Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S122S

biomechanical forces are quite different, commonly resulting in extrusionof the device, especially when within the nucleus pulposus. Finally, surgicalaccess to the disc space in the larger animals requires a lateral approach.Cadaveric small bovines are an established animal species for spinal biome-chanical studies since the vertebra are of similar size.PURPOSE: Hypothesis: We investigated the utility of this animal model(200 kg Corrientes with closed growth plates) for evaluation of the safetyof an intervertebral disc replacement on a chronic basis.STUDY DESIGN/SETTING: Materials and Methods: An artificial nu-cleus pulposus was placed by the described surgical technique in adultCorrientes breed cows.PATIENT SAMPLE: 25 adult Corrientes cows, weighing approximately200 kg.OUTCOME MEASURES: Necopsies with subsequent histological exami-nation was performed at 3, 6, 9 and 12 months after implantation.METHODS: A left lateral approach to the lumbar discs was made. Fornucleus pulposus replacements, a wedge osteotomy of adjacent vertebraewas made, retaining the superficial lateral ligament between the twobone blocks. A transverse annulotomy was made, the nucleus removed,and the test material implanted. The bone blocks were then replaced sothat the ligament covered the annulotomy, and a piece of titanium meshplaced over the osteotomies and held in place with appropriate screws.Closure was routine.RESULTS: No implants extruded from the implantation site. The implanteddisc spaces were embedded in PMMA, stained and evaluated. The interfacebetween the test material and the adjacent tissue and cellular reaction waseasily observed.CONCLUSIONS: This animal model seems to allow the investigator totest a device intended for use in humans, rather than size it down. Thewedge osteotomy and titanium mesh seems to prevent extrusion for nuclearreplacement. These methods are not necessary for evaluation of total discreplacements or spinal fusion.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.240

P27. Thoracoscopic spinal fusion vs. posterior spinal fusion for thetreatment of thoracic adolescent idiopathic scoliosis: a comparisonof outcomesBaron Lonner, MD1, Dimitry Kondrachov, MD2, Farhan Siddiqi, MD2,Victor Hayes, MD2, Carrie Scharf, BA3; 1Lenox Hill Hospital, Hospitalfor Joint Diseases-NYU Medical Center, New York, NY, USA; 2NorthShore–Long Island Jewish Health System, New Hyde Park, NY, USA;3New York, NY, USA

BACKGROUND CONTEXT: Posterior spinal fusion (PSF) with segmen-tal instrumentation has been the gold standard for the surgical treatmentof thoracic adolescent idiopathic scoliosis (AIS). More recently, anteriorsurgery and video assisted thoracoscopic surgery with spinal instrumenta-tion (VATS) have gained popularity.PURPOSE: The purpose of this study is to compare radiographic andclinical outcomes as well as pulmonary function in patients treated witheither posterior or anterior thoracoscopic surgery.STUDY DESIGN/SETTING: Retrospective analysis of consecutive pa-tients with thoracic adolescent idiopathic scoliosis treated surgically be-tween January 1999 and February 2002.PATIENT SAMPLE: Twenty-nine consecutive patients who underwentthoracoscopic spinal fusion with instrumentation and twenty-five consecu-tive patients who underwent posterior segmental spinal instrumentationmet the minimum requirement of 24 months, except one in the thoracoscopicgroup whose final follow-up was 15 months.OUTCOME MEASURES: Radiographic data, SRS-22 patient based out-come questionnaires, pulmonary function, and operative records were re-viewed for all patients in the study.METHODS: All parameters were analyzed preoperatively, immediatelypostoperatively, and at final follow-up Radiographic analysis included coro-nal curve correction, lowest instrumented vertebrae (LIV), LIV tilt anglecorrection, coronal balance, and thoracic kyphosis. Operative parameterswere evaluated and compared for each group included: operative time,estimated blood loss (EBL), blood transfusions, levels fused, type ofbone graft used, intra-operative and postoperative complications. Pulmo-nary function parameters analyzed were vital capacity and peak flow.

P26. A comparison of the osteoinductive ability of allograft boneafter treatment with a novel radiation technique vs. peroxide in arodent spinal fusion modelJeffrey Wang, MD, Arya Shamie, MD*, Lee Halevi, MD, Paul Tsou,MD; University of California, Los Angeles, Los Angeles, CA, USA

BACKGROUND CONTEXT: Allograft processing varies according todifferent tissue banks and the methods for processing range from asepticprocessing to radiation sterilization. Recent studies have demonstrated therapid loss of osteoinductive activity of Demineralized Bone Matrix (DBM)made from bone treated with hydrogen peroxide during processing (DePaulaet al.). A novel process has been recently discovered which allows forradiation sterilization of allograft bone utilizing special stabilizing solutionsand temperature conditions, however, it does not disrupt the biomechanicalintegrity of the graft. This technique is the “Clearant” process.PURPOSE: The purpose of this study was to determine whether thisnovel sterilization technique would affect the osteoinductive capacity ofthe allograft bone to induce a spinal fusion in an athymic rat model.STUDY DESIGN/SETTING: Radiographs were taken at 2 week intervalsand the groups were sacrificed at 8 weeks time. Spines were then harvestedand manual palpation was used to confirm either fusion or pseudarthrosis.The athymic rat offers a unique animal model with the advantage of a non-immunogenic environment for implantation of human tissues for an in vivoevaluation of fusion. The study groups employed in this study are: GroupI–no peroxide, Clearant processed Group II–no peroxide, not Clearantprocessed Group III–1 hour peroxide, Clearant processed Group IV–1hour peroxide, not Clearant processed Group V–6 hours peroxide, Clearantprocessed Group VI–6 hour peroxide, not Clearant processed Group VII–24 hour peroxide, Clearant processed Group VIII– 24 hour peroxide, notClearant processed Group IX–BMP-2 Group X -Sham.

PATIENT SAMPLE: There were eight rats in each of the ten study groups.OUTCOME MEASURES: Eight rats each in groups I through XIII wereimplanted with the DBM tissue, while groups IX and X were used as controlgroups. None of the differences in fusion were statistically significant.METHODS: Demineralized Bone Matrix (DBM) was created from allo-graft bone treated with and without the Clearant radiation sterilizationprocess. This allograft was also processed with varying times of hydro-gen peroxide treatments, and then made into DBM. This DBM was thenimplanted into an athymic rat intertransverse process spinal fusion modeland observed for spinal fusion.RESULTS: This study demonstrates that the increased time of soakingthe allograft in hydrogen peroxide does lead to a decrease in the abilityof the demineralized bone matrix to heal a rat intertransverse spinal fusion.However, it also demonstrates that this novel Clearant process does notnegatively affect the ability of the DBM to heal the spinal fusion modelas there were no statistically significant differences between the bone withor without the Clearant process. The groups with the Clearant pro-cess actually demonstrated a larger number of fusions compared with thenon-Clearant processed bone, however, this was again, not statisticallysignificant.CONCLUSIONS: The Clearant process employs robust pathogen inactiva-tion that can used to either eliminate or reduce the bioburden of the tissue,thereby reducing the time required to treat the DBM with hydrogenperoxide. By showing that the Clearant process does not effect the os-teoinductive properties of the bone, a possible improved processing tech-nique can be employed in the future by tissue banks.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.241