContentsPresident’s Message 2
Proud Supporters 3
Awards 4
Program Overview 5
Conference and Exhibition Floorplans 6
Exhibition Booth Allocations 7
Invited Presidential Guest, InternationalKeynote and Symposium Speakers 8 - 9
Editorial Secretary’s Report 10
DePuy Spine Clinical Fellowship Bursary 11
Scientific Program - Friday 15 April 12 - 14
Scientific Program - Saturday 16 April 15 - 17
Scientific Program - Sunday 17 April 18 - 19
Poster Presentations List 20
Supporter Advertising 21 - 25
Session Abstracts: Free Papers Session 1 27 - 34
Free Papers Session 2 35 - 42
Free Papers Session 3 43 - 50
Free Papers Session 4 51 - 58
President’s Session 59 - 64
Free Papers Session 5 65 - 72
Free Papers Session 6 73 - 80
Symposium 2 81 - 84
Free Papers Session 7 85 - 92
Poster Abstracts 93 - 107
Annual Meetings 108 - 109
Author Disclosure Statements 110
Poster Disclosure Statements 111
Delegate List 112 - 118
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President’s MessageOn behalf of the Spine Society of Australia I extend a warm
welcome to all those attending this 22nd Annual Scientific
Meeting of the Spine Society of Australia, here in Melbourne.
The Society and I also welcome the participation of the industry,
which has supported this Society and our patients so well.
Our 2011 meeting theme: ‘The Importance of Lumbar Lordosis,
and... are you restoring lordosis when you operate on lower lumbar
segments?’ will be addressed by a wide range of International and
local speakers.
Our esteemed Presidential Guest Speaker is Professor Jean-Charles
Le Huec, Chief of the Spine Unit and Chairman of the Department
of Orthopaedic Surgery and Traumatology at the Bordeaux
University Hospital, and Director of Surgical Research at
Bordeaux University School of Medicine.
International Keynote Speakers include Dr Christopher Ames,
Associate Professor and Co-Director of Spinal Surgery at the
University of California in San Francisco, and Professor Avinash
Patwardhan from the Department of Orthopaedic Surgery and
Rehabilitation, Loyola University Stritch School of Medicine, Chicago.
We look forward to high level academic presentations with lively
debate and the sharing of knowledge and fellowship in an
atmosphere of mutual respect.
Melbourne is a warm-hearted city and we hope you have a
chance to explore its many delights. The Conference Gala
Dinner being held on Saturday evening 16 April, in the stylish
Birrarung Gallery at Melbourne Museum, promises to be a
conference highlight. On behalf of the Organising Committee,
Welcome!
A/Prof Graeme Brazenor
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Proud Supporters
TITANIUM SUPPORT
GOLD SUPPORT
SILVER SUPPORT
BRONZE SUPPORT
AV SUPPORT
BREAKFAST SESSION SUPPORT
PRESIDENTIAL SPEAKER SUPPORT
KEYNOTE SPEAKER SUPPORT
CONFERENCE SATCHEL SUPPORT
WELCOME RECEPTION SUPPORT
Awards SPINAL RESEARCH AWARD Supported by
ROB JOHNSTON AWARD Supported by
BEST PAPER AWARD Supported by
BEST POSTER AWARD Supported by
TRAVELLING FELLOWSHIP BURSARY Supported by
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Conference Program Overview
Wednesday 13 April
AOA:COEMeeting
& Thursday 14 April Friday 15 April Saturday 16 April Sunday 17 April
10.10 Morning tea 10.20 Morning tea 10.00 Morning tea
12.30pm Lunch and Exhibition 12.00noon Award Presentations and Close
3.00 Afternoon tea
12.30pm Lunch and Exhibition
2.50 Afternoon tea
7.15 - 8.15am
SSA Registration
7.15 - 8.15am
Breakfast Session: Restoring
lumbar lordosis utilising the XLIF®
technique Dr Juan Uribe
8.30 Conference Opening
8.50 FREE PAPERS
SESSION 1:
Back Pain
8.30 FREE PAPERS SESSION 4:TDR / Sagittal Balance & The History of SpineBalance AnalysisProf Jean-Charles Le Huec
8.30 SYMPOSIUM 2
Surgery and Biomechanics
of Adult Degenerative Disease
A/Prof Chris Ames
Prof Avinash Patwardhan
10.40 SYMPOSIUM 1Vertebroplasty: Does it work?A/Prof Jacqui Close Dr Ralph StanfordProf Rachelle Buchbinder Dr Peter McCombe
Session combined with Australian Orthopaedic Association Continuing Orthopaedic Education
10.50 PRESIDENT’S SESSION
Lumbar Lordosis and Sagittal
Balance: The Masters Speak
Prof Jean-Charles Le Huec A/Prof Chris AmesProf Avinash Patwardhan
10.30 FREE PAPERS SESSION 7:Spinal Cord Injury
1.30 FREE PAPERS SESSION 5:Surgical
1.30 FREE PAPERS SESSION 2:Basic Science
3.30 FREE PAPERS SESSION 3:Cervical / BMP
3.10 FREE PAPERS SESSION 6:Scoliosis
5 - 7.00pm Welcome ReceptionSupported by
7.30 SSA GALA DINNERMelbourne Museum
4.30 - 6.00pm SSA Business Meeting
7.15 - 8.15am
Breakfast Session: Oracle: A new
approach to lumbar interbody
fusion Dr Bart Conix, MD
Conference & Exhibition Floorplans
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InternetCafe
! EXHIBITION FLOORPLAN | GRAND BALLROOM | LEVEL 1, SOFITEL MELBOURNE ON COLLINS
! LEVEL 1, SOFITEL MELBOURNE ON COLLINS
Grand Ballroom
Arthur Streeton Auditorium
Fitzroy Ballroom
Exhibition Booth AllocationsBooth 1. Internet cafe
Booth 2. OrthotechBooth 3. Orthotech
Booth 4. NuVasiveBooth 5. NuVasive
Booth 6. DePuy SpineBooth 7. DePuy Spine
Booth 8. Stryker
Booth 9. AO Spine
Booth 10. Biomet AustraliaBooth 11. Biomet Australia
Booth 12. Synthes Australia
Booth 13. Wright Medical Australia
Booth 14. Medyssey Spine
Booth 15. ETHICON (Johnson & Johnson Medical)
Booth 16. Neutron
Booth 17. Global Orthopaedic Technology
Booth 18. ArthroCare
Booth 19. B.BraunBooth 20. B.Braun
Booth 21. LifeHealthCareBooth 22. LifeHealthCareBooth 23. LifeHealthCareBooth 24. LifeHealthCare
Booth 25. Med-Chem Surgical Pty Ltd
Booth 26. Signature Spine
Booth 27. Zimmer Booth 28. Zimmer
Booth 29. MedtronicBooth 30. MedtronicBooth 31. MedtronicBooth 32. Medtronic
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Presidential Guest Speaker
International Keynote Speakers
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Professor Jean-Charles Le Huec Supported by
Chairman, Orthopaedic Department
University of Bordeaux Hospital, France
Jean-Charles Le Huec became a medical doctor in 1987,
continued his studies in Biomechanics and Biomaterials and
received his physical doctorate in 1997. In 1998 he was made
Professor of Orthopaedics and Traumatology and is now
Chairman, Spine Unit, and Head of Orthopaedics, Bordeaux University Hospital.
Professor Le Huec is a member of the French College and Society of Orthopaedic Surgery;
Vice President, Spine Society of Europe; a member of ISSLS and the North American Spine
Society; World Spine Society Treasurer and Spine Arthroplasty Society Vice President.
Professor Le Huec has numerous publications and participates in many research projects
relating to spine pathologies, biomaterials and computer-assisted surgery.
Associate Professor Chris Ames Supported by
Associate Professor of Neurosurgery
University of California, San Francisco, California, USA
Dr Ames is Director of Spinal Tumor and Spinal Deformity Surgery,
a Co-Director of the Neurospinal Disorders Program, and of the
UCSF Spine Centre, and Director of the Spine Tumor & Deformity
Fellowship Program. His clinical tumor practice focuses on spinal
deformity and complex tumor resection. While at UCSF, Dr Ames developed and published
the transpedicular approach to previously unresectable cervical and cervical thoracic tumors.
Professor Avinash Patwardhan Supported by
Dept of Orthopaedic Surgery & Rehabilitation,
Loyola University Stritch School of Medicine, Chicago, Illinois, USA
Professor Patwardhan is also Director of the Musculoskeletal
Biomechanics Lab at Edward Hines Jr. VA Hospital. A dynamic
teacher and pioneer in spinal biomechanics, his ‘follower load,’
testing technique is now recognised in biomechanical labs
worldwide. He has authored 100+ articles and13 book chapters, has presented at 267 conferences
and has received many research awards including the 2005 Outstanding Paper Award for his work
on lumbar disc arthroplasty, and the 2009 North American Spine Society’s Henry Farfan Award.
Symposium Speakers
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Associate Professor Jacqui Close
Consultant Geriatrician, Prince of Wales Hospital, Sydney,
NSW, Australia
A/Prof Close runs the Orthogeriatric and Falls, Balance and
Bone Health Service at Prince of Wales Hospital and is a
Principal Research Fellow at Neuroscience Research Australia.
She is conducting studies into the risk of falls in people with
cognitive impairment, piloting interventions to prevent falls in people with dementia and looking
at alternate pathways to care for older people using the ambulance service. She has a particular
interest in getting research generated evidence into practice and sits on a number of committees
and governing bodies to facilitate policy, guideline and practice development. She is medical
chair of the NSW ACI Aged Health Network which aims to enhance orthogeriatric services
across the State.
Professor Rachelle Buchbinder
Director, Monash Department of Clinical Epidemiology, Cabrini
Hospital, Melbourne, Vic, Australia
As a rheumatologist and clinical epidemiologist, Prof Buchbinder
is currently researching the management of soft tissue disorders.
She is also interested in the risk of malignancy in rheumatic diseases,
treatment and prevention of low back pain, magnetic resonance
imaging in rheumatoid arthritis, quality of life, patient education, complementary medicine and
outcome measurement. At present she coordinates and teaches the postgraduate course in
Measurement and supervises postdoc, BMedSci, MPH and PhD students.
Editorial Secretary’s Report Dear Members and Delegates,
2011 saw a sharp rise in the number of submitted abstracts over
2010 and so with the same amount of time available for paper
presentation, more authors were disappointed this year. In total
there were 85 abstracts submitted, 45 were accepted for oral
presentation and 17 for poster presentation. Twenty were rejected
and a further three authors did not reply to correspondence. The
process of abstract review was undertaken by a group of 5 reviewers,
including myself, representing the different clinical and scientific
disciplines that make up the Society. The review, as always, was
conducted in a fully blinded manner and each reviewer worked
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independently. The essential characteristic required of an abstract is scientific clarity. All abstracts not
making ‘the cut’ were re-appraised to ensure fairness. Once a selection had been made on the basis
of content alone, the conference secretariat contacted the relevant authors, who were still unknown
to me and the review panel. In many cases further information and clarification was requested of the
authors. The identity of abstract authors was only revealed after all correspondence had ceased and
the papers had been grouped for the purpose of building the program.
This process is unbiased and I believe leads to a better quality meeting. In my view quality is about
clear presentation of relevant data in a way that allows the audience to assess the worth of that
information. I do not subscribe to the view that an abstract is just a token for a paper, if the abstract
does not make sense, then it will suffer in the face of critical appraisal. Also, an abstract will not be
selected just because it reports a novel idea or new technology; it also has to meet minimum scientific
standards. I do not mean that data has to be collected blind or allocation randomised, I believe that
substantial case series can be useful. Critical reviews of published evidence also have merit. What is
important is that the methods used are reliable and transparent and the conclusions do not go beyond
the results. Even bias is acceptable as long as it is identified. The audience can then have confidence
in where this information came from and whether or not it has relevance to their own clinical or
scientific practice.
I congratulate the Society President, A/Prof Graeme Brazenor who has worked hard to bring together
an outstanding visiting faculty to highlight the importance of sagittal balance in surgical practice and
related biomechanical principles. The Spine Society is indebted to the tireless Prof Richard Williams
for collating the conjoint session with the Australian Orthopaedic Association on Friday morning, in
particular the symposium on vertebroplasty. I thank the scientific reviewers who gave much of their
time in silent homage to the principles of science and helped make this program a success; they are
Dr Kevin Seex, Prof Mark Pearcy, Prof Rob Moore and Dr Peter Robertson. I also thank Kate Ryall of DC
Conferences for her hard work and keeping me more or less to time, which is not easy.
I promise the delegates a stimulating and relevant program.
Dr Ralph Stanford, Editorial Secretary, Spine Society of Australia
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DePuy Spine Clinical Fellowship Bursary
Supported by
The DePuy Spine Clinical Fellowship Bursary is designed to
encourage and promote the pursuit of dedicated clinical spine
fellowship training. Bursary funds are granted to assist
successful applicants with the cost of attending an overseas
fellow program. Five individual bursaries are available for 2011,
each valued at Au$15,000. To be eligible for consideration,
applicants must satisfy the following criteria :
" Written confirmation of the applicant’s acceptance into a
Spine Fellowship Program (to be in writing from
Fellowship hospital’s department head or equivalent)
" Fellowship must be clinically based
" Fellowship program must be predominantly spine focused
(greater than 75% Spine)
" Fellowship Program to be at least 6 months duration
" Fellowship Program must be based outside Australia
" Applicants must currently be on an Australian Surgical
Training Program (Orthopaedic or Neurosurgical)
" Applications must relate to a Fellowship Program that will
commence in the calendar years of 2011 or 2012
To apply please provide details that satisfy the above
application criteria and send to:
Secretary, Spine Society of Australia
Email [email protected]
All 5 Bursaries will be awarded on a first come basis.
Successful applicants will be notified in writing within 1 month of
their application submission.
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Conference Program | FRIDAY 15 APRIL 2011
8.30am CONFERENCE OPENING | Arthur Streeton Auditorium
Chair | A/Prof. Graeme Brazenor
8.50 - 10.10am FREE PAPERS SESSION 1 | BACK PAIN | Arthur Streeton Auditorium
Chair | Prof Michael Ryan
8.50am 1.1 Facet joint injections: Are they safe or effective?
Matthew Beard
8.58am 1.2 Degenerative spondylolisthesis: The role of a weakened abdominal wall
Robert Fraser
9.06am 1.3 Why do some people experience no low back pain? Comparison of a middle-aged working
population to a population-based cohort
Markus Melloh
9.14am 1.4 Predicting the transition from acute to persistent low back pain
Markus Melloh
9.22am DISCUSSION
9.42am 1.5 Patient expectations, outcomes and satisfaction: Related, relevant or redundant?
Paul Licina
9.50am 1.6 Does posterior pedicle screw supplementation without posterolateral fusion improve anterior lumbar
interbody fusion when using anterior cage and screw constructs? A radiological study
Michael McCarthy
9.58am DISCUSSION
10.10am Morning Tea | Grand Ballroom
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Conference Program | FRIDAY 15 APRIL 2011 continued
10.40am - 12.30pm SYMPOSIUM 1 | VERTEBROPLASTY: DOES IT WORK? | Arthur Streeton Auditorium
This Session is combined with the Australian Orthopaedic Association Continuing Orthopaedic Education
Chair | Prof Richard Williams
10.40am Vertebral osteoporotic fractures: Natural history and prevention A/Prof Jacqui Close
11.00am Vertebroplasty: Technique, risks and benefits Dr Ralph Stanford
11.20am Vertebroplasty: Evidence based assessment of benefit Prof Rachelle Buchbinder
11.40am Observations on evidence based medicine and application to surgical practice Dr Peter McCombe
12.00 noon QUESTIONS and PANEL DISCUSSION
12.30pm Lunch | Grand Ballroom
1.30 - 3.00pm FREE PAPERS SESSION 2 | BASIC SCIENCE | Arthur Streeton Auditorium
Chair | Prof Clayton Adam
1.30pm 2.1 Biomaterial impregnation with bone marrow aspirate: Does it live up to the promise?
Claudia Eder
1.38pm 2.2 Recombinant human BMP-2 enhances local bone formation in the lumbar spine of osteoporotic sheep
Robert Moore
1.46pm 2.3 Elemental analysis of lumbar vertebral bone in an osteoporotic sheep model
Reza Zarrinkalam
1.54pm DISCUSSION
2.09pm 2.4 Biomechanical investigation of the stabilizing effect of a novel integrated device for intra-articular atlanto-axial stabilization
Peter Robertson
2.17pm 2.5 An intervertebral joint’s centre of rotation affects the forces experienced by the zygapophysial joints
Mark Pearcy
2.25pm 2.6 Development and validation of a spinal facet joint pseudarthrosis model
Ben Goss
2.33pm 2.7 Variations in annular defect characteristics in herniated lumbar discs: An annular repair feasability study and attempt to confirm Carragee data on defect size
David Wong
2.41pm DISCUSSION
3.00pm Afternoon Tea | Grand Ballroom
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Conference Program | FRIDAY 15 APRIL 2011 continued
3.30 - 5.00pm FREE PAPERS SESSION 3 | CERVICAL / BMP | Arthur Streeton Auditorium
Chair | Dr Greg Malham
3.30pm 3.1 Anterior cervical decompression and fusion with rhBMP-2: A prospective case series of 53 patients
Matthew Scott-Young
3.38pm 3.2 A non randomised single surgeon cohort study of rhBMP-2 versus rhBMP-7 in lumbar spinal
surgery: An outcome analysis of 186 patients
Michael McCarthy
3.46pm 3.3 The efficacy of bone morpheogenic protein (BMP-7) in posterolateral lumbar fusion surgery
Ellen Frydenberg
3.54pm DISCUSSION
4.09pm 3.4 Clinical outcomes following cervical disc replacement with PCM after a minimum 1-Year follow-up
Matthew Scott-Young
4.17pm 3.5 Seven years experience with C2 translaminar screws fixation: One surgeon's experience with 52 patients
Neill Wright
4.25pm 3.6 A radiological analysis of early failure of cervical fixation for trauma in the subaxial cervical spine
Michael McCarthy
4.33pm 3.7 Medium-term outcomes of elderly patients with odontoid fractures: Is quality of life associated
with radiographic evidence of union?
Amy Nall
4.41pm DISCUSSION
5.00pm Session closes
5.00pm - 7.00pm WELCOME RECEPTION
Grand Ballroom | Sofitel Melbourne on Collins
Supported by
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Conference Program | SATURDAY 16 APRIL 2011
7.15 - 8.15am BREAKFAST SESSION | Fitzroy Ballroom
Restoring lumbar lordosis utilising the XLIF® technique
Dr Juan Uribe
8.30 - 10.20am FREE PAPERS SESSION 4 | TDR / SAGITTAL BALANCE | Arthur Streeton Auditorium
and THE HISTORY OF SPINE BALANCE ANALYSIS | Prof Jean-Charles Le Huec
Chair | Dr Rob Kuru
8.30am 4.1 Prospective 10 year follow up of AcroFlex lumbar disc replacement
Robert Fraser
8.38am 4.2 Compliant artifical lumbar disc replacement (Cadisc-L): In vivo implant stability and
osseointegration in an animal model
Brian Freeman
8.46am 4.3 Early clinical performance of the Cadisc-L total disc replacement:
A prospective non-randomized multicentre clinical trial
Brian Freeman
8.54am DISCUSSION
9.09am 4.4 Correlation of age with spino-pelvic balance in degenerative lumbo-sacral disorder
Sabarul Mokhtar
9.17am 4.5 Association of chronic low back pain with loss of lumbar lordosis and the role of pelvic morphology
Jeb McAviney
9.25am 4.6 A software simulation of spinal sagittal balance
Peter McCombe
9.33am DISCUSSION
9.48am 4.7 History of spine balance analysis: Is there a reason to miss the target?
Prof Jean-Charles Le Huec
10.15am QUESTIONS
10.20am Morning Tea | Grand Ballroom
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Conference Program | SATURDAY 16 APRIL 2011 continued
10.50am - 12.30pm PRESIDENT’S SESSION | Arthur Streeton Auditorium
LUMBAR LORDOSIS AND SAGITTAL BALANCE: THE MASTERS SPEAK
Chair | A/Prof Graeme Brazenor
10.50am Pelvic parameters and spine parameters Prof Jean-Charles Le Huec
11.15am How to correlate parameters and global balance for daily practice Prof Jean-Charles Le Huec
11.35am QUESTIONS
11.45am Reciprocal changes and osteotomy planning in sagittal balance surgery A/Prof Chris Ames
12.05pm Geometric analysis of coronal balance in idiopathic scoliosis: Are there lessons for sagittal balance?
Prof Avinash Patwardhan
12.20pm QUESTIONS
12.30pm Lunch | Grand Ballroom
1.30 - 2.50pm FREE PAPERS SESSION 5 | SURGICAL | Arthur Streeton Auditorium
Chair | Dr Kevin Seex
1.30pm 5.1 Outcomes after decompressive laminectomy for lumbar spinal stenosis:
Comparison between minimally invasive unilateral laminotomy / laminectomy for
bilateral decompression (ULBD) vs. open laminectomy.
Ralph Mobbs
1.38pm 5.2 Lumbar spinal synovial cysts: Associations and treatment
Michael Ryan
1.46pm 5.3 Transforaminal endoscopic lumbar disc surgery application in upper lumbar discs: Method and results
Satishchandra Gore
1.54pm 5.4 Long-term outcomes following lumbar spine fusion for adult isthmic spondylolisthesis:
A comparison of PLIF vs PLF
John Cunningham
2.02pm DISCUSSION
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Conference Program | SATURDAY 16 APRIL 2011 continued
1.30 - 2.50pm FREE PAPERS SESSION 5 (continued) | SURGICAL | Arthur Streeton Auditorium
Chair | Dr Kevin Seex
2.22pm 5.5 Prospective computed tomography scan analysis of percutaneously inserted pedicle screws for posterior transpedicular stabilisation of the thoracic and lumbar spine: Accuracy and complication ratesDarryl Raley
2.30pm 5.6 The role of preoperative DVT prophylaxis in thromboembolic complications in spinal surgeryJohn Cunningham
2.38pm DISCUSSION
2.50pm Afternoon Tea | Grand Ballroom
3.10 - 4.30pm FREE PAPERS SESSION 6 | SCOLIOSIS | Arthur Streeton Auditorium
Chair | Dr Peter Woodland
3.10pm 6.1 The measurement of applied forces during anterior single rod correction of adolescent idiopathic scoliosis (AIS)Helen Fairhurst
3.18pm 6.2 The value of spinal cord monitoring in scoliosis surgery: A ten year experienceSusan Liew
3.26pm 6.3 Do reinfusion drains following posterior instrumented spinal fusion for adolescent idiopathic scoliosis reduce allogenic blood requirements? A prospective audit with historical controlsMichael Selby
3.34pm 6.4 Serum titanium levels following paediatric spinal arthrodesisThomas Cundy
3.42pm DISCUSSION
4.02pm 6.5 Post-operative CT assessment of interbody fusion two years after thoracoscopic scoliosis surgeryAlan Carstens
4.10pm 6.6 Minimally invasive spine surgery in adult deformity correction: A prospective case series of 37 patientsMatthew Scott-Young
4.18pm DISCUSSION Session closes at 4.30pm
4.30 - 6.00pm BUSINESS MEETING | Arthur Streeton Auditorium
7.30pm CONFERENCE GALA DINNER | Birrarung Gallery, Melbourne Museum
Coaches depart from Sofitel Melbourne on Collins at 7.00pm
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Conference Program | SUNDAY 17 APRIL 2011
7.15 - 8.15am BREAKFAST SESSION | Fitzroy Ballroom
Oracle: A new approach to lumbar interbody fusion Dr Bart Conix MD
8.30 - 10.00am SYMPOSIUM 2 | Arthur Streeton Auditorium
SURGERY AND BIOMECHANICS OF ADULT DEGENERATIVE DISEASE
Chair | A/Prof Graeme Brazenor
8.30am Sagittal balance and surgical strategy in adult high grade spondylolisthesis A/Prof Chris Ames
8.50am Stability of the osteoligamentous spine: The Follower Load and its implications to ex-vivo testing
and in-vivo spine stability Prof Avinash Patwardhan
9.15am A novel method of assessing facet joint motion using specimen-specific CT based model
Prof Avinash Patwardhan
9.30am QUESTIONS
10.00am Morning Tea | Grand Ballroom
10.30 - 12noon FREE PAPERS SESSION 7 | SPINAL CORD INJURY | Arthur Streeton Auditorium
Chair | Dr Gerald Quan
10.30am 7.1 VEGF & PDGF as an immunomodulatory strategy for the reduction of secondary degeneration
after a model spinal cord injury in rats
Ben Goss
10.38am 7.2 The pressure distribution of cerebrospinal fluid responds to residual compression and decompression
in an animal model of acute spinal cord injury
Claire Jones
10.46am 7.3 Gross morphological changes of the spinal cord immediately after surgical decompression in a large
animal model of traumatic spinal cord injury
Claire Jones
10.54am DISCUSSION
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Conference Program | SUNDAY 17 APRIL 2011 continued
10.30 - 12noon FREE PAPERS SESSION 7 (continued) | SPINAL CORD INJURY | Arthur Streeton Auditorium
Chair | Dr Gerald Quan
11.09am 7.4 The role of spinal injury units in Australia: The effects of early and direct admission in
spinal cord injured patients
Matt Schiller
11.17am 7.5 Sequential reduction protocol using vector principle for cervical fracture dislocations
Rajeshwar Srivastava
11.25am 7.6 MRI in spinal trauma: A predictor of neurological recovery
Rajeshwar Srivastava
11.33am 7.7 Traumatic central cord syndrome: Is it associated with better neurological recovery and functional
outcomes when compared to motor incomplete tetraplegia?
Joost Van Middendorp
11.41am DISCUSSION
12.00 noon AWARD PRESENTATIONS
12.30pm Conference closes
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Poster Presentations (See pages 93 - 107)
1. Dr Markus Melloh
Clinical validity of the nerve root sedimentation sign for
the diagnosis of lumbar spinal stenosis
Department of Orthopaedic Surgery, Dunedin School of
Medicine, University of Otago, Dunedin, New Zealand
2. Dr Aziza Mahomed
Flexural properties of an elastomeric total disc replacement
School of Mechanical Engineering, University of Birmingham,
Birmingham, United Kingdom
3. Dr Eugene Wong
Management of cervicothoracic junction fracture dislocations
Austin Health, Melbourne, Vic, Australia
4 Dr Eugene Wong
Surgery for cervical facet dislocations: Which approach?
Austin Health, Melbourne, Vic, Australia
5. Dr Eugene Wong
MRI changes in cervical cord injuries
Austin Health, Melbourne, Vic, Australia
6. Dr Michael McCarthy
Screw webpacs: Is pedicle sizing accurate and reproducible
on CT
Royal Devon and Exeter Foundation NHS Trust, Exeter, Devon, UK
7. Dr Ellen Frydenberg
The role of cervical cordotomy in the management of
refractory cancer pain
St Vincent's Hospital, Darlinghurst, NSW, Australia
8. Dr Kevin Seex
Initial experience with a novel internally fixed frame to
improve retraction for anterior upper cervical surgery
Macquarie University, Sydney, NSW, Australia
9. Dr John McCormick
Novel description of an all-osseous transpelvic approach to
the intervertebral space of the lumbosacral junction
University of Florida, Gainesville, Florida, United States
10. Dr Michael McCarthy
Implementation of the NICE guidelines for metastatic
spinal cord compression: Do they make a difference?
Royal Devon and Exeter Foundation NHS Trust, Exeter, Devon, UK
11. Dr GRC Howie
A simple mnemonic to reduce errors in spinal fusion
Ascot Hospital, Remuera, Auckland, New Zealand
12. Prof Rajeshwar Srivastava
SCIWORA in adults: Is C4 the soft target?
King Georges Medical College, CSM Medical University Chowk,
Lucknow, India
13. Prof Rajeshwar Srivastava
Spinal shock in spinal cord injuries: Is duration of shock
related to neurological level?
King Georges Medical College, CSM Medical University Chowk,
Lucknow, India
14. Prof Brian Freeman
In-vitro biomechanical comparison of the native
intervertebral disc and a compliant artificial lumbar disc
replacement (Cadisc-L)
University of Adelaide, Adelaide, SA, Australia
15. Dr Michael Selby
Cervical cord injury as a complication of percutaneous
cervical facet joint radiofrequency neurotomy
University of Adelaide, Adelaide, SA, Australia
16. Dr Ralph Mobbs
Prospective analysis of graft options for anterior lumbar
interbody fusion (ALIF): Fusion and complication rates
University of New South Wales, Sydney, NSW, Australia
17. Dr Roy Michael Domacena
Radiographic fusion rate of multilevel anterior cervical
discectomy and fusion using peek cages with DBM and
plate fixation: A descriptive study
St Lukes Medical Center, Quezon City, NCR, Philippines
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DePuy Ad
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LifeHealthCare Ad
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Nuvasive Ad
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Synthes Ad
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Zimmer Ad
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Notes & Questions page
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22 Free Papers Session 1
Back PainFriday 15 April | 8.50am - 10.10am
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
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FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 1
BACK PAIN | Chair | Prof Michael Ryan
Arthur Streeton Auditorium
8.50am | 1.1Facet joint injections: Are they safe or effective?
*Beard, MDI, Potter, GI
Royal Adelaide Hospital, Adelaide, SA, Australia
INTRODUCTION
The effective management of chronic low back pain (CLBP)
remains a 21st century challenge. Many conservative treatments
have limited efficacy despite their continued popularity. Ensuring
patient treatments are based on current clinical evidence rather
than historical practice remains challenging (Buchbinder et al
2009). Clinicians often recommend facet joint injections as the
mainstay of conservative treatment. The attraction to both
patient and clinician is an intervention with potential diagnostic
and therapeutic utility. The objective has been to establish
whether FJI is an effective treatment for patients with CLBP.
METHODS
A review of relevant literature was undertaken that focused on
English language Randomized Controlled Trials only. Data sources
included a search of MEDLINE, EMBASE and the Cochrane
Central Register of Controlled Trials (January 1990 to December
2010). The primary outcome measure examined was pain relief.
Other measures included functional improvement, return to
work and adverse outcomes.
