Bone Graft Substitutes in Single or Double Level Anterior Cervical Discectomy and Fusion: A Systematic Review.

STUDY DESIGN: Systematic Review OBJECTIVE.: To undertake a systematic review of published literature to evaluate efficacy of bone graft substitutes on radiographic and clinical outcomes in single or double level anterior cervical discectomy and fusion (ACDF) for degenerative disease.

SUMMARY OF BACKGROUND DATA: Anterior cervical discectomy and fusion (ACDF) is one of the most common spinal surgeries completed in the United States. Today bone graft substitutes including ceramic-based synthetic bone grafts, allografts, bone morphogenetic proteins, mesenchymal stem cells, and bone marrow aspirate are widely used to enhance fusions; even though the efficacy of these substitutes is poorly defined. Critical evaluation of these products is necessary to optimize radiographic and clinical outcomes for ACDF in degenerative disease.

METHODS: A systematic literature review of 22 published articles was conducted. All articles reported results on patients who underwent a single or double level ACDF performed using a bone graft substitute and reported results on radiographic fusion rates at least 6 months after surgery.

RESULTS: All studies using bone morphogenetic protein (BMP) showed 100% fusion rate despite length of the study or whether additional bone graft substitutes were used. Use of only ceramic-based synthetics had the lowest fusion rate, 80.5%. Use of only mesenchymal stem cells resulted in an average fusion rate of 87.7%. When used alone, allograft resulted in an average fusion rate of 87.3%. This was significantly influenced by one outlier, Kim, et al., which when removed, increased the fusion rate to 93.5%. Clinical outcomes were improved postoperatively irrespective of the graft used, though dysphagia was significantly greater in studies using BMP (p < 0.001).

CONCLUSIONS: Allograft alone has the lowest cost with similar fusion rates and clinical outcomes compared to other bone graft substitutes. Physicians should consider this when choosing to use bone graft substitutes for routine ACDFs.

LEVEL OF EVIDENCE: 4.