Proceedings of the NASS 20th Annual Meeting / The Spine Journal 5 (2005) 1S–189S116S

substantial nonsurgical treatment resources. Additional evaluation is neces-sary to determine the effectiveness of these nonsurgical treatments. It willbe important to assess the impact of each nonsurgical treatment regimen bothin terms of symptomatic improvement based on health status measures andupon the need for subsequent nonsurgical resource utilization or surgicalintervention.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: Authors (SG, JDI) Consultant: Consultantfor Medtronic Sofamor Danek; Authors (SG, JDI) Other: Royalties receivedfrom Medtronic Sofamor Danek; Authors (SG, JDI, WH, KB) Grant Re-search Support: Medtronic Sofamor Danek; Author (SB) Consultant: Med-tronic Sofamor Danek, DePuy Spine; Author (SB) Grant Research Support:Medtronic Sofamor Danek, Kyphon.

doi: 10.1016/j.spinee.2005.05.227

P14. Piriformis syndrome: a controversial and undertreated causeof sciaticaKingsley R. Chin1, Ashraf Ragab, MD2, Jeffrey Roh, MD3,Henry H. Bohlman, MD4; 1University of Pennsylvania, Philadelphia,PA, USA; 2University of Mississippi, Jackson, MS, USA; 3CornellUniversity Medical College, New York, NY, USA; 4Case WesternReserve University, Cleveland, OH, USA

BACKGROUND CONTEXT: Spine specialists continue to view pirifor-mis syndrome as a controversial diagnosis and as such many patientsare undertreated.PURPOSE: We assessed outcome after surgical decompression of thesciatic nerve to treat piriformis syndrome.STUDY DESIGN/SETTING: Retrospective Clinical.PATIENT SAMPLE: 34 consecutive patients.OUTCOME MEASURES: Hip Score.METHODS: We evaluated 34 of 38 consecutive patients diagnosed byexclusion of spinal or pelvic pathology as a cause of sciatica, pelvic MRIof a potential source of sciatic nerve compression, and relief of symptomsimmediately after an injection of 1% Lidocaine and Triamcinolone aroundthe sciatic nerve in some patients. The mean duration of preoperativesymptoms was 47 months and 5 patients had a history of preceeding trauma.15 patients had a previous lumbar operation. Outcome was based on painrelief and patient satisfaction. Potential compressive structures and thepiriformis muscle were excised using a posterolateral approach.RESULTS: MRI detected potential unilateral compressive lesions in 31patients and bilateral in 4 patients. 12 patients reported some relief withlocal anesthetic injection versus 8 patients with no relief. Fibrous bandsor a leash of vessels was found directly compressing the sciatic nerve in30 patients, a split sciatic nerve in 5 patients, and an anomalous piriformismuscle splitting the nerve in 2 patients. 24 patients reported complete reliefof symptoms immediately after surgery. 3 patients reported partial relief, and7 patients reported no relief. 2 patients were re-explored for recurrentsymptoms at 10 and 16 months after the indexed procedure.CONCLUSIONS: Surgical decompression effectively treated piriformissyndrome provided strict patient selection criteria to rule out spinal orpelvic causes of sciatica.DISCLOSURES: No disclosures.CONFLICT OF INTEREST: No conflicts.

doi: 10.1016/j.spinee.2005.05.229

P15. Assessment of the accuracy of in vivo placement of artificialdiscs in the lumbar intervertebral space using computedtomography along with its radiographic and clinical consequencesVikas V Patel, MA, MD1*, Ben B Pradhan, MD, MSE2, Carol Andrews,MD2, Hyun W Bae, MD2, Linda E A Kanim, MS2, Rick B Delamarter,MD2; 1University of Colorado, Denver, CO, USA; 2The Spine Instituteat Saint John’s Health Center, Santa Monica, CA, USA