RESULTS
Review of published trials is unable to demonstrate sustained
improvement in pain or function for this patient population
(Stall et al 2009). Few immediate adverse events are reported
with clinical trails. In contrast a recent cellular study has
highlighted potential corrosive effects of both local anaesthetic
and corticosteroid on articular cartilage. (Seshadri et al, 2009).
CONCLUSION
Current evidence would question the efficacy of FJI in the
treatment of CLBP, which may also have the potential to initiate
or hasten joint degenerative changes.
REFERENCES
1. BUCHBINDER, R. et al.
Spine 34, 1218-1226, 2009.
2. STALL, JB et al.
Cochrane Database of Systematic Reviews CD 001824, 2009.
3. SESHADRI, V.
Journal of Arthroscopic and Related Surgery 25, 337-347, 2009.
29
8.58am | 1.2Degenerative spondylolisthesis: The role of a weakened abdominal wall
Fraser, RD
Royal Adelaide Hospital, Adelaide, SA, Australia
INTRODUCTION
Degenerative spondylolisthesis (DS) is thought to arise from
failure in torsion with females more vulnerable due to their bony
anatomy (Farfan, 1970). The abdominal wall has been estimated
to provide 95% of resistance to torsion (Macintosh, 1993). The
anterior abdominal wall is stretched during childbearing and a
previous study found an association between DS and pregnancy
(Sanderson, 1996). The aim of the present study was to further
examine the association of weakened anterior abdominal
muscles and DS.
METHODS
This was a prospective observational study of all new patients
50 yrs of age or older presenting with LBP. Exclusions were
previous lumbar surgery, fracture, neoplasm and infection.
Details of age, height, weight, children, pregnancies and open
abdominal operations were recorded. Integrity of the linea alba
was determined by asking the supine patient to elevate his/her
head and shoulders and the presence of rectus separation and
ventral hernia were noted. CT or MRI images were examined for
DS and the displacement was graded as a percentage.
RESULTS
205 patients were enrolled over a 5 month period. Mean ages
(years) were 70.5 for DS males, 65.9 for non-DS males, 72.0
for DS females and 64.9 for non-DS females. BMI for males and
females with and without DS was similar. DS was present in 28
of 98 males and in 56 of 107 females (M:F=1:2). DS was
multilevel in 30% of females compared with 7% of males
(p=.017). There was a significant association between DS and
ventral hernia (p=.009), rectus separation (p=.024), open
abdominal surgery (p=.022) and pregnancy (p=.03). Ventral
hernia was present in 64.3% of DS males compared with 37.1%
of non-DS males. Rectus separation was detected in 71.4% of DS
males, 52.9% of non-DS males, 51.8% of DS females and 35.3%
of non-DS females. The average number of open abdominal
procedures was 0.29 for DS males, 0.32 for non-DS males, 1.5
for DS females and 0.94 for non-DS females. The average
number of pregnancies was 3.09 for DS females compared
with 2.43 for non-DS females.
CONCLUSION
DS is extremely common in patients over 50 years of age pre-
senting to a spinal surgical clinic. The associations of DS with rec-
tus divarication, previous open abdominal surgery and
childbearing support the view that a weakened anterior abdomi-
nal wall is a significant causative factor for DS. The findings have
particular relevance to prevention as well as conservative and
surgical management of DS.
REFERENCES
1. FARFAN, HV, COSSETTE, JN, ROBERTSON, GH et al.
The effects of torsion on the lumbar intervertebral joints.
JBJS 52-A; 468: 1970
2. MACINTOSH JE, PEARCY MJ, BOGDUK N.
The axial torque of the lumbar back muscles: Aust N Z J
Surg ;63: 205: 1993–
3. SANDERSON PL, FRASER RD.
Influence of pregnancy in degenerative spondylolisthesis. JBJS
78-B; 951: 1996
30
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 1 (continued)
BACK PAIN | Chair | Prof Michael Ryan
Arthur Streeton Auditorium
9.06am | 1.3Why do some people experience no low backpain? Comparison of a middle-aged working population to a population-based cohort
*Melloh, M,1 Rolli Salathé, C,2 Schenk, K,2 Odermatt, E,2
Lüthi, I,2 Elfering, A 2
1 Department of Orthopaedic Surgery, Dunedin School of
Medicine, University of Otago, New Zealand 2 Department of Work and Organizational Psychology,
Institute of Psychology, University of Berne, Switzerland
INTRODUCTION
With the majority of all individuals beyond 50 years of age
experiencing low back pain (LBP) at least once in their lifetime,
little is known about those persons never having had LBP
(Nachemson et al. 2000, Waddell et al. 2001). To minimize work
absenteeism and to decrease socio-economic costs, knowledge
about persons resilient to the occurrence of LBP may help to
enhance preventative behavior in personal as well as
occupational settings (Reigo et al. 2001).
METHODS
Out of 350 individuals aged between 52 and 65, a group of
32 who never had experienced LBP before was assessed for
potential factors for never having suffered from LBP and
completed a questionnaire which had been part of a nation-wide
assessment about LBP (Muller et al. 2008). Answers were
content-analyzed, questionnaires compared to a population-
based cohort (n=4,120) using percentile ranks (PR).
RESULTS
Three main categories emerged for reasons why some people
did not develop LBP:
a) Sports and hobbies;
b) Movements during activities of daily living and in work
environments;
c) Positive attitudes towards life.
Compared to the population-based group, the group of subjects
never having had LBP scored higher for the ability to achieve routine
movements (PR=65). Also, they less frequently attended physicians
(PR=13) and had more positive attitudes towards life (PR=87).
The group of individuals never having suffered from LBP coped
better with their job (PR=61) and felt treated less unfairly at work
(PR=39). For the will to achieve something or the determination
to work for success, this group was ranked with PR 65.
CONCLUSION
Individuals above 50 years of age never having experienced LBP
are more likely to be physically active during work and daily routine
activities. Opinions and motivations, such as conscious and careful
usage of one’s bodily resources and limitations or taking good
health not for granted, as well as active and proactive health
behavior and fair treatment at work, possibly help preventing
individuals from developing LBP.
REFERENCES
1. MULLER, U, TANZLER, K, BURGER, A, STAUB, L, TAMCAN, O,
ROEDER, C, JUNI, P, TRELLE, S 2008.
A pain assessment scale for population-based studies:
Development and validation of the Pain Module of the
Standard Evaluation Questionnaire. Pain, 136, 62-74.
2. NACHEMSON, AL, JONSSON, E 2000.
Neck and back pain, Philadelphia, Williams & Wilkins.
3. REIGO, T, TROPP, H, TIMPKA, T 2001.
Absence of back disorders in adults and work-related
predictive factors in a 5-year perspective.
Eur Spine J, 10, 215-20; discussion 221.
4. WADDELL, G, BURTON, AK 2001.
Occupational health guidelines for the management of low
back pain at work: evidence review.
Occup Med (Lond), 51, 124-35.
2731
9.14am | 1.4Predicting the transition from acute to persistent low back pain
*Melloh, M,1 Elfering, A,2 Egli Presland, C,2 Röder, C,3
Hendrick, P, 4 Darlow, B,4 Theis, JC 1
1 Department of Orthopaedic Surgery, Dunedin School of
Medicine, University of Otago, New Zealand2 Department of Work and Organizational Psychology,
Institute of Psychology, University of Berne, Switzerland3 MEM Research Center, University of Berne, Switzerland 4 School of Physiotherapy, University of Otago, New Zealand
INTRODUCTION
Most people experience low back pain (LBP) at least once in their
lifetime. Only a minority of them go on to develop persistent LBP.
However, the socioeconomic costs of persistent LBP significantly
exceed the costs of the initial acute LBP episode. Aim of this study
was to identify factors that influence the progression of acute
LBP to the persistent state at an early stage (Hilfiker et al. 2007).
METHODS
Prospective inception cohort study of patients attending a health
practitioner for their first episode of acute LBP or recurrent LBP
after a pain free period of at least six months. Patients were
assessed at baseline addressing occupational and psychological
factors as well as pain, disability, quality of life and physical activity,
and followed up at three, six, twelve weeks and six months.
Baseline and follow-up questionnaires were based on the
recommendations of the Multinational Musculoskeletal Inception
Cohort Study (MMICS) Statement (Pincus et al. 2008). Variables
were combined to the three indices ‘working condition’, ‘depression
and maladaptive cognitions’ and ‘pain and quality of life’.
RESULTS
The index ‘depression and maladaptive cognitions’ comprising of
depression, somatisation, a resigned attitude towards the job,
fear-avoidance, catastrophizing and negative expectations on
return to work was found to be a significant baseline predictor
for persistent LBP up to six months (OR 5.1; 95%CI 1.04-25.1).
The diagnostic accuracy of the predictor model had a sensitivity
of 0.54 and a specificity of 0.90. Positive likelihood ratio was
moderate with 5.3, negative likelihood ratio 0.5. Overall
predictive accuracy of the model was 81%. The area under the
curve in receiver operating characteristic (ROC) analysis of the
index was 0.78 (CI95% 0.65-0.92), demonstrating a satisfactory
quality of discrimination.
CONCLUSION
In this study of patients with acute LBP in a primary care setting
psychological factors at baseline correlated with a progression to
persistent LBP up to six months. The benefit of including factors
such as ‘depression and maladaptive cognition’ in screening tools
is that these factors can be addressed in primary and secondary
prevention.
REFERENCES
1. HILFIKER, R, BACHMANN, LM, HEITZ, CAM, LORENZ, T,
JORONEN, H, KLIPSTEIN, A 2007.
Value of predictive instruments to determine persisting
restriction of function in patients with subacute non-specific
low back pain. Systematic review. Eur Spine J, 16, 1755-1775.
2. PINCUS, T, SANTOS, R, BREEN, A, BURTON, AK,
UNDERWOOD, M. 2008.
A review and proposal for a core set of factors for
prospective cohorts in low back pain: a consensus statement.
Arthritis Rheum, 59, 14-24.
32
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 1 (continued)
BACK PAIN | Chair | Prof Michael Ryan
Arthur Streeton Auditorium
9.42am | 1.5Patient expectations, outcomes and satisfaction: Related, relevant or redundant?
*Licina, P,1,2 Ewing, L,1,2 Pearcy, M 1
1 ` Queensland University of Technology, Brisbane, Qld, Australia2 Holy Spirit Northside Hospital, , Brisbane, Qld, Australia
INTRODUCTION
Meeting patient expectations and achieving patient satisfaction
are now considered at least as important as more technical
measures of outcome such as fusion rate. However these
subjective variables are difficult to evaluate and interpret
objectively. Furthermore, their relevance to clinical practice and
how to change practice to optimize them is incompletely
understood. The purpose of this study was to determine patient
expectations before lumbar surgery and outcome after surgery,
to assess whether expectations had been met and whether
patients were subjectively satisfied after surgery.
METHODS
257 patients undergoing surgery for degenerative lumbar
conditions were identified. Those undergoing revision operations,
multi-level procedures and those with incomplete data were
excluded leaving 145 patients to be prospectively studied.
Oswestry Disability Index (ODI), back visual analogue scale
(VAS) and leg VAS were assessed pre-operatively and at 6
weeks and 6 months post-surgery. Patients’ expectations were
measured pre-operatively by asking them to score the level of
pain (back and leg VAS) and disability (ODI) that would be least
acceptable for them to undergo the operation and be satisfied.
Satisfaction was assessed six weeks post-operatively with a
5-point scale. To quantify patient expectations, the difference
between actual improvement and expected improvement was
calculated in terms of ODI, back VAS and leg VAS. This value was
termed the actual benefit change (AB ). To determine whether
this change was clinically relevant, an arbitrary margin of the
minimal clinically importance difference (MCID) of ± 15 points
for ODI and ±2 for VAS was applied, and this was termed the
clinically relevant benefit change (RB ).
RESULTS
Patient expectations were achieved in the minority of patients,
although most had a clinically relevant improvement. When the
margin of clinical relevance was applied to expectations, this
more closely approximated the outcome (Table 1).
6 weeks 6 months
AB � RB � MCID AB RB � MCID
ODI 37% 66% 73% 54% 83% 82%
Back VAS 48% 76% 76% 59% 85% 80%
Leg VAS 58% 85% 77% 63% 88% 79%
Table 1: Percentage of patients that :
AB Achieved expectations
RB Had expectations within clinically relevant margin
MCID Had clinically relevant improvement
At 6 weeks most patients (74%) reported being “very satisfied”,
with 19% stating they were “satisfied” and 7% being “somewhat
satisfied”. No patients expressed being “dissatisfied” or “very
dissatisfied”. Satisfaction did not correlate with the level of
pre-operative pain or disability, or with patient expectation of
improvement. Satisfaction correlated with post-operative back
pain and to a lesser extent ODI and type of surgery. All of the
10 patients that were only “somewhat satisfied” fell into the
highest quartile of postoperative back pain (VAS).
CONCLUSION
Satisfaction correlates with a positive outcome. Patient
expectations have little bearing on final outcome and satisfaction.
Its value probably lies in identifying patients with unrealistic
expectations and counselling them as part of the consent process.
9.50am | 1.6Does posterior pedicle screw supplementationwithout posterolateral fusion improve anteriorlumbar interbody fusion when using anterior cageand screw constructs? A radiological study
*McCarthy, MJH, Ng, L, Chan, D
Royal Devon and Exeter Hospital, Exeter, UK
INTRODUCTION
Anjarwalla et al. (2006) have shown that the addition of posterior
pedicle supplementation without posterolateral fusion during an
ALIF procedure significantly increases the rate of interbody fusion
when using a carbon fibre / PEEK cage packed with autogenous
iliac crest graft. Stand alone ALIF cages which utilise screws
passing through the interbody cage and into the vertebral bodies
were designed to obviate the need for a posterior procedure by
increasing the anterior construct stability and fusion rate. The
objective of this study was to assess the effect of posterior pedicle
screw supplementation without posterolateral fusion on the fusion
rate of ALIF when using anterior cage and screw constructs.
METHODS
Between 2003 and 2008 90 patients underwent ALIF procedure
under a single surgeon for low back pain associated with
degenerative disc disease or lytic spondylolisthesis. Routine CT
was performed at around 1 to 2 years follow up to ensure union
prior to discharge. It was noted that there was a significant number
of locked pseudathroses, especially in 2 level cases, and in 2006
the surgeon started to perform simultaneous supplementary
posterior pedicle screw stabilisation without posterolateral fusion
in the majority of cases.
RESULTS
Of the 90 patients, 76 (84%) had follow up at mean 21 months
and had CT imaging. 44 patients had anterior surgery alone (25
single level and 19 two level) and 32 had front back surgery (15
single level and 17 two level). Pseudarthrosis was seen in 16
patients (36%) of the anterior alone group and 2 (6%) of the front
back group. In the anterior alone group, pseudarthosis occurred
in 6 / 25 (24%) patients with single level surgery and 10 /19
(53%) of those with two level surgery. In this last group, the
pseudarthosis occurred in the upper fusion level in five patients
and at both fusion levels in other five.
CONCLUSION
Posterior pedicle screw supplementation without posterolateral
fusion improves the fusion rate of ALIF when using anterior cage
and screw constructs. We would recommend supplementary
posterior fixation especially in cases where more than one level
is being operated.
REFERENCES
1. ANJARWALLA et al.
Spine 31, 1281-1287, 2006.
33
Notes & Questions
34
35
22 Free Papers Session 2
Basic ScienceFriday 15 April | 1.30pm - 3.00pm
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 2
BASIC SCIENCE | Chair | Prof Clayton Adam
Arthur Streeton Auditorium
1.30pm | 2.1Biomaterial impregnation with bone marrow aspirate: Does it live up to the promise?
*Eder, C,1 Falkner, E,2 Meissner J,1 Tuschel A,1
Becker, P,1 Ogon, M1
1 Orthopedic Hospital Vienna-Speising, Vienna, Austria2 University of Vienna, Vienna, Austria
INTRODUCTION
The limited supply of autografts for spinal fusion has prompted
extensive research on bone graft substitutes. So far, various
biomaterials have been applied either stand alone or impregnated
with blood or bone marrow aspirate to promote spinal fusion.
Bone marrow aspirate harvested from the iliac crest is known to
contain osteoprogenitor cells, which are supposed to differentiate
into osteoblasts and form new bone at the desired fusion site.
But according to literature, only 0.001% - 0.01% of bone marrow
aspirate cells are in fact osteoprogenitor cells.1 So are we really
implanting what we think we are ?
METHODS
Surplus material remaining after cage and intervertebral space
preparation for routine spinal fusion surgery was analyzed.
Three different biomaterials (demineralised bone matrix - DBX,
ChronOS® and HealOS® were impregnated according to
specifications of the supplyer. Mesenchymal stem cell density was
assessed after impregnation and the cell seeded biomaterials
were investigated after implantation into the chick
chorionallantoic membrane model.
RESULTS
Most of the cells in bone marrow aspirate were identified as
erythrocytes while only a small fraction was identified as
nucleated stem cells. After biomaterial impregnation, average
stem cell density was 1.13 cells/mm2 (ChronOS® ), 0.92
cells/mm2 (HealOS® ) and 0.008 cells/mm2 (DBX). Only the
marginal pores of the biomaterials were filled with cells (mostly
erythrocytes) after biomaterial implantation. Despite the poor
cell yield, the cell impregnated biomaterials were able to
stimulate angiogenesis in the CAM-Model.
CONCLUSION
Impregnation of biomaterials with bone marrow aspirate can
only deliver very small amounts of osteoprogenitor cells to the
implantation site. Although these constructs are able to stimulate
angiogenesis, the number of osteoprogenotor cells delivered
seems too small to have a significant effect on osteogenesis.
Increasing cell density by centrifugation or expansion in culture
might therefore be required to improve fusion results.
REFERENCE
1. PITTENYER MF. et al.
Science 1999;248:143
36
1.38pm | 2.2Recombinant human BMP-2 enhances local bone formation in the lumbar spine of osteoporotic sheep
*Moore, RJ,1,2,4 Zarrinkalam, MR,1,2, Schultz, C,3
Arden DW,1 Vernon-Roberts, B,1,2,4
1 Adelaide Centre for Spinal Research, Adelaide, SA, Australia2 Hanson Institute, SA Pathology, Adelaide, SA, Australia3 Bone Densitometry Unit, Department of Nuclear Medicine,
Royal Adelaide Hospital, Adelaide, SA, Australia 4 Discipline of Anatomy and Pathology, University of Adelaide,
Adelaide, SA, Australia
INTRODUCTION
The failure of surgical implants in osteoporotic patients is
attributed to the lack of sufficient bone for initial stabilisation but
most current treatments for osteoporosis do not address bone
regeneration. rhBMP-2 has been used to promote bone
formation under normal conditions but has not been tested in
the osteoporotic condition. The objective of this study was to
investigate the potential for localized bone formation following
direct implantation of pellets containing rhBMP-2 in osteoporotic
vertebrae.
METHODS
Osteoporosis was induced in 19 ewes using ovariectomy, low
calcium diet and weekly steroid injection. Vertebral BMD was
monitored progressively. After induction, the steroid was
withdrawn and pellets containing inert carrier alone or carrier
with rhBMP-2 in either slow or fast release formulation were
implanted into three adjacent lumbar vertebrae of each animal.
After 2, 3 and 6 months the spines were harvested for histo-
morphometric analysis. Changes in BMD and histomorphometric
parameters were examined using ANOVA with Tukey’s
post-hoc test.
RESULTS
Within six months of induction BMD was reduced by 20.4%
from its baseline values (P<0.05), but did not change significantly
after cessation of steroid treatment or for the remainder of the
study. Micro CT analysis showed after two months BV/TV and
Tb.N increased by 12.8% and 10% respectively in the vicinity of
the fast-release rhBMP-2 pellets compared to the control
(P<0.05) and this was sustained for the duration of the study.
Focal voids surrounding all implants from the earliest time point
resolved with time.
CONCLUSION
Increased trabecular bone volume adjacent to pellets containing
rhBMP-2 within 2 months of implantation suggests that it could
be used for localised treatment of osteoporosis. Further
refinement of the delivery system and supplementary treatments
to overcome the initial catabolic effect of rhBMP-2 in trabecular
bone may be indicated.
37
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 2 (continued)
BASIC SCIENCE | Chair | Prof Clayton Adam
Arthur Streeton Auditorium
1.46pm | 2.3Elemental analysis of lumbar vertebral bone in anosteoporotic sheep model
*Zarrinkalam, MR,1 Mulaibrahimovic, A,1,2 Moore, RJ, 1,2,3
1 Adelaide Centre for Spinal Research, Adelaide, SA, Australia2 Hanson Institute, Institute of Medical & Veterinary Science,
Adelaide, SA, Australia3 Discipline of Pathology, University of Adelaide,
Adelaide, SA, Australia
INTRODUCTION
Hydroxyapatite is the main inorganic component that gives
strength and stiffness to bone. The purpose of this study was to
compare the elemental composition of hydroxyapatite in
trabecular bone of lumbar vertebrae from osteoporotic sheep.
METHODS
Osteoporosis was induced in 10 mature ewes (Zarrinkalam, 2009).
Five age matched sheep were used as controls. All animals were
humanely killed and the lumbar spines collected and processed
undecalcified. The surface of the specimens was polished with fine
grade abrasive paper and then carbon coated to conduct
electron probe Microanalysis (EPMA) at up to 30 random sites
using a Cameca SX51 Microprobe (beam current of 20 nA,
accelerating voltage 15 kV). Calcium, phosphorus and oxygen
content was measured as a percentage of the total bone mass.
RESULTS
Trabecular bone of osteoporotic sheep had lower percentage of
phosphorus (P) than control sheep (12.5% vs 12.8%, p<0.01) but
the calcium level was identical in each group. Consequently
trabecular bone of the osteoporotic sheep had higher Ca/P
ratio than the control sheep (2.1 vs 2.06, p<0.01).
CONCLUSION
Osteoporosis in this sheep model not only decreases the volume
and mineral content of the vertebral trabecular bone
(Zarrinkalam, 2009) but also influences its elemental composition
which may also influence its mechanical properties.
REFERENCES
1. ZARRINKALAM, MR, H. BEARD, et al.
Eur Spine J 18: 244-53, 2009.
38
2.09pm | 2.4Biomechanical investigation of the stabilizing effect of a novel integrated device for intra-articular atlanto-axial stabilization
*Robertson, PA,1 Lim, RK,2 Tsitsopoulos, PP, 3 Voronov, LI,3
Havey, RM,3 Patwardhan, AG 3
1 The Othopaedic Clinic, Auckland NZ2 Medtronic, Memphis TN, USA3 Musculoskeletal Biomechanics Laboratory,
Edward Hines, Jr. VA Hospital, Hines, Illinois, USA
INTRODUCTION
The unique function and anatomy of the C1/2 atlanto-axial joint,
combined with the vascular and neural anatomy, has made
stabilization at this level highly challenging. Early fixation to the
posterior laminae of C1 and spinous process of C2 was associated
with poor rotational and translational stability. Newer techniques
with oblique trans-articular screw fixation (Magerl) across the
lateral mass joints, or inserting segmental screw fixation at the
lateral mass complexes (Harms technique) give dramatically
improved stability. Unfortunately, both techniques may be
technically difficult or contraindicated by local vascular and
vertebral artery (VA) anatomy. A novel integrated device was
designed and developed to obtain intra-articular stabilization via
primary interference fixation within the C1/C2 lateral mass
articulation. This study characterized the extent of immediate
stabilization of C1/C2 using the integrated device in the setting
of C1/C2 instability consistent with Type 2 odontoid fracture,
with comparison to the Harms technique.
METHODS
Biomechanical testing was performed using 6 human cadaveric
cervical spines (C0-C5, mean age: 54.6 years) with load control in
Flexion/Extension (FE), Lateral Bending (LB), and Axial Rotation
(AR) under a moment of 1.5Nm. Comparison of C1-C2 Range
of Motion (ROM) was performed using optoelectronic tracking.
ROM was measured in intact state, following destabilization after
creation of a Type 2 odontoid peg fracture, after sequential stabi-
lization using the Harms technique and the integrated device.
RESULTS
F/E ROM of the intact specimens was a mean of 14.1±2.9
degrees. Destabilization increased the ROM to 31.6±4.6 degrees.
Instrumentation with the Harms technique reduced the motion
to a mean of 4.0±1.4 degrees (p=0.0001). The integrated device
reduced F/E motion to 3.6±1.8 degrees (p=0.00007). For
evaluation of lateral bending the respective mean rotations were
1.8±1.1, 14.1±5.8, 1.4±0.7 and 0.3±0.5 degrees for the intact,
destabilized, Harms technique and integrated device. For axial
rotation the respective mean values were 67.3±13.8, 74.2±16.1,
1.3±0.8 and 0.9±0.7 degrees. All comparisons between the
destabilized state and both the Harms and integrated device
were statistically significant (p<0.05). Direct comparison of the
Harms technique and the integrated device revealed no
significant difference (p>0.05).
CONCLUSIONS
The integrated device resulted in interference fixation at the
C1/2 lateral mass joint with comparable stability to the Harms
technique. Perceived advantages with the integrated device
include avoidance of fixation below the C2 lateral mass where
the VA is susceptible to injury, access to the C1 screw entry point
through the blade of the device avoiding extended dissection
superior to the C2 nerve root and its surrounding venous
plexus, the possibility of intra-articular fusion through and
around the device, and the absence of imaging difficulties when
looking at posterior interlaminar fusion. Biomechanical testing
demonstrated improved construct stiffness with removal of
articular cartilage from the lateral mass, and bi-cortical fixation
of the C1 screw in the integrated device.
39
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 2 (continued)
BASIC SCIENCE | Chair | Prof Clayton Adam
Arthur Streeton Auditorium
2.17pm | 2.5An intervertebral joint’s centre of rotation affectsthe forces experienced by the zygapophysial joints
Pearcy MJ
Institute of Health and Biomedical Innovation,
Queensland University of Technology, Brisbane, Qld, Australia
INTRODUCTION
Modifying the mechanics of an intervertebral joint through,
eg discectomy or implantation of an artificial disc will cause
changes to the forces components of the joint experience during
normal activities. This study examined how the forces on the
zygapophysial joints are affected by changes in the position of the
intervertebral joint’s centre of rotation in order to assess the
potential for accelerated degeneration to occur (Pearcy, 2010).
METHODS
Polymer models of the L4 and L5 vertebrae from the ‘Visible
Human Project®’ data set were made ensuring fidelity of the
shape of the zygapophysial processes. These were than mounted
in a robotic testing machine (de Visser et al., 2007) and aligned to
represent the functional L4/5 intervertebral joint. The superior
vertebra was rotated axially ±3.5º with the axis of rotation set at
60% of the depth of the disc. The forces caused by contact between
the faces of the zygapophysial processes were measured. The
test was then repeated with the axis of rotation moved 4mm
anteriorly then posteriorly, and then 4mm anteriorly plus 4mm
to the left and then to the right.
RESULTS
The maxima of the resultant forces experienced by the L5
vertebra.
CONCLUSION
The % difference shows that moving the centre of rotation
4mm can cause an increase in the force experienced by the
zygapophysial joints of up to 31%. As this is a purely geometric
phenomenon the displacement of the centre by 1mm would
cause an increase of nearly 8%. Repeated exposure to this
increased loading might be expected to lead to early degenerative
changes. The data also show that small asymmetries in the joints
cause significant changes to the forces experienced. Because of
geometric differences some individuals will be more susceptible
to degeneration caused by changes to the centre of rotation of
the intervertebral joint if it is altered by surgery.
REFERENCES
1. DE VISSER H, ROWE C, PEARCY MJ.
Journal of Engineering in Medicine, 2007. 221:221-227.
2. PEARCY MJ.
Expert Review of Medical Devices, 2010, 7: 855-860.
40
2.25pm | 2.6Development and validation of a spinal facet joint pseudarthrosis model
*Goss, B,1 Sugiyama, S,1 Wullschleger, M, 2
Williams,R,1 Wilson, K 3
1 AOSpine Reference Centre, Institute of Health and
Biomedical Innovation, Queensland University of Technology
Brisbane, Qld, Australia2 Institute of Health and Biomedical Innovation, Queensland
University of Technology, Brisbane, Qld, Australia3 Medical Engineering Research Facility, Prince Charles
Hospital, Queensland University of Technology,
Brisbane, Qld, Australia
INTRODUCTION
Despite the routine nature of spinal fusion, pseudarthrosis is still
a common complication with non-union rates reported to be as
high as 31% in some series (Steinmann 1992). Revision of a failed
fusion carries risk of further complications related to poor
vascularity, scaring, loss of bone and alterations in alignment.
Improved animal models may help advance new treatments for
pesudarthoris. Currently the only reported animal model of
spinal pseudarthrosis is the New Zealand White Rabbit (Grauer
2004) which shows a 77% pseudarthrosis rate at one month.
The limitations of this model are both the size of the animal and
possibility of spontaneous fusion later than 1 month. This study
reports an ovine model of pseudarthrosis, and determined the
efficiency of pseudarthrosis formation at 6 months.
METHODS
The experiments were approved by The QUT Animal Ethics
Committee and conducted according to NHMRC guidelines.
Eight sheep were used. After induction of anaesthesia and dorsal
approach to T13/L1 both facet joints were prepared by curetting
out the cartilage and cortical bone in the leaving 2 mm gap
between articulating surfaces.
Into the defects in each facet joint a piece of oxidised cellulose
cloth (Surgicel; Ethicon Inc. NJ. USA) was placed. A loose spinous
process wire was applied to prevent massive translation but
enable small movements of the spine. The wound was closed
and local anaesthetic was applied. Each sheep was released back
to the holding yard after recovery from anaesthesia.
Sheep were sacrificed 26 weeks after surgery by an overdose
of penthobartitone sodium. The spines were harvested and
examined by micro CT, histology and mechanical testing.
RESULTS
Micro CT imaging showed that 5 of 8 animals had a discontinuity
through the facet joint 26 weeks after surgery indicating a
pseudarthrosis rate of 62.5%. When examined by histology this
region was shown to contain fibrous tissue and bear the hallmarks
traditionally seen in other non-unions. There was limited amount
of ostoid tissue, which indicated that the joint would not
spontaneously fuse if more time was given.
The mean tensile strength of the pseudarthosed joints was joint
was 782.8 +/- 235 N compared with a mean tensile strength of
936.1 +/- 280 N for the fused joints. This difference was not
statistically significant (p=0.15) but this may reflect the
unidirectional nature of the measurement.
