Patellofemoral arthroplasty or kneecap replacement is usually done to treat arthritis of the kneecap and its groove, also known as the trochlea. It involves replacing the under-surface of the knee and the trochlea. The procedure is also referred to as patellofemoral replacement.
Some surgeons may recommend a total knee replacement as patellofemoral arthroplasty has a higher failure rate. Total knee replacement is usually done when the arthritis has spread to other parts of the knee. But there are also those experts who maintain the knee joint if the parts that are unaffected by arthritis are allowed to remain in place. Patellofemoral arthroplasty is recommended for only 1 in 10 people with osteoarthritis. The procedure is likely to have a better outcome if the arthritis does not spread. Since it's less invasive than a total kneecap replacement, the recovery time is quicker.
During a patellofemoral arthroplasty, the surgeon creates an area on the under-surface of the kneecap and the trochlea to accommodate an artificial joint. The implant consists of a metal groove that is fitted at the end of the thighbone and a plastic disc that is fixed on the underside of the kneecap. Bone cement is used to keep the artificial joint in place. It is important to ensure that the kneecap is able to move up and down in the trochlear groove. If this movement is hampered, the new joint may wear out in a short period of time.
Recovery after patellofemoral arthroplasty is quicker than in a total knee replacement. Soon after surgery, the individual needs to perform certain exercises to bend the knee. Once it is possible to rest the full weight on the knee, support aides like crutches or a walker may be used during the initial few weeks.
It is unclear as to how long a patellofemoral replacement may last. New artificial joints with improved designs are being produced these days and these may yield better results. Studies have shown that most individuals who undergo the procedure experience positive results in the first 10 years. Since there is not much long-term data, it is difficult to determine how long a replacement will hold. In many cases, a patellofemoral replacement wears out because of problems in those parts of the joint that were not replaced. Many individuals are eventually advised to undergo a total knee replacement to treat the progressing deterioration of the knee due to arthritis.