Recurrent Patellar Dislocation

About Recurrent Patellar Dislocation

Patellar dislocation occurs when the patella or kneecap slips out of its groove on the front of the lower end of the femur (thigh bone). A subluxation is a partial dislocation in which the patella slips but immediately goes back into place. In a true patellar dislocation the patella goes back into place as a distinct movement, usually when the knee is straightened. This may occur seconds to hours after the dislocation. The term knee dislocation is often used for a patellar dislocation but this is incorrect. A knee dislocation is a major injury and involves the tearing of the main ligaments around the knee.

When a patella dislocates the chance of another dislocation is immediately quite high, somewhere between 15% and 45%. The specific risk for an individual is difficult to calculate, but it is greater if there are associated predisposing factors. Predisposing factors include such things as the alignment of the leg, the shape of the groove in the femur for the patella, how high the patella sits in relation to the rest of the knee joint, and the alignment of the foot and ankle.

When the patella dislocates on more than one occasion the term recurrent patellar dislocation is used. After two dislocations, the risk of further episodes of dislocation is very high, somewhere in the order of 60% to 80%


Whatever operation is used to treat your knee, it will usually involve at least one night in hospital. The length of stay will depend on the complexity of your surgery as well as the response of your knee to surgery. However, most people can be discharged on the first or second day after surgery.

When you go home you will be putting weight through your leg on an as tolerated basis and using crutches for support. With some operations, usually those involving shifting the tibial tuberosity downwards, you may be required to wear some kind of brace or splint for the first few weeks after surgery. However, during this period you will be able to take the knee out of the brace to get it moving.

Most people are walking without support by four weeks. The focus of the early rehabilitation is to reduce the swelling, restore the function of your quadriceps muscle, and to get the knee bending and straightening normally.
If the tibial tuberosity has been moved then it is important to make sure the bone is healed before more aggressive rehabilitation is commenced. The same applies for a trochleoplasty. Healing can be monitored with X-rays.

Once the swelling has reduced and any bone healing has taken place, progression is essentially on an as tolerated basis. It usually takes up to 3 months before one can recommence running. From here it is really a matter of function and comfort before one can resume sporting activities. Depending on the procedure that has been performed, it will take 4 to 6 months to be able to resume sport on a competitive basis.