A patella fracture is a break of the kneecap. Symptoms include pain, swelling, and bruising to the front of the knee. A person may also be unable to walk. Complications may include injury to the tibia, femur, or knee ligaments.

It typically results from a hard blow to the front of the knee or falling on the knee. Occasionally it may occur from a strong contraction of the thigh muscles. The diagnosis is based on symptoms and confirmed with X-rays. In children, an MRI may be required.

Treatment may be with or without surgery, depending on the type of fracture. An undisplaced fracture can usually be treated by casting. Even some displaced fractures can be treated with casting as long as a person can straighten their leg without help. Typically the leg is immobilized in a straight position for the first three weeks and then increasing degrees of bending are allowed. Other types of fractures generally require surgery.

Patella fractures make up about 1% of all broken bones. Males are affected more often than females. Those of middle age are most often affected. Outcomes with treatment are generally good.