Session X1 - Tibia

Use of rhBMP-2 for Open Segmental Tibia Fractures from Iraq

COL Timothy R. Kuklo, CPT, MD (a-Medtronic Sofamor Danek);

Adam T. Groth, Maj(P), MS (n); LTC Romney C. Andersen, MD (n);

LTC Richard B. Islinger, MD (n);

Walter Reed Army Medical Center, Washington, District of Columbia, USA

Introduction: Various studies have espoused the success rate of recombinant bone morphogenic protein (rhBMP-2) in animal and human studies in the spine and trauma literature. However, there are no studies specifically addressing the use of BMP in severe segmental defects or contaminated war injuries. This series reports the early findings of the use of this emerging technology in these severe limb-threatening injuries.

Purpose: Our intent is to report the clinical outcomes of the use of rhBMP-2 in lower extremity trauma and segmental tibial defects sustained during Operation Iraqi Freedom.

Methods: We retrospectively reviewed the patient records, radiographs, and clinical outcomes of 54 consecutive patients treated with rhBMP-2 (1.50 mg/ml) at Walter Reed Army Medical Center who sustained open grade III tibia fractures during Operation Iraqi Freedom. Of these patients, 32 had 12-month follow-up (average 15.6 months), and all were male (average age 27.3 years; range, 20 to 42). Patients underwent from 2 to 14 wound debridements prior to placement of rhBMP-2 (placed from 6 to 29 days postinjury) to stabilize the wound and to minimize bacterial load. 14 patients were treated with supplemental external fixation (ringed or spanning), and 18 patients were treated with definitive internal fixation. More importantly, 9 patients had a segmental tibial defect (2 to 10 cm) treated with primary external fixation, rhBMP-2, and supplemental allograft (one iliac crest autograft).

Results: To date, there are two known nonunions, where abundant bridging bone is not easily visualized on both AP and lateral radiographs. Definitive union is present in 28 of 32 fractures (88%) with over 12-month follow-up, and in 6 of 9 segmental defects with over 6-month follow-up. One segmental defect not considered to be a solid union has bridging bone evident on 3 of 4 cortices (AP and lateral radiographs), but is not considered structurally sound at this time (10 cm tibial defect). As well, 31 of 32 patients are currently full weight bearing. There is one known superficial skin infection, and one osteomyelitis to date (3%). In 3 patients treated with a concomitant vacuum-assisted closure, there is a negligible filtration effect evident in the soft-tissue/muscular envelope around the fracture site.

Conclusions: rhBMP-2 proved to be effective in the supplemental treatment of severe open lower extremity fractures. There is a high union rate (88%) at 12 months with early return to full weight bearing. In addition, 6 of 9 segmental tibial defects with >12-month follow-up appear to have a solid union. Perhaps more importantly, there is a very low infection rate in these at-risk injuries, with only one superficial skin infection and one osteomyelitis. Further research on this exciting technology is warranted.