Biologics in the evolution of spine surgery

Abstract

Biologics have become central to modern spine surgery, providing tools to enhance fusion and promote biologic healing. Autologous bone graft remains the gold standard for its osteogenic, osteoinductive, and osteoconductive properties, while allografts and demineralized bone matrices expand graft availability and reduce morbidity, albeit with variability in biologic potency. Recombinant bone morphogenetic proteins offer potent osteoinduction and have demonstrated high fusion rates in challenging cases, though dose-related complications and cost have limited use. Advances in materials science have produced synthetic grafts and bioactive ceramics that provide consistent structure and surface-mediated biologic activity. Newer bioengineered constructs, including peptide-enhanced and nanosynthetic formulations, aim to combine osteoconductive scaffolds with molecular or cellular activation. Emerging therapies such as mesenchymal stem cell allografts and gene therapy seek to biologically stimulate bone formation and regeneration at the fusion site. Collectively, these biologics represent a shift from purely structural grafts toward integrated biologic systems that combine mechanical support with targeted molecular activity. Understanding their mechanisms, indications, and limitations is essential to optimize graft selection and advance biologically driven spine surgery.