Revision Knee Surgery
The knee is a hinge joint where the thigh bone (femur) and the shin bone (tibia) meet. The knee cap (patella) glides over the femur when the knee moves. In a healthy joint, a layer of smooth cartilage cushions the bone ends, working together with muscles, tendons and ligaments to allow you to bend your knee easily. Arthritis—particularly “wear-and-tear” arthritis or osteoarthritis—as well as certain knee injuries and diseases can damage the cartilage, causing the bones to rub together and leading to pain and stiffness.
In a total knee replacement, the damaged ends of the bones are removed and replaced with a prosthesis made of metal and plastic. A partial knee replacement for patients with damage on only one side of the joint can delay or prevent a total knee replacement. These artificial parts allow the joint to move smoothly so the patient experiences pain relief and a better quality of life. Knee replacement can also help restore motion to the joint, straighten the leg and improve stability. Various minimally-invasive techniques allow the joint to be replaced with less cutting and manipulation of muscles, tendons and ligaments around the joint and allow patients to enjoy a faster and less painful recovery.
Knee replacements today last about 20 years in 85-90% of well-selected patients. While knee replacement surgery has a very high success rate, there are a small percentage of cases in which it fails. At that point, a second procedure, known as a revision, will be recommended. Occasionally, an implanted prosthesis does not function as well as it was intended to. In this case, revision surgery may be performed to adjust or replace the mechanism.
Factors that Cause Implant Failure
Overuse: Older patients tend to be somewhat less active and therefore place less stress on their joint replacement implants. However, with a greater number of seniors living longer, more energetic lifestyles and a larger proportion of younger individuals requiring knee replacement, there are some patients who will need a revision knee surgery simply because over time, they have worn their implants out.
Loosening: While an implant is firmly secured to the bone during surgery, at times it can loosen up. This generally results from friction within the joint that wears part of the implant down and causes a slackening of the bond between the bone and the implant.
Infection: Post-surgical infection, however uncommon, is always a possibility after a procedure. If the tissue in the knee becomes infected, a revision may be necessary even if the implant remains successfully attached.
Dislocation :Another rare occurrence in the knees, it is nevertheless possible that the implant can shift out of position. If it is a recurrent situation, revision surgery may be recommended.
Diagnosing Post-Surgical Problems
Typically, after recovery from an initial knee replacement surgery, a patient will regain normal range of motion and the joint will feel stable and comfortable. However, a small number of patients will experience pain, stiffness or limited knee function. When this is the case, we will do a full assessment to determine the cause of the knee problems and whether the patient would benefit from a revision surgery.
A thorough physical examination will be performed and X-rays of the joint are taken. Lab tests and a needle aspiration of joint fluid may be included in the evaluation to check for the presence of infection as well.
The Revision Knee Surgery Procedure
Depending upon the reason for the failure of the first knee replacement and the length of time that has elapsed since, the surgical incision may be made at the same site or at a different location. Specialized tools are used to remove the existing implants. In some cases, the revision procedure replacing the components will be almost identical to the first. Others, however, require some reconstruction of the bone in the form of a bone graft or use of metal plates and screws to secure the implant. Once the materials are fixed and attached with cement, the surgeon will drain any excess fluid from the knee joint and suture up the incision.
After a revision knee surgery, you will likely be restricted from performing certain activities for six to 12 weeks. Patients may require a brace for stability or an assistive device such as crutches or a walker to limit weight bearing and promote mobility. Physical therapy is essential for two to three months to improve knee strength.