Use of hydroxyapatite in spine surgery

Hydroxyapatite- (HA-)based ceramics have been evaluated for a variety of ap plications in spinal surgery, utilizing in vivo animal models and human cli nical series. In vivo animal studies have shown efficacy for these material s as a bone graft substitute in interbody fusions and as a bone graft exten der or bioactive osteoinductive material carrier in posterolateral lumbar f usions. Clinically, HA ceramic has been shown to be effective as a bone gra ft extender in posterior spinal fusion surgery for childhood scoliosis, and as a structural bone graft substitute in anterior cervical spine fusions. As an osteoconductive material, it appears to function best as a bone graft extender or carrier for an osteoinductive bone growth factor rather than a s a stand-alone bone graft substitute in nonstructural. clinical applicatio ns. Injectable HA ceramics also hold promise as biocompatible and bioresorb able materials for use in spinal screw fixation strength augmentation and i n minimally invasive vertebral body strength augmentation either following fracture or prophylactically in osteoporotic vertebrae.