lessons learned after nine-year follow-up on eight different lumbar total disc replacement devices
TRANSCRIPT
29SProceedings of the NASS 27th Annual Meeting / The Spine Journal 12 (2012) 22S–44S
establish range of motion (ROM) values for each tested construct on a 6 de-
gree of freedom spine motion simulator. Data was normalized to intact
(Intact5100%) and analyzed. Significance was set at p!0.05.
RESULTS: All the surgical constructs offered significant stability in all
loading conditions compared to the intact condition. Mean ROM of differ-
ent constructs trended as follows: DDSODISO SSSOMGT. Overall, the
DDS construct provided 55%, 43%, and 60% additional stability, com-
pared to SSS, DIS, and MGT, respectively. This was significant in flexion-
extension compared to SSS and MGT. In lateral bending, no significant
differences among the instrumented constructs were found. In axial rota-
tion, DDS was found to be significantly stable compared to MGT.
CONCLUSIONS: In the setting of total sacrectomy, double-rod double il-
iac screw method provided the most rigid fixation, followed by double iliac
screw fixation, single-rod single screw, and modified Galveston technique.
In cases precluding double-rod double iliac screw, double iliac screw fix-
ation method may provide enough stability while minimizing rod contour-
ing and surgical incision. In spino-pelvic reconstruction, use of double iliac
screws is recommended over single illiac screw fixation techniques when
treating more unstable situations caused by total sacrectomy.
FDA DEVICE/DRUG STATUS: This abstract does not discuss or include
any applicable devices or drugs.
http://dx.doi.org/10.1016/j.spinee.2012.08.096
56. The Coflex� Versus Fusion US FDA IDE Trial: An In Vivo
Biomechanical Study of Adjacent Segment Motion Following Fusion
William R. Sears, MD, FRACS1, Reginald J. Davis, MD, FACS2, Joshua
D. Auerbach, MD3; 1Sydney, Australia; 2Greater Baltimore Neurosurgical
Associates, Baltimore, MD, US; 3Brooklyn, NY, US
BACKGROUND CONTEXT: Numerous in vitro biomechanical studies
have reported increased motion and stresses at segments adjacent to a sim-
ulated lumbar spinal fusion. However, some authors have questioned the
methodology & hence, the findings of these cadaveric studies. Questions
remain regarding the optimal methodology to replicate in vivo conditions;
in particular, should in vitro models use displacement, load or hybrid con-
trol? The recent FDA trial, which examined the Coflex� interlaminar de-
vice, included an examination of overall lumbar spinal and segmental
motion using digital quantitative motion analysis (QMA�). QMA� has
been found to be accurate to within 0.5-1�.PURPOSE: To prospectively examine in vivo lumbar segmental motion
before and after fusion to help resolve questions regarding: firstly, the af-
fects of fusion on adjacent segment motion and secondly, the optimization
of in vitro test methodology.
STUDY DESIGN/SETTING: In vivo biomechanical study of patients
participating in a multicenter, prospective, randomized FDA IDE trial.
PATIENT SAMPLE: One hundred ninety patients randomized 2:1 to the
investigational (decompression þ Coflex� interlaminar device) or control
(decompression þ instrumented, posterolateral fusion) arms. Inclusion cri-
teria: back pain (VASO50) with neurogenic claudication. ODIO40. Mod-
erate or severe canal stenosis and up to Grade 1 degenerative
spondylolisthesis. Mean age: 62.5 years 69(StDev).
OUTCOME MEASURES: Individual lumbar segmental and overall
(L1-S1) range-of-motion (ROM) in degrees.
METHODS: Dynamic x-rays were examined pre-operatively and at regu-
lar time-intervals for a minimum 24-months using QMA�. Total lumbar
(L1-S1) range-of-motion (ROM�), motion at the index level(s) and motion
at one level above, two levels above and one level below are reported in
this study. Non-parametric statistics were used with significance set at
p!0.05. Results are shown as means (6 Standard Deviation).