CONCLUSION
This study reports the development of a reasonably reliable large
animal model of spinal facet joint pseudarthrosis. This will be
beneficial in the further study of the applicability of new
osteogenic technologies in the treatment of non-union.
REFERENCES
1. GRAUER, JN et al
Spine 29 (13), 1405–1412, 2004.
2. STEINMANN JC. et al,
Clin Orthop 284 80 –90 1992
41
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 2 (continued)
BASIC SCIENCE | Chair | Prof Clayton Adam
Arthur Streeton Auditorium
2.33pm | 2.7Variations in anular defect characteristics in herniated lumbar discs: An anular repair feasability study and attempt to confirm Carragee data on defect size
*Wong, DA, Mauter, L, Murdock, V, Wong, CJ
Presbyterian St Luke’s Medical Center and Denver Spine,
Denver, Colorado, USA
INTRODUCTION
Carragee has studied the effect of defect size on the rate of
recurrent herniated disc and revision surgery. However,
Carragee’s paper did not report other characteristics such as
defect location (mid annulus vs. adjacent to the inferior or
superior end plate) nor tissue quality (intact / frayed / calcified).
These additional characteristics (along with defect size)
determine the feasibility of anular repair. Suturing (technically
easiest/cheapest-and already on the market) applies only where
the anular tear is mid substance with good adjacent tissue.
Defects adjacent to bone require a bone anchor for the suture
(just entering the market). Large anular holes necessitate a
technically challenging, expensive barrier reconstruction
(technology limited to clinical trials).
This study had two primary research questions:
1. What is the incidence of characteristics determining the
percentage of HNP patients who are candidates for anular
repair / reconstruction
2. Does our cohort confirm the Carragee population
distribution regarding anular defect size
METHODS
A 100 consecutive patient surgical cohort for single level, primary
HNP were prospectively studied. Size and location of the anular
defect (midsubstance/adjacent to superior or inferior end plate),
tissue quality and Carragee Type (fragment / fissure, fragment /
defect, fragment / contained, no fragment/contained) were noted.
RESULTS
• 68 males/ 32 females (higher risk for males p=0.0003),
average age 47.
• 55 right herniations/ 45 left.
• 64% mid substance defects/good adjacent tissues (suture
applicable). Defect adjacent inferior end plate (21%), adjacent
to superior end plate (8%) - bone anchor potentially
applicable (29%). Total potential repair patients (93%).
• Repair not feasible 7% due to disc calcification.
• Carragee categories (% ours/Carragee), Fragment Fissure
(33/49), Fragment Defect (11/18), Fragment Contained
(45/23), No Fragment Contained (11/8). Significant difference
between our cohort vs. Carragee all categories (chi-square
test p<0.0001).
• Using available anular suturing technology, 64% of the
patients in this study would be candidates for anular repair.
With a bone anchor, an additional 29% of patients would be
candidates for reconstruction.
• The primary reason for inability to repair was a calcified disc.
No patients had thinning or shredding of the annulus to a
degree that would prohibit anular reconstruction.
• The statistically significant variation in all Carragee defect
categories was a surprise. Carragee population data on
defect size was not confirmed. The true population incidence
remains uncertain.
CONCLUSIONS
With suturing technology and availability of a suture bone anchor
93% of patients in our cohort were potential candidates for
anular repair. Additional studies of Carragee defect categories
will be necessary to more accurately define the population
incidence of various types of anular failure. Determining reliable
population incidence is key for accurately calculating the cost
effectiveness of anular repair technologies.
REFERENCES
1. CARRAGEE E et al.
Clinical Outcomes After Lumbar Discectomy for Sciatica:
The Effects of Fragment Type and Anular Competence. J
Bone Joint Surg Am. 2003;85:102-108.
42
43
22 Free Papers Session 3
Cervical / BMPFriday 15 April | 3.30pm - 5.00pm
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 3
CERVICAL / BMP | Chair | Dr Greg Malham
Arthur Streeton Auditorium
3.30pm | 3.1Anterior cervical decompression and fusion withrhBMP-2: A prospective case series of 53 patients*Scott-Young, MN,1 Magno, C,2 Nielsen, D,2
Mitchell, E,2 Blanch, N 2
1 Bond University, Gold Coast, Qld, Australia 2 Gold Coast Spine, Gold Coast, Qld, Australia
INTRODUCTION
Anterior cervical decompression and fusion (ACDF) is a widely
accepted method for cervical spinal stabilization. A variety of
grafting techniques have been used to facilitate arthrodesis.
Autografts and allografts have been the standard with complications
including donor graft morbidity and non-union. Biological
innovations such as recombinant human bone morphogenetic
protein – 2 (rhBMP-2) have been studied extensively in the
lumbar spine to accelerate arthrodesis. rhBMP-2 in the cervical
spine has been complicated by insufficient knowledge of optimal
dosages. This study evaluates the safety, efficacy, clinical and
radiological outcomes of ACDF with rhBMP-2.
METHODS
This is a prospective study of 53 patients having a diagnosis of
cervical spondylotic radicular myelopathy and treated with ACDF
with local bone and rhBMP-2. The technique utilised a cage
and/or plate for stability following the decompression. The cage
was filled with local bone obtained during the decompression
mixed with rhBMP-2. It is recommended that 15% of a small
rhBMP-2 mixed with local bone should be used per level.
Management in the post operative period consists of ice to the
wound, IV dexamethasone, and patient education.
Clinical outcomes were measured using NDI, VAS (neck and
arm), SF-36 and radiological assessment. Patients were assessed
preoperatively and at 3, 6 and 12 months. Radiological assessment
consisted of AP lateral flexion/extension standing films and fine
cut CT. Mean, median, 95% confidence levels, and categorical data
have been measured.
RESULTS
Fifty-three patients had a total of 123 levels fused with an average
follow-up of 17.34 months (range 6-39 months). Thirty patients
were male and 23 patients female, with an average age of
59.92yrs (range=19-80 yrs). The average operation duration
was 72.69mins (range 50-100mins).
Results at latest follow-up versus baseline were compared using a
one-tailed paired t-test (p<0.05): mean reduction in mean back
VAS neck scores reduced by 59.7%; mean right VAS arm score
reduced by 58.3%, while left VAS arm scores reduced by 69.0%.
Mean NDI reduced by 50.4%. SF-36 PCS increased by 19.7% and
SF-36 MCS increased by 13.3%. All results were statistically
significant (p<0.05). No significant differences were noted in
functional scores between 3 and 6 months or 6 and 12 month
post-operative periods. Radiological evaluation by an independent
radiologist and the primary surgeon showed a 100% union rate
has been achieved with this technique. Post operatively one
patient (1.9%) required ICU admission for respiratory arrest
possibly related to BMP dose; one patient (1.9%) had post-
operative atrial fibrillation; and one patient (1.9%) had post-
operative dysphagia due to the inherent surgical approach of
treating multilevel spine disease.
CONCLUSION
The use of rhBMP-2 in the correct dosage, when mixed with
local bone, placed within a cage will result in a fusion. This negates
donor morbidity from autograft and non-union seen with other
bone substitutes. Correct dosage, combined with appropriate
post-operative care and education, effectively minimises the
post-operative affects of rhBMP-2 in ACDF.
44
3.38pm | 3.2A non randomised single surgeon cohort study of rhBMP-2 versus rhBMP-7 in lumbar spinal surgery: An outcome analysis of 186 patients
*McCarthy, MJH, Stanojevic,S, Goss, B, Williams,R
Queensland University of Technology, Brisbane Private Hospital
and Princess Alexandra Hospital, Brisbane, Qld, Australia
INTRODUCTION
Bone Morphogenic Proteins (BMP) have been used for several
years to improve the rates of spinal fusion. Complications of their
use include osteolysis, heterotropic bone formation and radiculitis
(Glassman et al. 2010). The aims of this study were to compare
the clinical and radiological outcomes and complication rates of
their use in lumbar spinal surgery.
METHODS
Between 2003 and 2009 all patients having spinal surgery under
a single Consultant Spinal Surgeon were identified using the
operative database and sales records of BMP. The surgeon used
rhBMP-7 routinely between 2003 and 2007 changing to rhBMP-2 in
2007 primarily because of its handling properties. A retrospective
review of the medical charts was performed and patients
selected using strict inclusion and exclusion criteria. Stage two of
the study involved a postal then telephone questionnaire and
radiological review. The primary end point was revision surgery
with secondary end points of:
1. Complications and
2. Other intervention including radiological procedures such as
root block, epidural and facet injections. The study received
Human Research Ethics Committee approval.
RESULTS
One hundred and eighty six patients matched the selection
criteria (80 rhBMP-2 and 106 rhBMP-7). There were no significant
differences between the groups for age, sex, employment,
preoperative walking distance, number of levels operated and
preoperative neurological deficits. 70% of each group had
decompression fusion surgery for spondylolisthesis. Preoperative
Oswestry Disability Index (ODI) was 41.8 (95% CI 38-46 range
8-70) in the rhBMP-2 group and 39.5 (95% CI 37-42 range 10-75)
in the rhBMP-7 group (p=0.32). The average follow up was 1 year.
At a mean of 1 year follow up, there was no significant difference
in postoperative ODI (rhBMP-2 = 15.7, 95% CI 9-22 and rhBMP-7
= 17.2, 95% CI 13-21 p=0.69) and postoperative walking distance
(p=0.37). In both groups the walking distance had doubled
compared to the preoperative distance. There was no difference
in the fusion rates between the two groups (p=0.42). Revision
surgery was required in ten rhBMP-2 patients (13%) and eighteen
rhBMP-7 patients (17%) (p=0.48). Six rhBMP-2 patients and
seven OP-1 patients required revision surgery directly related to
the index procedure. Symptomatic adjacent segment disease was
seen in four rhBMP-2 patients (5%), all of whom had surgery, and
fourteen rhBMP-7 patients (13%), eleven of whom had surgery.
This approached statistical significance (p=0.053). Post operative
non surgical interventional procedures were required in ten of the
rhBMP-2 group and twenty three of the rhBMP-7 group (p=0.23).
CONCLUSION
In our cohort, there does not appear to be a difference in
outcome between rhBMP-2 and rhBMP-7. The complication and
reintervention rates appear to be similar and match those in the
published literature.
REFERENCE
1. GLASSMAN et al.
Spine 35, 1621-1628, 2010.
Inclusion Criteria:
17 to 80 years of age, up to and including 3 level surgery, primary
lumbar surgery with use of INFUSE or OP-1 (low back fusion),
degenerative conditions only (including long term non dysplastic
spondylolysis), instrumented and uninstrumented cases with or
without canal decompression, ALIF with posterior instrumentation
and posterior BMP, TLIF, PLIF and PLF.
Exclusion criteria
any revision procedure, ALIF alone, greater than 3 level surgery,
degenerative spondylolisthesis greater than grade 2, non
degenerative conditions (such as trauma, tumour and infection)
and deformity surgery (scoliosis and kyphosis).
45
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 3 (continued)
CERVICAL / BMP | Chair | Dr Greg Malham
Arthur Streeton Auditorium
3.46pm | 3.3The efficacy of bone morpheogenic protein (BMP-7)
in posterolateral lumbar fusion surgery
Frydenberg, E St Vincent's Hospital, Darlinghurst, NSW, Australia
INTRODUCTION
Osteoinductive agents, such as Bone Morpheogenic Proteins
(BMP) have attracted considerable interest, and have become
common in spine surgery. So far there has been limited evidence
of their efficacy.
3 randomized controlled studies of the use of BMP-7 in lumbar
spine fusion have been published.
Only one study involved instrumented posterolateral lumbar
spine fusion surgery. 9 patients had OP-1 graft and 10 patients
had a combination of autograft and TCP (Kanayama et al, 2006).
Fusion was inspected and assessed at instrumentation removal
15 months post operatively. There was a higher fusion rate in the
autograft group (78% vs. 57%) (Kanayama et al., 2006).
2 studies involving non-instrumented lumbar fusion using either
autograft or BMP-7 graft material have been published. No
difference in outcome was found.
Our study is the first performed using BMP-7 that attempts to
quantify the efficacy of BMP-7 on the quality of bone formation.
A randomized controlled study of the efficacy of BMP-7,
(Osteogenic Protein-1 (OP-1 Stryker)) in posterolateral lumbar
fusion surgery was performed.
METHODS
20 patients undergoing single-level posterolateral lumbar fusion
for symptomatic degenerative spondylolisthesis were enrolled.
Surgery involved decompressive laminectomy, insertion of
pedicle screws and on-lay of bone graft with 5ml tri-calcium
phospate (TCP) bone substitute on each side. On one side 1 vial
of OP-1 was added to the graft material. The senior surgeon (TS)
was blinded to the side of BMP-7. Three months after surgery a
volumetric CT scan was obtained allowing volume and density of
the bonegraft material to be measured and compared.
In our study, by using both autograft and TCP, with BMP-7 on only
one side, each patient acted as their own control. Statistical
analysis, including Mann-Whitney U test was used.
RESULTS
9 of 20 patients had higher volume of new bone on the side
where BMP-7 had been added. 3 patients had more bone on the
contralateral side to the BMP-7. 6 patients had equal volume of
graft material. 2 patients did not have sufficient graft material for
analysis. There was not a statistically significant difference in bone
volume and density 3 months postoperatively.
CONCLUSION
We found no evidence that BMP-7 had any effect in posterolateral
spine fusion surgery at 3 months postoperatively.
REFERENCE
1. KANAYAMA, M, HASHIMOTO, T, SIHGENOBU, K, YAMANE, S,
BAUER, T, TOGAWA, D 2006.
A Prospective Randomized Study of Posterolateral Lumbar
Fusion Using Osteogenic Protein -1 (OP-1) Versus Local
Autograft with Ceramic Bone Substitute. Spine, 31, 8.
46
4.09pm | 3.4Clinical outcomes following cervical disc replacement
with PCM® after a minimum 1-year follow-up
*Scott-Young, MN,1 Magno, C,2 Nielsen, D,2
Mitchell, E,2 Blanch, N 2
1 Bond University, Gold Coast, Qld, Australia 2 Gold Coast Spine, Gold Coast, Qld, Australia
INTRODUCTION
Randomised controlled trials comparing cervical total disc
replacement (CTDR) with anterior cervical discectomy and fusion
(ACDF) have been published. These trials show CTDR at one
level is an option for treatment of cervical myelopathy and
radiculopathy. An evaluation of the use of the PCM® cervical
disc system (PCM®) (NuVasive®, San Diego, CA) in patients
diagnosed with myelopathy (CSM), radiculopathy (CSR), and
adjacent motion segment degeneration (AMSD) was undertaken.
Clinical outcomes of a consecutive 73 patient cohort, treated by
a single surgeon were assessed and compared.
METHODS
Patients were divided into 3 groups - CSM, CSR, and AMSD.
Surgical sub-categories included single-level and multi-level
CTDR. Clinical outcomes were measured using Visual Analogue
Score (VAS) neck and arm, Neck Disability Index (NDI), and
SF-36 data at 3, 6, and 12 months, and annually thereafter. A
one-sided paired student t-test was used to assess improvements
at each postoperative date compared to preoperative baseline.
RESULTS
Average follow-up of the 73 patients was 39.74 months (range
13-61 months). Forty patients were male and 33 patients female,
with an average age of 54.7yrs (range=32-79 yrs). Preoperative
diagnosis included CSR in 50 patients, CSM in 16, and AMSD in
7. Seventeen patients underwent single-level CTDR, while 56
patients underwent multi-level CTDR. ACDF was also performed
in 11 patients. Three patients required additional surgery. One
patient was involved in a motor-vehicle accident postoperatively
and subluxation occurred in two patients prior to the introduction
of the V-teeth model of the PCM®.
Statistically significant clinical improvements from baseline were
observed in VAS, NDI, and SF-36 (PCS and MCS) outcomes
scores from 3 months to 48 months (p<0.05). VAS neck scores
decreased from 63.50±30.62 preoperatively to 19.21±23.43
(-70%) at latest follow-up. VAS arm scores decreased from
61.13±31.85 to 12.06±19.22 (-80%). NDI scores decreased by
59%, while SF-36 PCS increased by 33% and SF-36 MCS
increased by 24%. Patient satisfaction surveys indicated that
91.9% patients rated their satisfaction with the surgery as
“excellent” or “good” 1-year following their operation.
An analysis was undertaken in relation to the preoperative
diagnosis and clinical outcomes. Preoperative, VAS neck scores
decreased by 64% for AMSD, 72% for CSM and 70% for CSR
groups. VAS arm scores decreased by 87% for AMSD, 75% for
CSM and 81% for CSR groups. NDI scores were reduced by
56% for AMSD, 68% for CSM, and 57% for CSR groups.
One-level CTDR was compared with multi-level CTDR. In the
one-level group, VAS neck improved by 67% versus 70% for the
multi-level group. VAS arm scores for the one-level group
improved by 84% compared to 79% for the multi-level group
CONCLUSION
CSM, AMSD, and CSR can be treated with single or multi-level
CTDR. This study suggests that significant improvements in VAS
and SF-36 functional scores can be expected notwithstanding
differences in preoperative diagnosis or number of levels treated.
47
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 3 (continued)
CERVICAL / BMP | Chair | Dr Greg Malham
Arthur Streeton Auditorium
4.17pm | 3.5Seven years experience with C2 translaminar screws
fixation: One surgeon’s experience with 52 patients
*Wright, NM, Dorward, IG
Department of Neurosurgery, Washington University
School of Medicine, St. Louis, Missouri, USA
INTRODUCTION
C2 translaminar screws offer similar biomechanical stability as
other C2 fixation methods, but with greater technical ease and
minimal risk to neural and vascular structures. To advance the
understanding of C2 translaminar screw fixation, we review the
literature relating to the technique and report our experience
since developing the technique in 2002.
METHODS
52 consecutive adult patients with cervical disorders requiring
axis stabilization were treated with C2 translaminar screws by a
single surgeon between 2002 and 2009. All patients underwent
preoperative plain radiographs and CT scans to confirm feasibility
of screw placement. Patients were followed with serial flexion /
extension radiographs and/or CT scans to assess fusion; indicators
of fusion included absence of motion on dynamic radiography
and evidence of bony bridging across instrumented levels.
RESULTS
Average age at surgery was 58.1 years (range 15.8-90.8). Surgical
indications included trauma (63%), degenerative (17.3%), congenital
(7.8%), inflammatory (5.8%), and other (5.8%). A total of 103 C2
translaminar screws were placed (average length 28.9 mm,
diameter 3.5 or 4 mm). No vascular or neurologic injuries occurred.
Ventral cortical disruption occurred with in two patients, without
CSF leak or neurological injury, and was managed by placing
shorter (20mm) screws. Arthrodesis was accomplished with
structural grafts (19 patients), bone morphogenetic protein
(21 patients), or synthetic (12 patients). 40 patients had sufficient
follow-up (average 13.3 months) to evaluate fusion; 1 likely
pseudoarthrosis was identified in a patient with fractured C1
screws, though imaging indicated successful bony fusion and no
revision was required. Other surgical complications included one
durotomy and one C2 distribution dysesthesia. 5 patients
(average age 78.7 years) died within 2 months of surgery from
complications related to medical comorbidities.
CONCLUSION
This study reports on 103 C2 translaminar screws, the largest
single-surgeon series to date. The findings suggest that C2
translaminar screws are a technically feasible, low-risk, robust
option for C2 fixation, with at least 97.5% fusion rate in this series.
REFERENCES
1. CASSINELLI, E, LEE, M, SKALAK, A, AHN, N, WRIGHT, NM
Spine 31(24):2767-2771, 2006.
2. LEONARD, JJ, WRIGHT, NM
Journal of Neurosurgery: Pediatrics 104(1):59-63, 2006
[cover article].
3. WRIGHT, NM
Journal of Neurosurgery: Spine 3:409-14, 2005.
4. WRIGHT, NM
Journal of Spinal Disorders and Techniques 17(2):158-162,2004.
48
4.25pm | 3.6A radiological analysis of early failure of cervicalfixation for trauma in the subaxial cervical spine
*McCarthy, MJH, Jenkins,O, Williams, R
Princess Alexandra Hospital, Brisbane, Qld, Australia
INTRODUCTION
A previous study by Johnson et al. (2004) identified a 13% loss of
postoperative alignment in patients with single level cervical facet
fracture subluxations treated with single segment anterior surgery.
The aim of the study was to define the rate of early loss of fixation
in fusion for cervical trauma and to identify potential failure modes.
METHODS
Patients treated operatively over the last 5 years for subaxial
cervical trauma were identified using the Spinal Surgery Operative
Database and the Spinal Injury Unit Database. All injuries from
C3 to C7/T1 treated operatively were included by decompression
and stabilisation. A radiological analysis of pre-, intra- and post-
operative imaging was performed. Early failure was defined as loss
of position in the postoperative follow up period as determined
by change in angular kyphosis. The following parameters were
measured: age, sex, diagnosis, preoperative presence of endplate
and facet fractures, treatment modality, immediate and follow up
reduction and alignment, time to follow up, Bridwell fusion grade,
screw pullout / lucency and pseudarthrosis.
RESULTS
We identified one hundred and four cases of which eighty four
had a minimum 8 week radiological follow available (81%). The
mean age was 38 years with 70% males. The mean follow up was
30 weeks. There were 33 bifacet fracture dislocations, 13 unifacet
fracture dislocations, 27 vertebral body fractures with or without
dislocation, 5 chalkstick fractures and 6 other miscellaneous types
of injury. 46% of cases had facet fractures and 49% had endplate
fractures. Using strict criteria, 13 cases (15%) showed early
implant failure but only 6 of these required reoperation (7%).
A further 6 patients underwent an additional procedure during
the first 2 post operative weeks. Increasing age was associated
with the requirement of an additional post operative procedure
(p<0.05). As an index procedure, 40 patients had an Anterior
Cervical Discectomy and Fusion (ACDF) and 22 had an anterior
corpectomy. ACDF alone as a primary procedure was deemed
inadequate in 25% (10/40 cases). Patients with significant endplate
fractures tended not to have ACDF as a sole intervention. In
our series the presence of a facet fracture was not statistically
associated with failure of ACDF, however, when it was present
one third of those cases required a further intervention. None
of the corpectomy patients required an additional procedure.
CONCLUSION
Our results are comparable to those in the published literature.
Patients undergoing ACDF as a sole treatment for subaxial cervical
trauma should be followed up closely and should be warned
preoperatively of the possible need for more than one operation.
REFERENCE
1. JOHNSON et al.
Spine, 29, 2815-2820, 2004.
49
FRIDAY 15 APRIL 2011
FREE PAPERS SESSION 3 (continued)
CERVICAL / BMP | Chair | Dr Greg Malham
Arthur Streeton Auditorium
4.33pm | 3.7Medium-term outcomes of elderly patients withodontoid fractures: Is quality of life associatedwith radiographic evidence of union?*Nall, A, Easton, J, Mercuri, D, Hall, J, Martinelli, B, Wilde, P
Department of Orthopaedics, Austin Hospital,
Heidelberg, Vic, Australia
INTRODUCTION
Odontoid fractures are a common injury in elderly patients.
Traditional treatment has involved halo thoracic device
application with the aim of achieving a solid fusion but this may
not equate to a better clinical outcome.
We therefore ask: Is stable non-union of an odontoid fracture
associated with poor quality of life in patients over 65?
METHODS
Ethics approval was obtained. A retrospective cohort study was
undertaken. All patients over the age of 65 who presented to
our orthopaedic spinal unit between 2003 and 2008 with a C2
odontoid fracture were included. Patients who were suitable for
the study underwent a CT scan and cervical spine radiographs.
Patients or their carers were asked to complete a Neck Disability
Index (NDI) and Quality of Life - Arthritis Version III (QOL)
surveys. Patients were divided into two groups: evidence of union
and evidence of non-union. A pre-study power calculation
suggested that to detect a 5% difference within each survey
domain with a certainty of 80% (power = 0.8) and level of error
of 5% (alpha = 0.05) 42 patients would be required with a
minimum of 21 patients in each group.
RESULTS
48 patients presented to the Austin Hospital within the previous
5 years who met the inclusion criteria. 20 patients were deceased,
5 declined to participate due to transport difficulties and 3
patients did not consent to participation. 2 patients died within
6 weeks of their fracture from general complications without
discharge from our hospital. 7 patients passed away from causes
unrelated to their spinal fracture. Cause of death was unknown in
11 patients, however they all lived greater than six months post
injury and most greater than twelve months.
The average age of the patient cohort was 77. 12 patients
displayed radiographic evidence of non union, and 8 patients
demonstrated union. All patients who underwent halo fixation
united. Patients in the non-union group had a combination of
halo, hard collar and soft collar fixation.
We found no statistically significant difference between the two
groups in either NDI or QOL scores (p=0.171 for NDI and
p=0.243 for QOL index).
We recognise there were insufficient numbers to meet the
pre-study power calculations, which reduces the validity of our
findings. Currently ethics applications are in process to expand
the study to other institutions.
CONCLUSION
We conclude that there is no difference between quality of life
or neck disability scores between the two groups. We suggest
that internal fixation or application of a halo brace may be
over-treating this cohort of patients and propose that cervical
collar immobilisation for pain control may be more appropriate.
50
51
22 Free Papers Session 4
TDR / Sagittal BalanceSaturday 16 April | 8.30am - 10.20am
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 4
TDR / SAGITTAL BALANCE
Chair | Dr Rob Kuru
Arthur Streeton Auditorium
8.30am | 4.1Prospective 10 year follow up of AcroFlex lumbar disc replacement
*Fraser, RD,1,2, Freeman, BJC,1 Meir, AR,1 Fowler, S 1
1 St Andrew’s Hospital, Adelaide SA, Australia2 Royal Adelaide Hospital, Adelaide SA, Australia
INTRODUCTION
The AcroFlex device consists of two titanium end plates bound
together by a hexane-based polyolefin rubber core. Extensive
biomechanical testing predicted at least 10 years of in-vivo use
(Serhan 2001).
Significant improvements in ODI and LBOS were observed in
a pilot study of AcroFlex (Fraser 2004), but a high rate of early
mechanical failure caused its removal from clinical use. This study
aimed to assess long-term clinical and radiological outcome and
causes of implant failure.
METHODS
28 subjects (14 male, mean age 41years) with chronic discogenic
LBP were enrolled into a prospective non-randomized trial of
the AcroFlex device. VAS for LBP, ODI, LBOS and SF36 were
administered pre-operatively at 2 years and 10 years (for 23
subjects) after the index procedure. All subjects were invited to
undergo lumbar MRI and those with the device in-situ a CT scan.
Kaplan-Meier survival analysis was performed with revision
surgery as the end point.
RESULTS
At a mean of 9 years and 8 months (range 8.67-11.47 yrs), the
cumulative rate of survival for implants was 60.7%. Indications for
revision included device failure in 7 and disabling pain in 4. Mean
time to revision was 3 years 10 months (range 23 months to 8
years 4 months). Eleven of 28 patients (39.3%) had a total of 14
revision procedures; 9 of the 11 were converted to ALIF
supplemented with pedicle screw fixation.
Mean ODI for non-revision cases was 27.5 (+/-17.6) compared to
41.8 (+/-26) for revision cases. Mean improvement in ODI for non
revision cases was 17.9 (+/-16.9) compared to 12 (+/-16.1) for
revisions. Similar trends were observed in LBOS and SF-36 scores.
Radiographic findings in revision group included mid-substance
rubber tears, osteolysis, and implant displacement. CT findings in
11 of 17 survivors included heterotopic bone formation (85%),
osteolysis (50%) and subsidence (14%). MRI in 14 of 23
demonstrated adjacent level disc degeneration in 68% of those
with AcroFlex in situ and 40% of those converted to fusion.
Skip degeneration was present in 44% of those with AcroFlex
in situ and 20% of those converted to fusion.
CONCLUSION
A revision rate of 39.3% for lumbar disc replacement is
unacceptable. The aetiology of implant failure included failure of
osseointegration, mid-subtance rubber tears and osteolysis. The
mean time to revision was 3 years and 10 months (range 23
months to 8 yrs 4 months). Guyer (2009) reported 7.7% revision
rate following Charite TDR at 5 years. Long term follow up of these
devices is clearly indicated. The incidence of adjacent level disc
degeneration for AcroFlex is comparable to that observed above
spinal fusions. Salvage procedures involving conversion to spinal
fusion are technically demanding, but appear to improve outcomes.
REFERENCES
1. SERHAN H.
Podium presentation, ISSLS, Edinburgh, June 19-23, 2001.
2. FRASER RD.
The Spine Journal: 4, 245S-251S, 2004
3. GUYER RD.
The Spine Journal: 9, 374-386, 2009
52
8.38am | 4.2Compliant artifical lumbar disc replacement(Cadisc-L): In vivo implant stability and osseointegration in an animal model
*Freeman, BJC,1 Steffen, T, 2 Aebi, M 3
1 University of Adelaide, Adelaide, SA, Australia2 McGill University, Montreal, Quebec, Canada3 University of Bern, Bern, Switzerland
INTRODUCTION
Early migration and / or expulsion of Total Disc Replacements
(TDR) are recognized complications that are mitigated by the
incorporation of primary fixation features. Longer term secondary
implant fixation can be enhanced by the use of hydroxyapatite
or similar osseo-conductive coatings. The elastomeric TDR,
Cadisc™-L has been designed with primary and secondary
fixation features applied to both polymeric end-plates. These
endplates conform to the topography of the adjacent vertebrae
for optimized load sharing. The aim of this in vivo study was to
investigate the Cadisc™-L implant stability and subsequent
osseointegration over a period of six months in an animal model.
METHODS
Institutional animal care and use committee (IACUC) approval
was obtained prior to commencement of this project. A total
of six skeletally mature male baboons (Papio annubis) were
included and followed for a period of 6 months. Under general
anaesthesia (GA), using a transperitoneal exposure, a custom
made Cadisc™-L device was implanted into the disc space one
level above the lumbo-sacral junction in all 6 subjects.
Antero-posterior (AP) and lateral radiographs of the lumbar spine
were performed under GA prior to surgery, and post-operatively
under GA at intervals up to 6 months. Systematic examination of
these radiographs was carried out by an independent radiologist
looking specifically at disc height, and for any evidence for
subsidence or implant migration. Flourochrome markers (which
contain molecules that bind to mineralization fronts) were
injected at specified intervals in order to investigate bone
remodeling with time.
