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Improving Results after Unicompartmental Knee Implant

Did you know that, for many people with knee osteoarthritis, only part of the joint is affected? Most often the inside edge of the joint, called the medial compartment, is damaged. A large loss of joint cartilage here puts more pressure on the bone. The angle of the knee can also begin to change. Then the joint may become unstable. Is a total knee replacement really needed if only part of the knee is damaged with osteoarthritis?

Not always. When only one compartment is a problem, the most common treatment is an osteotomy. The doctor removes a piece of bone and realigns the joint. A second option is a unicompartmental knee arthroplasty (UKA). With this implant the joint is realigned using a plastic spacer placed on only one side of the knee joint.

There are some problems with the UKA, and outcomes have varied. The benefits are intriguing enough that doctors are looking for ways to improve the results. For example, not as much bone is lost with the UKA, and the ligaments inside the knee are saved.

In this study doctors in Japan found that better results occur when the knee has full extension. Releasing soft tissues in and around the knee to gain motion may be needed when using the UKA. The authors conclude that choosing patients with full knee motion and improving the operation itself can help increase success with UKA.

References: T. Saito, MD, et al. Unicompartmental Knee Arthroplasty for Osteoarthritis of the Knee. In The Journal of Arthroplasty. August 2003. Vol. 18. No. 5. Pp. 612-618.

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