There are several different types of knee replacement procedures that are used to substitute either all or part of the knee. Non-constrained and partially attached knee replacement procedures are performed on those who still have some usable muscle and ligaments to support the knee. A constrained procedure, sometimes referred to as a hinged knee replacement, is performed on patients who require all of the ligaments and muscles to be removed.
A partial knee replacement is typically performed on arthritis patients who only have damage in one part of the knee joint; the surgery is known as a unicondylar replacement. These types of knee replacement procedures are considered less invasive than a total replacement, and rehabilitation typically only takes three to four months. While recovery is often easier with this surgery, many doctors prefer a total knee replacement to prevent the need for further surgery in the future. Even after a partial knee replacement, damage to the good part of the knee is probable, meaning that a full knee replacement could be needed later.
A total replacement is typically performed when a patient has suffered a massive injury or arthritis has worn out the entire knee joint. In this procedure, the entire kneecap is replaced with metal or polyethylene prostheses. Physical therapy is necessary after these types of knee replacement procedures, and the majority of patients can start therapy a few days after the surgery is completed. In most cases, a knee immobilizer will need to be worn for several weeks post-op. There are three main types of a total knee replacement: non-constrained, semi-constrained, and constrained.
The most common knee replacement surgery is a non-constrained replacement, a form of total replacement. With this surgery, the artificial parts are supported by the patient’s own ligaments and muscles. This procedure is only performed on patients who have little to no damage to the muscles.
A semi-constrained knee replacement surgery is performed on patients who still have a good amount of healthy ligaments and muscles in their knees. The surgeon will typically remove any damaged tissue and utilize the healthy tissue for support. Partial attachments are made in the areas where the ligaments are removed.
When there is severe damage to the entire knee, including all of the ligaments and muscle, a constrained or hinged knee replacement procedure is performed. The knee is replaced with two different artificial pieces that are hinged together. As this procedure relies entirely on artificial parts, it does not tend to last as long as other types of knee replacement procedures. A constrained replacement is typically a last resort, and is commonly used for those who have already undergone other types of knee replacement procedures in which the artificial pieces have worn out.