Silicate-Substituted Calcium Phosphate Ceramic Bone Graft Replacement for Spinal Fusion Procedures

Study Design. Retrospective study. Objective. To assess the clinical and radiographical outcomes in spinal fusion procedures using silicate-substituted calcium phosphate (Si-CaP). Summary Of Background Data. Si-CaP is a newer-generation synthetic ceramic designed to maximize osteoinduction and osteoconduction. Methods. This is a retrospective analysis of a prospectively collected patient database including 108 patients (204 individual spinal levels). Different surgical procedures performed included 25 anterior cervical discectomy and fusions, 17 posterior cervical fusions, 7 combined anterior and posterior cervical fusions, 10 thoracic fusion surgeries, 18 transforaminal lumbar interbody fusions with 12 axial lumbar interbody fusions, 11 transpsoas discectomy and fusions, and 8 combined thoracolumbar fusion procedures. Si-CaP was used as bone extender without any additional graft material, bone marrow aspirate, or bone morphogenetic protein. Clinical outcomes were assessed using the visual analogue scale (VAS), Oswestry Disability Index, and Neck Disability Index. Fusion was determined by the presence of bony bridging on 2 consecutive sections in at least 2 planes on computed tomographic imaging. Results. At a follow-up of 12 (+/- 4.7) months, 90% of all patients demonstrated radiographical fusion. Fusion rates were highest in the cervical spine (97%) followed by thoracic and lumbar spines (86% and 81%, respectively). There were significant improvements in all clinical outcome measures-Oswestry Disability Index, 11.1 (+/- 10.2) and Neck Disability Index, 9.0 (+/- 11.4); VAS-back, 3.1 (+/- 3.0); VAS-leg, 3.5 (+/- 3.6); VAS-neck, 3.7 (+/- 2.5); and VAS-arm 4.0 (+/- 3.2). There was no radiographical loosening of instrumentation due to infection or nonunion in this series, and no subsequent revisions for nonunion were required. Conclusion. Si-CaP is an alternative to autogenous bone graft in spinal arthrodesis procedures. At 12-month follow-up, we detected high levels of bony fusion using Si-CaP in combination with various surgical spinal techniques.