Case Report: Treatment of Femoral Non-union With Rib and Iliac Crest Autografts and rhBMP-2 in a Cat

A 5-year-old, intact male Bengal cat weighing 5.2 kg was referred for the fixation failure of a right femoral fracture. Multiple surgical revisions failed, and atrophic non-union was diagnosed. The cat was then admitted for a final revision surgery using locking plate fixation in conjunction with rib and iliac crest autografts and recombinant human bone morphogenetic protein 2 (rhBMP-2). The fracture site was debrided and stabilized before filling the defect with 1.8 cm of rib bone autograft. The residual space in the defect was then filled with an iliac crest autograft. Finally, a 3 ×5 cm absorbable collagen sponge soaked with 0.5 mL of 0.2 mg/mL rhBMP-2 solution was placed around the defect. No significant complications were noted postoperatively. Bone healing was noted 2 months postoperatively, and it continued for 12 months. Although mild lameness remained, the cat's ambulatory function and quality of life were good. To the authors' knowledge, this is the first case report of a clinical transplantation of a rib segment as an autograft in combination with rhBMP-2 in a cat with a large bone defect.

BMP-2 Promotes Bone Formation in Bone Defects in Which Bone Remodeling Is Suppressed by Long-Term and High-Dose Zoledronic Acid

Background: The use of long-term and high-dose bisphosphate is associated with severely suppressed bone turnover and the delayed union of fractures. However, therapeutic methods to overcome the negative effects of bisphosphonate use are lacking. Bone morphogenetic proteins (BMPs) are powerful osteoinductive proteins. We hypothesized that BMPs had similar effects as autografts in patients with decreased bone healing potential due to long-term bisphosphonate treatment. The purpose of this study was to compare BMPs with demineralized freeze-dried bone grafts and autografts in a rat femoral bone defect model with long-term and high-dose bisphosphonate treatment. Methods: Forty rats were divided into the following four groups depending upon the materials implanted into the femoral defect after ten weeks of bisphosphonate (zoledronic acid) injections: Group I: absorbable collagen sponge (control); group II: demineralized freeze-dried bone graft; group III: autogenous bone graft; and group IV: rhBMP-2 with an absorbable collagen sponge. Radiographic union, micro computed tomography (CT) analysis, manual palpation, and histologic analysis were evaluated. Results: The radiographic union rate, manual union rate, and micro-CT bone volume in groups III and IV were significantly higher than those in groups I and II. Groups III and IV showed similar results to each other. Although the amount of immature bone in the BMP-treated group was large, the effect was similar to that of autografts in the bone defect model in which bone turnover was severely reduced by bisphosphonate treatment. Conclusion: BMP might be a good substitute for autografts in patients with decreased bone healing potential due to long-term bisphosphonate treatment.

BMP-2 Promotes Bone Formation in Bone Defects in Which Bone Remodeling Is Suppressed by Long-term and High-dose Zoledronic Acid

Background: The use of long-term and high-dose bisphosphate is associated with severely suppressed bone turnover and the delayed union of fractures. However, therapeutic methods to overcome the negative effects of bisphosphonate use are lacking. Bone morphogenetic proteins (BMPs) are powerful osteoinductive proteins. We hypothesized that BMPs had similar effects as autografts in patients with decreased bone healing potential due to long-term bisphosphonate treatment. The purpose of this study was to compare BMPs with demineralized freeze-dried bone grafts and autografts in a rat femoral bone defect model with long-term and high-dose bisphosphonate treatment. Methods: Forty rats were divided into the following four groups depending upon the materials implanted into the femoral defect after ten weeks of bisphosphonate (zoledronic acid) injections: Group I: absorbable collagen sponge (control); group II: demineralized freeze-dried bone graft; group III: autogenous bone graft; and group IV: rhBMP-2 with an absorbable collagen sponge. Radiographic union, micro computed tomography (CT) analysis, manual palpation, and histologic analysis were evaluated. Results: The radiographic union rate, manual union rate, and micro-CT bone volume in groups III and IV were significantly higher than those in groups I and II. Groups III and IV showed similar results to each other. Although the amount of immature bone in the BMP-treated group was large, the effect was similar to that of autografts in the bone defect model in which bone turnover was severely reduced by bisphosphonate treatment. Conclusion: BMP might be a good substitute for autografts in patients with decreased bone healing potential due to long-term bisphosphonate treatment.