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3rd Annual UCSF Techniques in Complex Spine Surgery Program

Murat Pekmezci, MD

Assistant Clinical Professor

UCSF/SFGH Orthopedic Trauma Institute

Thoracolumbar Trauma:

Minimally Invasive

Techniques

Disclosures

• Research Support:

– Stryker

Minimal Invasive Spine Surgery Advantages of MISS

• Smaller incisions/minimal soft tissue

disruption

– Improved healing and decreased infection

risk

• Less blood loss

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Trauma Perspective:

•Ability to perform surgery in “Silver day”

•Mobilize the patient

– decreased risk of ARDS,

– Head injury

Advantages of MISS Disadvantages of MISS

• Learning Curve

• Accuracy

• Long term outcomes (pain, etc)

– Need for hardware removal ???

• T-L reductions difficult

Thoracolumbar Trauma:

Minimally Invasive Techniques

• Posterior – Percutaneous posterior segmental instrumentation

• Anterior – Balloon-assisted reduction

– Endoscopic assisted approaches

– Mini Open Anterior Approach

Posterior Techniques

• Percutaneous posterior segmental fixation

– Temporizing Measure

• Damage Control

– Definitive Care

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New Strategy for T-L Trauma

• Polytrauma patient with spine fracture

- Too sick ….

Temporizing Measure

Damage Control

• “maintaining a ship’s functions while it has taken on damage”

• Trauma/General surgery

– to quickly stop bleeding and surgically resuscitate a patient

Damage Control Spine Surgery

• Trauma patients are often

too sick for the “BIG” spine procedure

• Percutaneous posterior

spinal fixation

Damage Control Spine Surgery

• Retrospective review of 10 patients with > 24 month f/u

• MISS within 48 hrs

• No revision surgery except planned hardware removal

• Blood loss avg 177 ml

• Surgery time 95 min

Poelstra et al, 2009 AAOS Annual Meeting, Las Vegas, NV

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SFGH Data

• Oct 2008 -

– 24 patients (age, 17-80)

– Average level of instrumentation

• 3.8 (2-10)

– Mean OR Time: 173 min (66-360)

– Mean EBL: 180cc (50-500)

– Complication:

• Superficial infection (1), DVT (1), PE (1)

Case Example

X-ray Indirect Reduction

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New Strategy for T-L Trauma

• Isolated unstable spine fracture

- Is there a less invasive technique ….

Definitive Fixation

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52 y/o female s/p 2 story fall sustaining an unstable T10 fracture, rib fractures and SAH

Screw and Rod Placement

Percutaneous Pedicle Screw Instrumentation for

Temporary Internal Bracing of Nondisplaced Bony

Chance Fractures

• 2 cases

• L2 and L4 (neuro intact)

• Short-segment pedicle screw construct for

Chance fractures

J Spinal Disorders and Techniques, May 2007

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Technique

Technique Technique

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Technique Technique

Technique Technique

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Technique Technique

Technique Accuracy & Reduction

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SFGH Data

• Patients who had percutaneous instrumentation

and postoperative CT scan

• Accuracy evaluated by

– Neuro-radiologist,

– Ortho-spine surgeon

– Neuro-spine surgeon

Accuracy with C-Arm

Criteria developed by Gertzbein et al.

A: lateral pedicle wall penetration

B: superior or inferior pedicle wall penetration

C: medial pedicle wall penetration

D: anterolateral vertebral body penetration

Quantitative grade

1: >0 and _2 mm

2: >2 and _4 mm

3: >4 mm

4: >4 mm w/o pedicle or vertebral body contact

• Sixteen patients

• 102 screws

Accuracy with C-Arm

NeuroRad Ortho-Spine Neuro-Spine

No Breach 90.2 99.1 94 100 57 98.1

Lateral Breach 2.0 1.0 19.6

Sup-Inf Breach 0 0 2.9

Medial Breach 1.0 2.0 27.4

Anterior Breach 6.9 4.9 10.7

Posterior Techniques

• Percutaneous posterior segmental fixation

– Temporizing Measure

• Damage Control

– Definitive Care

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Indications for Anterior Approach

• Decompress neural elements

• Anterior column support

– Load Sharing Classification

Anterior Approach

• Sixty-two patients

– General satisfaction (82%)

– Postoperative pain (32.3%),

– Bulging (43.5%),

– Functional disturbance (24.2%)

Anterior Techniques

–Balloon-assisted reduction

–Endoscopic assisted approaches

–Mini Open Anterior Approach

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Balloon Assisted Reduction and Augmentation

with Calcium Phosphate Cement

• Preservation of motion segments (short

segment posterior fusion)