Animals were humanely euthanized six months after index
surgery. Both test and control specimens were retrieved, fixed
and subjected to histological processing to assess the
bone-implant-bone interface. Fluorescence microscopy and
confocal scanning laser microscopy were utilized in combination
with BioQuant image analysis to determine the bone mineral
apposition rates and gross morphology.
RESULTS
Systematic radiographic evaluation revealed no loss of disc
height at the level of surgery or adjacent levels. No evidence of
subsidence or significant migration of the implant up to 6 months
following surgery was observed. Heterotopic ossification (HO)
was observed to varying degrees at the operated level.
Histology revealed that the primary fixation features of the
implant were embedded within the adjacent vertebral endplates.
Flourochrome distribution revealed active bone remodeling
occurring adjacent to the polymeric end-plate with no evidence
of adverse biological responses. Mineral apposition rates at the
implant surface of between 0.7 - 1.7 microns / day are in keeping
with literature values for hydroxyapatite coated implants in
cancellous sites of various species.
CONCLUSIONS
Radiographic assessment demonstrates that the Cadisc™-L
implant remains stable in vivo with no evidence of subsidence or
significant migration. Histological analysis suggests the primary
fixation features are engaged, and in close apposition with the
adjacent vertebral bone. Flourochrome markers provide
evidence of a positive bone remodelling response in the
presence of the implant.
53
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 4 (continued)
TDR / SAGITTAL BALANCE
Chair | Dr Rob Kuru
Arthur Streeton Auditorium
8.46am | 4.3Early clinical performance of the Cadisc-L totaldisc replacement: A prospective non-randomizedmulticentre clinical trial
*Freeman, BJC,1 Quirk, I,1 Bertagnoli, R,2 Conix, B,2 Hes, R,3
McConichie, A,5 Zeilstra, D,6
1 Ranier Technology, Cambridge,UK2 ProSpine Clinics, Straubing / Bogen, Germany3 ZNA Middelheim, Antwerp, Belgium4 University of Adelaide, Adelaide, SA, Australia5 University of Glasgow, Glasgow, Scotland6 Isala klinieken, locatie Sophia, The Netherlands
INTRODUCTIONThe Cadisc™-L is a compliant polyurethane-polycarbonate
graduated modulus compliant total disc replacement (TDR)
designed to mimic the biomechanical properties of the natural
lumbar disc. In vitro biomechanical studies of this elastomeric
device have demonstrated very similar biomechanical behaviour
to the native L4/5 intervertebral disc. In vivo studies, in an animal
model, have shown the device to be stable, with no evidence of
subsidence or migration and excellent osseointegration, six months
after insertion. This paper reports the early clinical performance of
Cadisc™-L in a prospective non-randomized multicentre clinical
trial treating subjects with debilitating chronic low back pain (LBP).
METHODSTwenty-eight subjects with chronic LBP (>6 months), unresponsive
to conservative treatment, with an Oswestry Disability Index
(ODI) of >30 points, aged between 25-65 years with single level
degenerative disc disease between L3 and S1 were recruited
from three European centres. Clinical success was defined as a
minimum of 15 points improvement in ODI. Visual Analogue
Scores (VAS,1-100) for back and leg pain, EQ-5D and SF-36
scores were compared to data obtained from published literature
using improvement ratio analyses. Clinical outcomes were
independently monitored and statistical analysis carried out
independently. The study follow-up period will run for 5 years.
RESULTS
The mean follow-up for 28 subjects to date is 6 months (range
1.5 to 12 months). There was one non-device related serious
adverse event requiring revision in an osteopenic patient with a
degree of spinal instability. The percentage of subjects achieving
an ODI reduction of 15 points or more was 52% (95% CI:
31.3%, 72.2%), 70% (95%CI: 47.1%, 86.8%) and 83% at 6 weeks,
3 months and 6 months respectively. ODI reduction ratio over
time is presented in the figure below, with comparisons to
published results for the Charite, Prodisc and Maverick TDR.
Charite: (Data from FDA) , Prodisc: (Data from FDA)i, Maverick: (Le Huec, 2005)
Mean VAS (back) reduced over time (30.7 units, p<0.001; 30.3
units, p=0.001; 52.0 units, p=0.013) at 6 weeks, 3 months and 6
months respectively. Mean VAS (leg pain) were lower than baseline
over time (by 11.8, 17.5 and 27.2 units, p=0.041) at 6 weeks, 3
months and 6 months respectively. EQ-5D data demonstrated
significant increases in quality of life (0.31, p<0.001; 0.64, p<0.001;
0.57, p=0.036) at 6 weeks, 3 months and 6 months respectively
and demonstrated an increase of 0.14 QALYs in the first 3 months.
CONCLUSION
The Cadisc™-L appears safe and effective for the treatment
of debilitating chronic LBP in this study, however the authors
acknowledge the short follow-up. There have been no device
related adverse events to date. The clinical results are superior
to those previously reported in other TDR cohorts.
REFERENCES
1. www.accessdata.fda.gov/cdrh_docs/pdf4/P040006b.pdf
2. LE HUEC JC Orthop Clin North Am. 36 (3): 315-22; 2005
54
9.09am | 4.4Correlation of age with spino-pelvic balance in degenerative lumbo-sacral disorder
*Mokhtar, SA,1 White, G 2 Sears,WR 2
1 Australian School of Advanced Medicine, Macquarie
University, Sydney, NSW, Australia2 Dalcross Adventist Hospital, Sydney, NSW, Australia
INTRODUCTION
Several measures of spinal sagittal alignment have been found to
vary between those found in normal, volunteer subjects and
those in patients with certain degenerative spinal conditions.
Measures of sacro-pelvic alignment, such as Pelvic Incidence, are
believed to reflect developmental morphology and to remain
constant over time.
There is little data in the literature regarding the effect of age on
changes in spinal sagittal alignment. The purpose of this study
was to determine whether univariate correlations exist between
age and changes in measures of spino-pelvic alignment, in a series
of patients with degenerative lumbo-sacral spinal disorders.
METHODS
A cross-sectional, observational study was undertaken of 674
patients with degenerative lumbo-sacral disorders (416 females,
258 males, mean age 66 ± 13 years) who underwent surgery
between September 2000 and September 2010. Patients who
had undergone previous lumbar fusion surgery were excluded.
Pre-operative measures of spinal sagittal alignment were made
using the pelvic radius (PR) technique of Jackson. Parameters
measured were: overall lumbar lordosis (OA lordosis), total
lumbopelvic lordosis (PRT12), sacro-pelvic morphology (PRS1),
pelvic angulation (PA) and distances of sagittal plumb lines from
the hip axis (HAS1, HAT4 and HASP).
Univariate relationships between the measured parameters and
age were assessed by Spearman rank order correlation for all
patients and for the subgroups: degenerative spondylolisthesis
(DS), lytic spondylolisthesis(LS), degenerative scoliosis(DSc) and
nil deformity(NIL). Significance was set at p < 0.05.
RESULTS
The mean values (± standard deviations) were: -50° ± 15° for
OA lordosis, 81° ± 14° for PRT12, 26° ± 12° for PRS1 and 27°
± 8° for PA, The sagittal plumb line from HA were: -60 ± 22 mm
for HAS1, -72 ± 36 mm for HAT4 and -31 ± 18 mm for HASP.
Significant correlations were found between age and: OA lumbar
lordosis (r =0.17), PRT12 (r =0.21), PA (r=0.24), HAS1 (r = 0.18 ),
HAT4 (r=0.15) and HASP (r = 0.16 ). No correlations were
found between age and PRS1.
Subgroup analysis was done for DS(N=297, mean age 69±10
years), LS(N=85.mean age 54±17 years), DSc(N=136,mean age
70±9 years) and NIL(N=129,mean age 64±15 years). Significant
correlation were found in subgroup DS between age and PA
(r=0.16), subgroup LS between age and:
PRT12(r=0.37),PA(r=0.36),HAS1(r=0.34) and HASP(r=0.32),
subgroup DSc between age and HAT4(r=0.36). No correlation
were found between age and measured sagittal parameter in
subgroup NIL.
CONCLUSION
Age was found to correlate with changes in several measures
of spino-pelvic alignment, in patients with degenerative spinal
disorder. As expected, sacro-pelvic morphology, as measured by
PRS1, did not vary with age. Further studies are required to
assess the effects of confounding variables such as hip flexibility,
which change with age and are likely to affect standing spinal
sagittal alignment.
REFERENCES
1. JACKSON, RP et al.
Congruent Spinopelvic Alignment on Standing Lateral
Radiographs of Adult Volunteers. Spine 25(21), 2808-2815,
2000
2. JACKSON, RP et al.
Pelvic lordosis and alignment in spondylolisthesis.
Spine 28:151–160, 2003.
55
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 4 (continued)
TDR / SAGITTAL BALANCE
Chair | Dr Rob Kuru
Arthur Streeton Auditorium
9.17am | 4.5Association of chronic low back pain with loss oflumbar lordosis and the role of pelvic morphology
*McAviney, J,2 Harrison, DE,1 Harrison, DD,3 Janik, JJ, 4
Cailliet, R, 5 Holland, B 6
1 Sydney Scoliosis Clinic, Sydney, NSW, Australia2 Private Practice, Elko, Nevada, USA3 Universite du Quebec a Trois Rivieres, Quebec, Canada4 CompMath Research, Alabama, USA5 Department of Rehabilitative Medicine, University of Southern
California School of Medicine, Los Angeles, California, USA6 Department of Statistics, Temple University,
Philadelphia, Pennsylvania, USA
INTRODUCTION
Measures of lumbar lordosis and elliptical modelling have been
shown to discriminate between normal and chronic low back
pain subjects (Harrison 1998). Pelvic morphology influences an
individual’s lumbar lordosis (Vaz 2002). However, few studies
have systematically looked at the interdependence of pelvic
morphology and lumbar lordosis in normal and pain groups.
The purpose of this study was to investigate the sensitivity and
specificity of sagittal plane radiographic alignment and modelling
variables to discriminate between controls and chronic low back
pain subjects. Also to determine if group variations in pelvic
morphology explain possible differences in elliptical modelling
and angular measurements of lumbar lordosis or angle of pelvic
incidence (API) in controls versus low back pain subjects.
METHODSFifty healthy control subjects were attained from a pre-employmentphysical examination. 29 men and 21 women (mean age of 27years) with no history of low back pain, a normal spinal examination,and no radiographic evidence of pathologies, anomalies, and instability. From the same clinic files, 50 chronic low back painsubjects were randomly chosen from a population that matchedthe control group characteristics. Inclusion criteria required noabnormalities on lumbar spine radiographs. Computer analysis ofdigitised vertebral body corners and sacral segments on laterallumbar sacral radiographs was undertaken. Radiographic variablesincluded L1-L5 lordosis, T12-S1 lordosis using Cobb’s and Posteriortangent Average Rotation Angle (ARA) methods, b/a ellipticalratio, sacral base angle (SBA), and sacral tilt to vertical using posterior tangent S1 (PTS1). Two measures of pelvic morphologywere determined for each subject: API and posterior tangent pelvicincidence angle (PTPIA). Descriptive statistics and correlationsamong the primary variables were determined. Receiver OperatingCharacteristic curves (ROC curves) for primary variables wereanalysed for diagnostic comparisons between groups.
RESULTSThe mean values of lumbar lordosis (ARA L1-L5, ARA T12-S1,Cobb T12-S1) were statistically different between the normal andchronic low back pain groups (p < 0.001) indicating a hypo-lordosislumbar spine for the chronic group. The mean b/a ratio was statistically less in the chronic pain group (p = 0.0066). Pelvicmorphology variables were similar between the groups (p > .05).The API had stronger correlation to the SBA and Cobb T12-S1than did PTPIA, while PTPIA had stronger correlation to S1 tangentand ARA T12-S1 than did API. ROC curve analyses identified thatlordosis T12-S1 (69°), L1-L5 (36°), sacral tilt (46°), and b/a, hadgood discrimination between groups (AUC= .83, .78, .75, and .72).
CONCLUSIONSBased on this study, it was found that chronic low back pain subjects have an abnormal decreased lumbar lordosis, not relatedto their pelvic morphology.
REFERENCES1. HARRISON et al,
Journal of Spinal Disorders. 11(5):430-439, October 1998.2. VAZ et al
European Spine Journal, Volume 11, Number 1, 80-87,February 2002
56
9.25am | 4.6
A software simulation of spinal sagittal balance
McCombe, PF
St Andrews War Memorial Hospital and Royal Brisbane
Hospital, Brisbane, Qld, Australia
INTRODUCTION
There is significant variation in normal sagittal alignment. This
causes difficulty in determining if a particular spinal shape is due
to normal variation or pathology. A fundamental problem is the
inability to simply geometrically construct a spinal shape and to
modify it in a way that allows compensatory changes to be
resolved after proposed corrective surgery.
Pelvic morphology, defined by pelvic incidence (PI), primarily
determines spinal shape. The lumbar lordosis (LL) and thoracic
kyphosis (TK) correlate directly or indirectly with PI. The
parameters of PRT12 (pelvic radius-T12 angle), spinal tilt angle
(STA) and spinosacral angle (SSA) (Roussouly 2006) are
relatively constant. Despite these observations, a unified model
of spinal balance remains elusive. Simulation software that allows
user input may therefore be clinically useful.
METHODS
A digitized normal lateral erect radiograph was used to create an
articulated graphical model in software (MATLAB) that could be
modified by user input. Angles of motion segments, LL, TK, PI and
pelvic tilt (PT) were modifiable. The distribution of segmental
changes for global changes in LL and TK could be specified. Angle
changes could either reset neutral segmental angles or produce
offsets from neutral values. Motion segment flexibility curves
were modeled by fitting third degree polynomial functions to
published normative data (Busscher 2009). The polynomial
constants for each level could be modified to change neutral
zone stiffness and range of motion. An arbitrary centre of mass
of the trunk was defined anterior to the T10 vertebral body in
line with the femoral heads. Perturbation of the model caused
recalculation of the segmental and total spinal moments required
to overcome segmental stiffness and to resist flexion by the
gravity load. An attempt was made to create reasonable facsimiles
of published different normal sagittal profiles by modifying PI and
then variables to maintain the published values of STA at
approximately 95 degrees and SSA at approximately 0.9*SS + 99
(Roussouly 2006). The simulator also was used to model obvious
cases of sagittal malaligment.
RESULTS
Variations in PI between 25 and 65 degrees were modeled.
Iterative changes to LL, TK and SS could be performed rapidly
in 3-4 cycles to produce close approximation to SSA and STA
targets. The final shapes reasonably approximated the normal
sagittal types described by Roussouly(2005), though was
improved by fine tuning the distribution of lumbar lordosis.
Appropriate values for LL were slightly higher than PI and TK was
slightly lower than PI. A series of 5 cases with significant sagittal
disturbance could be quickly modeled by entering only 4 basic
parameters (PI,SS,LL,TK). It was relatively easy to simulate corrective
surgery and to be guided by the avoidance of potentially painful
large changes in the segmental and total moments.
CONCLUSION
Software simulation of sagittal spinal alignment may be of clinical
use.
REFERENCES
1. ROUSSOULY, P.
Spine, 31, E320-E325, 2006.
2. ROUSSOULY, P.
Spine, 30, 346-353, 2005.
3. BUSSCHER, I.
Spine, 34, 2858-2864, 2009.
57
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 4 (continued)
TDR / SAGITTAL BALANCE
Chair | Dr Rob Kuru
Arthur Streeton Auditorium
9.48am | 4.7History of spine balance analysis: Is there a reason to miss the target?
Prof Jean-Charles Le Huec
Orthopaedic Department, University of Bordeaux Hospital,
Bordeaux, France
58
59
22 President’s Session
Lumbar Lordosis and Sagittal Balance: The Masters SpeakSaturday 16 April | 10.50am - 12.30pm
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
SATURDAY 16 APRIL 2011
PRESIDENT’S SESSION
LUMBAR LORDOSIS AND SAGITTAL BALANCE:
THE MASTERS SPEAK
Chair | A/Prof Graeme Brazenor
Arthur Streeton Auditorium
10.50am Pelvic parameters and spine parameters
Prof Jean-Charles Le Huec
Orthopaedic Department, University of Bordeaux Hospital,
Bordeaux, France
PELVIC PARAMETERS
The adoption by humans of an upright position resulted in
broadening and verticalisation of the pelvis together with the
appearance of characteristic spinal curves, has profoundly
modified the structure of the muscles supporting the spine.
In order to characterise the sagittal balance of the pelvis, it is
necessary to define parameters based on notable biomechanical
forces involved in the transmission of constraints. The angle of
incidence was constructed to enable reproducible analysis of the
anatomical characteristics of the pelvis in the sagittal plane. The
angle of incidence is the algebraic sum of two complementary
angles: pelvic tilt (PT) and sacral slope (SS). Since the value of
incidence is fixed for any given patient, the sum of pelvic tilt and
sacral slope is a constant value: when one increases, the other
necessarily decreases. The position of the lumbar spine, attached
to the sacral plateau, is thus affected by the pelvic tilt and by the
sacral slope. Consequently, the pelvic parameters affect the entire
underlying sagittal spinal profile. Global spinal balance involves
harmonisation of lumbar lordosis and thoracic kyphosis taking
into account the pelvic parameters.
SPINE PARAMETERS
According to the anatomical segmentation, spine curves are the
sacral kyphosis (sacrum), lumbar lordosis (L1 to L5), thoracic
kyphosis (T1 to T12) and cervical lordosis (C1 to C7). From
the morphological point of view the vertebrae of a curve are
not identical: from cranial to caudal and vice-versa there is a
progressive anatomical modification. Both curves of the thoraco-
lumbar spine may be divided at the Inflexion Point where lordosis
turns into kyphosis. A geometrical construct of each curve by
two tangent arcs of circle allows understanding the reciprocal
changes between both curves. Lumbar Lordosis is mainly
dependent on SS orientation, and the top of thoracic curve on
C7 is very stable over the sacrum. Thoracic curve is dependent
on lumbar lordosis orientation and C7 positioning. On a reverse
effect, structural changing of thoracic kyphosis may affect the
shape of the lumbar lordosis and the orientation of the pelvis.
60
11.15amHow to correlate parameters and global balance for daily practice
Prof Jean-Charles Le Huec
Orthopaedic Department, University of Bordeaux Hospital,
Bordeaux, France
Standing erected position is a human property. The pelvis anatomy
and position defined by the Pelvis Incidence, interacts with the
spinal organisation in shape and position to regulate the sagittal
balance between both spine and pelvis. Sagittal balance of the
human body may be defined by a setting of different parameters:
1. Pelvic parameters: Pelvic Incidence (PI), Pelvic Tilt (PT) and
Sacral Slope (SS)
2. C7 positioning: Spino Pelvic Angle (SSA) and C7plumb line
3. Shape of the spine: lumbar lordosis
In case of pathological kyphosis, different mechanical compensations
may be activated. When the spine remains flexible, the hyper
extension of the spine below or above compensates the kyphosis.
When the spine is rigid the only way is rotating backward the
pelvis (retroversion). This mechanism is limited by the value of PI.
Hip extension is a limitation factor of big retroversion when PI is
high. Knees flexion may occur when hip extension is overpassed.
The quantity of global kyphosis may be calculated by the SSA.
The more SSA decreases, the more the severity of kyphosis
increases. We used Roussouly’s classification of lumbar lordosis in
four types to define the shape of the spine. The forces acting on
a spinal unit are combined in a Contact Force (CF). CF is the
addition of gravity and muscle forces. In case of unbalance, CF is
tremendously increased. Distribution of CF depends on vertebral
plate orientation. In an average tilt (45°) the two resultants,
parallel to the plate (sliding force) or perpendicular (pressure),
are equivalent. If the tilt increases, the sliding force is predominant.
On the contrary, with a horizontal plate, the pressure increases.
Importance of curvature is another factor of CF distribution. In a
flat or kyphosis spine, CF is acting more on the vertebral bodies
and disc. In case of important extension curvature, it is on the
posterior elements that CF is playing more.
According to the shape of the spine we may expect different
degenerative evolution:
1. Type 1 is a long thoraco lumbar kyphosis and a short hyper
lordosis: Discopathies in TL area, arthritis of the posterior
facets in the distal lumbar spine. In younger patients L4 S1
hyper extension may induce a nut cracker L5 spondylolysis.
2. Type 2 is a flat lordosis: Stress is at its maximum on the discs
with a high risk of early disc herniation then lately with multi
level discopathies.
3. Type 3 has an average shape without characteristics for a
specific degeneration of the spine.
4. Type 4 is a long and curved lumbar spine: This is the spine
for L5 isthmic lysis by shear forces.
When the patient keeps the lordosis curvature, a posterior arthritis
may occur and lately a degenerative L4L5 spondylolisthesis. In
older patients, they may lose the lordosis curvature, SSA decreases
and pelvis tilt increases. A widely retroverted pelvis with a high
pelvic incidence is certainly a previous Type 4 and a restoration
of a big lordosis is needed in case of arthrodesis
CONCLUSION
The genuine shape of the spine is probably one of the main
mechanical factors of degenerative evolution. This shape is
oriented by a shape pelvis parameter, the pelvis incidence.
In case of pathology, this constant parameter is the only signature
to determine the original spine shape we have to restore to
balance the patient.
61
SATURDAY 16 APRIL 2011
PRESIDENT’S SESSION (continued)
LUMBAR LORDOSIS AND SAGITTAL BALANCE:
THE MASTERS SPEAK
Chair | A/Prof Graeme Brazenor
Arthur Streeton Auditorium
11.45am Reciprocal changes and osteotomy planning in sagittal balance surgery
A/Prof Chris Ames
Neurosurgery Department, University of California,
San Francisco, California, USA
Current strategies to optimize post operative sagittal balance
will be explained. Recent analyses of cervical, thoracic and pelvic
reciprocal changes will be presented and ways to incorporate
these expected changes in treatment planning will be described.
62
12.05pm Geometric analysis of coronal balance in idiopathic scoliosis: Are there lessons for sagittal balance?
Prof Avinash Patwardhan
Department of Orthopaedic Surgery and Rehabilitation,
Loyola University Stritch School of Medicine,
Chicago, Illinois, USA
This review will cover a discussion of the author’s original work
on geometric analysis of coronal balance, followed by a review of
current findings regarding sagittal balance.
Coronal decompensation or imbalance is a possible complication
in the management of idiopathic scoliosis when selective correction
and fusion of the thoracic curve is performed. Previous studies
have suggested that overcorrection of the primary thoracic curve
may be the principal cause of coronal decompensation. The
objective of the authors study was to determine if a balanced
spinal configuration is possible when the lumbar curve is larger
than the thoracic curve, and to determine the limits on the relative
curve magnitudes beyond which a spinal configuration with
acceptable balance cannot be achieved. The underlying premise of
this study is that spinal configuration cannot be uniquely defined by
the thoracic and lumbar curve magnitudes alone. There may be
multiple configurations that have the same thoracic and lumbar
curve magnitudes but different magnitudes of decompensation.
The take home finding of this work is that decompensation in
coronal plane does not appear to be caused by the relative
magnitudes of the thoracic and lumbar curve, but is a result of
inadequate relative distance between the thoracic and lumbar
apical vertebrae and the tilts of the junctional and end vertebrae
of the thoracic and lumbar curves.
The review of sagittal balance literature will highlight the findings
concerning the compensatory mechanisms that distinguish the
issues of sagittal balance from coronal balance.
63
Notes & Questions
64
65
22 Free Papers Session 5
SurgicalSaturday 16 April | 1.30pm - 2.50pm
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 5
SURGICAL
Chair | Dr Kevin Seex
Arthur Streeton Auditorium
1.30pm | 5.1
Outcomes after decompressive laminectomy
for lumbar spinal stenosis: Comparison
between minimally invasive unilateral
laminotomy / laminectomy for bilateral
decompression (ULBD) vs. open laminectomy
*Mobbs, RJ,1,2 Li, J,1 Sivabalam, P 1
1 University of New South Wales, Sydney, NSW, Australia2 Prince of Wales Hospital, Spinal Unit, Sydney, NSW, Australia
INTRODUCTION
To compare outcomes following minimally-invasive unilateral
laminectomy / laminotomy for bilateral decompression (ULBD)
or open laminectomy for degenerative lumbar spine stenosis (LSS).
METHOD
We conducted an analysis of 54 patients who underwent a
ULBD (27 patients) or open laminectomy (27 patients) for
degenerative LSS between 2007 and 2009. Patient demographics
and post-operative course outcomes (ie duration of
post-operative stay, time-to-mobilise, post-operative analgesic
consumption, complication / re-operation rates) were collected
from medical records. A standardised questionnaire obtained
clinical outcomes using pre-operative and post-operative
Oswestry Disability Index (ODI) scores, Visual Analogue Scale
(VAS) scores, Patient Satisfaction Index scores and post-operative
Short-Form 12 (SF-12) scores.
RESULTS
The conventionally-treated group had a significantly longer period
of follow-up (30.22 months versus 12.83 months; p<0.0001).
MIS-treated patients were significantly older at the time of
operation (71.55 years versus 64.64 years; p=0.0471). There
were significant improvements in mean pre-operative to
post-operative ODI and VAS scores within each group
(MIS-treated group: p<0.0001 and p<0.0001 respectively;
conventionally-treated group: p=0.0004 and p<0.0001
respectively), however no significant difference in improvement
between groups (mean ODI improvement: p=0.0630; mean VAS
improvement: p=0.0767). MIS-treated patients had a significantly
shorter length of post-operative hospital stay (55.08 hours
versus 120.9 hours; p=0.0031), time-to-mobilise (15.59 hours
versus 33.27 hours; p<0.0001) and were more likely to not use
opioids for post-operative pain (55.55% versus 14.8%; p=0.0038).
CONCLUSION
Based on short-term follow-up, microscopic ULBD is equally
effective as open decompressions in improving function and
decreasing leg/back pain, with the additional benefits of a
significantly shorter post-operative hospital recovery time and
time-to-mobilise, less post-operative pain and opioid use.
REFERENCES
1. SASAI, K, UMEDA, M, MARUYAMA, T, WAKABAYASHI, E,
LIDA H
Microsurgical bilateral decompression via a unilateral approach
for lumbar spinal canal stenosis including degenerative
spondylolisthesis. J Neurosurg Spine. 2008; 9:554-559
2. KHOO, LT, FESSLER, RG.
Microendoscopic decompressive laminotomy for the
treatment of lumbar stenosis.
Neurosurgery. 2002; 51 (5 Suppl):S146-154.
3. COSTA, F, SASSI, M, CARDIA, A, ORTOLINA, A, DE SANTIS, A,
LUCCARELL, G, FORNARI, M.
Degenerative lumbar spinal stenosis: Analysis of results in a
series of 374 patients treated with unilateral laminotomy for
bilateral microdecompression. Journal of Neurosurgery
Spine. 2007; 7(6):579-586.
66
1.38pm | 5.2Lumbar spinal synovial cysts: Associations and treatmentRyan, MD
Notre Dame University, Sydney, NSW, Australia
and RNS, NPR and Mater Hospitals, Sydney, NSW, Australia
INTRODUCTION
The cause, natural history and appropriate management of
symptomatic synovial cysts remain elusive. Regimens are largely
based on dogma. Pathological interpretation is purely descriptive
with little which allows the formulation for a scientific study of
causation.
METHODS
A retrospective review of 96 consecutive patients presenting to a
solo private practice was performed. Those managed operatively
and non-operatively were included. A comparison was made
between the outcomes of those who were managed by surgical
decompression alone, and those managed by decompression and
spinal fusion. Possible biomechanical precipitants for synovial cyst
formation were identified
RESULTS
Of the 96 subjects, 57 were female (59%). The average age at
presentation was 69 years (range: 46-89 years).
• Cysts occurred at L2/3 (2%), L3/4 (15%), L4/5 (67%), and
L5/S1 (15%)
• 52% were right-sided
• 34 were managed non-operatively, 36 underwent
decompression alone and 26 underwent decompression
and spinal fusion
• Comorbidities in patients managed conservatively were
cardio-vascular disease 26%, arthritis 24 %, prior malignant
disease 9%, diabetes, thyroid dysfunction & asthma, 6% each.
• Comorbidities in patients managed operavatively were
cardio-vascular disease 52%, Arthritis 35 %, prior malignant
disease 18%, diabetes and thyroid dysfunction 8% each, and
asthma, 5%.
• Those managed non-operatively had minimal symptoms and
no evidence of neurological deficit.
• In those managed surgically, there was no mortality,
neurological complication or infection.
• Of the 36 who underwent decompression alone, 10 (27%)
are comfortable, unrestricted, and need only occasional
analgesics. 6 have back pain that requires regular analgesics.
11 have had recurrence of back and leg pain, and 8 (22%)
have undergone further surgery.
• Of the 26 treated by decompression and spinal fusion, 17
(65%) are comfortable and unrestricted. 7 need regular pain
relief for low back pain. One required a revision of spinal
fusion after falling down a stairs, and another has trochanteric
bursitis.
• If the ‘comfortable’ and ‘occasional analgesics only’ groups
above are deemed acceptable, then only 44% of the
decompression group achieved that status, whereas 92% of
the decompression and fusion group were deemed acceptable.
CONCLUSION
The results suggest that decompression and fusion is the best
option for management of a synovial cyst that must be excised.
Recurrences of synovial cyst formation occurred in the decom-
pression only group. In those who under went fusion, synovial
cysts occurred at adjacent levels. This observation suggests that
clinically significant synovial cysts require movement and stress
concentration for their development.
REFERENCES
1. WILBY MJ et al.,
Spine 34, 2518-24, 2009.
2. RISHENG XU et al.,
Spine 35, 1044-53, 2010.
67
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 5 (continued)
SURGICAL
Chair | Dr Kevin Seex
Arthur Streeton Auditorium
1.46pm | 5.3Transforaminal endoscopic lumbar disc surgery application in upper lumbar discs: Method and results
Gore, S
Consultant Spine Endoscopist, Ratna Memorial Hospital,
Pune, India
INTRODUCTION
Lumbar disc herniation is commonest at L4/5 and L5/S1 levels.
Higher lumbar discs are comparatively less common.(Wei et al.,
1989) Endoscopic surgery at high lumbar levels is safe and
precise and can be done and is done in awake aware patients.
