175SProceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

who subsequently underwent a Lumbar Discectomy (63030) over a three

year time period from 2004–2006.

RESULTS: Within our population of 482,893 patients with the diagnosis

of a disc herniation, 27,799(5.76%) underwent a lumbar discectomy. Of

the 29,941 patients who received SNRB for a disc herniation, 3,235

(10.80%) later underwent a lumbar discectomy.

CONCLUSIONS: The rate of lumbar discetomy after SNRB appears

smaller than that reported in a previous randomized control trial. This

may suggest that either SNRB is more beneficial than previously suspected

or that patients are receiving SNRB earlier and more frequently in the

conservative treatment of their disc herniation.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.401

P154. Lumbar Hybrid Arthroplasty Outcomes Analysis

Pablo Pazmino, MD1, Carl Lauryssen, MD2, Todd Lanman, MD3; 1Beverly

Spine Institute, Beverly Hills, CA, USA; 2Director Neurological Spine

Olympia Medical Center, Beverly Hills, CA, USA; 3Director Neurological

Spine Century City Doctors Hospital, Los Angeles, CA, USA

BACKGROUND CONTEXT: A considerable subset of patients demon-

strate symptomatic multiple level lumbar discogenic disease. The rationale

behind arthroplasty in preserving adjacent level segments becomes more

important in this group of patients given the larger cantilever forces at play.

In efforts to preserve motion and limit force concentrations at the remain-

ing lumbar segments hybrid disc arthroplasty is gaining momentum as

a new treatment modality.To our knowledge there are no clinical studies

which evaluate the outcomes of patients with hybrid disc arthroplasty.

The present study evaluates our subset of patients through their patient

perceived outcomes, return to sport and their return to work.

PURPOSE: Assess the efficacy and benefits of lumbar hybrid arthroplasty

in the treatment of multiple level disc pathology.

STUDY DESIGN/ SETTING: A retrospective observational cohort study

of consecutive patients with multiple level lumbar discogenic disease

recalcitrant to conservative therapy.

PATIENT SAMPLE: A total of 28 Lumbar arthroplasties in 26 patients

were reviewed. Arthroplasty was performed using either the Charite or Pro-

disc prosthesis in concert with fusion in 26 consecutive patients. 13 males

(50%) and 13 females (50%) were evaluated with a mean age of 42 years

(range 28 to 58) and mean followup of 20.6 months.The mean duration of

back pain before surgery was 3.3 years. All patients were available at each

follow-up interval except two patients who were lost to followup.

OUTCOME MEASURES: Outcome variables included radiographic

fusion based on postoperative films (2 weeks, 1 month, 3 month, 6 month,

1 year, 18 months, 2 years from surgery), computed tomography (6 months

and 1 year) and clinical assessment using visual analog scale for back pain,

the Oswestry disability instruments,and the modified Stauffer-Coventry

classification.

METHODS: Patient completed ODI,VAS outcome measures and were

interviewed on followup to assess return to,type,and frequency of sport, re-

turn to and type of work. Determination for return to work and sport was

based on postoperative pain, radiographic and CTevidence of interim fusion.

RESULTS: Patients showed statistically significant improvement in ODI

scores at all follow-up periods compared to baseline (P!0.001).The mean

ODI score at baseline was 67.38, which improved to a mean of 46.62. Pa-

tients also showed statistically significant improvement in VAS scores at

all follow-up periods compared to baseline (P!0.0001). The mean VAS

score at baseline was 7.40, which improved to a mean of 3.73. Improve-

ment at each interval and overall was statistically significant (p!0.05) us-

ing the Wilcoxon Rank Sum Test. Using the modified Stauffer-Coventry

classification the mean outcome was 3.44 (range 2–4,SD 0.616). The mean

interval from surgery to return to work for the 17 patients in employment

was 3.61 months or 112.8 days (range 14–351,SD 98.71).The mean

interval from surgery for the 20 patients who returned to sports was 3.58

months or 110.89 days (range 1–360,SD 98.51).Among the reasons for

the four patients who had not resuming sport, 71% gave pain and 29% gave

sociopsychological reasons such as anxiety or lack of time.

