A partial knee replacement is an alternative to total knee replacement for some people with osteoarthritis of the knee. This surgery can be done when the damage is confined to a particular compartment of the knee. In a partial knee replacement, only the damaged part of the knee cartilage is replaced with a prosthesis.

Once partial knee replacement was reserved for older patients who were involved in few activities. Now partial knee replacement is often done in younger people as their recovery is quicker and usually less painful. About 5% to 6% of people with arthritic knees are estimated to be eligible for partial knee replacement.

Who is a candidate for partial knee replacement?

People with medial, or lateral, knee osteoarthritis can be considered for partial knee replacement. "Medial" refers to the inside compartment of the joint, which is the compartment nearest the opposite knee, while "lateral" refers to the outside compartment farthest from the opposite knee. Medial knee joint degeneration is the most common deformity of arthritis.

Other factors to consider:

• You may want to consider a knee replacement if your knee pain persists despite your taking anti-inflammatory drugs and maintaining a healthy weight.
• Your provider will ask you to identify the area of pain in your knee, then check your range of motion and the knee's stability. An X-ray of the knee will determine your eligibility for partial knee replacement. However, your surgeon may not know for certain if you are a good candidate until the surgery has begun.
• You must have an intact anterior cruciate ligament, a sufficient range of knee motion, damage to only one compartment and a stable knee. The angulation of the deformity is also considered.
• In the past, a partial knee replacement was considered only in people 60 and over who were sedentary. Now younger, more active people are increasingly being considered.

What are the advantages of partial knee replacement over total knee replacement?

Compared to total knee replacement, partial knee replacement better preserves range of motion and knee function because it preserves healthy tissue and bone in the knee. For these reasons, patients tend to be more satisfied with partial knee replacement compared with total knee replacement. They are still candidates for total knee replacement should they ever need it in the future.