(Ahn et al., 2009)The safety and precision makes it a natural
choice in high level nuclear herniation. Morbidity and risks of
open surgery are well known. Instability is common after open
surgery. (Cui and Zhang, 2008) An oblique paraspinal approach
has been described for accessing upper lumbar herniation with
excellent results.(Kim et al., 2009) This study was to apply
technique of transforaminal endoscopic lumbar disc surgery to
D12/L1 and L1/L2 and L2/L3 levels.
METHODS
14 cases of L1/2 D12//L1 and L2/3 herniation were operated
by transforaminal surgery under local anesthesia with laser
assistance during jan 2002 and December 2007. Average follow
up is 48 months or more. The main clinical presentation of
anterior thigh pain was noted. The patient is awake and aware
and herniated fragment is accessed under C arm and then
removed under direct visualization under local anesthesia.
Clinical results were assessed using VAS and ODI scale.
RESULTS
The relief of pain was noted within 24 hours in all cases. In case
of neurological recovery it took 7 months to recover. Targeted
removal of herniated fragment resulted in relief of symptoms of
front thigh pain. Surgical time was average 35 minutes. Blood loss
was about 5 cc. Hospital stay average was 20 hrs. All surgeries
were under local anesthesia and in awake and aware state. There
were no complications. One patient did not have full recovery
of neuro status. One patient needed a fusion later due to
progressive deformity. Due to non invasive nature of the surgery
there was less morbidity and very rapid return to work. There
were no instabilities or recurrence. There was recovery on VAS
from 7/8 to 2 over 3 weeks. Significant improvement in ODI was
seen in 4 weeks, and then maximum 8 weeks.
CONCLUSION
Transforaminal endoscopic targeted removal of herniation of
upper lumbar disc is not morbid, results in rapid return to work.
It is associated with no complications and is safe even in patients
with medical co morbidities. Relief of pain and neurological
symptoms were rapid and near full. Our results have been
comparable with recent series with similar approach.
(Ahn et al., 2009)
REFERENCES
1. AHN, Y, LEE, SH, LEE, JH, KIM, JU, LIU, WC 2009.
Acta Neurochir (Wien), 151, 199-206.
2. CUI, ZJ, ZHANG, XL 2008.
Zhonghua Yi Xue Za Zhi, 88, 619-21.
3. KIM, JS, LEE, SH, MOON, KH, LEE, HY 2009.
Neurosurgery, 65, 95-9; discussion 99.
4. WEI, CP, CHENG, WC, CHANG, CN, LEE, ST, LUI, TN,
WANG, AD 1989.
Changgeng Yi Xue Za Zhi, 12, 193-9.
68
1.54pm | 5.4Long-term outcomes following lumbar spine fusion for adult isthmic spondylolisthesis: A comparison of PLIF vs PLF
*Cunningham, JE, Robertson, PA
Auckland City Hospital, Auckland, New Zealand
INTRODUCTION
Posterior lumber interbody fusion (PLIF) has the theoretical
advantage of optimising foraminal decompression, improving
sagittal alignment and providing a more consistent fusion mass
in adult patients with isthmic spondylolisthesis (IS) compared to
posterolateral fusion (PLF). Studies to date though have not
shown a clinical difference, with follow-up to two years.
METHOD
An observation cohort study was performed of a single
surgeon’s patients with IS over a ten year period, treated by
either PLF or PLIF. Preoperative and 12-month data were
collected prospectively, and long-term follow-up was by mailed
questionnaire. Preoperative patient characteristics between the
two groups were not significantly different. Average follow-up
was 7 years, 10 months, and 81% of questionnaires were
returned. Outcome measures were Roland Morris Disability
Questionnaire (RMDQ), Low Back Outcome Score (LBOS),
SF-12v2 and SF-6D R2. The SF-6D R2 is a “whole of health”
measure.
RESULTS
PLIF provided better short- and long-term results than PLF. The
PLIF group had significantly better LBOS scores in the long term,
and non-significantly better RMDQ scores in the long term. As
measured by RMDQ MCID short term set at 4, RMDQ MCID
set at 8, the LBOS MCID set at 7.5 points and by SF-12v2
physical component score (PCS), PLIF patients performed better
than PLF patients. When analysing single level fusions alone, the
difference is more pronounced, with PCS, mental component
scores and SF-6D R2 all being significantly better in the PLIF
group rather than the PLF group.
CONCLUSION
This paper strongly supports the use of PLIF to obtain equivalent
or superior clinical outcomes than PLF for spinal fusion for lumbar
isthmic spondylolisthesis. Although there are considerable issues
when commenting on the results of observational studies, the
results of this study are the first to report to such a long-term
time point, and further larger long-term randomised studies are
suggested.
69
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 5 (continued)
SURGICAL
Chair | Dr Kevin Seex
Arthur Streeton Auditorium
2.22pm | 5.5Prospective computed tomography scan analysisof percutaneously inserted pedicle screws for posterior transpedicular stabilisation of the thoracic and lumbar spine: Accuracy and complication rates
*Raley, D,1 Mobbs, RJ 1,2
1 Prince of Wales Hospital, Sydney, NSW, Australia2 Sydney Spine Clinic, Sydney, NSW, Australia
INTRODUCTION
Percutaneous insertion of cannulated pedicle screws has been
developed as a minimally invasive alternative to the open
technique during instrumented fusion procedures of the thoraco-
lumbar spine. Given the reported rate of screw misplacement
using open techniques (up to 40%), and the paucity of data on
the exact failure rate of the percutaneous technique, we
considered a study important to analyse the misplacement rate
and related clinical complications of this relatively new and
evolving technique.
METHODS
A total of 424 percutaneously inserted pedicle screws from 2007
- 2009 were analysed in 88 patients, from a single surgeon series
(RJM). Axial and sagittal reformatted computer tomography
images were examined by two independent observers and
individual and consensus interpretation was obtained for each
screw position. A simple grading system was used for assessment
of screw accuracy:
Grade 0: screw within cortex of pedicle;
Grade 1: screw thread breach of wall of pedicle >2mm;
Grade 2: significant breach >2mm with no neurological
compromise;
Grade 3: complication including pedicle fracture, anterior
breach with neuro-vascular compromise lateral or
medial breach with neurological sequelae.
RESULTS
The indications for percutaneous pedicle screw insertion include:
degenerative (78%), trauma (13%), tumour (8%) and infection
(1%). 381 out of 424 screws (90%) were placed in the cortical
shell of the pedicle (Grade 0). 43 screws (10%) were misplaced
from T4 to S1. Of these, the majority were Grade 1 pedicle
violations (25 screws; 6%), with 16 Grade 2 violations (4%) and 2
Grade 3 violations (<1%). Of the two Grade 3 pedicle violations,
both were pedicle fractures but only one had associated
neurological deficit (L4 radiculopathy post-op). Both pedicle
violations could be attributed, in part, to incorrect angulation
of screw insertion.
CONCLUSION
This study has shown that percutaneous insertion of cannulated
pedicle screws in the thoracic and lumbar spine is an acceptable
technique with a low complication rate in experienced hands.
The overall rate of perforation is below the higher rates
reported in the literature for the open technique. Complication
rates including pedicle fracture was low. It remains a technically
demanding technique and should be performed with appropriate
training and attention to detail.
REFERENCE
1. RINGEL, F, STOFFEL, M, STÜER, C, MEYER, B
Minimally invasive transmuscular pedicle screw fixation of the
thoracic and lumbar spine. Neurosurgery. Oct; 59, 2006.
70
2.30pm | 5.6The role of preoperative DVT prophylaxis inthromboembolic complications in spinal surgery*Cunningham, JE, Swamy, G, Thomas, K
University of Calgary, Calgary, Alberta, Canada
INTRODUCTION
The American College of Chest Physicians recommends only the
use of postoperative pharmaceutical deep venous thrombosis
(DVT) prophylaxis in spine surgery. The effects of preoperative
DVT prophylaxis, specifically with respect to DVT, pulmonary
embolism (PE) and spinal epidural haematoma (SEH) rates
remain unknown.
METHOD
A 5-year retrospective review of all elective spine operations at
one major institution was carried out. Patients were separated
into 2 groups, based on the presence or absence of preoperative
DVT prophylaxis. The DVT, PE and SEH rates were compared
between the two groups. The study was adequately powered to
detect a halving of the DVT rate.
RESULTS
Of the 3870 elective spinal operations conducted between
2004 and 2008, 37% of patients received preoperative DVT
prophylaxis as either 5,000 units of unfractionated heparin or
40mg of enoxaparin. Preoperative DVT prophylaxis administration
was not found to have a significant effect on DVT or PE rates
(relative risk 0.91, 95% CI 0.37 – 2.23, p=1.00). There was no
apparent significant effect on SEH rates, although the overall
incidence of SEH was very low at 0.4% (RR 1.33, CI 0.50 – 3.56,
p=0.61). The timing of presentation of SEH was usually within
three days of surgery, but there were also several cases that
presented out to 20 days.
CONCLUSION
Administration of preoperative DVT prophylaxis does not
influence the rate of clinically relevant postoperative DVT or
PE, and probably does not affect SEH rates. Given the cost and
human resource burden of its administration, the use of
preoperative DVT prophylaxis is not recommended. In light of
the continued drive for early discharge, physicians need to be
cognizant that late presentation of SEH is possible, and that a
vigilance mechanism is required. Patients need to be informed
of the signs and symptoms of SEH, and counselled to present
immediately should they arise.
71
Notes & Questions
72
73
22 Free Papers Session 6
ScoliosisSaturday 16 April | 3.10pm - 4.30pm
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 6
SCOLIOSIS
Chair | Dr Peter Woodland
Arthur Streeton Auditorium
3.10pm | 6.1The measurement of applied forces during anterior single rod correction of adolescent idiopathic scoliosis (AIS)
*Fairhurst, H, Little, JP, Adam, CJ
Queensland University of Technology, Brisbane, Qld, Australia
INTRODUCTION
Following anterior thoracoscopic instrumentation and fusion for
the treatment of thoracic AIS, implant related complications have
been reported as high as 20.8% (Reddi, 2008). Currently the
magnitudes of the forces applied to the spine during anterior
scoliosis surgery are unknown. The aim of this study was to
measure the segmental compressive forces applied during
anterior single rod instrumentation in a series of AIS patients.
METHODS
A force transducer was designed, constructed and retrofitted
to a surgical cable compression tool, routinely used to apply
segmental compression during anterior scoliosis correction.
Transducer output was continuously logged during the compression
of each spinal joint, the output at completion converted to an
applied compression force using calibration data. The angle
between adjacent vertebral body screws was also measured
on intra-operative frontal plane fluoroscope images taken both
before and after each joint compression. The difference in angle
between the two images was calculated as an estimate for the
achieved correction at each spinal joint.
RESULTS
Force measurements were obtained for 15 AIS patients (Ages
11-19 years) with single thoracic curves (Cobb angles 47˚- 67˚).
In total, 95 spinal joints were instrumented. The average force
applied for a single joint was 540 N (± 229 N) ranging between
88 N and 1018 N. Experimental error in the force measurement,
determined from transducer calibration was ± 43 N. A trend for
higher forces applied at joints close to the apex of the scoliosis
was observed. The average joint correction angle measured by
fluoroscope imaging was 4.8˚ (±2.6˚, range 0˚-12.6˚).
CONCLUSION
This study has quantified in-vivo, the intra-operative correction
forces applied by the surgeon during anterior single rod
instrumentation. This data provides a useful contribution towards
an improved understanding of the biomechanics of scoliosis
correction. In particular, this data will be used as input for
developing patient-specific finite element simulations of scoliosis
correction surgery.
REFERENCE
1. REDDI, V.
Spine 33(18), 1986-1994, 2008.
74
3.18pm | 6.2The value of spinal cord monitoring in scoliosissurgery: A ten year experience *Liew, SM, Torode, IP, Nattrass GR, Johnson, MB,
Dickens, DRV, Watson, S, Simons, M
Royal Children’s Hospital, Melbourne, Vic, Australia
INTRODUCTION
Spinal cord monitoring in posterior scoliosis surgery is a standard
of care. At the Royal Children’s Hospital in Melbourne, we have
routinely monitored the somato-sensory potential (SEP) and
motor evoked potential (MEP) in all such procedures on ambulant
patients. We report on and discuss alterations in the spinal cord
monitor signal occurring in 33 of 374 consecutive patients.
METHODS
A retrospective review was undertaken of all patients who
underwent spinal cord monitoring during their procedure for
scoliosis +/- kyphosis correction and fusion. Data collection
included details on demographics, diagnosis, intraoperative course
including changes in potential, postoperative course, and
outpatient follow-up.
RESULTS
There were 374 ambulant patients who underwent spinal cord
monitoring during their posterior instrumented procedures
between 1999 and 2009. Surgery was performed by paired
combinations of five of the authors. In 33 cases there was a
change in one or both signals during the procedure. Seven signal
changes were directly related to changes in blood pressure, three
changes attributed to other anaesthesia-related issues, and the
rest thought to be implant or correction associated.
Fifteen patients had a post-operative neurological deficit, two of
whom had an intra-operative cardiac arrest. In these 15 cases,
five had complete loss of both the SEP and MEP signals, three
had more than 50% loss of both signals, three had complete loss
of the MEP signal only, and four had more than 50% loss of the
SEP signal only. Twelve patients had complete neurological
recovery within nine months but three patients continue to have
a residual neurological deficit.
Eighteen patients did not have a post-operative neurological
deficit. Of these patients, six had more than 50% loss of the SEP
signal only, four had complete loss of the MEP signal with one of
these four also having a <50% loss of SEP, and eight had <50%
loss of MEP.
CONCLUSION
On review of the management and outcome of these cases, we
conclude that profound hypotension will alter the SEP and may
herald a catastrophic cardiovascular or neurological event.
Continuous spinal cord monitoring can provide specificity in the
diagnosis of an actual or impending neurological insult and allow
for appropriate and timely intervention. We believe spinal cord
monitoring in the posterior approach for spinal deformity is an
invaluable tool and is in fact mandatory for all idiopathic, and
ambulant non-idiopathic spinal deformity surgery.
75
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 6 (continued)
SCOLIOSIS
Chair | Dr Peter Woodland
Arthur Streeton Auditorium
3.26pm | 6.3Do reinfusion drains following posterior instrumented spinal fusion for adolescent idiopathic scoliosis reduce allogenic blood requirements? A prospective audit with historical controls
*Selby, MD,1,3 Rehn, J,2 Sutherland, LM,2
Freeman, BJC,1,2,3 Cundy, PJ 1,2
1 University of Adelaide, Adelaide, SA, Australia2 Department of Orthopaedics, The Women’s and
Children’s Hospital, Adelaide, SA, Australia3 Spinal Injuries Unit,The Royal Adelaide Hospital, SA, Australia
INTRODUCTION
The management of blood loss in posterior instrumented spinal
fusion for the correction of Adolescent Idiopathic Scoliosis
remains a significant challenge. Allogenic blood transfusion carries
a risk of complications in addition to high costs and ongoing
availability issues (Shander, 2007). Many techniques are available
to reduce allogenic blood requirements but controversy remains
over the effectiveness of these interventions (Bowen, 2010).
This study aimed to confirm the effectiveness, safety and clinical
utility of reinfusion drains in this patient population.
METHODS
A prospective audit was undertaken of 18 consecutive patients
undergoing posterior instrumented spinal fusion for correction
of Adolescent Idiopathic Scoliosis in which a reinfusion drain was
used. This group was compared to a historical control group of
12 consecutive patients operated on by the same surgical team
in which no drain was used. Complete data was available for all
patients and statistical analysis performed.
RESULTS
There was a significant difference in the use of post-operative
allogenic blood transfusion between the two groups (p = 0.02),
with no patient requiring post-operative allogenic blood transfusion
in the reinfusion drain group. Post-operatively, a mean of 0.5 units
of allogenic blood was transfused in the no drain group (range
0-2). Autologous units were under-utilized in both groups with a
mean of 0.5 units transfused (range 0-2) and 1.17 units collected
(range 0-3) in the drain group, and a mean of 0.85 units transfused
(range 0-3) and 1.08 units (range 0-3) collected in the no drain
group. There were no other significant differences between the
two groups, including surgical time and number of levels fused.
There were no complications related to the use of a reinfusion
drain. Each drain costs $211 AUD and a unit of allogenic blood
is estimated to cost $690 AUD. Based on the mean usage of
allogenic blood, reinfusion drains were found to be cost-effective,
with an estimated saving of $41 AUD per patient.
CONCLUSION
We have shown that reinfusion drains in posterior instrumented
spinal fusion reduce the requirement for post-operative allogenic
blood transfusion in this patient population. Reducing allogenic
blood transfusion decreases risks of infection and other transfusion
related complications. Additionally, an increased rate of delayed
infection and wound complications has been reported where
wound drainage is not used in similar patient populations (Ho,
2007 and Blank, 2003). There have been concerns about the
cost-effectiveness and safety of reinfusion drains in total joint
arthroplasty (de Jong, 2007), however, we found the use of
reinfusion drains to be both safe and cost-effective.
REFERENCES
1. SHANDER et al.
Best Practice Research Clincal Anaesthesiology 2007;21:271-289
2. BOWEN et al.
Spine 2010;15:246-251
3. HO et al.
Spine 2007;15:2272-2277
4. BLANK et al.
J Spinal Disord Tech 2003;16:508-512
5. DE JONG
Clin Orthop Relat Res 2007;456:238-242
76
3.34pm | 6.4Serum titanium levels following paediatric spinal arthrodesis
*Cundy, TP, 1,2 Sutherland, LM,1,2 Antoniou, G, 3
Freeman, BJ, 2,4 Cundy, PJ 1,2
1 Department of Paediatrics, Faculty of Health Sciences,
University of Adelaide, Adelaide, SA, Australia2 Department of Orthopaedic Surgery, Women’s and
Children’s Hospital, Adelaide, SA, Australia3 Public Health Research Unit, Women’s and Children’s
Hospital, Adelaide, Adelaide,SA, Australia 4 Department of Orthopaedics and Trauma,
Royal Adelaide Hospital, Adelaide, SA, Australia
INTRODUCTION
Instrumented spinal arthrodesis is a common procedure to
correct scoliosis. Titanium-based instrumentation is becoming
increasingly favoured due to enhanced biomechanical properties,
but concerns have arisen regarding metal debris release and the
potential for local and systemic complications. The objectives of
this study were
1. To determine serum titanium, niobium and aluminium levels
at specific time points in paediatric patients following
instrumented spinal arthrodesis, and
2. To investigate predictive factors for the determination of
such serum metal concentrations including specific implant
characteristics.
METHODS
A prospective cohort study was designed to evaluate the pattern
of systemic metal release over time by comparing serum metal
levels at specific intervals: pre-operatively and at one-week,
one-month, six-months and one-year post-operatively. Serum
metal levels were measured using high-resolution inductively
coupled plasma mass spectrometry. Instrumentation for each
patient was catalogued and total construct surface area, total
exposed metal surface area and total metal-on-metal interface
surface area determined.
RESULTS
Twenty patients were included in the study group. Mean age
at surgery was 14.8 years. A significant difference between
pre-operative and post-operative concentrations was determined
for titanium and niobium (p=0.0001). Median post-operative
concentrations of titanium and niobium were elevated 2.5- and
6.0-fold above the normal range respectively with 98-99% of
samples elevated post-operatively. The critical period of metal
release was within the first week post-operatively. Significant
positive correlation was determined with metal levels and a
number of predictors. Multivariable linear regression analysis
revealed the number of screws to be the strongest predictor
of titanium and niobium levels (p<0.0001).
CONCLUSION
This study is the first prospective, longitudinal study measuring
serum metal levels at sequential time intervals in patients with
spinal implants. We report abnormally elevated serum titanium
and niobium levels in patients with titanium-based spinal
instrumentation and identify predictors of metal levels.
Previous studies of spinal arthrodesis cohorts have not sampled
patients for serum metal analysis within the first six-months
post-operatively. This may reveal why the critical chronological
period of surge in systemic debris release within the first week
post-operatively has not been captured before. The long-term
systemic consequences of debris generated by wear and
corrosion of spinal instrumentation is unclear but concerning,
particularly as these implants inserted into the paediatric
population may remain in-situ for beyond six decades.
77
SATURDAY 16 APRIL 2011
FREE PAPERS SESSION 6 (continued)
SCOLIOSIS
Chair | Dr Peter Woodland
Arthur Streeton Auditorium
4.02pm | 6.5Post-operative CT assessment of interbody fusiontwo years after thoracoscopic scoliosis surgery
*Carstens, A, Adam, C, Izatt, M, Labrom, R, Askin, GN
Paediatric Spine Research Group, Queensland University of
Technology and Mater Children’s Hospital, Brisbane, Qld, Australia
INTRODUCTION
The relationship between radiologic union and clinical outcome
in thoracoscopic scoliosis surgery is not clear, as apparent
non-union of a spinal fusion does not always correspond to a
poor clinical result. The aim of this study was to evaluate CT
fusion rates 2yrs after thoracoscopic surgery, and to explore the
relationship between fusion scores and;
1. rod diameter,
2. graft type,
3. fusion level,
4. implant failure, and
5. lateral position in the disc space.
METHOD
Between 2000 and 2006 a cohort of 44 patients had thoracoscopic
scoliosis correction. Discectomies were performed at instrumented
levels and defect was packed with either autograft (n=14), or
allograft (n=30). Instrumentation consisted of either 4.5mm
(n=24) or 5.5mm (n=20) single titanium anterior rod and vertebral
body screws (Medtronic). Fusion quality and implant integrity
were evaluated 2yr following surgery using low-dose CT. At each
disc space, left, right and mid-sagittal CT reconstructions were
generated and graded (ImageJ software, NIH, USA) using the
Sucato 4-point scale (Sucato, 2004) which is based on calculated
percentage of fusion across disc space.
RESULTS
Fusion scores were measured for 259 disc spaces in 44 patients.
Rod diameter had a strong effect on fusion score, with a mean
score of 2.12±0.74 for 4.5mm Ti rod, decreasing to 1.41+0.55
for 5.5mm Ti rod, and to 1.09+0.36 for 5.5mm Ti-alloy rod. Mean
fusion scores for autograft and allograft subgroups were 2.13±0.72
and 2.14±0.74 respectively. Fusion scores were highest in the
middle of implant construct, dropping off by 20-30% toward the
upper and lower ends. Fusion scores adjacent to the rod
(2.19±0.72) were significantly higher than on the contralateral
side of the disc space (1.24±0.85). Levels where rod fracture
occurred (n=11) had lower fusion scores than those without
fracture (1.09±0.67 vs 1.76±0.80). Levels where top screw
pullout occurred (n=6) had lower CT fusion scores than those
without (1.25±0.60 vs 1.83±0.76).
DISCUSSION
This is the first detailed investigation of CT fusion scores after
thoracoscopic scoliosis surgery. Rod diameter (larger), intervertebral
level (proximal or distal), lateral position in disc space (further
from rod) and rod fracture or top screw pullout all reduce fusion
scores, while graft type (autograft or allograft) does not affect
scores. However, the assumed link between higher fusion score
and better clinical outcome must be treated with caution, because
in this study rod fractures did not necessarily occur in patients
with lower fusion scores. It is possible that with a stiffer 5.5mm
rod, less bony fusion mass is required for a stable construct. We
propose that moderate fusion scores on the Sucato scale secure
successful clinical outcomes in thoracoscopic scoliosis surgery.
REFERENCE
1. SUCATO et al.
Recombinant human bone morphogenic protein-2 enhances
anterior spinal fusion in a thoracoscopically instrumented
animal model. JBJS (Am) April 2004; 86-A (4): 752-62
78
4.10pm | 6.6Minimally invasive spine surgery in adult deformitycorrection: A prospective case series of 37 patients
*Scott-Young, MN, 1 Magno, C,2 Nielsen, D,2
Mitchell, E, 2 Blanch, N 2
1 Bond University, Gold Coast, Qld, Australia 2 Gold Coast Spine, Gold Coast, Qld, Australia
INTRODUCTION
Adult spinal deformity is a complex musculoskeletal problem in
the aged patient. One of the drawbacks of an open technique is
the morbidity associated with the extensive soft tissue dissection
that is associated with traditional deformity correction. Minimally
invasive spinal surgery (MISS) techniques can be employed in
conjunction with modern surgical solutions to restore sagittal
balance and spinal alignment in degenerative spinal deformity.
This study evaluates the safety, efficacy, and outcomes of MISS
for complex de novo degenerative scoliosis.
METHODS
A prospective study including 37 patients with degenerative
spinal deformity were treated by MISS techniques. The patients
received MISS anterior lumbar interbody fusion (ALIF), direct
lateral interbody fusion (DLIF) and percutaneous and minimal
access technology with biological solutions, being recombinant
human bone morphogenetic protein – 2 (rhBMP-2). Diagnosis
was based on history, examination, MRI, CT discography, AP
lateral whole spine, and electrophysiological studies. The minimum
follow-up was 12 months. Ten patients were male and 27 patients
female, with an average age group of 66.51years (range = 44-82
yrs). The average operation duration was 146.73mins (range
75-300mins) with an average blood loss of 338.0mls (range
0-910.0mls).
Clinical outcomes were measured using Oswestry Disability Index
(ODI), Visual Analogue Score (VAS) back and leg, Roland Morris
Disability Questionnaire (RMDQ) and SF-36 questionnaires.
Patients were assessed preoperatively and at 3, 6 and 12 months.
Radiological assessment consisted of AP lateral whole spine,
flexion/extension standing films and a fine cut CT at 6 months.
Cobb analysis of sagittal and coronal balance was performed.
RESULTS
Analysis of results at latest follow-up vs. baseline were: mean
reduction in mean back VAS back scores reduced from
77.08±17.85 to 22.11±20.79 (-71.3%); mean right VAS leg score
reduced from 44.0±32.50 to 16.84±22.13 (-61.7%), while left
VAS leg scores reduced from 41.73±32.89 to 27.32±27.76
(-34.5%). Mean RMDQ reduced from 16.50±4.23 to 7.44±5.59
(-54.9%). ODI reduced from 46.54±17.08 to 25.46±17.89
(-45.3%); SF-36 PCS increased from 29.47±5.56 to 39.26±8.58
(+24.9%) and SF-36 MCS increased from 40.13±11.38 to
48.19±13.12 (+16.7%). Patient satisfaction surveys indicated that
77.78% patients rated their satisfaction with the surgery as
“excellent” or “good” 3-months following their operation. All
patients had greater than 50% correction of the preoperative
coronal and sagittal Cobb angles. Complications included one
vascular injury, one reoperation, and one L4 nerve root dysfunction.
No infections occurred, no blood transfusions were performed,
and there was no pseudoarthrosis.
CONCLUSION
Technological advances innovations appear to enhance the safety
and efficacy of MISS in elderly patients with adult spinal deformity.
This study has shown comparable clinical and functional outcomes
with traditional open techniques, as well as reduced complications.
Improvement in pre to post operative sagittal and coronal
balanced was achieved. The results of this preliminary study
suggest there is a role for MISS in the care of degenerative spinal
deformity. Confirmation through a controlled randomised
prospective study would be desirable.
79
Notes & Questions
80
81
22 Symposium 2
Surgery and Biomechanicsof Adult Degenerative DiseaseSunday 17 April | 8.30am - 10.00am
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
SUNDAY 17 APRIL 2011
SYMPOSIUM 2
SURGERY AND BIOMECHANICS
OF ADULT DEGENERATIVE DISEASE
Chair | A/Prof Graeme Brazenor
Arthur Streeton Auditorium
8.30am Sagittal balance and surgical strategy in adult high grade spondylolisthesis
A/Prof Chris Ames
Neurosurgery Department, University of California,
San Francisco, California, USA
High grade spondylolisthesis is in large part a disorder of spinal
pelvic alignment and global sagittal balance. Strategies to classify
and treat based upon this principal will be described in detail.
82
8.50am Stability of the osteoligamentous spine: The Follower Load and its implications to ex-vivo
testing and in-vivo spine stability
Prof Avinash Patwardhan
Department of Orthopaedic Surgery and Rehabilitation,
Loyola University Stritch School of Medicine,
Chicago, Illinois, USA
Muscle forces stabilize the osteoligamentous spine in vivo and
enable it to sustain bending moments as well as large compressive
preloads induced during activities of daily living (ADL). In the
absence of muscle forces, the multi-segment osteoligamentous
spine supports less than one-tenth of the compressive load
experienced during ADL. However, simulation of muscle forces in
experiments on the osteoligamentous spine has not been feasible
due to the large number of muscles and the uncertainty in load
sharing among the various muscles during different activities. As
a result, multi-segment specimens have been tested under pure
moments without a physiologic compressive preload. Since
biomechanical testing is an essential part of understanding spine
instability and developing appropriate treatment methods, ignoring
the effect of physiologic preload may lead to erroneous conclusions.
We reasoned that co-activation of trunk muscles could alter the
direction of the internal compressive force vector such that its
path followed the lordotic or kyphotic curve of the spine, passing
close to the instantaneous centers of rotation of each segment.
This would minimize the segmental bending moments and shear
forces induced by the compressive load, thereby allowing the
osteoligamentous spine to support loads that would otherwise
cause buckling of the column or tissue damage. The compressive
load vector described above is called a “follower load.”
This presentation will summarize our work leading to the
development of:
1. An experimental methodology to test multi-segment
osteoligamentous spines under loads of in vivo magnitude, &
2. A new hypothesis for the mechanism by which muscles
provide stability to the spine in vivo.
83
SUNDAY 17 APRIL 2011
SYMPOSIUM 2 (continued)
SURGERY AND BIOMECHANICS
OF ADULT DEGENERATIVE DISEASE
Chair | A/Prof Graeme Brazenor
Arthur Streeton Auditorium
9.15am A novel method of assessing facet joint motionusing specimen-specific CT based model
Prof Avinash Patwardhan
Department of Orthopaedic Surgery and Rehabilitation,
Loyola University Stritch School of Medicine,
Chicago, Illinois, USA
Recent clinical studies have shown accelerated degeneration of
facet joints at the index level after total disc replacement in the
lumbar and cervical spine. These changes may be due to a
mismatch between the kinematics of the native anatomy and the
prosthesis, leading to abnormal facet motions and loading. Our
goal was to develop a tool to assess facet joint motions without
making any assumptions regarding the host anatomy, tissue
properties, or the performance of the prosthesis implanted in a
motion segment.