176S Proceedings of the NASS 23rd Annual Meeting / The Spine Journal 8 (2008) 1S–191S

CONCLUSIONS: Hybrid lumbar arthroplasty appears to be a safe and

effective treatment for painful lumbar discogenic disease.The rate of im-

provement is rapid and sustained through 1.6 years.This study observes

outcomes and times to return to work and sport which may serve as a guide

for patient education and post-operative expectation.

FDA DEVICE/DRUG STATUS: Prodisc and Charite Artificial Disc

Replacements: Not approved for this indication.

doi:10.1016/j.spinee.2008.06.402

P155. Lumbar Spine Fusion Rates in Patients with Osteoporosis: A

Case Control Study

Elias C. Papadopoulos, MD1, Alexander Richter2, Frank P. Cammisa,

MD3, Federico P. Girardi, MD3; 1University of Athens, School of

Medicine, Athens, Greece; 2Albany, NY, USA; 3Hospital for Special

Surgery, New York, NY, USA

BACKGROUND CONTEXT: Too few studies are available on the differ-

ences of fracture healing in normal and osteoporotic individuals to suggest

a difference in capacity for bone remodeling and bone healing in osteopo-

rosis. Similarly, no experimental or clinical data are available in spine

literature regarding spinal fusion rates.

PURPOSE: To investigate the possible difference in spinal fusion rates in

osteoporotic patients versus patients with normal bone mass, with or with-

out segmental instrumentation.

STUDY DESIGN/ SETTING: Retrospective controlled study.

PATIENT SAMPLE: 287 consecutive patients that underwent lumbar

spine fusion; 124 (43.2%) had a diagnosis of osteoporosis based on spinal

or femoral neck DEXA studies.

OUTCOME MEASURES: Fusion mass and instrumentation for possible

failure were evaluated in plain and dynamic radiographs.

METHODS: A retrospective review of all patients undergoing lumbar

fusion surgery performed between January 2000 and December 2004. 287

patients were analyzed (mean age 68.08). Patients were divided in to two

groups based upon osteoporotic status; then subdivided by instrumentation

status. Osteoporotic patients were then matched with non-osteoporotic pa-

tients of the same instrumentation status; 24 matched pairs with instrumen-

tation and 35 matched pairs without instrumentation with follow-up six

months or more. The fusion status of the matched pairs was then compared.

RESULTS: The matched pairs with instrumentation had a mean age of

64.35 years (SD57.71) and 2 (SD50.71) levels of fusion. The matched pairs

without instrumentation had a mean age of 74.26 years (SD55.42) and 1.31

(SD50.53) levels of fusion. Both the osteoporotic and non-osteoporotic

patients with instrumentation demonstrated a 100% fusion rate by 6 months.

The group without instrumentation had an overall fusion rate of 95.8% with

one (2%) osteoporotic patient and one (2%) non-osteoporotic patient

demonstrating non-fusions. No instrumentation failure was recorded.

CONCLUSIONS: In this retrospective controlled study, osteoporosis was

not found to be a risk factor for pseudarthrosis in lumbar spine fusion.

FDA DEVICE/DRUG STATUS: This abstract does not discuss or include

any applicable devices or drugs.

doi:10.1016/j.spinee.2008.06.403

P156. Artificial Disc Replacement (ADR) in the Presence of an

Adjacent Degenerate Level in Lumbar Degenerative Disc Disease

(DDD)

John Nathaniel Ruiz, Hwan-Tak Hee, MD, FRCS, Joseph Thambiah, MD,

Hee-Kit Wong, MD; National University Hospital, Singapore, Singapore

BACKGROUND CONTEXT: The role of surgery in the presence of

multi-level lumbar DDD is not defined. There are few reports on accuracy

of identifying symptomatic degenerate discs. Not all degenerate-looking

discs in DDD may be symptomatic. It is hypothesized that ADR may the-

oretically limit adjacent level stress and delay further degeneration. This

may be more advantageous than fusion surgery if a single symptomatic

level is identified in multi-level DDD.

