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

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).