Lumbar and cervical spine specimens were instrumented with
radiopaque markers on each vertebra. A 3-D specimen-specific
anatomical model of each specimen was reconstructed using
fine-slice axial CT scans. A digital link was established between
the radiopaque markers in the CT reconstruction and the
motion sensors attached to each vertebra by digitizing the
marker location relative to the motion sensors. Next, the
specimen’s kinematic response was measured in response to
flexion-extension, lateral bending, and axial rotation moments.
Three-dimensional motion of each vertebral body was tracked
using an optoelectronic motion measurement system. The motion
data obtained during the flexibility test was used to drive the
anatomical model. As a result, motion of anatomic landmarks on
the specimen could be assessed in response to the loads applied
to the specimen during flexibility tests.
The model was validated by comparing model-predicted motions
of anatomical points on each vertebra to those measured using
sensor data not used in the model development. The model
predicted motions were reliable within ±0.3mm of measured
motions. The model was used to visualize and quantify facet
kinematics in terms of facet overlap area, facet gapping, and
capsular strains in flexion-extension, lateral bending and axial
rotation.
This model couples an individual specimen’s 3-D CT-reconstruction
with its own kinematic data collected in the laboratory in order
to assess facet kinematics. This approach differs from the
traditional finite element models in that there are no assumptions
made regarding material properties, host anatomy or in situ
implant response. In addition to assessing the motion of facet
joints, the specimen-specific model can be also used to make
quantitative measurements of intervertebral foraminal and spinal
canal areas, and ligament stretches in the specimen’s intact state and
after a surgical procedure, at both the index and adjacent levels.
84
85
22 Free Papers Session 7
Spinal Cord InjurySunday 17 April | 10.30am - 12.00noon
Arthur Streeton Auditorium
S e s s i o n A b s t r a c t s
SUNDAY 17 APRIL 2011
FREE PAPERS SESSION 7
SPINAL CORD INJURY
Chair | Dr Gerald Quan
Arthur Streeton Auditorium
10.30am | 7.1VEGF and PDGF as an immunomodulatory strategy for the reduction of secondary degenerationafter a model spinal cord injury in rats
*Goss, B,3 Young, WY, 1, 2 Lutton, C,1 Williams, R,2
Meedeniya, ACB,3 Mackay-Sim, A,3
1 Institute of Health and Biomedical Innovation, Queensland
University of Technology, Brisbane, Australia 2 AOSpine Reference Centre, Institute of Health and
Biomedical Innovation, Queensland University of Technology,
Brisbane, Qld, Australia3 National Centre for Adult Stem Cell Research,
Griffith University, Brisbane, Qld, Australia
INTRODUCTION
Inflammation in most tissues is initially a protective attempt to
facilitate the removal of damaged tissue which ultimately transitions
to an anti-inflammatory nature thereby initiating a healing response.
However, after spinal cord injury (SCI), the inflammatory response
is prolonged and the anti-inflammatory response delayed, leading
to secondary degeneration and glial scarring. Here, we investigate
the potential of sustained delivery of vascular endothelial growth
factor (VEGF) and platelet derived growth factor (PDGF) to
increase early inflammatory events and promote inflammatory
resolution in both hemisection and contusion injury models of SCI.
METHODS
Animal ethics approval was obtained from the Queensland
University of Technology. Adult Wistar-Kyoto rats (12-16 weeks
old) were subjected to laminectomies and T10 hemisections or
150 kDyne T10 contusion with an infinite horizions impactor.
Animals were then randomised to low dose treatment
(implantation of osmotic pump (Alzet) loaded with 5ug VEGF &
5 g PDGF) high dose treatment (implantation of osmotic pump
(Alzet) loaded with 15ug VEGF & 15 g PDGF) or control
groups (lesion control or lesion plus pump delivering PBS).
Rats were sacrificed at one month and the spinal cords were
harvested and examined by immunohistology, using anti-
neurofilament-200(NF200) and anti- ionized calcium binding
adapter molecule 1 (Iba1) and the chondroitin sulphate
proteoglycan NG2. Behaviour was assessed using open field and
digigait analysis. One way ANOVA was used for statistic analysis.
RESULTS
At 1 month, both high and low dose active pump-treated cords
showed a high level of axonal filament throughout the defects.
The mean lesion size, as measured by NF200, was 0.53+/-0.12
mm2 for the lesion control, 0.39+/-0.10mm2 for the vehicle
control and 0.10+/- 0.03mm2 for the low dose active pump
group and 0.001+/-0.001 mm2 for the high dose pump
(p<0.001). Animals undergoing a contusion injury showed that
the lesion area was reduced to 5% of the control animals. Iba-1
and NG2 co-staining also showed significant differences in the
post-injury inflammatory response and indicated the presence of
a regenerative phenotype of inflammatory cells.
CONCLUSION
We have shown that delivery of VEGF/PDGF from the time of
spinal cord injury reduces or eliminates secondary degeneration.
In these experiments, the high dose growth factors eliminated
the lesion cavity at 1 month. These experiments were based on
the hypothesis that secondary degeneration would be reduced if
inflammation could be resolved at the injury site, and that VEGF
and PDGF would do this by stimulating the initial availability and
activation of macrophages early in the inflammatory process and
accelerate inflammatory resolution.
86
10.38am | 7.2The pressure distribution of cerebrospinal fluid responds to residual compression and decompression in an animal model of acute spinal cord injury
*Jones, CF,1,2,3 Newell, RS,1,2,3 Lee, JHT, 1 Cripton, PA,1,2,3
Kwon, BK,1,3
1 International Collaboration on Repair Discoveries
University of British Columbia, Vancouver, Canada 2 Department of Mechanical Engineering
University of British Columbia, Vancouver, Canada3 Department of Orthopaedics
University of British Columbia, Vancouver, Canada
INTRODUCTION
Lowering intrathecal pressure via the drainage of cerebrospinal
fluid (CSF) through a lumbar intrathecal catheter is currently
instituted to prevent ischemia-induced spinal cord injury (SCI)
during aortic aneurysm surgery (Estrera, 2005). This was recently
investigated as a potential intervention for patients with acute
traumatic SCI (Kwon, 2009). However, in such patients, persistent
extradural compression can occlude the subarachnoid space,
either partially or completely. This may generate differential CSF
pressures across the injury site, which cannot be fully appreciated
in the clinical setting because the lumbar intrathecal catheter
resides caudal to the injury. The purpose of this study was to
measure CSF pressure (CSFP) and pulse pressure amplitude
(CSFPPA) cranial and caudal to the injury site, and to assess
changes that occur with extradural compression, subarachnoid
occlusion, and decompression.
METHODS
Fourteen pigs received a moderate or severe acute contusive
SCI at T11 (N=6 each) or sham surgery (N=2), followed by
eight hours of sustained compression at the injury site. Pressure
transducers in the subarachnoid space cranial and caudal to the
injury site measured CSF pressure during compression and for
six hours post-decompression.
RESULTS
A linear mixed model indicated that the CSFP differential (cranial
- caudal) increased at 0.39 mmHg/hr, predominantly due to
increased cranial CSFP. Cranial CSFP decreased on average
by -1.16 mmHg and caudal CSFP increased by 0.65 mmHg in
immediate response to decompression. The CSFP differential did
not change significantly in the post-decompression period. At the
time of decompression the caudal CSFPPA increased in some
but not all animals; the mean change was not significant
(-0.01±0.1 mmHg, p=0.63).
CONCLUSION
While extradural compression remains on the site of SCI, the
CSF pressure measured caudally may not be an accurate indicator
of CSF pressure cranial to the injury. Decompression may provide
immediate, though perhaps partial, resolution of the pressure
differential. Pulse pressure amplitude was not a consistent indicator
of successful decompression in this animal model. These findings
extend our observations of CSF pressure changes that occur
after human SCI, and may have implications for future clinical
protocols in which CSF pressures are monitored after acute SCI.
REFERENCES
1. ESTRERA, AL et al.
Ann Thorac Surg. 80(4) 1290-6, 2005.
2. KWON, BK., et al.
J Neurosurg Spine. 10(3) 181-93, 2009.
87
SUNDAY 17 APRIL 2011
FREE PAPERS SESSION 7 (continued)
SPINAL CORD INJURY
Chair | Dr Gerald Quan
Arthur Streeton Auditorium
10.46am | 7.3Gross morphological changes of the spinal cordimmediately after surgical decompression in alarge animal model of traumatic spinal cord injury
*Jones, CF,1,2,3 Kwon, BK,1,3 Cripton, PA,1,2,3
1 International Collaboration on Repair Discoveries
University of British Columbia, Vancouver, Canada 2 Department of Mechanical Engineering
University of British Columbia, Vancouver, Canada3 Department of Orthopaedics
University of British Columbia, Vancouver, Canada
INTRODUCTION
The role of surgical decompression for traumatic spinal cord injury
(SCI) is controversial (Furlan, 2010). Intra-operatively, surgeons
can typically confirm the adequacy of their decompression
(Lerch, 2002). However, postoperative imaging often reveals the
cord has swollen to fill the subarachnoid space. The objective of this
study was to use ultrasound in a large animal model of traumatic
SCI to study morphologic changes of the spinal cord and dura
during six hours immediately following surgical decompression.
METHODS
Anaesthetised Yucatan miniature pigs (~20 kg) were subjected to
a moderate (N=6, 20 g, 2.3 m/s) or high (N=6, 20 g, 4.7 m/s)
severity weight drop SCI at T11, with a 100g weight providing
ongoing compression afterwards; one animal received sham
surgery. At 8 hr post-injury the weight was removed to simulate
surgical decompression. Prior to injury and for 6 hours post-
decompression, mid-sagittal ultrasound images were taken to
measure cord and thecal sac diameters.
RESULTS
We identified three main patterns of cord response:
1. residual deformation followed by swelling;
2. gradual swelling leading to thecal occlusion; and,
3. rapid swelling and interruption of the anterior pia / spinal cord
Moderate injury severity animals exhibited residual cord
deformation of up to 0.64 mm within 10 mins of decompression,
which tended to resolve over six hours. High severity injuries
exhibited substantial swelling immediately after decompression,
resulting in occlusion of the subarachnoid space in all animals,
while this occurred for only 50% of the moderate injury group.
CONCLUSION
Swelling of the spinal cord can occur very quickly after surgical
decompression, and may occlude the subarachnoid space within
hours. The pressure that the dura may exert upon the swollen
cord may attenuate the benefits of surgical decompression. These
observations suggest that it may be important to reduce cord
swelling in order to optimize the clinical outcome after acute
traumatic SCI.
REFERENCES
1. FURLAN, JC et al.,
J Neurotrauma. 27, 2010.
2. LERCH, K, et al.
Ultrasound Med Biol, 28(1), 27-32, 2002.
88
11.09am | 7.4
The role of spinal injury units in Australia:
The effects of early and direct admission in
spinal cord injured patients
*Schiller, MD,1 Mobbs, RJ,1,2 Lee, BB,1,2 Stanford, RE,1,2 Marial, O2
1 University of New South Wales, Sydney, NSW, Australia2 Prince of Wales Hospital, Sydney, NSW, Australia
INTRODUCTION
The importance of specialised multidisciplinary care at a spinal
injury unit (SIU) in the early management of acute traumaticspinal
cord injury (ATSCI) is not clearly established or differentiated
from care provided at general trauma centres. This study compared
the outcomes of spinal cord injured patients presenting at a SIU
early vs. late, and those referred directly vs. indirectly, in order to
determine the benefit or otherwise of care provided at SIUs.
METHODS
A prospective cohort study was conducted on ATSCI patients
admitted to a Sydney SIU between 2001 and 2009, using the
New South Wales Spinal Cord Injury Database. 296 persons
were identified. Patients were divided into those admitted within
24 hours of injury or later, and also into those who were admitted
directly or indirectly to the SIU hospital. Groups were analysed for
potential differences in ASIA Grade at admission, neurological level
of injury at admission, and Injury Severity Score. Main outcome
measures were complications during stay, length of stay, and cost of
stay. Logistic regression was used to control for differences in age.
RESULTS
There were no significant differences between either sets of
groups in any of the potential confounders except age. Compared
to delayed admission, admission within 24 hours led to significantly
decreased number of pressure ulcers, UTIs, and total number of
complication types (out of five), as well as decreased length and
cost of stay. Compared to indirect admissions, direct admission
led to significantly decreased numbers of pressure ulcers, as well
as decreased length and cost of stay.
CONCLUSION
Early management of ATSCI at a SIU may improve patient
outcomes by reducing the rate of major complications, as well as
length and cost of hospitalisation. We believe that wherever it is
safe and feasible, ATSCI patients should be admitted directly into
a SIU, or transferred to a SIU within 24 hours from injury.
89
Variable Timing of admission Type of admission
Early (!24 hours) Late (>24 hours) Significance Direct Indirect Significance
n 184 112 - 81 215 -
Age (years) Mn: 34.9 SD: 14.9 Mn: 44.3 SD: 19.0 p<0.001* Mn: 34.9 SD: 16.5 Mn: 39.9 SD: 17.3 p=0.025*
Neurological level of injury Md: C6 R: C2-S3 Md: C7/C8 R: C2-L3 p=0.234 Md: C6 R: C2-L5 Md: C6 R: C2-S3 p=0.847
ASIA Grade Md: C R: A-D Md: C R: A-D p=0.922 Md: 3 R: A-D Md: 3 R: A-D p=0.669
ISS† Mn: 23.8 SD: 8.5 Mn: 26.2 SD: 10.4 p=0.056 Mn: 23.0 SD: 7.8 Mn: 25.3 SD: 9.7 p=0.076
Pressure ulcers (number) Md: 0 R: 0-9 Md: 1 R: 0-10 p=0.007* Md: 0 R: 0-9 Md: 1 R: 0-10 p=0.002*
UTIs (number) Md: 0.5 R: 0-6 Md: 1 R: 0-9 p=0.035* Md: 1 R: 0-5 Md: 1 R: 0-9 p=0.502
DVT (number) Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.837 Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.057
PE (number) Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.094 Md: 0 R: 0-2 Md: 0 R: 0-2 p=0.478
Pneumonia (number) Md: 0 R: 0-4 Md: 0 R: 0-10 p=0.503 Md: 0 R: 0-3 Md: 0 R: 0-10 p=0.906
Complication types (number) Md: 1 R: 0-5 Md: 2 R: 0-5 p=0.023* Md: 1 R: 0-5 Md: 2 R: 0-5 p=0.240
Total LOS (days) Md: 129 R: 1-791 Md: 170 R: 9-837 p=0.005* Md: 125 R: 1-434 Md: 151 R: 2-837 p=0.026*
Cost of stay (AU$) Md: 151k R: 3-1065k Md: 192k R: 14-1398k p=0.023* Md: 138k R: 3-514k Md: 174k R: 3-1398k p=0.049*
n = no. of patients
Mn = mean
SD = standard deviation
Md = median
R = range
* Statistically
significant (p<0.05)
† n = 170 for early,
n = 77 for late;
n = 76 for direct,
n = 171 for indirect.
DemographicsOutcomes
SUNDAY 17 APRIL 2011
FREE PAPERS SESSION 7 (continued)
SPINAL CORD INJURY
Chair | Dr Gerald Quan
Arthur Streeton Auditorium
11.17am | 7.5Sequential reduction protocol using vector principle for cervical fracture dislocations Srivastava, RN
KG Medical College, CSM Medical University, Lucknow, India
INTRODUCTION
Management of cervical fracture-dislocation by skull-tongs is the
best & safest method for reduction of the skeletal injury and
decompression of the spinal cord. Controversial is the upper
limits of weight recommended. As per Sabiston,CP et al.
(J.Trauma. 1988 Jun; 28(6):832-5) traction up to 70% body weight
and Star AA et al. (Spine 1990 Oct; 15(10):1068-72) up to 100
lbs is safe.
This study was undertaken to evaluate:
1. A step wise reduction protocol for safe & effective reduction in
traumatic quadriplegia by judicious application of traction vector
2. Upper limit of weight required for reduction by skeletal traction
METHODS
A sequential protocol was followed in treatment of all the cases.
Skeletal traction was applied by Crutchfield tongs on the day of
admission and by judicious application of traction in following
steps. Bricks of standard size weighing 6.14 lbs each were used as
traction weights. To begin with 18.42 pounds, traction vector was
kept in flexion by elevating the horizontal bar supporting the
traction cord and placing bolsters beneath one or both the
shoulder blades. After 6-8 hours, maintaining traction, vector
angle was brought to neutral position by lowering the horizontal
bar and removing the bolsters. By gentle palpation of spinous
processes, realignment was judged and X-rays were taken to
confirm the reduction. If reduction was achieved it was
maintained in extension by further lowering the horizontal bar
and placing the bolsters or neck rolls beneath the neck at the site
of the lesion. If reduction was not achieved, then weights were
added in 6.14 pound increments at 6 hourly interval and the
sequential steps of traction in flexion, neutral and then extension
were repeated. Traction vector was easily altered with the help of
bolsters under shoulders or neck and proper placement/level of
the horizontal rod supporting the traction cord.
RESULTS
Reduction was achieved in 41 of 47 cases (87.22%) within 48
hours. Maximum weight needed was 36.84 pounds. Six irreducible
dislocations showed symptoms of cord stretching when more
than 36.84 pounds weight were applied, and needed open
reduction. Manipulation under anaesthesia was also tried in 4 of
these 6 patients but reduction could not be achieved and were
taken up for open reduction thereafter.
CONCLUSION
Cervical fracture-dislocations can be reduced without the need
of heavy traction of 100lbs or 70% body weight, if traction is
applied on vector principles. The sequential reduction protocol
suggested here is safe, effective and easily monitored. If traction
vector is altered as described only 36.84 lbs is sufficient for
reduction and recovery. The proposed protocol requires much
less weights than recommended.
90
11.25am | 7.6MRI in spinal trauma: A predictor of neurological recovery Srivastava, RN
KG Medical College, CSM Medical University, Lucknow, India
INTRODUCTION
Use of Magnetic Resonance Imaging appears to be of great help
in diagnosing spinal trauma because of better contrast resolution,
absence of bony artifacts, multiplanar imaging and choice of pulse
sequences. In cases of spinal cord ischemia, hemorrhage, edema,
and contusion, MRI findings may serve as prognostic indicators.
Aims and Objective
To compare and correlate the MRI findings with those of patients
clinical profile and neurological outcome to assess prognostic and
clinical value of MRI in patients with acute spinal cord injury.
METHODS
We performed this prospective study on sixty two patients of
acute spinal trauma. We evaluated the epidemiology of spinal
trauma & various traumatic findings by MRI. Then the MRI findings
were correlated with clinical findings at admission & discharge
according to ASIA impairment scale. Four types of MR signal
patterns were seen in association with spinal cord injury - cord
edema / non haemmorhagic cord contusion (CC), severe cord
compression (SCC), cord hemorrhage (CH) and epidural
hematoma (EH). Isolated lesion of cord contusion was found in
40%. All other MR signal patterns were found to be in combination.
In cord contusion we further subdivided the group into contusion
of size < 3 cm and contusion of size > 3 cm to evaluate any
significance of length of cord contusion. In cord haemmorhage
involving >1cm of the cord, focus was said to be sizable.
RESULTS
On bivariate analysis, there was a definitive correlation of cord
contusion (CC) involving <3cm & > 3cm of cord with sensory
outcome. In >3cm, chances of improvement was 5.75 times
lesser than in patients with CC involving <3cm of cord (odds
ratio = 5.75 (95% CI: 0.95, 36), Fisher’s exact p = 0.0427 (p<.05).
In severe cord compression (SCC) the risk of poor outcome was
more (odds ratio 4.3 and p=0.149) however was not statistically
significant. It was noted that the patients in which epidural
hematoma (EH) was present, no improvement was seen,
however, by statistical analysis it was not a risk factor and was
not related with the outcome (odds ratio – 0.5 and p = 0.22).
Presence of cord oedema / non haemorrhagic contusion was not
associated with poor outcome (odds ratio 0.25 and p=0.178).
On multiple logistic regression / multivariate analysis for estimating
prognosis, sizable focus of haemorrhage was most consistently
associated with poor outcome (odds ratio -6.73 and p= 0.32)
however it was not statistically significant. The risk of retaining a
complete cord injury at the time of follow up for patients who
initially had significant haemorrhage in cord was more than 6 fold
with patients without initial haemorrhage (odds ratio 6.97 and
p= .0047).
CONCLUSION
Besides being helpful in diagnosis, MRI findings may serve as a
prognostic indicator for clinical, neurological and functional
outcome in acute spinal trauma patients.
8791
SUNDAY 17 APRIL 2011
FREE PAPERS SESSION 7 (continued)
SPINAL CORD INJURY
Chair | Dr Gerald Quan
Arthur Streeton Auditorium
11.33am | 7.7Traumatic central cord syndrome: Is it associated with better neurological recoveryand functional outcomes when compared tomotor incomplete tetraplegia?
*Van Middendorp, JJ,1 Pouw, MH,1 Hosman, AJF,1
Van de Meent, H,1 Curt, A,2
1 Spine Unit, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
2 Spinal Cord Injury Center, University Hospital Balgrist, Zürich, Switzerland.
INTRODUCTION
The traumatic central cord syndrome (TCCS) is a clinical diagnosis
which is characterized by the following:
1. A disproportionate impairment (weakness & reduced function)
of the upper limbs compared with the lower limbs,
2. Neurogenic bladder dysfunction and
3. Varying degrees of sensory loss at and below the level of
lesion. In a prospective European multicenter cohort study,
we compared the neurological recovery and functional
outcomes between TCCS patients and motor incomplete
tetraplegic patients.
METHODS
In 248 traumatic motor incomplete tetraplegics, initial phase
(0 -15 days) American Spinal Injury Association (ASIA) impairment
grading, upper and lower extremity motor scores (UEMS & LEMS),
upper and lower sensory scores and chronic phase (6 or12 mths)
neurological outcomes were analyzed. In addition, chronic phase
self-care and indoor mobility Spinal Cord Independence Measure
(SCIM) items were studied. Tetraplegics were subdivided into
three groups:
1. Non-TCCS group (UEMS"LEMS),
2. Intermediate-TCCS group (UEMS=(1–9 points)<LEMS) and
3. TCCS group (UEMS=("10 points)<LEMS). Student’s t-tests
and 2-tests were applied.
RESULTS
A total of 89 non-TCCS subjects (AIS D, n=28), 62 int-TCCS
(AIS D, n=43) and 97 TCCS (AIS D, n=80) subjects were analyzed.
Although minimal significant differences in chronic phase LEMS
and UEMS outcomes were identified between TCCS and
non-TCCS patients after stratification by the AIS grade, our data
showed no significant differences in functional upper and lower
extremity outcomes at 6 or 12 months post-injury.
CONCLUSION
The AIS grading system, and not the diagnosis TCCS, continues to
be the best available prognostic parameter for neurological and
functional outcomes in motor incomplete tetraplegics. We
recommend that for future outcome studies in motor incomplete
tetraplegia, patients should not be selected based on, or stratified
by, the diagnosis TCCS.
REFERENCES
1. POUW, MH, VAN MIDDENDORP, JJ, VAN KAMPEN, A,
HIRSCHFELD, S, VETH, RP
EM-SCI study group, Curt A, Hosman AJ, van de Meent H.
Diagnostic criteria of traumatic central cord syndrome,
Part 1: A systematic review of clinical descriptors and scores.
Spinal Cord. 48(9), 652-56, 2010
2. VAN MIDDENDORP, JJ, POUW, MH, HAYES, KC, WILLIAMS, R,
CHHABRA, HS, PUTZ, C, VETH, RPH, GEURTS, ACH, AITO, S,
KRIZ, J, MCKINLEY, W, VAN ASBECK, FWA, CURT A,
FEHLINGS, MG, VAN DE MEENT, H, HOSMAN, AJ.
Diagnostic criteria of traumatic central cord syndrome,
Part 2: A questionnaire survey among spine specialists.
Spinal Cord. 48(9), 657-63, 2010.
3. POUW, MH,* VAN MIDDENDORP, JJ,* VAN KAMPEN, A,
CURT, A, VAN DE MEENT, H, HOSMAN, AJ for the EM-SCI
study group. Diagnostic criteria of traumatic central cord
syndrome. Part 3: Descriptive analyses of neurological and
functional outcomes in a prospective cohort of traumatic
motor incomplete tetraplegics. Spinal Cord. 2010. [Epub
ahead of print] *: Both authors contributed equally.
92
93
22 Poster Presentations
S e s s i o n A b s t r a c t s
POSTER PRESENTAT IONS
1. Clinical validity of the nerve root sedimentation sign for the diagnosis of lumbar spinal stenosis
*Melloh, M,1 Barz, T, 2 Staub, LP, 3 Lord, SJ,3,4 Merk, HR,5 Theis, JC1
1 Department of Orthopaedic Surgery, Dunedin School of
Medicine, University of Otago, New Zealand2 Department of Orthopaedic Surgery, Asklepios Klinikum
Uckermark, Germany3 NHMRC Clinical Trials Centre, University of Sydney,
Sydney, NSW Australia4 The Screening and Test Evaluation Program, University of
Sydney, Sydney, NSW Australia5 Department of Orthopaedic Surgery, University of Greifswald,
Germany
INTRODUCTION
The Nerve Root Sedimentation Sign in transverse magnetic
resonance imaging has been shown to discriminate well between
selected patients with and without lumbar spinal stenosis (LSS),
but the performance of this new test, when used in a broad
patient population, is not yet known (Barz et al. 2010).
METHODS
We conducted a retrospective study of consecutive patients with
suspected LSS from 2004-2006, before the sign had been described,
to assess its association with health outcomes. Based on clinical
and radiological diagnostics, patients had been treated with
decompression surgery or conservative treatment (physical therapy,
oral pain medication).Changes in the Oswestry Disability Index(ODI)
from baseline to 24 month follow-up were compared between
Sedimentation Sign positives and negatives in both treatment arms.
RESULTS
Of the 146 included patients (52% female, mean age 59 yrs), 71
underwent surgery. Baseline ODI in this treatment arm was 52%,
the sign was positive in 44 patients (mean ODI improvement 25
points) & negative in 27 (ODI improvement 24), with no significant
difference between groups. In the 75 patients of the conservative
treatment arm, baseline ODI was 44%, the sign was negative in
45 (ODI improvement 17), and positive in 30 (ODI improvement
5). Here a positive sign was associated with a smaller ODI
improvement compared with sign negatives (t-test, p=0.003).
CONCLUSION
This study allowed an unbiased clinical validation of the
Sedimentation Sign by avoiding it influencing treatment selection.
In patients commonly treated with decompression surgery, the
Sedimentation Sign does not appear to predict surgical outcomes.
Patients with beginning LSS due to spondylolisthesis or scoliosis
were also included here, which explains the sign negatives. In the
conservative treatment arm a positive sign appears to identify a
group of patients who are less likely to benefit. In these cases,
surgery might be effective; however, this needs confirmation in
prospective studies.
REFERENCES
1. BARZ, T, MELLOH, M, STAUB, LP, LORD, SJ, LANGE, J,
RODER, CP, THEIS, JC, MERK, HR 2010
Nerve root sedimentation sign: Evaluation of a new
radiological sign in lumbar spinal stenosis. Spine, 35, 892-7.
2. Flexural properties of an elastomeric total disc replacement
*Mahomed, A,1 Moghadas, PM,1 Shepherd, DET, 1
Hukins, DWL,1 Roome, A,2 Johnson, S 2
1 University of Birmingham, UK2 Ranier Technology Limited, Cambridge, UK
INTRODUCTION
Elastomeric Total Disc Replacements (TDR) have been developed,
whose aim is to provide motion properties resembling those of
the natural disc. Unlike articulating TDRs, elastomeric devices
attempt to restore axial stiffness and flexural stiffness. It is not
clear how the flexural properties of elastomeric implants may
alter with varying axial compressive loads and flexural rates. The
flexural stiffness of the natural spine increases as the applied axial
load increases (Stokes et al., 1999; Patwardhan et al., 2003; Janevic
et al., 1991). It was anticipated that elastomeric TDR would
94
exhibit similar characteristics. The aim of this study was to
quantify the change in flexural properties of an elastomeric TDR
(Cadisc™-L) when subjected to increasing magnitudes of axial
load and at different flexural rates.
METHOD
Six CadiscTM-L lumbar devices (MC-10mm-12° size, Ranier
Technology Ltd, Cambridge, CB5 8AA, UK), were tested using a
BoseTM spinal disc testing machine (Bose Corporation,
ElectroForce Systems Group, Minnesota, USA.) in Ringer’s
solution at 37 °C. A fixed static load of (1000 N, 1500 N or
2000 N) was applied to a device and it was then subjected to
motions of 0° to 6° to 0° (flexion) and 0° to -3° to 0° (extension)
at rates of 0.5 °/s, 1.0 °/s and 2.0 °/s as recommended by BS ISO
18192-1:2008 and previous literature (de Visser et al., 2007).
Results were compared statistically using a Student’s t-test.
RESULTS
Figure 1 shows the variation of torque with flexion and extension
angle at different compressive loads and flexural rates. Torque
increases linearly with flexion and extension angles at all flexural
rates (results shown for 1500 N and 2000 N to make graphs
clearer). Figure 2 shows the change in implant stiffness at different
flexural rates at 1000 N, 1500 N and 2000 N; the flexural
stiffness of the implant increases with increasing load in both
flexion and extension motions.
FIGURE 1: Change in implant torque response (expressed as a % of the total torque) at the different load
FIGURE 2: Change in implant flexural stiffness in response to increasing load
CONCLUSION
Elastomeric TDRs are intended to provide mechanical and motion
properties that resemble those of the natural disc. Natural discs
loaded under a pure bending moment between 3-10 N.m
achieved flexion angles between 5-15° (Wilke et al.,1997); the
results presented show the Cadisc™-L to be within this range.
In this investigation, flexural stiffness increases with load which is in
agreement with changes observed within the natural lumbar spine
(Patwardhan et al., 2003; Stokes et al., 2003; Janevic et al., 1991).
