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57SProceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S
based synthetic fibrosis inhibitor (DuraSeal Xact�) in the reduction of low
back pain following lumbar microdiscectomy.
STUDY DESIGN/ SETTING: 20 blinded patients were randomized in
two groups of 10 : one group was treated with DuraSeal Xact� and the
other group received the local standard of care treatment (control group).
In the DuraSeal Xact group, a thin layer of a synthetic absorbable gel was
applied after microdiscectomy. Both groups were similar in terms of gen-
der ratio, weight, height, age, BMI and ASA score.
PATIENT SAMPLE: The included patients were aged between 19 and
71, and had to be elective for lumbar single level discectomy. Patients pre-
senting with infections, pregnancy, compromised immuninty, autoimmune
diseases were excluded as were known keloid formers.
OUTCOME MEASURES: Physical, neurological, Oswestry LBP scale,
SF 36 and VAS scores.
METHODS: The patients were assessed preoperatively by physical exam,
neurological status, Oswestry low back pain scale, SF 36 questionnaire and
VAS score. They were reviewed at their discharge from the hospital, and at
the 30, 90 and 180 days F/U visits with the same screening and for wound
assessment.
RESULTS: The involved level were L4L5 (9 patients, 5 DuraSeal Xact, 4
control) and L5S1 (11 patients, 5 DuraSeal Xact, 6 control). The procedure
duration averaged 52 min in the DuraSeal Xact group and 57 min in the con-
trol group. The DuraSeal Xact volume used averaged 1.3 ml. There was one
dural tear during surgery for one patient in the control group, treated with
fibrin glue. At 30 days, the Oswestry pain score showed a 41.5% reduction
in the DuraSeal Xact group vs a 34.3% reduction in the control group. At 90
days, the pain reduction was 68.2% in the DuraSeal Xact group vs 42.4% in
the control group. The same trend was observed at 180 days, with a 73.3%
reduction in the DuraSeal Xact group vs a 55.4% reduction in the control
group. VAS measurements showed progressive pain reduction in both
groups, but more pronounced in the DuraSeal Xact group (43.9% vs
35.6% at 30 days, 64.3% vs 44.8% at 90 days, and 75.4% vs 59.6% at
180 days). The DuraSeal Xact group showed better SF36 score changes
from baseline at 30 days for physical functioning, vitality, social function-
ing, mental health and emotional patterns, and at 90 and 180 days* for
the same items with addition of physical role, bodily pain and general
health. All patients in the treatment group had normal wound healing. There
were no complications related to the use of the gel and no reoperations. One
infection in the treatment group was treated conservatively with success and
was not device-related. * 180-day SF36 outcomes reported are based on data
from approximately half of evaluated subjects.
CONCLUSIONS: The use of Duraseal Xact� after microdiscectomy for
fibrosis prevention is not only safe, but also reduces postoperative pain and
allows better functional results.
FDA DEVICE/DRUG STATUS: Duraseal X-Act: Investigational/Not
approved.
doi:10.1016/j.spinee.2008.06.133
112. Long-Term Effect of the Intervertebral Dynamic Stabilization
as a Protective Technique for Adjacent Levels
Gilles Perrin, MD, Alessandro Cristini, MD; Bron, France
BACKGROUND CONTEXT: Rigid fusion is often associated with adja-
cent segment degeneration (ASD). Dynamic stabilization devices may pal-
liate this drawback, by preventing mechanical failures and stress-shielding
phenomena. However, there are few comparative studies available, regard-
ing ASD after rigid fusion versus dynamic stabilization, mainly because of
the lack of long term follow-up of dynamic fusion systems available in
clinical practice.
PURPOSE: To assess long-term ASD after dynamic stabilization with hy-
brid constructs (semi-rigid fusion with dynamic component) versus rigid
fusion in two comparable populations.
STUDY DESIGN/ SETTING: Retrospective comparative study on two
series of patients.
PATIENT SAMPLE: Sixty (60) consecutive patients with lumbar isthmic
spondylolisthesis operated on from 1991 to 1997 were enrolled in this ret-
rospective comparative analysis. Mean follow-up in this series was 8.3
years [6-13].
OUTCOME MEASURES: The evaluation criteria for the assessment of
the clinical outcome and the occurrence of ASD were: 1. Fusion status (in-
tervertebral bone bridges, no intervertebral motion on dynamic X-rays, no
subsidence, no device fracture or dismantling). 2. Radiological evidence of
ASD (loss of disc height, loss of intervertebral motion, spontaneous facet
fusion). 3. Clinical outcome (occurrence of recurrent symptoms and sec-
ond surgery with extension of the posterior fixation).
METHODS: All patients underwent posterior lumbar interbody fusion
with posterior fixation for isthmic spondylolisthesis and adjacent patholog-
ical but non compressive disk: - Group1: 36 (16 women / 20 men) under-
went postero-lateral stabilization and rigid fusion for the adjacent
pathological disc - Group2: 24 (10women / 14men) underwent adjacent
dynamic stabilization by means of a hybrid (rigid-and dynamic) construct.