PURPOSE: To define patient outcomes after selective single-level ADR in

multi-level DDD and compare them to outcomes after single-level ADR in

single-level DDD.

STUDY DESIGN/ SETTING: Single-institution prospective observa-

tional study of patient outcomes after ADR.

PATIENT SAMPLE: There were 2 patient groups: 25 patients (mean age

33.6 yrs) with 1-level lumbar DDD on MRI who underwent single-level

ADR (S-ADR grp); 18 patients (mean age 36.1 years) with 2-level lumbar

DDD on MRI who underwent selective single-level ADR (SS-ADR grp).

Selection of the symptomatic level in the SS-ADR group was identified

by either provocative discography or associated lower limb dermatomal

symptoms.

OUTCOME MEASURES: Visual Analogue Score (VAS), Oswestry

Disability Index (ODI), Short Form-36 (SF-36), and segmental range of

motion (ROM) were used as outcome measures.

METHODS: 43 consecutive patients with symptomatic lumbar DDD that

fulfilled inclusion criteria underwent single-level ADR at either L4L5 or

L5S1. There were 25 patients in S-ADR grp (8 L4L5 ADR, 17 L5S1

ADR) and 18 patients in SS-ADR group (11 L4L5 ADR, 7 L5S1 ADR).

VAS, ODI and SF-36 were prospectively administered at pre-op, and at

6- 12- and 24 months post-op. Segmental ROM was determined from erect

dynamic lumbar radiographs during the same follow-up periods. Statistical

analysis was performed using a General Linear Model to determine differ-

ences between the 2 patient groups (p!.05).

RESULTS: Both S-ADR and SS-ADR grps showed significant time trend

improvements in VAS, ODI and SF-36 at 6 and 12-months post-op com-

pared to pre-op levels(p!.01). After 12-months, divergent patterns of fur-

ther improvement were noted. SS-ADR grp was noted to sustain initial

gains after surgery, whereas S-ADR grp continued to have improved scores

in VAS, ODI and the physical and pain domains of SF-36 by 24-months

post-op (p!.05). Three (16.7%) of the 18 patients in the SS-ADR group

were noted to have deteriorating symptoms at 24-months post-op that re-

quired further investigations. ROM at that time revealed O5 � motion of

the ADR level. Repeat MRI & provocative discography revealed that the

previously asymptomatic degenerate level adjacent to the ADR level had

become symptomatic O24 months after ADR. Two of them required sur-

gery of the adjacent degenerate level (L5S1) while the other had to stop

working. There was no correlation between ROM at 24 months (stratified

to operated level) and clinical outcome in both patient groups.

CONCLUSIONS: Pain and dysfunction brought about by symptomatic

DDD can be treated by ADR. The best results of this intervention can

be seen in single-level DDD. Selective ADR in the presence of multi-level

DDD can also improve pain and dysfunction but results are inferior to sin-

gle-level DDD by 24 months post-op. Selective ADR in multi-level disease

resulted in symptomatic adjacent level disease in 16.7% of our patients

some of which required further surgery. Indications for surgery in multi-

level DDD are still evolving and further follow-up is required.

FDA DEVICE/DRUG STATUS: ProDisc: Approved for this indication.

doi:10.1016/j.spinee.2008.06.404

P157. Lumbar Disc Arthroplasty via an Oblique Insertion Safety

and Position Analysis

Le Huec Jean-Charles, MD, PhD1, Stephane Aunoble, MD1,

Richard Meyrat, MD1, Yasser Al-Sawad, MD1, Pierre Arne, MD2;1CHU Bordeaux, Pellegrin-Tripode, Bordeaux, France; 2Bordeaux CHU,

Bordeaux, France

BACKGROUND CONTEXT: At the L4-L5 level, extreme retraction of

the great vessels may be necessary to provide enough space for the central

placement of disc prosthesis. Recent studies have shown that up to 57% of