Canine investigation of rhBMP-2, autogenous bone graft, and rhBMP-2 with autogenous bone graft for the healing of a large segmental tibial defect.

Abstract

The purpose of this study was to compare the effects of bone morphogenetic protein, bone morphogenetic protein with autogenous bone graft (ABG), and ABG alone on the healing of a large bone defect in the canine tibia. Fifteen 45- to 55-lb canines were randomly assigned to 1 of 5 treatment groups, 3 per group. The groups included (1) recombinant human bone morphogenetic protein (rhBMP-2, 0.43 mg/mL)/absorbable collagen sponge (ACS) + collagen/ceramic matrix (CCM), (2) rhBMP-2 (0.22 mg/mL) ACS + CCM, (3) rhBMP-2 (0.43 mg/mL) ACS + ABG, (4) rhBMP-2 (0.22 mg/mL) ACS + ABG, and (5) ABG alone. A 5-mL defect was created in the right tibia and fixed with a 4.5 mm locking plate and 1 of the grafts described above implanted. X-rays were taken biweekly for 12 weeks and evaluated for radiographic union. Representative histology was also examined. All defects treated with rhBMP-2 (any combination) healed at 6.0 +/- 0.9 weeks. None of the ABG alone-treated defects were healed at 12 weeks. Dogs receiving rhBMP-2/ACS + CCM healed at 5.7 +/- 0.8 weeks, whereas rhBMP-2/ACS + ABG defects healed at 6.3 +/- 0.8 weeks. Histology showed healing consistent with 12-week radiologic results. Large segmental defects in canine tibiae can be effectively healed with stable fixation and rhBMP-2/ACS + ABG or CCM. These conclusions may offer insight into the clinical treatment of segmental defect nonunions in the human.