• Avoids morbidity of anterior approach

• Less blood loss

• Lower infection rate

• Less pain / improved recovery time

Balloon Assisted Reduction and Augmentation

with Calcium Phosphate Cement

Technique:

Open or Percutaneous

+/- Posterior Fixation

• 28 patients

• A3 burst injury / 13 with incomplete deficit

• Balloon assisted reduction with Norian Ca Phosphate cement

• 22 (79 %) laminectomy

• Operative time 116 min (80-165)

• Blood loss 316 (50-1200)

Short segment fixation with cement

augmentation of burst fractures

Thoracolumbar Burst Fractures Treated with Posterior Decompression and

Pedicle Screw Instrumentation Supplemented with Balloon-Assisted

Vertebroplasty and Calcium Phosphate Reconstruction

JBJS 2009

• 80yo F s/p syncopal fall with back

pain December 28, 2009

• PMH: HTN, hyperlipidemia, asthma

• Physical Exam:

5/5 strength in BUE, BLE, intact rectal

tone

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Thoracoscopic-assisted treatment of thoracic

and lumbar fractures

• 373 pts (T3-L3)

• Supplemental posterior

instrumentation

– 65%

• Complication rate

– 1.3%

• Steep learning curve

Neurosurgery. 2002 Nov;51(5 Suppl):S104-17.

Thoracoscopic transdiaphragmatic approach

to thoracolumbar junction fractures

• 212 patients

• Supplemental posterior

fixation

– 64.6%

• Complication rate

– 11.7%

• Conversion to open

– 1.4%

Spine J. 2004 May-Jun;4(3):317-28

MISS Techniques for Anterior Column Reconstruction

Mini Open Technique

Advantages of MOA

• Reduced pain

• Better cosmesis

• Excellent direct visualization

• No approach surgeon

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46 y/o F with L1 burst

Positioning C-arm localization

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Retractor Placement Cage Placement

Post op X-rays

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SFGH Data SFGH Data

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SFGH Data SFGH Data

Clinical Outcomes

ODI 17.6 ± 12.1

SF 12 PCS 45.0% ± 6.70%

SF 12 MCS 54.4% ± 9.68%

Cage Subsidence

• Subsidence remains a problem

– Robertson et al, 2004

• 7%

– Uchida et al, 2006

• 17%

– Blattert et al, 2008

• 12%

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56 y/o female, fall from 3rd floor

Novel Footplate Design

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BIOMECHANICS Footplate Design and Resistance to Subsidence • Pekmezci et al

E1180 www.spinejournal.com September 2012

plate on an intact endplate. This further suggests that the ring

apophysis is the key anatomic structure that resists subsidence

more than the central portion of the endplate and could have

important clinical implications. For example, defects in the

central portion of the endplate can occur when preparing the

endplate for implantation of an interbody cage or they are

created when a primary vertebral body replacement fails. This

study suggests that rectangular cages may be safely employed

in these situations in which the structural integrity of the cen-

ter of the endplate has been compromised.

After the ultimate load to failure, the average force required

for further displacement was lower in all 3 groups, explained

by the failure of the endplate. Compared with the force

required for the initial load to failure, the circular footplates

had more variability and required less force to result in further

subsidence, whereas rectangular designs had less variability

and required more load to result in further subsidence when

compared with the circular footplate. This suggests that the

type of bone under the endplate infl uences the amount of sub-

sidence. For example, the circular endplates crush and com-

pact the trabecular bone in the central portion of the vertebral

body whereas the rectangular footplates span the vertebra and

compress on the stronger cortical apophysis in addition to the

centralized trabecular bone. Thus, a higher variability after

the ultimate load to failure was observed in the circular cages

traversing trabecular bone after endplate failure. In addition,

higher loads compared with the circular cage were required

for further subsidence after endplate failure in the rectangular

cage. This suggests that rectangular footplates may be advan-

tageous when compared with circular footplates even after an

initial subsidence occurs.

There are several limitations to this study. First, a motion

segment with adjunctive instrumentation was not used, which

prevented the direct correlation of stiffness in the clinical set-

ting; however, the goal of this study was to investigate the

subsidence characteristics of the footplate designs. Second,

cyclic testing was not performed and should be considered in

future studies. Strength of this study was that using the same

vertebral level for both the circular and rectangular cages, a

corpectomy defect, the goal is to implant the largest foot-

plate suitable. The higher contact area results in a lower force

per unit area, which in turn should lead to lower subsidence

rate. Reinhold et al 9 recently confi rmed that bigger endplate

surface areas are associated with higher resistance to subsid-

ence. Although an increase in the surface area with a larger

footplate will decrease the force per unit area, circular cages

are placed on the central portion of the endplate and not on

the ring apophysis. Bailey et al 6 showed that the endplate

was stronger at the periphery than at the center. Steffen et al 8

reported similar results and suggested that the ideal inter-

body implant should rest on the periphery of the endplate.

