Partial Knee Replacement Surgery

Knee arthritis doesn't always wear the whole knee evenly. In many people, especially those who are slightly bow-legged, it starts on the inner side, where most of the body's weight passes. The pain sits on that inner side, the outer side feels fine, and the knee still feels stable. X-rays show bone on bone in one part and a healthy gap in the rest.

The knee has three compartments: inner (medial), outer (lateral) and behind the kneecap (patellofemoral). A partial knee replacement (unicompartmental knee arthroplasty) resurfaces only the damaged one, with a metal cap on the thigh bone, a metal tray on the shin bone and a plastic bearing between them. The other compartments and the cruciate ligaments, including the ACL, are left alone. The cut is smaller and less bone is removed than in a total knee replacement.

Because your own ligaments stay, many people say the knee feels more natural, and it usually bends further. Recovery often takes about half as long as after a total knee. The catch is that arthritis can later develop in the parts that weren't replaced, so partial knees are more likely than total knees to need another operation over the years.

Our orthopaedics team offers both total and partial knee replacement, and your surgeon will recommend the one that suits the pattern of your arthritis. Physiotherapy usually starts within 24 hours.

Only some people with knee arthritis have the pattern that suits a partial replacement. Surgery is considered when pain limits daily life, other treatment hasn't worked and the damage is confined to one compartment.

Most people find this recovery quicker and less painful than after a total knee, but daily exercises still decide how well the knee bends and how strong it gets.