A Randomized Controlled Trial Comparing RhBMP-2/Absorbable Collagen Sponge Versus Autograft for the Treatment of Tibia Fractures With Critical Size Defects

Objectives: To compare radiographic union of tibia fractures with bone defects treated with recombinant bone morphogenetic protein-2 (rhBMP-2) with allograft to autogenous iliac crest bone graft (ICBG).

Design: FDA-regulated multicenter randomized trial.

Setting: Sixteen US trauma centers.

Patients/participants: Thirty patients (18-65 years of age) with Type II, IIIA, or IIIB open tibia fracture and bone defect treated with an intramedullary nail.

Intervention: rhBMP-2 (n = 16) versus ICBG (n = 14).

Main Outcome Measurements: Radiographic union within 52 weeks. Secondary outcomes included clinical healing, patient-reported function, major complications, and treatment cost. Equivalence was evaluated by testing whether a 90% two-sided confidence interval for the difference in the probability of radiographic union between rhBMP-2 or ICBG is contained with the interval [220% to +20%]. A post hoc Bayesian analysis, using data from a previous trial, was also conducted.

Results: Twenty-three patients had union data at 52 weeks: 7/12 (58.3%) rhBMP-2 were radiographically united compared with 9/11 (81.8%) ICBG, resulting in a treatment difference of -0.23 (90% CI: -0.55 to 0.10). Patients treated with rhBMP-2 had lower rates of clinical healing at 52 weeks (27% vs. 54%), higher mean Short Musculoskeletal Function Assessment scores (dysfunction: 33.3 vs. 23.7; bother score: 32.8 vs. 21.4) and experienced more complications (5 vs. 3). Mean treatment cost for rhBMP-2 was estimated at $14,155 versus $9086 for ICBG.

Conclusions: These data do not provide sufficient evidence to conclude that ICBG and rhBMP-2 are equivalent regarding radiographic union.

Level Of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.