Mean age was 32 years [22,51] in Group1 and 29 years [23,47] in Group2.
RESULTS: No specific complications occurred per-operatively. Post-oper-
ative complications occurred in 2 patients (i.e. screws or plate breakage) in
Group 1. No post-operative complication was recorded in Group 2. At last
follow-up, solid fusion at the treated level was documented in 100% of pa-
tients in both groups. Radiographic analysis showed ASD in 16 (44.4%)
patients in Group 1 and in 1 (4.2%) patient in Group 2. Five patients
(13.9%) underwent revision surgery for ASD in Group 1. None of the pa-
tients in Group 2 underwent revision surgery.
CONCLUSIONS: The results of this retrospective analysis show that
dynamic stabilization is an efficient procedure for the prevention of lumbar
adjacent early degeneration in association with other measures like
restoration of efficient posterior musculature, lumbar lordosis and physio-
logical sagital lumbopelvic balance. A better load sharing pattern results
in less mechanical complications, mostly due to the neo-hinge phenome-
non between a fused spinal segment and an adjacent overstressed and
hypermobile intervertebral segment. The results of the current study
are most encouraging; however, a prospective long-term comparative
randomized study seems to be necessary in order to fully confirm these
findings.
FDA DEVICE/DRUG STATUS: Isobar TTL: Approved for this indication.
doi:10.1016/j.spinee.2008.06.134
113. Long-Term Outcome Evaluation after PARS Defect Repair in
Adults with Low-grade Isthmic Spondylolithesis
Thierry David, MD1, Sabina Champain, PhD2, Wafa Skalli, PhD3;1Rouvroy, France; 2Laboratoire de Biomecanique, ENSAM, Paris, France;3Laboratoire de Biomecanique, ENSAM Paris, Paris, France
BACKGROUND CONTEXT: Adult low-grade isthmic spondylolisthesis
is often treated by posterolateral lumbar fusion (PLF), with a certain rate
of complications and non-return to work. Alternatives to fusion, like pars de-
fect repair (PDR), were used with encouraging results in young populations
and athletes but their outcomes were rarely evaluated for adult patients.
PURPOSE: To quantitatively assess the long-term clinical and biome-
chanical outcomes in an adult population with isthmic spondylolisthesis
treated by PLF and PDR.
STUDY DESIGN/ SETTING: This is a retrospective comparative study.
PATIENT SAMPLE: Among patients surgically treated for grade 1 or 2
lytic spondylolisthesis from 1990 to 2000 in our institution, 60 [38m/22w]
(mean age 42612y) could be reviewed at long-term. Mean follow-up in
this series was 9 years [5-14].
OUTCOME MEASURES: Clinical, socio-professional and radiographic
data as well as the Stauffer-Coventry score were measured by an indepen-
dent operator for all patients in the series. The modified Stauffer-Coventry
score allowed the classification of patients’ outcome as excellent, good,
fair and poor for both groups. The biomechanical analysis included static
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58S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S
spinal and pelvic parameters assessment as well as a kinematic analysis of
the instrumented levels and the adjacent ones (i.e. Flexion-Extension
Range of Motion and Mean Center of Rotation). A comparative analysis
was performed on the clinical, socio-professional and biomechanical data
in patients operated with PLF versus PDR.
METHODS: 39 patients underwent PLF with a rigid rod and screws con-
struct (CD, Medtronic: L5S2:82%, L4L5:12%, L4S1:6%) whereas 21 un-
derwent PDR without spinal fusion (DOS, SpineNetwork: L5S1:59%,
L4L5:13%, L4S1:28%).
RESULTS: No per-operative complications were reported in this series.
The overall post-operative complication rates were only 51% vs. 33% in
the PLF versus PDR groups, whereas a major difference was found in me-
chanical complications (implant related) that occurred in 28% in the PLF
group versus 5% in the PDR group. The revision rate was comparable be-
tween the groups (8% in the PLF group vs. 5% in the PDR one). At a mean
follow-up of 9 years, the overall clinical outcomes were comparable in
both populations (good or excellent: 88% after PDR vs. 80% after PLF),
with a larger proportion of excellent results (56% vs. 10%) in the PDR
group versus the PLF group. 60% of patients in the PLF group resumed
their previous activities versus 80% in the PDR group; 2 (blue collar/heavy
workers: 33% in PLF group versus 75% in PDR group). Radiological
quantitative analysis showed stationary evolution and comparable out-
comes for the two groups, except for vertebral slip evolution and adjacent
level degeneration rate. Abnormal kinematic patterns documented a 20%
rate of pseudarthrosis in the PLF group of patients and adjacent levels hy-
permobility in 42% of patients who underwent PDR. Low mobility at the
levels adjacent to instrumented vertebra was also observed in 40% of cases
in the PDR group.
