Patellar Dislocation and Subluxation

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.

After immediate reduction (repositioning of the bones of the joint), treatment consists of ice and medications 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. Your doctor may drain the blood from your knee.

Immobilization by splinting, casting, or bracing without immobilization for up to six weeks is 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.