RESULTS: In the 45 patients who underwent 1-level and 24 patients who
underwent 2-level fusions, a trend toward increased ROM was evident at
the segments immediately above the fused segments at 12-months: pre-
operative ROM measured 3.4�(63.3�) and 3.8�(62.8�) in the 1- and 2-
level fusions, respectively and measured 4.6�(64.6�, p50.08) and
All referenced figures and tables will be available at the Annual Mee
5.2�(64.3�, p50.18) at 12-months. By 24-months, ROM at these segments
had increased further & significantly to: 4.9�(64.5�, p50.035) above 1-
level and 7.6�(64.8�, p50.0005) above 2-level fusions. The mean increase
in ROM above 2-level fusions at 24-months was 3.7�(95%CI:1.8�-5.6�). Asmall but apparently significant increase in ROM was seen at 24-months at
the level immediately below 1-level fusions (1.6�, p50.02). Otherwise, no
significant changes in ROM were observed at segments two-levels above
or one-level below the fusions. In the 1-level fusion patients, ROM at
the fused levels decreased by 2.8� at both 12- and 24-months. In the 2-level
fusion patients, mean ROM at the fused segments reduced by 4.0� and 3.6�
at 12 & 24-months, respectively (p!0.0001). Despite the reduction in mo-
tion at the fused segments, total (L1-S1) ROM did not change over the
pre-, 12- and 24-month time-points: 20.4�(613.1�), 19.8�(613.2�,p50.62), 22.2�(613.3�, p50.33), respectively. No significant changes
were observed in any motion parameters in patients implanted with the
Coflex� device.
CONCLUSIONS: The current in vivo study has shown a trend, both over
time and with more fused levels, towards increasing ROM at levels imme-
diately above a spinal fusion – most apparent at 24-months, above 2-level
fusions, where a two-fold increase in mean ROM was evident. While inter-
and intra-patient variations were observed, likely related to factors such as
patient effort or pain, analysis of mean values over 12 & 24-months
showed no significant change in L1-S1 ROM, despite significant reduc-
tions in motion associated with fused segments. This would appear to in-
dicate that the presence of a fusion does not naturally lead to a reduction
in patients’ subsequent L1-S1 ROM and that displacement or hybrid
control in vitro methodology may be appropriate. Examination of x-rays
at additional postoperative time points may confirm the apparent trend to-
wards increasing motion, evident at segments above fusions, over time. If
so, this finding may also require attention in in vitro experimental
methodology.
FDA DEVICE/DRUG STATUS: Coflex� (Investigational/Not approved)
http://dx.doi.org/10.1016/j.spinee.2012.08.097
57. Lessons Learned After Nine-Year Follow-Up on Eight Different
Lumbar Total Disc Replacement Devices
Luiz H. Pimenta, MD, PhD, Luis Marchi, MD, Leonardo Oliveira, MD;
S~ao Paulo, Brazil
BACKGROUND CONTEXT: Charit�e prothesis has over than 20.000 pa-
tients worldwide and has been implanted since the early 1980’s. Over these
years, new prostheses have been developed, differing in disc materials, bio-
mechanical features, indications and implantation approaches. Nowadays
we can be supported by literature and clinical experience.
PURPOSE: Here we show our experience in 8 different lumbar TDR de-
vices up to 9 years follow up
STUDY DESIGN/SETTING: The senior author’s wide clinical experi-
ence was analyzed.
PATIENT SAMPLE:More than 400 single or multi-level implanted pros-
theses with up to 9 years of follow-up.
OUTCOME MEASURES: We have evaluated the pitfalls in the lumbar
arthroplasty history and how is possible to minimize this problems.
METHODS: The clinical experience lay on different prostheses, including
charit�e, prodisc, mobidisc, triumph, maverick, physio-L, active-L and lat-
eral disc. Patients had been prospectively monitored, using the clinical and
imagining outcomes assessment. Complications and success have been
recorded and related to pre-existing conditions, prostheses design, ap-
proaches and indications.
RESULTS: Overall clinical outcomes testify TDR benefits, but point out
to long term complications appearance. Complications type depends on the
prosthesis model, covering facet join pain, subsidence, bad positioning,
core fracture, pedicle fracture, iatrogenic scoliosis, heterotopic ossification
and CrCo allergy. Persistent back pain-9.1%; facet degeneration - 25%;
ting and will be included with the post-meeting online content.
