Dislocated Kneecap

A dislocated kneecap, or patellar subluxation, is a common running injury. Knowledge and understanding of this injury is important for its effective treatment.

Kneecap, or patella, is a triangle-shaped bone that covers the knee. The kneecap is designed to fit in the centre of the groove called trochlea. As the knee turns, the kneecap slides down and up a groove on the end of the femur (the thigh bone). Dislocation occurs when the kneecap slips to one side and around to the outside of the knee. A dislocated kneecap produces acute indications like pain and it can leave patients unable to walk. For the first few hours, muscle spasms and swelling develop. For a 2nd degree sprain, pain is usually average to severe. A dislocated kneecap can damage the knee joint and can lead to constant knee pain.

A dislocated kneecap can be prevented through proper practise when exercising and playing sports. It is also important to maintain the flexibility and strength of the knee. Physical therapy exercises are also recommended to help recover leg and joint strength. Patients can undergo x-rays to examine how the kneecap fits in its groove and to eliminate other potential causes of pain, such as tear in the ligaments of the knee or in cartilage.

Initial remedies for a dislocated kneecap include a cylinder cast or knee immobiliser, and light and dynamic range-of-motion (‘ROM’) exercises. Bracing of the knee can be also applied as a short-term solution. Better footwear, like motion control running shoes, can help control the running pace and decrease the pressure on the kneecap. Surgery is recommended if patients are not cured with conventional therapy.