The rationale of the rectangular design was to engage with

the ring apophysis and provide a stronger biomechanical sup-

port. This study confi rmed that rectangular footplates, which

engage the ring apophysis, have a higher ultimate load to fail-

ure than circular footplates. Reinhold et al 9 reported the ulti-

mate load of the X-Tenz (1470 N), Obelisc (1310 N), Synex I

(1690 N), and Synex II (1790 N) cages, using a similar testing

protocol. In this study, all were equal or lower than the ulti-

mate load of the rectangular footplate with or without cen-

tral defect. This suggests that the rectangular footplate design

may offer potential advantages over the circular footplate

design as well as other nonrectangular designs.

Interestingly, the ultimate load was higher for rectangular

footplates with a central defect than for the circular foot-

Figure 5. Slope of the force displacement curve after the ultimate load

shown in 1-mm increments, with all curves normalized to the values

at the ultimate load. There were no statistically signifi cant differences

between any group at any displacement.

Figure 3. The ultimate load and stiffness results for the 3 test groups.

Error bars represent the 95% confi dence intervals of the mean.

Figure 4. Mean load values for 1-mm intervals after the ultimate load.

Error bars represent the 95% confi dence interval around the mean.

Copyright © 2012 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

BRS205137.indd E1180 05/08/12 10:38 AM

BIOMECHANICS Footplate Design and Resistance to Subsidence • Pekmezci et al

Spine www.spinejournal.com E1179

average force typically decreased between 0 and 3 mm of

displacement after the ultimate load and slightly increased

between 3 and 5 mm of displacement.

The stiffness, or slope of the force displacement curve, along

the same 1-mm increments after the ultimate load showed dif-

ferent trends for all 3 groups. In the circular footplate group,

the force-displacement curves (stiffness) tended to be steeply

decreasing after the ultimate load except at the 3- to 4-mm

interval in which the curve was relatively horizontal. The rect-

angular cage without a defect showed the least variation in

the slope of the force displacement curve after the ultimate

load, whereas the circular cage showed the highest variation;

however, these 2 groups were signifi cantly different only at the

4- to 5-mm interval ( Figure 5 ). In comparing the rectangular

cage with a defect versus the circular cage, there was a signifi -

cant difference in the slope of the curves at 1- to 2-mm, 3- to

4-mm, and 4- to 5-mm intervals. There was no signifi cant dif-

ference between the rectangular cage with and without the

central defect in stiffness over any of the 5 intervals examined.

DISCUSSION Expandable cages are frequently used in the reconstruction of

defects after thoracolumbar corpectomy; however, subsidence

remains a problem. Subsidence of expandable cages depends

on several variables, including bone quality, fi t on the end-

plate, size and shape of the footplate, and adjunctive fi xation.

The majority of the current cage designs use a circular foot-

plate resting on the central portion of the endplate. Recently, a

novel rectangular footplate design that loads the ring apophy-

sis was introduced. This study showed that the novel rectan-

gular footplate design had a higher ultimate load as well as

higher stiffness values than a circular footplate design. The

new design was also at least equal to the circular footplate,

even in the presence of an endplate defect. These results sug-

gest the rectangular footplate design may provide higher resis-

tance to subsidence than circular footplates in reconstruction

of thoracolumbar corpectomy defects.

The subsidence of the cages is a function of footplate-

vertebral endplate interaction. In the reconstruction of a

TABLE 1. Demographic Information and BMD of the Specimens

Age (yr) DXA Sex

Levels (# of Specimen)

T12 L1 L2 L3 L4 L5

Circular 68.8 − 0.75 2M/2F 2 2 2 2 2 2

Rectangular with defect 68.8 − 0.75 2M/2F 2 2 2 2 2 2

Rectangular without defect 68.8 − 0.75 2M/2F 2 2 2 2 2 2

DXA indicates dual-energy x-ray absorptiometry; BMD, bone mineral density.

Figure 2. The test groups were group

A with the circular footplate over an

intact endplate, group B with the rect-

angular footplate spanning a central

circular defect, and group C with the

rectangular footplate over an intact ver-

tebral endplate.

Copyright © 2012 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.

BRS205137.indd E1179 05/08/12 10:38 AM

27 y/o female, 4 story fall

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Lumbopelvic Dissociation

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Lumbopelvic Dissociation

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26 yo M

Thank You