CONCLUSIONS: Quantified analyses of biomechanical parameters inter-
preted altogether with clinical outcome, complications and economic bur-
den of the patient, provided accurate objective data for a better
appreciation of the overall outcome, allowing for a preliminary view on
long-term outcomes after PDR in adult low-grade isthmic spondylolisthe-
sis, unreported in the literature until now.
FDA DEVICE/DRUG STATUS: DOS: Not approved for this indication;
CD: Approved for this indication.
doi:10.1016/j.spinee.2008.06.135
114. Spondylolysis Repair with Rigid Fixation: A Prospective
Clinical and Radiographic Outcome Study
Matthew Hepler, MD1, Matthew Walker, MD2, Eugene Lautenschlager2;1Vero Orthopaedics, Vero Beach, FL, USA; 2Northwestern University,
Chicago, IL, USA
BACKGROUND CONTEXT: Spondylolysis is a common source of back
pain and chronic defects can produce continued pain and disability, alter
spinal biomechanics, and increase stress to the adjacent disc. Surgical
treatment has had variable results and there are no prospective studies eval-
uating the clinical and radiologic outcome of patients treated with fracture
repair using rigid fixation with a pedicle screw-sublaminar hook(claw)
construct.
PURPOSE: The purpose of this study was to prospectively evaluate the
clinical and radiological outcome of patients with spondylolysis treated
with debridement, bone grafting, and rigid fixation with a pedicle screw-
sublaminar claw construct.
STUDY DESIGN/ SETTING: Prospective cohort study of 11 patients (12
lytic lesions) who had failed a thorough course of nonoperative treatment.
Patients were treated with fracture debridement, bone grafting, and rigid
fixation with a pedicle screw/hook construct. All patients were evaluated
with preoperative examination, xray, MRI +/- CT scan and outcome ques-
tionaires (SF-36, ODI, Roland-Morris, and VAS). Follow-up evaluation oc-
curred at 6 wk, 3, 6, 12, and 24 months including physical examination,
xray, and outcome questionaires. CT scans were performed prior to return-
ing to contact sports (6 months).
PATIENT SAMPLE: 11 patients with 12 spondylolysis lesions. There
were 2 females and 11 males. The average age was 28 years old and ranged
from 17–51.
OUTCOME MEASURES: Outcome measures included SF-36, ODI, Ro-
land-Morris, and VAS (repeated measures ANOVA and Tukey post hoc
testing) questionaires completed preop and 3, 6, 12, and 24 months postop.
Radiologic evaluation included flex/ext xrays and CT scan for those return-
ing to contact sports.
METHODS: A prospective cohort study evaluating spondylolysis repair
with debridement, bone grafting, and pedicle screw-sublaminar hook fixa-
tion. Inclusion criteria included back pain, spondylolysis on CT/MRI, di-
agnostic injection (if concomitant pathology), and failure to improve
with non-operative treatment including bracing. Patients were evaluated
preoperatively and at 3, 6, 12, and 24 months postoperatively with SF-
36, ODI, Roland-Morris, and VAS (repeated measures ANOVA and Tukey
post hoc testing). Radiologic evaluation included flex/ext xrays and CT
scan for those returning to contact sports.
RESULTS: All patients returned to full activities including contact sports
within 6 months of surgery. Statistically significant improvement (p!.05)
was seen in each outcome instrument (except SF-36 RE and MCS) at 6,
12 and 24 month follow-up. Flexion-extension x-rays and CT demon-
strated fusion in all cases. There were no infections and no revision sur-
geries. One patient developed discogenic back pain 18 months
postoperatively.
CONCLUSIONS: Spondylolysis repair with rigid fixation has excellent
clinical and radiologic outcome. This technique successfully repairs the
underlying defect and restores physiologic motion and lumbar biomechan-
ics. Symptomatic lesions (confirmed by injection study) did equally well
even in the presence of concomitant diagnosis demonstrating the primary
significance of this lesion.
FDA DEVICE/DRUG STATUS: This abstract does not discuss or include
any applicable devices or drugs.
doi:10.1016/j.spinee.2008.06.136
115. Is There a Euphoric Bias Effecting the Outcomes of
Randomized vs. Non-Randomized Patients Enrolling in New
Technology Trials?
Jack Zigler, MD1, Donna Ohnmeiss, MD2; 1Texas Back Institute, Plano,
TX, USA; 2Texas Back Institute Research Foundation, Plano, TX, USA
BACKGROUND CONTEXT: There has been some question concern-
ing the impact of randomization on the outcomes of clinical trials eval-
uating new technologies. One potential impact may be if patients who
‘‘have the euphoria of winning the drawing’’ in getting the new technol-
ogy vs. the control treatment tend to provide more favorable responses
on post-operative self-assessment outcome questionnaires than patients
who were not randomized (knowing that they would receive the new
technology).