Avulsion fracture (distal and proximal)

Patellar avulsion fractures are usually debilitating. Distal avulsion fractures are more common than proximal avulsion fractures.

TPLO is a predisposing factor for distal avulsion fractures.

Patellar avulsion fractures can result from strenuous exercise in athletic dogs or from direct impact to the patella.

Due to its proximity to the skin surface patellar fractures can be open and require immediate attention.

Most common clinical signs are:

• Weight bearing lameness of the affected limb
• Skin bruising over the patella
• Pain response to palpation of the stifle joint
• Edema over the patella
• Stifle joint effusion
• Crepitus during flexion/extension of the stifle joint

High quality craniocaudal and mediolateral radiographs of the stifle joint are needed.

Small fragments or comminution may be visible on a tangential ("skyline") view of the patella or a CT scan.