30S Proceedings of the NASS 27th Annual Meeting / The Spine Journal 12 (2012) 22S–44S
misplacements-8.5%; subsidence-7%; partial explantations-2%; bone frac-
tures-2% and retrievals-6.21%.
CONCLUSIONS: Our analyses can point out various lumbar arthroplasty
aspects, including its pros: better biomechanical results, better clinical re-
sults, restoration of global motion, no bone graft needed; and its cons: ex-
pensive technology, short follow up in comparison to fusion, important
adverse events, ideal prosthesis yet nonexistent. Constant patient monitor-
ing, data sharing, concept and technology adapting are essential for
achieve crescent success.
FDA DEVICE/DRUG STATUS: Charit�e (Investigational/Not approved),
XLTDR (Investigational/Not approved), Triumph (Investigational/Not ap-
proved), Phisio-L (Investigational/Not approved), Maverick (Investiga-
tional/Not approved), Prodisc (Investigational/Not approved), Mobidisc
(Investigational/Not approved), Active-L (Investigational/Not approved)
http://dx.doi.org/10.1016/j.spinee.2012.08.098
58. Five-Year Adjacent Level Degenerative Changes Comparing
Lumbar Total Disc Replacement to Circumferential Fusion in
Patients with Single-Level Disease in a Prospective Randomized
Cohort Analysis
Jack E. Zigler, MD1, Rick B. Delamarter, MD2; 1Texas Back Institute,
Plano, TX, US; 2Los Angeles, CA, US
BACKGROUND CONTEXT: Acceleration of degeneration at the seg-
ment adjacent to a spinal fusion is a concern. It was proposed that one po-
tential advantage of total disc replacement (TDR) for the treatment of
painful disc degeneration may be to reduce the occurrence of adjacent seg-
ment deterioration.
PURPOSE: The authors report the five year results of radiographic adja-
cent level degenerative changes seen in patients enrolled in a prospective
multicenter study in which they were randomized to either TDR or circum-
ferential fusion for single-level lumbar degenerative disc disease.
STUDY DESIGN/SETTING: Data were collected prospectively as part
of a multicenter FDA IDE trial.
PATIENT SAMPLE: Two hundred thirty six patients with single-level
lumbar degenerative disc disease were enrolled and randomly assigned
to two treatment groups: 161 in the total disc replacement (TDR) group
treated with the ProDisc-L (Synthes Spine) and 75 treated with circumfer-
ential fusion. Complete radiographic follow-up at 5 years was available for
123 TDR patients and 43 fusion patients.
OUTCOMEMEASURES: Theprimaryoutcomemeasurewas radiographic
assessment of adjacent level degeneration assessed by radiologists at an inde-
pendent facility. Range of motion (ROM) and translation were also evaluated.
METHODS: ALDwas characterizedbya composite score comprisedof disc
height loss, endplate sclerosis, osteophytes and spondylolisthesis. At 5 years,
changes in ALD (DALD) were compared to the pre-operative assessment.
RESULTS: At five years, no change in adjacent level degeneration was
observed in 90.8% of the TDR patients compared to 71.4% of the Fusion
patients (p50.004). For patients with no adjacent level disease pre-opera-
tively, new findings of ALD at five years were found in 6.7% of the TDR
patients and in 23.8% of the Fusion patients. Adjacent level surgery lead-
ing to secondary surgery was reported for 2.9% of the TDR patients and
4.0% of the Fusion patients (p50.6819). TDR patients had a mean pre-
operative, index level range of motion (ROM) of 7.2� that was maintained
at 5 years. Neither treatment group had significant changes at 5 years in
either ROM or translation at the superior level.
CONCLUSIONS: At five years following index surgery, TDR maintained
ROM and was associated with a significantly higher rate of no DALD com-
pared to results in prospectively randomized patients treated with circum-
ferential fusion. Fusion patients had a 4.5 times higher rate of DALD
compared to TDR patients. Even in the follow-up window of five years,
there is a significant radiographic protective effect of TDR on the adjacent
lumbar segment, particularly in patients with no adjacent level disease at
the time of the index surgery. It is anticipated that, over time, this may
be reflected in a lower rate of secondary surgery.
