Faculty Bibliography

BACKGROUND:Recombinant human bone morphogenetic protein-2 (rhBMP-2) applied on an absorbable collagen sponge improves open tibial fracture-healing as an adjunct to unreamed intramedullary nail fixation. We evaluated rhBMP-2 and a new, injectable calcium phosphate matrix (CPM) formulation in acute closed tibial diaphyseal fractures treated with reamed intramedullary nail fixation. METHODS:Patients were randomized (1:2:2:1) to receive standard of care, which consisted of definitive fracture fixation within seventy-two hours of injury with a locked intramedullary nail after reaming; standard of care and injection with 1.0 mg/mL of rhBMP-2/CPM; standard of care and injection with 2.0 mg/mL of rhBMP-2/CPM; or standard of care and injection with buffer/CPM, to evaluate the activity of the CPM delivery matrix and provide for sponsor and investigator blinding. The co-primary end points of the study were the effects of rhBMP-2/CPM on the time to fracture union (based on blinded assessment of radiographs) and the time to return to normal function (based on blinded assessment of the time to full weight-bearing without pain at the fracture site) compared with standard of care alone. RESULTS:Three hundred and sixty-nine patients were randomized and included in the intent-to-treat population. This study was terminated after an interim analysis (180 patients with six months of follow-up) revealed no shortening in the time to fracture union in the active treatment arms compared with the standard of care control (the SOC group). In the final primary analysis, the median time to radiographic fracture union was not significantly different for the SOC (13.1 weeks), 1.0-mg/mL rhBMP-2/CPM (13.0 weeks), 2.0-mg/mL rhBMP-2/CPM (15.9 weeks), or buffer/CPM (15.4 weeks) treatment groups. The median time to pain-free full weight-bearing was also not significantly different among the SOC (13.4 weeks), 1.0-mg/mL rhBMP-2/CPM (13.4 weeks), 2.0-mg/mL rhBMP-2/CPM (14.3 weeks), and buffer/CPM (16.4 weeks) treatment groups. CONCLUSIONS:In patients with closed tibial fractures treated with reamed intramedullary nailing, the time to fracture union and pain-free full weight-bearing were not significantly reduced by rhBMP-2/CPM compared with standard of care alone. 24306696

BACKGROUND: Currently, the treatment of diaphyseal tibial fractures associated with substantial bone loss often involves autogenous bone-grafting as part of a staged reconstruction. Although this technique results in high healing rates, the donor-site morbidity and potentially limited supply of suitable autogenous bone in some patients are commonly recognized drawbacks. The purpose of the present study was to investigate the benefit and safety of the osteoinductive protein recombinant human bone morphogenetic protein-2 (rhBMP-2) when implanted on an absorbable collagen sponge in combination with freeze-dried cancellous allograft. METHODS: Adult patients with a tibial diaphyseal fracture and a residual cortical defect were randomly assigned to receive either autogenous bone graft or allograft (cancellous bone chips) for staged reconstruction of the tibial defect. Patients in the allograft group also received an onlay application of rhBMP-2 on an absorbable collagen sponge. The clinical evaluation of fracture-healing included an assessment of pain with full weight-bearing and fracture-site tenderness. The Short Musculoskeletal Function Assessment (SMFA) was administered before and after treatment. Radiographs were used to document union, the presence of extracortical bridging callus, and incorporation of the bone-graft material. RESULTS: Fifteen patients were enrolled in each group. The mean length of the defect was 4 cm (range, 1 to 7 cm). Ten patients in the autograft group and thirteen patients in the rhBMP-2/allograft group had healing without further intervention. The mean estimated blood loss was significantly less in the rhBMP-2/allograft group. Improvement in the SMFA scores was comparable between the groups. No patient in the rhBMP-2/allograft group had development of antibodies to BMP-2; one patient had development of transient antibodies to bovine type-I collagen. CONCLUSIONS: The present study suggests that rhBMP-2/allograft is safe and as effective as traditional autogenous bone-grafting for the treatment of tibial fractures associated with extensive traumatic diaphyseal bone loss. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.