Object: Autograft and allograft, the standard approaches for lumbar fusion procedures, have important disadvantages. Bone graft substitutes such as recombinant human bone morphogenetic proteins (rhBMP-2 and rhBMP-7) have emerged as viable alternatives. The authors conducted a systematic review to compare the efficacy and safety of osteoinductive bone graft substitutes using autografts and allografts in lumbar fusion.
Methods: A search for prospective controlled trials was conducted on MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases. Data were extracted for key outcomes including radiographically demonstrated nonunion, Oswestry Disability Index, operating time, blood loss, and length of hospital stay. The quality of randomized controlled trials was assessed using the Jadad scale. Meta-analyses were performed when feasible, and heterogeneity was assessed using the Q statistic and the I(2) statistic.
Results: Seventeen of 732 potential studies met the inclusion criteria, with 9 examining rhBMP-2, 3 examining rhBMP-7, 3 examining demineralized bone matrix, and 2 examining autologous growth factor. Recombinant human BMP-2 significantly decreased radiographic nonunion when compared with autologous iliac crest bone graft (AIBG) in a meta-analysis (relative risk 0.27, 95% CI 0.16-0.46). Stratification of meta-analyses by the type of surgical procedure performed yielded similar results. Funnel plots suggested publication bias. Trials of rhBMP-2 suggested reductions in the operating time and surgical blood loss, with less effect on the length of hospital stay. There was no difference in radiographic nonunion with the use of rhBMP-7 when compared with AIBG (relative risk 1.02, 95% CI 0.52-1.98). Neither rhBMP-2 nor rhBMP-7 demonstrated a significant improvement on the Oswestry Disability Index when compared with AIBG. The limited data on demineralized bone matrix and autologous growth factor showed no significant improvement in radiographic outcomes.
Conclusions: Recombinant human BMP-2 may be an effective alternative to AIBG in lumbar fusion. Data are limited for other bone graft substitutes.