Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S180S

6 months postADR (88%) versus preADR (76%). 12% of patients out ofwork on disability were able to return to work by 6 months postADR.There were no statistical outcome differences in patients with preADR severedisc height collapse verses those with minimal collapse.CONCLUSIONS: Patients were able to significantly increase recreationalactivities and reduce medication use following ADR. RTW rate, even inpatients out on disability may be significantly increased in patients followingADR. Patients with severe disc height collapse may experience similarimprovements in outcomes as those patients with minimal disc heightcollapse.DISCLOSURES: FDA device/drug: Charite Artificial Disc (SBIII). Status:Approved for this indication.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.360

P147. In vitro evaluation of soak time-dependent release ofrhBMP-2 in the immediate postoperative environmentHyun Bae, MD1, Li Zhao, MD2, Pamela Wong, BS3, Ben Pradhan, MD1,Michael Kropf, MD1, Rick Delamarter, MD1, L.E.A. Kanim, MPH, MA1;1Spine Institute at Saint John’s Health Center, Santa Monica, CA, USA;2Saint John’s Health Center, Santa Monica, CA, USA; 3Spine ResearchFoundation, Santa Monica, CA, USA

BACKGROUND CONTEXT: Typically rhBMP-2 is applied to anabsorbable type I collagen sponge (ACS) at least 15 minutes prior toimplantation during a spinal fusion procedure. After careful preparation,rhBMP-2/ACS implant is placed in a surgically prepared bed or a containedsite such a titanium cage or a femoral allograft. Most of the studies onBMP retention and preparation soak time have been performed beforeimplantation. However, the biologic activation of BMP-2 occurs at implan-tation and the immediate postoperative period. During this critical period,the BMP-2/ACS are exposed to different cell types in a fluid sanguine-ous environment.PURPOSE: This in vitro study investigates the influence of preimplantationsoak time on BMP-2/ACS retention in the critical postoperative periodimmediately after implantation.STUDY DESIGN/SETTING: In vitro.PATIENT SAMPLE: NA.OUTCOME MEASURES: NA.METHODS: Sixteen ACS sponges, 1 cm long 0.5 cm wide, 0.5 cm thickwere prepared with 125 ul of 1.5mg/ml rhBMP-2 and allowed to soak for1, 20, 60, or 120 minutes (n�4 sponges / soak time). The prepared spongeswere then placed in normal saline solution at 37 Celsius and continuouslyagitated. Aliquots were withdrawn from each vial at 1, 20 minutes (short-term soak), 1, 12 or 24 hours (long-term soak). The concentration of rhBMP-2released from the sponge into the solution were assessed by ELISA.ANOVA was used with a grouping factor of ‘preparation soak time’ witha repeated measure for ‘sampling release time’ to test for significance.RESULTS: The concentration of rhBMP–2 released from the ACS intothe saline solution was significantly decreased as a function of preparationsoak times of 1, 20, 60 and 120 minutes. (The longer the prep soak time,the less rhBMP-2 in solution.) However, the difference in concentrationwas quite small. The concentration of rhBMP-2 significantly increasedin aliquots sequentially withdrawn at 1 min, 20 min, 1 hr, 12 hrs, and 24hrs from the same vials. (The mean rhBMP-2 concentration in fluid thatwas leached from the ACS was greater over time.) The pattern of release wassimilar for 4 preparation soak times. Overall the total amount of release

P146. Direct stabilization of lumbar spondylolysis with a hook screwAnand Agarwal, Alan Hammer; Medway Maritime Hospital, Kent,United Kingdom

BACKGROUND CONTEXT: Treatment methods for spondylolisthesisin adolescents and young adults are a matter of controversial discussion.The hook screw method is a direct repair technique that permits restitutioad integrum for a functional segment.PURPOSE: Spondylolysis with instability can produce low back pain.This technique has been successful in young adults and adolescent. Thisstudy shows the postoperative outcome of this patients.STUDY DESIGN/SETTING: A retrospective study involving 32 patientswith spondylolysis who underwent direct repair with a hook screw wasconducted.PATIENT SAMPLE: 34 patients who underwent direct repair for spondy-lolysis.OUTCOME MEASURES: OLDI score preoperative and postoperative.METHODS: A subjective study of direct repair with a hook screw forspondylolysis using the Oswestry Low Back Disability Index (OLDI) andthe Short Form 36 (SF-36) Score. All the patients who underwent a directrepair with a hook screw for spondylolysis between 1996 and 2005 werecontacted and asked to complete an OLDI Score and an SF-36 Score. OLDIand SF-36 scores were obtained preoperatively and postoperatively andthe results compared.RESULTS: A total of 34 patients were included in this study. Responserate was 100%. Mean age of patients was 34 years. Mean preoperative OLDIscore was 18 and postoperatively was 36. The results were subdivided intopoor, no change, good, very good, and excellent results. Good resultsmeant a 5–10 point improvement; very good result meant 10–15 pointimprovement; excellent result meant a greater than 15 point improve-ment. Good to excellent results were reported by 94% of patients. Goodand Very Good results were reported by 23% respectively. Excellent resultwas reported by 76% of patients. One patient had no change and 1 waspoor. Pseudoarthrosis rate was 6%.

Fig. 1

CONCLUSIONS: Direct repair of spondylolysis can be recommended foryoung patients which would save a functional segment. The above mean6 year follow-up shows encouraging results.DISCLOSURES: FDA device/drug: Hook screw. Status: Approved forthis indication.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.361

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