Patellar Dislocation and Subluxation

Description
Patellar dislocation and subluxation are injuries to the kneecap (patella) affecting the joint it forms with the thigh bone (femur). The patella is a V-shaped convex bone that sits within a V-shaped concave groove of the femur, known as the trochlea. Patellar dislocation is a condition in which the patella is displaced from its normal position and no longer sits in the trochlea. Patellar subluxation is a condition in which the patella is not centered within the trochlea, but the joint surfaces still touch; thus the patella is not in normal relationship to the trochlea. This tends to occur in adolescents and young adults.

Common Signs and Symptoms – Notify a physician if you have any of the following:

Severe pain when attempting to move the knee and a feeling of the knee giving way
Tenderness, swelling and bruising of the knee
Numbness or paralysis below the dislocation from pinching, cutting, or pressure on the blood vessels or nerves (uncommon)
Often patellar dislocation to the outer side of the knee, causing an obvious deformity; often relocates on its own when the knee is straightened, leaving no deformity; damage is the same in both cases
Lump on the inner knee, which is the end of the inner part of the thigh bone (femur)

Treatment
After immediate reduction (repositioning of the bones of the joint usually done by straightening out the leg), treatment consists of ice to relieve pain. Reduction can be performed without surgery, although surgery may be necessary to remove loose fragments of bone or cartilage caused by the dislocation or reduction or to help prevent further dislocation. Elevating the injured knee at or above heart level helps in reducing swelling. Immobilization by bracing for up to 6 weeks may be recommended to protect the joint while the tissues heal. After immobilization, stretching and strengthening of the injured, stiff, and weakened joint and surrounding muscles (due to immobilization and the injury) are necessary. These may be done with or without the assistance of a physical therapist or athletic trainer.

RICE Principle
With all acute injuries, follow the RICE principle to reduce swelling, pain and inflammation.

Rest- Walk with crutches if you cannot bear weight or it is extremely painful.
Ice- Use an ice pack for 20 minutes every two to three hours during the first 72 hours.
Compression- Use an ace wrap on the knee. Start at the top of the calf and wrap to mid-thigh
Elevation- Keep the injured leg above the level of the heart when sitting or lying down.