Partial knee replacement (also known as unicompartmental knee arthroplasty) is a surgical treatment for knee arthritis. This treatment is suitable for people who experience arthritis only in one compartment (section) of the knee joint, rather than throughout the joint. It can also provide relief from pain and stiffness in some people who have medical conditions that make them poor candidates for total knee replacement surgery (condylar arthroplasty).

In a partial knee replacement, damaged cartilage and bone are removed and replaced only in one diseased compartment of a person's knee. This differs from a total knee replacement, in which bone and cartilage from the entire joint are replaced.

Video: Animation of a partial knee replacement

What are the types of partial knee replacement?

There are two basic types of unicompartmental knee replacement.

• Unicondylar knee arthroplasty (more common), in which one side – the medial (inner side) or lateral (outer side) – of the knee joint surfaces are replaced.
• Patellofemoral joint replacment (less common), in which only the patella (kneecap) and the part of the femur it connects to are diseased).

For more detailed information, read the articles below.