Tibial tuberosity avulsion

Q: What radiographic findings in the right stifle of the Golden Retriever are indicative of a tibial tuberosity avulsion fracture, and how is the injury oriented? show answer

A: The radiographic findings indicative of a tibial tuberosity avulsion fracture include an avulsion fracture of the right tibial tuberosity with proximal and slight lateral displacement. Additionally, a smaller fracture fragment is noted just distal to the displaced tibial tuberosity. The orientation of the injury involves displacement towards the proximal end of the bone and slightly laterally, indicating the direction in which the patellar tendon was pulling when the injury occurred.

Q: Compare the radiographic appearances of the soft tissues in the affected pelvic limb to the non-affected limb. What abnormalities are noted in the affected limb? show answer

A: On the affected right pelvic limb, there is soft tissue swelling on the dorsal and lateral aspects, extending from the proximal tibia to the mid distal tibial diaphysis. In contrast, the left pelvic limb appears normal, with no such abnormalities.

Q: Explain the typical mechanism causing a tibial tuberosity avulsion fracture in a juvenile dog, and why comparison radiographs of the opposite limb can aid in diagnosis. show answer

A: A tibial tuberosity avulsion fracture typically occurs due to excessive tension on the patellar tendon, which overcomes the resistance of the cartilaginous physis that joins the tuberosity to the tibia. In juvenile dogs, the physeal plate (growth plate) can be weaker than the tendons and muscles surrounding it, making it susceptible to avulsion injuries during traumatic incidents or sudden forceful contractions. Since there is normally a radiolucent line at the location of the physeal plate, which can sometimes be difficult to distinguish from a fracture line, comparison radiographs of the opposite limb that is presumed to be normal can be immensely helpful. These comparative images provide a reference for what the physis should look like, allowing for a more accurate assessment and confirmation of the presence of an avulsion fracture on the affected limb.