Revision of a Nonunion Femur Fracture in a Dog with an Interlocking Nail and Cortical Bone Allograft

Nonunion after fracture repair is an uncommon but severe, limb-threatening complication. Resolution of adverse mechanical and biological conditions at the fracture site is necessary to achieve bone healing. This report describes the novel use of a femoral cortical bone allograft combined with autogenous cancellous bone and rhBMP-2 stabilized with an angle-stable interlocking nail (AS-ILN) and bone plate to treat a nonunion femoral fracture in a dog. A 7-year-old, FS Pitbull presented for persistent nonweight-bearing lameness after surgical repair of a comminuted mid-diaphyseal femoral fracture 14 months prior. Radiographs showed evidence of implant loosening and fracture site changes consistent with a dystrophic, nonviable nonunion. The surgical intervention included implant removal followed by a partial ostectomy resulting in a 2.5 cm critical-size defect. The medullary canal of a 2.5 cm cortical allograft was packed with cancellous autograft and rhBMP-2 and inserted into the ostectomy defect. A precontoured AS-ILN was inserted through the medullary canal of the femoral segments and allograft. A locking plate was applied to the cranial femur and allograft with monocortical locking screws. Eight weeks postoperatively, the patient was consistently weight-bearing with a mild lameness. Partial allograft integration was appreciated on radiographs. At 38 weeks postoperatively, the patient had a normal gait. Radiographs revealed a healed femoral fracture site with full integration of the cortical allograft. Based on our results, a cortical bone allograft combined with autogenous cancellous bone and rhBMP-2 can be utilized in conjunction with AS-ILN and bone plate stabilization to treat a chronic, canine nonunion femoral fracture.

Acknowledgment

None.

 

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Publication History

Article published online:
15 July 2025