REFERENCES
1. STOKES, IAF, et al
J. Electromyo. .Kinesiol.13, 397-402, 2003
2. PATWARDHAN, AG, et al
J. Orthop. Res. 21, 540-546, 2003
3. JANEVIC, J, et al
J. Orthop. Res. 9; 228-236. 1991
4. DE VISSER, H, et al
Proc. Inst. Mech. Eng. [H], 221, 221-227, 2007
5. WILKE, HJ, et al
Spine, 22, 2365-2374, 1997
95
POSTER PRESENTAT IONS
3. Management of cervicothoracic junction fracture dislocations
*Wong, E,1 De La Harpe, D,2 Ton, L, 2 Rogers, M,2 Wilde, P 2
1 Emory University, Decatur, Georgia, USA2 Vertebral Column Surgical Group and Victorian Spinal Cord
Injury Service, Austin Health, Heidelberg, Vic, Australia
INTRODUCTION
Unstable fractures at the cervicothoracic junction is a rare injury
with a variation of injury patterns and poor neurological outcome.
Diagnosis of these injuries require good imaging and fixation is
biomechanically challenging. The aim of this study was to evaluate
the surgical experience in treating traumatic fractures at the
cervicothoracic junction.
METHODS
There were 11 patients who underwent surgery for unstable
fractures / dislocation at the cervicothoracic junction between
2006 to 2008. Clinical outcome was evaluated using ASIA scoring
and radiological outcomes using CT scans and plain radiographs.
Follow-up periods ranged from 11 to 48 months, with an average
of 18 months.
RESULTS
9 patients sustained complete neurologic deficits with no recovery
ASIA A with the remaining in ASIA B. Neurologic deficit was
related to the degree of anterior displacement of C7 on T1.
8 patients sustained a C7 burst fracture and 3 had a C7 T1 fracture
dislocation. Anterior corpectomy and fusion was performed in 8
patients. Posterior reduction and rod - screw fixation was done in
1 patient while a combined approach and fixation was performed
for 2 patients. There was a complication of misplaced upper
cervical plate screws with tilting of the mesh cage inferiorly. No
subsequent displacement of the implant was noted on follow-up.
CONCLUSIONS
Fracture-dislocation at the cervicothoracic junction is a rare
injury with a poor neurologic outcome. The anatomic and
biomechanical features of the cervicothoracic junction require
the selection of suitable approach and implants. The anterior
approach is valuable in treating burst fractures at C7. Facet
dislocations at the cervicothoracic junction are best treated with
a posterior lateral mass and pedicle screw fixation or with a
combined approach.
4. Surgery for cervical facet dislocations: Which approach?
*Wong, E,1 De La Harpe, D,2 Ton, L, 2 Rogers, M,2 Wilde, P 2
1 Emory University, Decatur, Georgia, USA2 Vertebral Column Surgical Group and Victorian Spinal Cord
Injury Service, Austin Health, Heidelberg, Vic, Australia
INTRODUCTION
The surgical treatment of traumatic cervical facet dislocations is
highly variable. There is lack of consensus on the surgical approach
and the variables that influence it in these patients. The aim of this
study is to determine the fracture patterns involving unilateral or
bilateral facet fractures and analyse optimum management
strategies and approaches for these injuries.
METHODS
This is a retrospective study of patients with cervical facet
dislocations surgically treated at a spinal trauma and cord injury
referral center. All 36 consecutive cases of surgically treated
unilateral and bifacetal fracture dislocations were included in this
study. No preoperative reduction was performed in all cases.
Presenting history, neurologic examination (ASIA grading),
imaging findings and type of surgery were recorded. All patients
had CT and MRI scans of their cervical spine prior to surgery.
Injury patterns were characterized using the Subaxial Cervical
Spine Injury Classification System (SLIC) classification.
RESULTS
Between 2004 - 2008, there were 21 cases with bilateral facet
dislocation, of which 9 were associated with a vertebral burst
fracture. Unifacetal dislocation was found in 15 cases (right n=9
and left n= 6). All fractures had 6 - 9 points on the SLIC scale. All
fractures had distraction or distraction with translational type
96
morphology. 50% of the cases in the bifacetal group had a
combined anterior and posterior approach and fixation compared
to 20% in the unifacetal group (p <0.05). The average follow-up
was 24 months. There were three complications in the bifacetal
dislocation group. One patient developed kyphosis at the level of
injury while another had inadequate cord decompression and a
misplaced lateral mass screw.
CONCLUSIONS
Cervical bilateral facet fractures are associated with higher
complication rates and more severe injury patterns often with
disruption of all discoligamentous complexes. The integrity of the
discoligamentous structure and surgeon preference were the
significant factors influencing the surgical approach in treating
these fractures.
5. MRI changes in cervical cord injuries
*Wong, E,1 Calver, N,3 De La Harpe, D,2 Ton, L, 2 Rogers, M,2
Wilde, P 2
1 Emory University, Decatur, Georgia, USA2 Vertebral Column Surgical Group and Victorian Spinal Cord
Injury Service, Austin Health, Heidelberg, Vic, Australia3 Department of Radiology, Austin Health, Heidelberg,
Vic, Australia
INTRODUCTION
There is lack of data in the literature regarding the extent of
discoligamentous injuries, cord and canal changes which occur in
patients with bifacetal and burst fractures with complete
neurologic injury. The aim of this study was to compare the findings
in both the groups and determine if there was any correlation
between the cord compression, canal changes and space available
for the spinal cord.
METHODS
Clinical data and radiologic studies of patients with cervical spinal
cord injury (SCI) involving the subaxial spine (C3-T1) were
included in the study. The neurologic status of each patient was
classified according to the standardized American Spinal Injury
Association (ASIA). Imaging performed included lateral radiographs,
(CT) scans and sagittal T1- and T2-weighted magnetic resonance
images (MRI). Data obtained from the CT scan was the Maximum
Canal Compromise (MCC). MRI imaging provided data on the
status of the discoligamentous injuries and changes within the
spinal cord. The amount of Maximum Spinal Cord Compression
(MSCC) was calculated from midsagittal T2 scans. The SAC data
was compared the various injury levels with data from normal
patients.
RESULTS
There were 9 patients with cervical bifacetal fracture and 9 with
burst fractures included in the study. 5 patients with normal MRI
findings were used as controls with cord and canal measure-
ments done at C3-C7 levels. All patients had ASIA A neurologic
grading and were all surgically stabilized. In the bifacetal dislocation
group MSCC was 19.28% and MCC 28.44%. The mean
discoligamentous score (MDLS) was 8.33.
Cord signal changes and haematoma was found in 88.9% and
33.3% respectively. Cord to canal ratio at the level of injury was
0.63 with the mean SAC of 2.88mm. In the burst fracture group
MSCC was 13.4% and MCC 32.05%. The MDLS was 5.78. Cord
signal changes and haematoma was found in 88.9% and 77.8 %
respectively. Cord to canal ratio at the level of injury was 0.73
with the mean SAC of 2.56mm.
There was significantly higher MDLS in the bifacetal dislocation
group and greater haematoma formation in the cervical burst
group. There was no correlation between canal compromise and
cord compression. SAC was significantly smaller in both the cervi-
cal bifacetal fracture 2.88mm and burst fracture groups 2.56mm
when compared to the normal group at all levels 6.44mm.
CONCLUSIONS
In this study group of neurologically complete patients there
were extensive discoligamentous changes. A significant number
had cord signal changes and haematoma. The amount of cord
and canal changes did not reflect final neurologic outcome.
97
POSTER PRESENTAT IONS
6. Screw webpacs: Is pedicle sizing accurate andreproducible on CT
*McCarthy, MJH,2 Bucher, TA,1 Redfern, A,1 Hutton, MJ1
1 Peninsula Spinal Unit, Princess Elizabeth Orthopaedic
Centre, Royal Devon and Exeter Foundation NHS Trust,
Exeter, UK2 The Princess Alexandra Hospital, Brisbane, Qld, Australia
INTRODUCTION
Crawford et al. (2009) showed that the WEBPACS angulation
tool was accurate and reproducible when measuring spinal
angulation. Preoperative CT scans can be used to plan spinal
instrumentation, in particular, the accurate sizing of pedicles in
order to assess their suitability for screw insertion. We could find
no studies validating the WEBPACS ruler tool. The objectives of
this study were:
1. To determine whether the ruler tool on WEBPACS is accurate
2. To determine whether measuring pedicle size on CT is
accurate and reproducible
METHODS
Study Design: Radiologial analysis.
Subject: A human cadaveric spine along with 5 geometrical
shapes were scanned using a multislice spiral CT scanner with
1mm cuts. The objects were measured independently using the
WEBPACS ruler tool by a spinal consultant (Observer 1) and a
spinal fellow (Observer 2). The pedicle diameters for lumbar and
thoracic vertebrae in the axial plane were then measured. The
measurements were then repeated a week later. The geometrical
shapes and pedicle size on the skeleton were then measured
using Vernier callipers by an independent observer and again
repeated a week later. All measurements were taken to the
nearest 0.1mm.
Outcome Measures: Reproducibility of the measurements was
assessed using Bland and Altman plots. Accuracy was assessed
using the Vernier calliper measurements as the gold standard and
comparing the plots.
RESULTS
The independent observer achieved perfect reproducibility when
measuring the geometric objects with the Vernier callipers (all
measurements were exactly the same). The error of the
measurement associated when measuring the pedicles was
0.5mm. The error of the measurement for the geometric objects
for observers 1 and 2 was 0.5 and 0.6mm respectively, and for
the pedicles it was 1.0 and 0.6mm respectively.
CONCLUSION
The WEBPACS ruler on a CT scan is accurate to within 0.5-0.6mm
of the true size of an object. The error for pedicle measurements is
marginally higher (0.6-1.0mm) and this may reflect the fact that
they are ill defined geometric shapes. Measuring pedicle size on
CT for surgical planning may have implications for small pedicles
when sizing them up for a pedicle screw.
7. The role of cervical cordotomy in the management of refractory cancer pain
*Frydenberg, EM, Steel, TR
St Vincent’s Hospital, Darlinghurst, NSW, Australia
INTRODUCTION
Over the last two decades the administration of intrathecal
morphine has improved and simplified pain management for
many malignant processes. The reduced number of patients being
referred for cordotomy in recent years have led to fewer surgeons
developing the necessary expertise to perform cordotomy with
the ease and precision previously reported (Steel & Burchiel, 2002).
Infusion pumps have been successful in controlling pain in more
than 90% of patients in whom pain is unrelieved by standard
opioid regimens. However there may still be a role for destructive
surgical approaches.
We report two cases of open cervical cordotomy for treatment
of refractory cancer-related pain.
98
METHODS AND RESULTS
Case 1: 78-year-old man with invasive SCC of chest wall, left
axilla and brachial plexus causing severe arm pain that could not
be controlled with maximum medical therapy and local anaesthetic
infusion. The patient was hospitalised for analgesia pre-operatively
and still reported severe arm pain. A right open C2/3 cordotomy
was performed. The left arm pain was completely alleviated by
the surgery. He was pain free independent at home 6 weeks
after surgery.
Case 2: 16-year-old girl with pelvic malignancy, incapacitated from
severe pelvic and lower extremity pain. Cervical cordotomy was
performed with complete relief of symptoms. She was able to travel
overseas without analgesia for a period of 12 months after surgery.
CONCLUSION
Cordotomies were first performed in 1912. For several decades
after cordotomy remained one of the most successful procedures
for the management of chronic pain from malignant processes.
There have been few recent surgical series presented or published
as open cordotomy is a procedure that is only rarely performed
today. Jones et al published a series of 9 open cordotomies
performed over a period of 10 years for patients with intractable
cancer-related pain(Jones et al., 2003). They found that all patients
experienced near complete pain relief from the pre-operative
pain with reduction in analgesia use (Jones et al., 2003).
While 90% of patients with cancer-related pain obtain relief with
oral analgesia or intrathecal opioids there is a small group of
patients where pain control remains difficult and neuro-ablative
procedures should be considered.
We report the successful use in 2 patients with intractable
malignant pain who were able to discontinue all opioid analgesia
following their surgery.
REFERENCES
1. JONES, B, FINLAY, I, RAY, A, SIMPSON, B 2003.
Is there still a role for open cordotomy in cancer pain
management? Journal of pain & Symptom management, 25, 6.
2. STEEL, T, BURCHIEL, K 2002.
Ablative Neurosurgical Techniques in the Treatment of
Chronic Pain: Overview. In: BURCHIEL, K. (ed.) Surgical
Management of Pain. Thieme.
8. Initial experience with a novel internally fixedframe to improve retraction for anterior uppercervical surgery
*Seex, KA,1 Koustais, S,1 Macdonald, M 2
1 Macquarie University, Sydney, NSW, Australia2 Royal Adelaide Hospital, Adelaide, SA, Australia
INTRODUCTIONAnterior upper cervical surgery is made more difficult because
conventional self retaining retractors are poorly designed for use
in this area and handheld retractors lack stability. Except for
transoral surgery all approaches to this area create asymmetrical
wounds which produces unequal tissue forces that work against
retractors stability. This is further complicated because such
approaches work under the overhang of the jaw and its tissues.
Such surgery is commonly associated with post operative
swallowing and airway complications most likely due to retraction
injury indicating that efforts to improve retraction are worthwhile
and may benefit patients as well as address surgeons frustrations.
METHODSA novel retractor was developed for this indication and cadaveric
tests confirmed its feasibility prior to clinical use. A small
radiolucent rectangular frame is fixed to spine beneath the
prevertebral fascia. Radiolucent retractor blades are clipped to
the sides of the frame. The blades may rotate in 3 planes, medial,
lateral and cranial, with the fixed frame providing a stable axis for
rotation. The design allows for easy intermittent retraction.
Depending on the geometry of the blades, blades can provide
retraction at right angles to the frame or obliquely in the line of
the wound. Surgery is carried out within the frame. We present
this novel device and show its use in its first 3 cases of upper
cervical spine surgery.
RESULTS2 cases of Type 2 odontoid fracture anterior fixation and one
case of partial c2 and c3 4 corpectomy for tumour. The frame
was secured with 2 small screws into C4 vertebrae for odontoid
screw fixations and C5 for the vertebrectomy. The radiolucent
cranial retraction blade could be held by an elastic band and a
hook. This improved stability, ease of imaging and assistants
radiation exposure. No retraction complications were observed
post operatively.
99
POSTER PRESENTAT IONS(Poster 8 continued)
CONCLUSION
The design principle of bone fixation with rotation were recently
described (Seex, 2010. Pattavilokam, 2010.) however this fixed
frame with retractor blade rotation in the cranial plane and
angled blades have not been previously described. This frame
made the tissue retraction much easier in these difficult operations
without causing injury. Inventors (KAS) regularly misjudge the
value of their inventions. One of the authors (MM) has no bias.
Some ideas immediately seem sensible and require more
independent appraisal.
REFERENCES
1. SEEX, KA
J Neurosurg Spine 12:547-551,2010
2. PATTAVILOKAM, A, SEEX, KA
J Neurosurg Spine 12:552-559,2010
9. Novel description of an all-osseous transpelvic approach to the intervertebral spaceof the lumbosacral junction
*McCormick, J, Macmillan, M, Rice, JW
University of Florida, Gainesville, Florida, USA
INTRODUCTION
The position of the lumbosacral junction within the pelvis and
the surrounding structures can complicate the access to the
lumbosacral disc. This has resulted in different techniques
described to obtain entry into the disc to perform a fusion.
The development of minimally invasive instruments and computer
navigation has enabled techniques that were not previously
feasible. We describe a trans-pelvic technique to access the
intervertebral space of the L5/S1 junction, through an all-osseous
tunnel. Our hypothesis was that with the use of computer
guidance the disc space could be reliably accessed. The purpose
of this study was to anatomically describe this pathway.
METHODS
Three cadaveric specimens were obtained and soft tissue was
removed from the specimen. Under direct visualization, a
transosseous portal was created from the iliac crest through the
sacrospinous space into the sacral ala before accessing the L5/S1
intervertebral disc space. This was performed from each iliac
crest allowing us to evaluate six transosseous portals. The
integrity of the portals and the preparation of the disc space was
evaluated grossly and with computer tomographic scans within
the sagittal, coronal and axial planes. Measurements were then
obtained to determine the length of the portals, the location of
the isthmus in all planes, endplate diameters, and angles necessary
to access the space.
RESULTS
A transosseous portal was successfully created in all specimens
from the right and left iliac crest. The computer tomographic
scans and the anatomic evaluations confirmed that the portal
was bound by cortical bone at all times until it entered the L5/S1
disc space. Upon sectioning the specimens it was determined
that the isthmus of the approach is within the sacral ala. The
sacral ala was not breached when entering the L5/S1 disc space.
The narrowest point was found within the axial and sagittal plane
of all specimens within the sacral ala. The average angle of the
approach was 45 degrees superior within axial plane with the
pelvis in a prone position and 25 degrees caudally in the coronal
plane for the pelvis. The average length of the transosseous por-
tal was 69mm. The average angle between the L5/S1 endplates
was 15 degrees.
CONCLUSION
A transosseous approach to the lumbosacral junction is feasible
with computer tomography and navigation. Further studies will be
required to determine optimal surgical instrumentation, optimal
implantation devices and the biomechanical stability of the
approach.
100
10. Implementation of the NICE guidelines for metastatic spinal cord compression: Do they make a difference ?
*McCarthy, MJH, 2 Berry, CL,1 Cumming, D,1 Hutton, MJ 1
1 Peninsula Spinal Unit, Princess Elizabeth Orthopaedic
Centre, Royal Devon and Exeter Foundation NHS
Trust, Exeter, UK2 The Princess Alexandra Hospital, Brisbane, Qld, Australia
INTRODUCTION
Historically, the main treatment for Metastatic spinal cord
compression (MSCC) was radiotherapy. Very few patients
were referred to the spinal team and even less went on to
have surgery. We have conducted a comparative audit to
assess whether the introduction of the UK NICE guidelines in
2008 have changed our practices.
METHOD
Single site study comparing a retrospective audit of patients
diagnosed with MSCC in 1999-2000 to a prospective audit of
patients diagnosed with MSCC in 2009-2010. During this study
specific outcomes were monitored, time from referral to MRI,
percentage of patients with spinal stability documented,
percentage of patients referred for a spinal opinion and
definitive management of patients presenting with MSCC.
RESULTS
In 1999-2000 over a 16 month period there were 38 patients
diagnosed with MSCC. Diagnosis was reached by MRI in 27 (71%)
of patients. MRI scan was performed at a mean of 42 hours. The
referral rate to a spinal surgeon was 8 (21%) patients. All patients
were treated with radiotherapy. Spinal stability was documented
in only one case. The average time on bed rest was 5.5 days.
In 2009-10 over a 12 month period 56 patients were diagnosed
with MSCC. All patients with neurological deficits had MRI within
a mean of 6 hours from presentation. All patients were referred
to the spinal team, 14 (25%) had surgery, 35 (63%) radiotherapy,
3 chemotherapy, 2 other form of therapy and 2 patients passed
away prior to any treatment. Spinal stability was documented in
all cases. The average time on bed rest was 2 days.
CONCLUSION
These results suggest that the introduction of the NICE guidelines
(2008) have resulted in a significant improvement in the care
pathway of patients with MSCC and in the time to imaging, and an
increase in patients receiving surgery for the treatment of their
MSCC. It is uncertain whether these results are attributed to the
introduction of the NICE guidelines or wider knowledge of the
condition.
REFERENCE
1. UK NICE Guidelines 2008.
11. A simple mnemonic to reduce errors in spinal fusion
Howie, GRC
Ascot Hospital, Remuera, Auckland, New Zealand
INTRODUCTION AND METHOD
Pre-operative check lists have reduced the incidence of “surgical”
errors such as wrong patient, wrong operation and wrong side /
level problems but errors of omission can still occur. These may
result in re-operation or affect outcome.
By using a simple mnemonic (ABCDEFG), occasional errors have
been corrected.
A is for X-rAy
B is for Bone graft
C is for Cage
D is for Drain
E is for Epidural and Epidural space
F is for Fixation
G is for Go home when the count is correct
Examples:
A. at the conclusion of spinal fusion the radiographs should be
checked Again for level and positioning of implants (cages,
screws, &c). This should be confirmed with Another doctor.
B. Has all the Bone graft or substitute been placed appropriately?
C. Is the Cage optimally positioned?
D. Is the Drain placed properly (not sutured to the fascia)?
101
POSTER PRESENTAT IONS(Poster 11 continued)
E. Will an Epidural be required for post-op analgesia?
Have you checked the nerve roots to ensure there are no
bone fragments or other compression.
F. Is the Fixation satisfactory (two views are better)?
Have all the nuts been tightened?
Are the rods too long?
Do you need a cross-link?
G. Count correct, all suture needles, swabs and instruments
accounted for? Well done
Constant use of this aide memoire at the end of every spinal
fusion has reduced the incidence of “return to theatre”. Problems
with each of these seven categories have occurred and have
been rectified prior to the end of surgery.
CONCLUSION
This simple mnemonic can be used at the completion of every
spinal fusion.
12. SCIWORA in adults: Is C4 the soft target?Srivastava, RN
King Georges Medical College, CSM Medical University,
Lucknow, India
INTRODUCTION
First described by Rang & Wilberger, SCIWORA was initially
defined as a syndrome of traumatic myelopathy without vertebral
column disruption as visualized on plain spine films, flexion-
extension films, myelography or CT. The mean incidence was
reported to be around 40% with majority ( two thirds) in young
child less than 8 to 10 years of age, less commonly in adolescents
and rare in adults. With improved imaging capability and increased
use of MRI the true incidence is likely to be 15 - 20%. We initiated
a study to evaluate the incidence, prevalence and outcome of
SCIWORA in adults. In literature, spinal cord injury without
radiological abnormality is rare in adults. We present seven adult
patients with SCIWORA seen over two years.
METHODS
A study was undertaken to evaluate the incidence, prevalence
and outcome of SCIWORA in adults. 5180 patients were admitted
in the Department of Orthopaedic Surgery at our institution.
708 of these (13.66%) were spinal cord injuries. 7 cases of adult
SCIWORA were diagnosed in these two years. A case by case
analysis was done and evaluated systematically. Following trauma,
these patients had quadriparesis. Conventional radiographs were
within normal limits. MRI showed lesions only in four and three
had absence of any abnormal cord signal.
RESULTS
The incidence of SCIWORA in adults was < 1% of SCI ( 7/708),
The mean age was 33.28 years, and male/female ratio was 6:1.
The mode of injury was FFH in 4/7 (AK, MK, RV & S), RTA in 2/7
(KS & RB) and SOG in 1/7 (SK). Associated injuries were found
in 3/7 (AK, KS & MK).
Clinical presentation at admission was ASIA A in 2/7 (AK & RV),
ASIA C in 2/7 (KS & RB) and ASIA D in 3/7 (MK, SK & S). ASIA
A remained A and C & D recovered to ASIA E within 6 weeks.
Neurological level was C4 in 6/7 (AK, KS, MK, RB, RV & SK), and
T2 in 1/7 (S). Motor level was C4 in 6/7 and T1 in 1/7. Sensory
level was C4 in 4/7 (AK, KS, RB & RV), and normal sensations in
3/7 (MK, SK & S).
At MRI, isolated cord contusion was found in 3/7 (RB, RV & S),
combined contusion with hemorrhage in 1/7 (AK) and absence
of abnormal cord signal in 3/7 (KS,MK&SK).
CONCLUSION
SCIWORA is no more an injury of children. In our series a rare
presentation is neurological level of C4 in all but one case. MRI
findings for the cord are highly correlated with the prognosis -
hemorrhage with poor outcome, contusion with moderate to
good recovery and absence of abnormal cord signal with
complete recovery. Management is essentially conservative and
prognosis is better than that seen in patients with fracture or
dislocation of cervical spine.
102
13. Spinal shock in spinal cord injuries: Is duration of shock related to neurological level?*Srivastava, RN, Arya, S
KG Medical College, CSM Medical University, Lucknow, India
INTRODUCTION
The definition and etiology of spinal shock remain controversial.
The factors influencing this duration and its clinical significance
are not well studied. A study was undertaken to study the
duration and the factors influencing spinal shock. An arithmetical
relationship was seen to exist between the duration of spinal
shock and the segmental level of spinal cord injury.
A study was done to determine the duration of spinal shock in
spinal cord injury (SCI), the first reflex to return while recovering
from spinal shock & the factors influencing duration of spinal shock.
METHODS
116 patients in spinal shock following SCI were included. A
detailed neurological examination of sensory, motor and reflex
activity was done everyday till the patients were out of spinal
shock. The duration of spinal shock by appearance of any reflex,
the first reflex to return & the influence of variable factors on
duration of spinal shock were studied
RESULTS
In 76 patients (85.4%) anal wink (AW) was the first reflex to
return either alone or simultaneous with BC / DPR.In 7 patients
cremastric reflex, in 3 pathological reflexes & in 2 deep tendon
reflexes ( ankle) were the first to return.
Mean duration of spinal shock (MD of SS) was shorter in
children, shorter in malnourished, shorter in untrained / laborers,
shorter in patients admitted early and shorter in patients without
any complications. "MD of SS" was not influenced by sex of patient,
associated injuries and by different modalities of treatment.
CONCLUSION
On statistical analysis of duration of spinal shock with neurological
level as a variable "MD of SS "was 1.7 days in cervical cord lesions,
8.2 days in upper thoracic, 15 days in lower thoracic and 17 days
in lumbar cord lesions. Such an arithmetical progression was also
found at each segmental level i.e. the duration of spinal shock
progressively increased at every segmental level. "MD of SS" was
1.36days at C4, 1.60 at C5, 1.72 at C6, 8.1 at T6, 12.4 at T8, 13.1
at T10, 15.3 at T12 & 21.6 at L2.
An arithmetical relationship exist between the duration of spinal
shock and the segmental level of spinal cord injury - the duration
of spinal shock was directly proportional to level of injury. Higher
or proximal the lesion, shorter is the duration. We do not have
the answer of this important observation. Does the duration of
spinal shock dependant on the cord length / neuronal mass
involved / spared?
14. In-vitro biomechanical comparison of the native inter-vertebral disc and a compliant artificial lumbar disc replacement (Cadisc-L)
*Freeman, BJC,2 Naylor, J,1 McNally, DS1
1 University of Nottingham, UK 2 University of Adelaide, Adelaide, SA, Australia
INTRODUCTION
The majority of lumbar Total Disc Replacements (TDR)
currently available are low friction devices with designs based
on ball-and-socket articulate bearings. Whilst these devices allow
motion, they possess no shock absorbing capacity. The Cadisc™-L
is a polyurethane-polycarbonate graduated modulus compliant
TDR designed to restore the elastomeric properties of the disc,
including normal shock absorption and physiological centres of
rotation (CoR).
This study aims to assess the in-vitro biomechanical behaviour
of the native intervertebral disc and that observed following
implantation of the Cadisc™-L Specifically, the effects of
implantation on the location of the CoR, the compressive stiffness
and the bending moment vs. bending angle characteristics, will be
studied. The hypothesis to be tested is that implantation of the
Cadisc™-L will not significantly change the biomechanical
behaviour of the cadaveric motion segment.
103
POSTER PRESENTAT IONS(Poster 14 continued)
METHODS
Ten L4-5 fresh frozen cadaveric motion segments were dissected
to remove all non-osteoligamentous tissues. This number was
determined using a power analysis (p=0.05, =0.8) to detect
differences greater than the sample standard deviation. Care was
taken to preserve specimen hydration. The L4-5 motion segments
were mounted in loading cups using the low melting point alloy.
Testing was performed in an environmental chamber at 37°C
with 80-90% humidity. Specimens were pre-conditioned with a
1kN load for 30 minutes to restore physiological disc hydration.
The location of the static CoR was determined by adjusting the
anterior/posterior position of a single loading roller until no
flexion / extension was produced on application of a small test load.
Compressive stiffness of the specimen was determined on the
5th of a series of 6 loading cycles to 1kN (0.5Hz). The bending
stiffness of the specimen was determined by a physiologically
relevant combination of bending moment, compressive load and
forward shear. The position of the roller was offset to 15mm
anterior to the static CoR producing a bending moment that
increased to approximately 15Nm at 1kN applied load. Bending
angle, measured using an electronic inclinometer, was used to
calculate the bending moment from the applied load and roller
offset geometry. Data was captured on the 5th of 6 cycles.
Following testing of the intact motion segment, the L4/5
intervertebral disc was removed and a medium-sized CAdisc™-L
implant inserted. The location of the new CoR was determined
and the mechanical testing protocol repeated. Data from the
intact and implanted conditions were then compared using
paired students ‘t’ tests.
RESULTS
Compressive stiffness and bending stiffness were reduced by 50%
and 20.5% respectively following implantation of the CAdisc-L. The
instantaneous axis of rotation locus maintained its characteristics
with a centrode displaced 4.1 mm at 3° flexion.
CONCLUSION
The results of this study support the hypothesis that implanting
the elastomeric TDR, Cadisc™-L, produces very similar in-vitro
biomechanical behaviour to that observed when studying the
native L4/5 intervertebral disc.
104
15. Cervical cord injury as a complication of percutaneous cervical facet joint radiofrequencyneurotomy
*Selby, MD,1,2 Clark, SR,2 McDonald, M,2,3 Marshall, R,1,2
Freeman, BJC 1,2
1 The University of Adelaide, Adeleaide, SA, Australia2 Spinal Injuries Unit, Royal Adelaide Hospital, SA, Australia 3 Department of Neurosurgery, Flinders Medical Centre,
Flinders University, Bedford Park, SA, Australia
INTRODUCTION
Cervical facet joint radiofrequency neurotomy, also know as
cervical facet rhyzolysis, is a procedure for addressing chronic
axial neck pain in patients with a previous response to diagnostic
blocks (Lord 1996). While the application of this procedure
remains controversial, it is commonly employed by surgeons, pain
physicians and radiologists as the benefits are thought to clearly
outweigh potential risk (Falco 2009). We report the first case, to
our knowledge, of cervical cord injury as a result of incorrect
probe placement during radiofrequency neurotomy.
METHODS
A single case of this devastating injury is reported, following
repeat left sided cervical facet radiofrequency neurotomy at the
C4/5 level. The procedure was performed by a pain physician
with extensive experience with this technique.
RESULTS
We present the clinical and radiographic outcome of this case
at 6 months following injury. The patient presented with an
incomplete cervical cord injury defined as C4, ASIA D, with
predominantly dorsal column involvement. Initial treatment was
non-surgical and intravenous high dose dexamethsone was
commenced. The patient made a slow and as yet incomplete
neurological recovery. Serial MRI demonstrates the progression
of a focal cord lesion at C4/5 two hours post injury to diffuse
cord oedema from C2 to T1 level at one week.
We review the potential reasons for this technical error and
discuss the various available techniques for performing this
procedure.
