Differential diagnoses for this patient’s stifle swelling, pain, and lameness included fracture, patellar luxation, cranial cruciate ligament injury or avulsion, muscle or tendon strain, osteochondritis dissecans, and septic arthritis. Although there was no known trauma, fracture remained on the differential list, as juvenile bone is soft and the physes are weaker than the adjacent bone and ligaments, which can lead to fractures that can occur with little or no apparent trauma.1-4 Early identification and treatment of physeal fractures are important to minimize the risk for development of significant limb deformities, joint incongruities, and intractable lameness.1-3
Hydromorphone (0.05 mg/kg IV) was administered for analgesia, and lateral and ventrodorsal thoracic radiographs were obtained to evaluate for thoracic trauma. Radiographic findings were within normal limits; however, lateral and craniocaudal radiographs of the right pelvic limb (Figure 1) revealed a Salter-Harris type II fracture of the distal femur with caudal and medial displacement.
Although Maggie’s fracture was not difficult to identify on radiographs, not all physeal fractures are as easily identified. Radiography of the contralateral joint for comparison can help confirm diagnosis.5,6 Radiography can also be repeated 10 to 14 days later to look for signs of physeal damage if the diagnosis remains unclear.5,6