All referenced figures and tables will be available at the Annual Mee
FDA DEVICE/DRUG STATUS: ProDisc-L (Approved for this
indication)
http://dx.doi.org/10.1016/j.spinee.2012.08.099
59. New Strategy for Treatment of Lower Back Pain: Molecular
Restoration of Intervertebral Disc Using an Injection of Biomimetic
Aggrecan
Katsiaryna Prudnikova, PhD1, Edward J. Vresilovic, MD, PhD2,
Michele Marcolongo1; 1Drexel University, Philadelphia, PA, US;2Ardmore, PA, US
BACKGROUND CONTEXT: Early degeneration of the intervertebral
disc is accompanied by a decrease in aggrecan content in the nucleus pulpo-
sus. Aggrecan is composed of negatively charged chondroitin sulfate (CS)
bristles attached to a protein core. During degeneration, aggrecan is cleaved
along the protein backbone by enzymes, reducing the aggrecan content in the
nucleus and leading to a loss of hydration and disc height as well as mechan-
ical instability. We hypothesize that restoration of aggrecan to normal levels
will restore disc function, however, injection with natural aggrecan is
cost prohibitive and natural aggrecan would still be subject to enzymatic
degradation.
PURPOSE: We have synthesized a low-cost, enzymatically resistant bio-
mimetic analogue to natural aggrecan which can easily be injected into the
nucleus pulposus to molecularly engineer the matrix to restore the osmotic
pressure of the disc.
METHODS: Biomimetic aggrecan was synthesized by grafting CS bris-
tles to poly(acrylic acid) (PAA) (250 kDa MW) and poly(acryloyl chlo-
ride) (PAC) (10 kDa MW) cores (enzymatically resistant backbones).
Reaction was performed at different ratios (mol/mol) of CS molecules to
functional groups 1:10 (PAC-CS), 1:15 and 1:30 (PAA-CS). Reaction ki-
netics were monitored using a fluorescamine assay. Macromolecules were
purified and chemical structures were confirmed with 1H NMR. Biomi-
metic aggrecan was chjaracterized via rheometry and osmotic pressure.
Initial cytocompatibility of biomimetic aggrecan samples was assessed us-
ing L9292 fibroblasts.
RESULTS: Natural aggrecan has about 100 CS bristles, spaced 3-5 nm
apart along the length of the core with an overall molecular weight of
~2,000 kDa. The synthesized biomimetic aggrecan was shown to have
~85 CS bristles on the 250 kDa PAA core with bristles spaced at 4-8 nm
and a total estimated molecular weight of ~2,000 kDa. 1H NMR spectra
showed no degradation of CS with processing. Remarkably, an 8X increase
in osmotic pressure from CS alone and equal osmotic pressure to natural ag-
grecan was measured for our biomimetic analogue. The shorter 10 kDa
PAA results scaled to the length of the core. Biomimetic aggrecan was
cytocompatible.
CONCLUSIONS: Novel biomimetic aggrecan, which mimics the 3-D ar-
chitecture and osmotic properties of the natural aggrecan, was shown to
have comparable osmotic pressure of natural aggrecan and to be cytocom-
patible. Biomimetic aggrecan can be used as a low-cost augmentation to
molecularly engineer the nucleus pulposus matrix for mechanical stabiliza-
tion of the disc.
FDA DEVICE/DRUG STATUS: This abstract does not discuss or include
any applicable devices or drugs.
http://dx.doi.org/10.1016/j.spinee.2012.08.100
60. Biomechanical and Early Clinical Results of Stand-Alone
Anterior Cervical Fixation for Rotationally Unstable Facet
Fractures
Christopher D. Chaput, MD1, David M. Gloystein, MD2, Mark Rahm,
MD3, Aditya M. Muzumdar4, Mark Moldavsky5, Suresh Chinthakunta4,
Saif Khalil, PhD4; 1Scott & White Hospital, Temple, TX, US; 2Fort Hood
Orthopaedics, Harker Heights, TX, US; 3Texas A & M Scott & White
ting and will be included with the post-meeting online content.