Practical Strategies for Bone Graft Selection in Spinal Fusion: A Narrative Review with Regional Perspectives.

INTRODUCTION: Successful spinal fusion depends on achieving reliable arthrodesis, and bone graft selection is a critical determinant of outcomes. Although autologous iliac crest bone graft remains the biological gold standard, limitations such as donor-site morbidity and insufficient volume have prompted the use of alternatives, including allograft, demineralized bone matrix (DBM), hydroxyapatite, and β-tricalcium phosphate. The introduction of biologics-such as recombinant human bone morphogenetic protein-2 (rhBMP-2) and cell- or peptide-based constructs-has further expanded grafting options internationally. However, in Japan, the clinical use of biologics remains unapproved, and allograft availability is restricted, necessitating reliance on autograft, DBM, and ceramic substitutes.

METHODS: A narrative review of recent clinical and experimental studies was conducted, emphasizing graft performance across cervical, lumbar, anterior/lateral, multilevel, and minimally invasive procedures. Practical considerations, including cost, storage, supply stability, and regional regulatory constraints, were integrated into the analysis.

RESULTS: Graft performance varied substantially according to surgical context. DBM and ceramic grafts often achieved satisfactory outcomes in cervical fusion, whereas lumbar fusion required mechanically robust extenders. Multilevel and deformity correction surgeries demanded blended strategies, while minimally invasive procedures benefited from moldable DBM and granular ceramics. Cost-effectiveness and logistical feasibility strongly influenced material selection. In Japan, the lack of rhBMP-2 approval and limited bone bank infrastructure further constrained options, reinforcing pragmatic combinations such as "autograft plus ceramics" or "DBM plus ceramics."

CONCLUSIONS: No single graft material is universally optimal. Reliable spinal fusion requires context-specific selection and combination strategies tailored to biological, mechanical, and regional factors. In Japan, strengthening bone bank systems and establishing robust domestic clinical evidence are essential. Future integration of regenerative grafts and next-generation biomaterials will require careful regulatory adaptation and cost-effectiveness validation.