CONCLUSION
Despite controversy over the efficacy of cervical facet radio-
frequency neurotomy, it has previously been thought to be a low
risk procedure. We report this case as a serious potential
complication that patients should be informed about prior to
treatment.
REFERENCES
1. LORD et al.
N Engl J Med 1996;335:1721-1726
2. FALCO et al.
Pain Physician 2009;12:323-244
16. Prospective analysis of graft options for anterior lumbar interbody fusion (ALIF): Fusion and complication rates
Mobbs, RJ
University of New South Wales and Sydney Spine Clinic,
Sydney, NSW, Australia
INTRODUCTION
Anterior Lumbar Interbody Fusion (ALIF) is an acceptable
technique for a variety of indications including the management
of Degenerative Disc Disease, Spondylolisthesis, foraminal
stenosis and symptomatic non-union of posterior fusion. There
are a variety of graft options avaliable to the surgeon including
Autograft, BMPs, allografts and a variety of synthetic based bone
graft substitutes. This study aims to compare early fusion rates
and complication rates of a variety of avaliable graft options.
METHODS
Over an 18 month time period, the data from 35 consecutive
ALIF's has been prospectively collected; including 10 autograft
(Iliac crest), 10 Infuse (rhBMP-2) and 15 i-Factor (P-15) patients.
Patients were reviewed at 2, 6, 12 and 24 weeks postoperatively.
(Clinical outcomes are the subject of a separate study.) Early
radiological outcomes based on fine cut coronal CT assessment,
and graft associated complications were prospectively recorded.
105
POSTER PRESENTAT IONS(Poster 16 continued)
RESULTS
Early fusion rates were positive throughout all patient groups.
By 3 months, there was bridging bone on coronal CT in 4/10
patients in the autograft group, 7/10 in the Infuse group and 11/15
in the iFactor group. By 12 months there was one non-union in
the autograft group (smoker / diabetic) and no non-union in the
Infuse group. The average followup in the i-Factor group is only 5
months, however fusion rates at time of reporting were 13/15 in
the i-Factor group. Complication rates at the 3 month mark
include; 3/10 patients suffering from significant graft site pain in
the autograft group, 1/10 patients suffering a severe Infuse
related radiculitis, and no complications in the i-Factor group.
CONCLUSION
From this early data analysis with regards to fusion and
complications, all groups demonstrated excellent early fusion
rates. Bone bridging appears to develop faster in the Infuse and
iFactor group based on the 3 month data. The major graft related
complication is from residual graft.site harvest pain, followed by a
severe Infuse radiculitis in one patient. Issues of cost and graft
related complications will require longer term follow-up and
larger patient cohorts to define more accurately. No firm
conclusions can be made in terms of the most suitable bone
graft option for ALIF based on this early data analysis.
REFERENCES
1. CHAU, AM, MOBBS, RJ.
Bone graft substitutes in anterior cervical discectomy and
fusion. Eur Spine J. Apr;18(4):449-64. 2009
2. FOLDAGER, C, BENDTSEN, M, NYGAARD, JV, ZOU X,
BÜNGER, C.
Differences in early osteogenesis and bone micro-architecture
in anterior lumbar interbody fusion with rhBMP-2, equine bone
protein extract, and autograft. Bone. Aug;45(2):267-73. 2009
17. Radiographic fusion rate of multilevel anterior cervical discectomy and fusion usingpeek cages with DBM and plate fixation: A descriptive study
*Domacena, RM, Ver, M
St Luke’s Medical Center, Quezon City, NCR, Philippines
INTRODUCTION
Background: The issue in the management of multilevel cervical
spondylotic radiculopathy/ myelopathy continues to be debated
in the literature. One controversy is the high non union rate of
multilevel fusion and the use of allograft instead of autologous
bone. Spinal surgery using autogenous bone graft is currently the
standard method of fusion and is a common procedure for spinal
pathology. Despite being the optimal graft solution, autogenous
graft is associated with a certain rate of pseudoarthrosis, and the
potential complications and morbidity from the donor site
(Park HW et al, Spine 2009)
Objective: The purpose of this study was to assess the
radiographic fusion rate of patients treated for cervical
radiculopathy / myelopathy with multiple anterior decompression
and spinal fusion (ADSF) using PEEK cages with DBM and
cervical plate fixation.
METHODS
Radiographs of 12 patients, non randomized, surgically treated by
a single surgeon was reviewed. The anterior Smith-Robinson
technique was performed for all patients with adjunct cervical
plate instrumentation. Postoperative radiographs of 38 cervical
levels of all cases were reviewed by 2 orthopedic surgeons and a
radiologist who were not involved in the care of the patients.
Radiographic fusion criteria is based on the presence trabecular
bridging between the PEEK cages and the vertebral bodies
RESULTS
A solid fusion was obtained in 37 out of 38 cervical levels in all
patients (97%) as observed by the orthopedic surgeons and
100% fusion as observed by a radiologist with a high concordance
rate (92%) and a fair interobserver agreement ( coefficient
0.22) among the evaluators. Average time to fuse was 3 months.
106
CONCLUSIONS
This study demonstrates that a high fusion rate may be achieved
with the use of PEEK cages and DBM in managing multilevel
cervical pathology without the morbidity of harvesting IBG.
REFERENCES
1. BOHLMAN, HH, EMERY, SE, GOODFELLOW, DB
J Bone Joint Surg Am. 1993;75:1298-1307.
2. BOLESTRA, MJ, et al
Spine. 2000 Aug 15;25(16):2040-4.
3. PARK, HW, LEE, JK, MOON, SJ, SEO, SK, LEE, JH, KIM, SH
Spine (Phila Pa 1976). 2009 Aug 1;34(17):E591-5.
4. ROBINSON, RA, WALKER, AE, FERLIC, DC, WIECKING, DK
J Bone Joint Surg. 1962; 44-A: 1569-1587
5. VACARRO, AR, MADIGAN, L., LIM, R
J Am Acad Orthop Surg, 2007 May Vol 15, No 5, 274-280.
107
108
Annual Meetings
Year President Date / Site / Guest(s)
1990 Prof Robert Fraser 14 - 15 JULY | Royal North Shore Hospital, Sydney, NSWGuest: Dr Henry Bohlman
Dept of Orthopedic Surgery, Case Western Reserve University, Cleveland, Ohio, USA
1991 Prof Robert Fraser 4 - 5 JUNE Australian Academy of Sciences, Canberra, ACT
1992 Prof Robert Fraser 8 - 9 AUGUST | Adelaide Festival Centre, Adelaide, SAGuests: Dr Daniel Chopin
Centre d’Etude et de Traitement des Affections du Rachis, Institut Calot, Berck-sur-mer, France
Dr John O’BrienDept of Spinal Disorders, Robert Jones & Agnes Hunt Orthopaedic Hospital, Oswestry, Shropshire,UK
Dr Arthur SteffeeDivision of Orthopaedics, Cleveland Spine & Arthritis Center,Lutheran Medical Center, Cleveland Medical Center, Cleveland, Ohio, USA
1993 Prof Michael Ryan 26 - 27 JUNE | Hyatt Hotel, Coolum, QldGuests: Dr Stephen Esses
Dept of Orthopedic Surgery Baylor College of Medicine, Houston, Texas, USADr James WeinsteinDept of Orthopedic Surgery, University of Iowa, Iowa City, Iowa, USA
1994 Prof Michael Ryan 14 - 15 MAY | RACS, Melbourne, VICGuest: Dr Gunnar Andersson
Dept. of Orthopedic Surgery, Rush-Presbyterian-St Luke’s Medical Center, Chicago, Illinois, USA
1995 Assoc Prof Bruce McPhee 18 - 22 SEPTEMBER | Combined SSA/NSA Meeting | Cable Beach Resort, Broome, WA
Guest: Dr Tom ZdeblickDept of Orthopaedic Surgery, University of Wisconsin, Madison, Wisconsin, USA
1996 Assoc Prof Bruce McPhee 13 - 15 SEPTEMBER | Cairns Convention Centre, Cairns, QldGuest: Dr Iain McCall
Dept of Radiology Robert Jones and Agnes Hunt Orthopaedic Hospital Oswestry, Shropshire, UK
1997 Dr Richard Vaughan SEPTEMBER | Sanctuary Cove, Gold Coast, Qld
1998 Dr Richard Vaughan SEPTEMBER | Queenstown, NZGuest: Prof H. Alan Crockard
The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
1999 Dr Richard Vaughan SEPTEMBER | Coffs Harbour
2000 Dr Ian Torode Adelaide Festival Centre, Adelaide, SAGuest: Dr Howard An
Dept of Orthopdeic Surgery, Rush-Presbyterian-St Luke’s Medical Center, Chicago, Illinois, USA
109
Annual Meetings
Year President Date / Site / Guest(s)
2001 Dr Barrie Slinger 27 - 29 APRIL | The Esplanade Hotel, Fremantle, WAGuest: Dr Frank Eismont
Dept of Orthopedics and Rehabilitation, University of Miami School of Medicine, Miami, Florida, USA
2002 Dr Barrie Slinger 26 - 28 APRIL | Hilton Hotel, Melbourne, VICGuest: Dr Randy Davis John Hopkins University Baltimore, Maryland, USA
2003 Prof Nigel Jones 25 - 27 APRIL | Canberra Hyatt, Canberra, ACTGuest: Prof Bernard George Dept of Neurosurgery Dublin, Eire
2004 Prof Nigel Jones 16 - 18 APRIL | Hyatt Hotel, Coolum, QLDGuests: Prof Ciaran Bloger National Centre of Neurosurgery, Dublin, Eire
Prof Robert Gunzburg Free University of Brussels, Antwerp, Belgium
2005 Dr Ian Farey 14 - 17 APRIL | Auckland Hilton Hotel, Auckland, NZGuest: Dr John Hellier Emory Spine Center, Dept of Orthopaedic Surgery
Emory University School of Medicine, Atlanta, Georgia, USA
2006 Dr Ian Farey 28 - 30 APRIL | Sofitel Wentworth Hotel, Sydney NSWGuest: Dr Alexander Vaccaro Dept of Othopaedic Surgery, Rothman Institute,
Thomas Jefferson University, Philadelphia, Pennsylvania, USA
2007 Dr Roy Carey 20 - 22 APRIL | Hotel Grand Chancellor, Hobart, Tas.Guest: Prof Eugene Carragee
Dept of Orthopaedic Surgery, Stanford University School of Medicine, California, USA
2008 Dr Roy Carey 18 - 20 APRIL | Hilton Adelaide, Adelaide, SAGuests: Prof Dieter Grob
Dept of Spinal Surgery, Stanford University School of Medicine, California, USA
2009 Dr Peter McCombe 17 - 19 APRIL | Sofitel Hotel, Brisbane, QldGuests: Dr Marcel Dvorak, Dr Charles Fisher, Dr Tom Oxland
University of British Columbia, Vancouver, Canada
2010 Dr Peter McCombe 9 - 11 APRIL | Christchurch Convention Centre, Christchurch, NZGuests: Prof Paul Anderson Dept of Orthopaedics, University of Wisconsin-Madison
Dr Adam La Caze School of Pharmacy, University of Queensland, Brisbane, Qld Prof Kerrie Mengersen Dept of Statistics, QUT, Brisbane, Qld Dr Paul Mernagh Health Economics Manager, Health Technology Analysts, Sydney, NSW
2011 Assoc Prof Graeme Brazenor 15 - 17 APRIL | Sofitel Melbourne on Collins, Melbourne, Vic, AustraliaGuests: Prof Jean-Charles Le Huec Orthopaedic Dept University of Bordeaux Hospital, France
Assoc Prof Chris Ames Neurosurgery Dept, University of California, San Francisco, USAProf Avinash Patwardhan Dept of Orthopaedic Surgery & Rehabilitation, Loyola University
Stritch School of Medicine, Chicago, Illinois, USAAssoc Prof Jacqui Close Geriatrician, Prince of Wales Hospital, Sydney, NSW, AustraliaProf Rachelle Buchbinder Monash Clinical Epidemiology Dept, Cabrini Hospital, Melbourne, Vic
110
Author Disclosures
Free Papers Session 1
1.5 QUT Research Assistant position (second author) is
funded by the Queensland Orthopaedic Research Trust
which receives funding from Synthes.
Free Papers Session 2
2.1 Consultancy: TeTec
Research grant: FFG / Generation Innovation
2.2 Research grant from Medtronic
2.4 Peter Robertson is a Consultant to Medtronic and De Puy,
and has a Royalty agreement with Medtronic unrelated to
this presentation.
Roy Lim is an employee of Medtronic, Memphis, TN, USA
2.6 Support from Synthes, Stryker and Medtronic
2.7 Royalties: Lippincott, Williams and Wilkins
Stock: Neurotech, Colorado Orthopaedic and Surgical
Hospital, Greenwood Ambulatory Surgery Center,
Denver Integrated Imaging
Consultant: Stryker, Synthes, United Healthcare, Allos
Free Papers Session 3
3.3 The presenting author's position as a spine research fellow
is funded by donations from Stryker to St Vincent's Hospital.
Stryker is not involved in the selection of candidates for the
position.
3.5 Nuvasive (consultant, royalities); Orthovita (speakers
bureau); Ulrich Medical GER (consultant)
3.7 Medtronic Australia provided funding for costs associated
with radiographic studies performed outside of Austin
Health, licensing fees associated with the use of quality of
life measures eg SF36 and transportation of patients.
Free Papers Session 4
4.1 DePuy Spine: consultancy, research grant and travel support
4.2 Professors Freeman, Steffen and Aebi are members of the
Scientific Advisory Board for Ranier Technology and all have
an option agreement relating to shares with Ranier
Technology Limited
4.3 BJC Freeman serves on the Scientific Advisory Board for
Ranier Technology Limited and hold an option agreement
relating to shares in Ranier Technology Limited
4.4 Dr William Sears and Gavin White are consultants for
Medtronic.
4.5 CBP Non Profit
4.6 Consultant Medtronic, Royalties Medtronic
Free Papers Session 5
5.1 1. Stocks in Medtronic and Johnson & Johnson.
2. Travel support from Stryker and Synthes
5.3 Dr Gore is consultant to KARL STORZ endoscopy and
receives travel support and royalties on his designs
5.4 Peter Robertson is a consultant for Medtronic.
Free Papers Session 6
6.1 This research was supported by a Mater Children's Hospital
Golden Casket Research Grant (Beginner) of amount
$12,549. Medtronic kindly loaned the surgical tool
required for the completion of this research.
6.3 Dr Michael Selby received financial support from Synthes
in 2009 to attend the Spine Society instructional course
and meeting as an Orthopaedic registrar. No financial
support has been received this year.
6.4 Non-commercial funds were received for this study from
the Bone Growth Foundation Inc, Women’s and Children’s
Hospital Foundation and Florey Medical Research Fund.
Free Papers Session 7
7.1 Support from Synthes, Stryker and Medtronic
7.2 / 7.3 Implants for the injury device were donated by Medtronic
111
Poster Disclosures
Poster Number 2
This project and the equipment used was funded by the
Engineering and Physical Sciences Research Council, UK
(grant reference EP/F014562/1).
Support from Ranier Technology Limited, Cambridge, UK
Poster Number 7
The presenting author fills a position as a spine fellow at
St Vincent's Hospital, Sydney. This position is funded by donations
from Stryker Spine to St Vincent's Hospital.
Poster Number 8
Dr Seex has patents pending in regard to this device and its
principles. Synthes provided a research grant
Poster Number 14
BJC Freeman and DS McNally serve on the scientific advisory
board of Ranier Techniology Limited and both hold stock options
relating to shares in Ranier Technology Limited.
Poster Number 15
Dr Michael Selby received financial support from Synthes
in 2009 to attend the Spine Society instructional course and
meeting as an Orthopaedic registrar. No financial support has
been received this year.
Poster Number 16
Stocks in Medtronic and Johnson & Johnson.
Travel support with Synthes and Stryker.
Research grant with Cerapedics.
Research grants with the University of New South Wales.
112
Mrs Kathleen Adams
Mr Lloyd Adams
Mr Tom Afzal
Mr Stephen Alfrich
Mr Michael Allan
A/Prof Christopher Ames
Dr Geoffrey Andrews
Dr Richard Appleyard
Dr Bryan Ashman
Dr Geoffrey Askin
Mrs Helen Bale
Ms Lisa Barry
Mr Gary Bateman
Mr Matthew Beard
Miss Kylie Beddoes
Mr Graeme Bond
Dr Janusz Bonkowski
A/Prof Graeme Brazenor
Dr Michael Brighton-Knight
Ms Kirstin Brown
Mr Paul Buhle
Mr Andrew Burne
Mr Roy Carey
Dr Alan Carstens
Mr Marcel Challita
Ms Tina Clark
Mr Damian Clarke-Bruce
Mrs Jill Conlin
Mr Lyndon Crossley
Dr Thomas Cundy
Mr John Cunningham
Ms Helen Cunningham
Dr Chris Daly
Dr Gordon Dandie
Ms Pip Daniell
A/Prof Gregory Day
Mr Greg Desmond
Miss Stephanie DeVreker
Delegate List
Global Orthopaedic Technology
LifeHealthcare
Spinal Kinetics
Medtronic
Medtronic
University of California
Ranier Technology Ltd
Australian School of Medicine
Bryan Ashman
Askin Spine
DePuy Spine (Johnson & Johnson Medical)
Medtronic
GB Orthopaedics Australia Pty Ltd
Spinal Unit Orthopaedics Royal Adelaide
Medtronic
B. Braun Australia Pty Ltd
Neurosurgical Medical Services Trust
Zimmer
DePuy Spine (Johnson & Johnson Medical)
Zimmer
Paediatric Spine Research Group Mater
Medtronic
LifeHealthcare
Zimmer
DePuy Spine (Johnson & Johsnon Medical)
Global Orthopaedic Technology
Women's and Children's Hospital
Royal Melbourne Hospital
Queensland University of Technology
Gold Coast Hospital
Westmead Hospital
Stryker
Gold Coast Spine Service
Medtronic
NuVasive Aust/NZ Pty Ltd
NSW
NSW
NSW
NSW
NSW
ACT
QLD
VIC
SA
QLD
SA
NSW
NSW
VIC
VIC
VIC
NSW
VIC
QLD
NSW
NSW
NSW
VIC
NSW
SA
VIC
QLD
QLD
NSW
NSW
QLD
VIC
Delegate Organisation Country Email AddressState or
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United Kingdom
United States
New Zealand
New Zealand
New Zealand
New Zealand
113
Mr Jonathan Dewey
Mr Robert Dickens
Mr Angus Dixon
Dr Roy Michael Domacena
Mr David Edis
Mr Albert Erasmus
Mrs Allison Erp
Mr Michael Falkenberg
Dr Ian Farey
Dr Wendy Findlay
Ms Emma Fitzgerald
Mr Nathan Foote
Ms Sussan Frame
Prof Robert Fraser
Prof Brian Freeman
Mr David French
Dr Ellen Frydenberg
Mrs Elisha Gaddes
Dr Matthew Giblin
Dr Satishchandra Gore
Dr Ben Goss
Mr Rob Gourlay
Mr Angus Graham
Mr Tobin Grantley
Dr Angus Gray
Dr Paul Graziotti
Mr Brenden Grib
Dr Michael Gross
Mr Simon Hadlow
Dr Alastair Hadlow
Mr David Hamilton
Mr Brian Hansen
Mr Tony Harrington
Mrs Jacqueline Hart
Dr Dennis Hartig
Mr Louise Higginson
Mr Daniel Hill
Mr Terence Hillier
Delegate List
Medtronic
Stryker
St. Luke's Medical Center
Tasmanspine
Royal Hobart Hospital
Medtronic Spinal Tap Surgical
Royal Brisbane Hospital
Zimmer
LifeHealthcare
Johnson & Johnson Medical
St Andrews & Royal Adelaide Hospitals
Royal Adelaide Hospital
Biomet QLD
St Vincent's Private Hospital
Medtronic
Ratna Memorial Hospital
AOSpine Reference Centre
Stryker
LifeHealthcare
Zimmer
Sydney Children's Hospital
Cambridge Pain Management Centre
DePuy Spine (Johnson & Johnson Medical)
Taranaki Base Hospital
Auckland City Hospital
Medtronic
Medtronic
Biomet Australia
Medtronic
Royal Brisbane Hospital
LifeHealthcare
Stryker
Alpine Orthosport
NSW
VIC
NSW
TAS
TAS
VIC
VIC
NSW
QLD
VIC
NSW
VIC
SA
SA
QLD
NSW
NSW
NSW
India
QLD
NSW
NSW
NSW
NSW
WA
VIC
NSW
NSW
WA
NSW
NSW
QLD
NSW
NSW
NSW
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Philippines
New Zealand
New Zealand
114
Mr Shane Hodder
Dr Chris Hoffman
Mr Shannon Holdsworth
Dr GRC Howie
Miss Nicola Hunter
Ms Jenny Huntley
Mr David Jennings
Dr Rondhir Jithoo
Miss Christine Joe
Mr Michael Johnson
Ms Claire Jones
Mr Richard Jones
Mr Michael Jordan
Dr Andrew Kam
Mr Kenneth Kher
Mr Merv Kiley
Mr Shawn Kim
Dr Emily Kong
Mr Matt Kostiainen
Mr Jarek Kowalczyk
Dr Rob Kuru
Mr Dominic Langford
Prof Jean-Charles Le Huec
Dr Paul Licina
Dr John Liddell
A/Prof Susan Liew
Mr Roy Lim
Dr Ferraby Ling
Dr Andreas Loefler
Mr Justin Lousfel
A/Prof Peter Lowthian
Mr Alex Lukianov
Dr Kris Lundine
Mr Christopher Lyons
Mr Ross Lyte-Mason
Mr Peter Mackie
Dr Aziza Mahomed
Dr Greg Malham
Delegate List
DePuy Spine (Johnson & Johnson Medical)
Wellington Hospital
NuVasive Aust/NZ Pty Ltd
Howie LTD
NuVasive Aust/NZ Pty Ltd
Zimmer
Medtronic
Neurological Surgery Victoria
Medtronic
Adelaide Centre for Spinal Research
Signature Spine + Joint
Zimmer
B. Braun Australia Pty Lyd
NuVasive Aust/NZ Pty Ltd
Meddyssey Co. Ltd.
Australian Orthopaedic Association
Biomet Australia
DePuy Spine (Johnson & Johsnon Medical)
Synthes
University of Bordeaux Hospital
Medtronic
North West Regional Hospital
K2M
Cabrini Institute
NuVasive Inc
Austin Hospital
NuVasive Aust/NZ Pty Ltd
DePuy Spine (Johnson & Johnson Medical)
Medtronic
University of Birmingham
VIC
VIC
VIC
NSW
NSW
VIC
VIC
SA
NSW
QLD
NSW
NSW
VIC
VIC
NSW
VIC
NSW
NSW
France
QLD
WA
VIC
TAS
NSW
NSW
VIC
VIC
VIC
VIC
VIC
NSW
VIC
Delegate Organisation Country Email AddressState or
This list includes only those delegates who have given permission for their details to be included and is correct at time of printing - 4/4/2011.
South Korea
New Zealand
New Zealand
United States
United States
United Kingdom
115
Mr Justin Maynard
Mr Eamonn Mc Closkey
Mr Steve McAdoo
Dr Jeb McAviney
Dr Michael McCarthy
Dr Peter McCombe
Mrs Sue McCombe
Dr John McCormick
Ms Lisa McDonald
Mr Rob McPhee
Mrs Amanada McPhee
A/Prof Ian Bruce McPhee
Dr Markus Melloh
Ms Christine Migliore
Mr Chris Miller
Mr Jon Mills
Dr Bruce Mitchell
Mr Matthew Mitchell
Miss Marzena Mizgalska
Dr Ralph Mobbs
Dr Milan Mody
Dr Sabarul Mokhtar
Dr Peter Moloney
Mr Rob Montauti
Mr Alexander Montgomery
Prof Robert Moore
Dr Andrew Morokoff
Mr Paul Mullert
Mr Matt Muscio
Dr Amy Nall
Dr Naveen Narayanasamy
Dr Pierce Nunley
Mr Paul O'Brien
Mr Peter Oatey
Mr Ertan Ozer
Mr Andrew Parker
Mr Alpesh Patel
Mr Chris Patterson
Delegate List
B. Braun Australia Pty Ltd
St John of God
Cerapedics Inc
Sydney Scoliosis Clinic
AO Spine Centre Brisbane
Brisbane Spine Centre
University of Florida
Zimmer
LifeHealthcare
B. Braun Australia Pty Ltd
Dunedin School of Medicine
Medtronic
Medtronic
Medtronic
Metro Spinal Clinic
Medtronic Spinal Tap Surgical
Med-Chem Surgical
Prince of Wales Hospital
Louisiana State University
The Australian School of Advanced Medicine
Stryker
Auckland City Hospital
The Adelaide Centre for Spinal Research
Medtronic
DePuy Spine (Johnson & Johnson Medical)
Austin Health
NW Regional Hospital Burnie & Alfred Health
K2M
Synthes
Global Orthopaedic Technology
Medtronic Spine + Biologics
Middlemore Hospital
Medtronic
NSW
WA
NSW
QLD
QLD
QLD
VIC
NSW
NSW
QLD
NSW
NSW
QLD
VIC
VIC
NSW
NSW
NSW
NSW
NSW
SA
VIC
NSW
VIC
VIC
TAS
NSW
NSW
SA
NSW
Delegate Organisation Country Email AddressState or
This list includes only those delegates who have given permission for their details to be included and is correct at time of printing - 4/4/2011.
United States
United States
New Zealand
United States
New Zealand
New Zealand
New Zealand
United States
116
Prof Avinash Patwardhan
Dr Ronjon Paul
Prof Mark Pearcy
Mr Travis Perera
Mr Paul Petherbridge
Dr Justin Pik
Mrs Debbie Pohl
Mr George Potter
Ms Dianne Price
Mr Markus Priede
Mr Michael Pullar
Dr Gerald Quan
Dr Darryl Raley
Mr Jeff Reid
Mr Ben Reynolds
Dr Risantoso Tjuk Risantoso
Ms Amy Ritson
Dr Peter Robertson
Mr Daniel Robinson
Mr Jon Rogers
Mr Glen Ross
Dr William Edmond Ryan
Prof Michael D. Ryan
Dr Alan Sacks
Dr Davor Saravanja
Mr Matt Schiller
Mr Stan Schofield
Ms Sharon Scott
A/Prof Matthew Scott-Young
Mr Paul Seddon
Dr Kevin Seex
Dr Michael Selby
Mr Cameron Short
Ms Peta Sitcheff
Ms Helen Smith
Mr Michael Son
Mr Brett Spence
Dr Ralph Stanford
Delegate List
Loyola University Stritch School of Medicine
Queensland University of Technology
T.S.Perera Pty Ltd
LifeHealthcare
ACT Neurospine Clinic
Medtronic SA
Adelaide Spine Clinic
ArthroCare
DePuy Spine (Johnson & Johnson Medical)
Monash Medical Centre
Austin Health
St George Hospital
LifeHealthcare
LifeHealthcare
Indonesian Orthopaedic Association (IOA)
Medtronic/National Surgical
The Orthopaedic Clinic Mercy Specialist Centre
Medtronic
Synthes
LifeHealthcare
W.E. Ryan Medical Pty Ltd
University of Notre Dame (Sydney)
Centre for Minimally Invasive Neurosurgery
Highfield Park Specialist Centre
Medtronic
Gold Coast Spine
Synthes
Spinal Injuries Unit Royal Adelaide Hospital
Medtronic/National Surgical
Stryker
Signature Spine + Joint
Medyssey Co.Ltd.
DePuy Spine (Johnson & Johnson Medical)
Prince of Wales Hospital
VIC
QLD
VIC
NSW
ACT
SA
SA
NSW
VIC
VIC
VIC
NSW
NSW
NSW
East Java
QLD
WA
NSW
NSW
QLD
NSW
NSW
NSW
NSW
VIC
NSW
QLD
NSW
NSW
SA
QLD
NSW
NSW
VIC
NSW
Delegate Organisation Country Email AddressState or
This list includes only those delegates who have given permission for their details to be included and is correct at time of printing - 4/4/2011.
United States
New Zealand
United States
117
Dr Ellison Stephenson
Mr Anthony Strbik
Mrs Autumn Sutterland
Mr Anthony Swoboda
Mr Takakki Tanaka
Mr Max Tawadrous
Prof Thomas Taylor
Mrs Kathryn Temby
Dr Clayton Thomas
Mr Alex Thompson
Mrs Erica Tieu
Mr Lu Ton
Mr Emerik Trinajstic
Dr Peter Turner
Dr Juan Uribe
Dr Jacob Van Der Westhuizen
Ms Chantal Van Geel
Dr Joost Van Middendorp
Dr Richard Vaughan
Dr Paul Verrills
Ms Michelle Walkden
Mr Yi Yuen Wang
Mr Tom Wells-Quinn
Mrs Katherine Westland
Mrs Belinda Wiemers
Dr Peter Wilde
Ms Lucy Williams
Dr David Wong
Dr Peter Woodland
Ms Susan Wordsworth
Prof Neill Wright
Dr Steven Yang
Dr Reza Zarrinkalam
Delegate List
Synthes
K2M
Medtronic
NuVasive Inc
Medtronic
University of Sydney
LifeHealthcare
Synthes
DePuy Spine (Johnson & Johnson Medical)
Melbourne Orthopaedic Spine
Mater Hospital
Medtronic
QUT IHBI
RJV P/L-ML Consulting
Metro Spinal Clinic
Tasman Spine
Stryker
NuVasive Aust/NZ Pty Ltd
Johnson & Johnson
Austin Health & Epworth Hospital
AOSpine
Presbyterian St. Luke's Medical Center
DePuy Spine (Johnson & Johnson Medical)
Washington University School of Medicine
Royal Brisbane Hospital
ACSR-IMVS
QLD
NSW
NSW
NSW
VIC
NSW
NSW
NSW
VIC
NSW
VIC
VIC
WA
VIC
VIC
QLD
NSW
QLD
WA
VIC
TAS
VIC
NSW
VIC
QLD
VIC
NSW
WA
VIC
QLD
SA
Delegate Organisation Country Email AddressState or
This list includes only those delegates who have given permission for their details to be included and is correct at time of printing - 4/4/2011.
United States
United States
Notes & Questions
118