P13. Posterior lateral lumbar spine fusion with silicate substitutedcalcium-phosphateDonna Wheeler, PhD1, Jason Marini1, Matthew Kovach1,Tatiana Motta1, Amy Lyons1, A. Turner, DVM1, Howard B. Seim, III,DVM, DRDES1, Louis Jenis, MD2*; 1Colorado State University, FortCollins, CO, USA; 2Boston Spine Group, Boston, MA, USA

BACKGROUND CONTEXT: Autograft has proven fusion efficacy overbone graft substitutes due to its cellularity and biological activity. Thesynthetic silicate substituted calcium-phosphate (Pore-Si, ApaTech) hasincreased bioactivity compared with pure hydroxyapatite.PURPOSE: To compare Pore-Si (AP) (without bone marrow supplementa-tion) with iliac crest autograft (AG) in an ovine single-level instrumentedlumbar dorsolateral intertransverse fusion.STUDY DESIGN/SETTING: Sheep underwent fusion with either AP orAG and healed for 2 (n�3/grp) or 6 months (n�6/grp).PATIENT SAMPLE: Skeletally mature ewes (50–80 kg).OUTCOME MEASURES: Plain radiographs, peripheral quantitativecomputed tomography (pQCT), biomechanics, histopathology, and histo-morphometry.METHODS: Anesthesized sheep (n�18) underwent decortication of L3and L4 transverse processes, L3-L4 facetectomies to induce instability, andgrafting with either AP or AG. Stabilization was accomplished with bilateraltranspedicular fixation. After 2 or 6 months of healing, spines were har-vested, plain radiographs acquired and films scored for fusion efficacy.pQCT scans were acquired at 2 and 4 months and at euthanasia (n�3/grp)and evaluated for fusion volume and fusion mass density. Lumbar segmentswere prepared and subjected to 5 nondestructive load cycles ranging from–5.0 N-m to 5.0 N-m in flexion/extension, lateral bending and torsion whilevertebral body motion was monitored with an optical tracking system.Stiffness and range of motion were quantified at the fusion site. The fusedmotion segments were trimmed and processed for undecalcified histology.Histopathology scores for graft integration, bone remodeling, cellular activ-ity, and inflammatory cells were made. Histomorphometric measurementsof total reactive area of fusion, bone and graft within fusion mass, andconnectivity characterized fusion.RESULTS: Plain radiographs revealed a strong trend for improved fusionscores in the AP group compared with AG. Similarly, trends towards greaterfusion volume in the AP group were seen using pQCT analysis. Densitycharacterization showed AP treated animals had denser fusion masses thanAG animals. Biomechanically, the AP and AG treatment groups had equiva-lent stiffness and range of motion in flexion/extension and lateral bending.Both AP and AG treatments showed similar progression of healing from 2to 6 months with equivalent bone remodeling, osteoblast activity, osteoclastactivity scores and minimal or no inflammatory cells. Both AP and AGgrafts were well integrated into the new bone matrix. The reactive area(fusion mass) was significantly greater for AP compared with AG animalswith equal percentages of bone and graft within the fusion. The connectivity(bone between transverse processes) was equivalent for AP and AG.CONCLUSIONS: This unique synthetic silicate substituted calcium-phos-phate material proved to successfully stimulate bone bridging between

transverse processes and achieve fusion equivalent to that seen with osteoge-nic autograft. The biocompatible silicate substituted calcium-phosphate ma-terial stimulated robust fusion and active cellular response throughout theosteoconductive matrix. Histological observations suggest the AP matrixresorbed through both cell-mediated and dissolution mechanisms. The APmatrix is a promising scaffold for posterior lateral fusion due to its initialmechanical support, interconnected porous structure, and silicate-initiatedosteostimulatory properties.DISCLOSURES: FDA device/drug: Pore-Si. Status: Not approved forthis indication.CONFLICT OF INTEREST: Author (DW) Consultant: ApaTech Lim-ited; Author (DW) Grant Research Support: ApaTech Limited #037281.

doi: 10.1016/j.spinee.2005.05.228