Repair of a pathological radial fracture secondary to radioulnar ischemic necrosis in a dog.

Case Description: A 3-year-old 2.5-kg (5.5-lb) sexually intact male Pomeranian was presented with a 1-day history of non-weight-bearing lameness of the right forelimb.

Clinical Findings: Signs of pain were localized to the proximal portion of the right antebrachium. Radiography revealed a minimally displaced fracture of the proximal portion of the radius that had propagated from a well-demarcated, ovoid, osteolytic lesion within the cortex of the caudolateral aspect of the radius. Computed tomographic findings supported the radiographic findings and did not reveal lesions in other evaluated body sites.

Treatment And Outcome: At surgery, the lateral aspect of the radial cortex appeared expanded, and tenacious fibrous tissue filled the gap between the fracture fragments. Fibrous tissue was resected and submitted for histologic examination, and the fracture was reduced and stabilized with a bone plate and a positional screw. Histologic examination revealed the presence of viable bone, fibrous tissue, and areas of coagulative necrosis. Imaging and histologic findings were consistent with radioulnar ischemic necrosis (RUIN). The patient ambulated normally at reexamination 12 days after surgery. At reexamination 15 weeks after surgery, the patient continued to ambulate normally, and radiography and CT indicated healing of the fracture and resolution of the RUIN lesion.

Clinical Relevance: RUIN should be considered as a differential diagnosis for a dog with forelimb lameness and radiographic focal osteolysis between the proximal and middle thirds of the diaphysis of the radius or ulna. Prognosis for dogs with RUIN may be good with surgical intervention.