Internal Radioulnar Fixation for Treatment of Nonunion of Proximal Radius and Ulna Fractures in a Toy Breed Dog

Abstract In this case report, we describe an alternative surgical procedure to treat proximal radius and ulnar nonunion in a toy breed dog. A 14-month-old, Maltese cross-breed dog was referred after previous treatment with external and internal fixation had failed, resulting in a nonunion of a fracture of the proximal radius and ulna with the proximal radius fragment too small and friable to be used for fixation. A craniomedial approach was made to debride the radius nonunion site and a second approach to the lateral aspect of the ulna was made. The fracture was realigned and a titanium locking plate was applied in bridging fashion, fixed to the proximal ulnar fragment with three locking screws in the most proximal plate holes, a fourth screw was inserted in the mid-shaft of the distal ulnar fragment and three locking screws were inserted in the distal most holes of the plate through the distal ulna to engage the distal radial fragment. A recombinant bone morphogenetic protein 2 graft was inserted into the radius and ulna fracture sites. The dog had a successful clinical and radiographic outcome with bridging of the defect 4 weeks postoperatively and complete callus formation 8 weeks postoperatively. Implants have undergone dynamization and then removal. Use of a locking plate as an internal fixator achieving fixation of the proximal ulna and distal radius can be considered an option for the treatment of proximal radioulnar nonunions with a small proximal radial fragment.