Partial Knee Replacement (unicondylar or half knee replacement) is a treatment for end stage arthritis that is isolated to one part of the knee, most commonly the inside or medial compartment. Partial knee replacement has been shown to have some benefits when compared to total knee replacement in terms of fewer post-operative complications and improved function. This has to be weighed against higher revision rates (redo surgery) which have also been shown for partial knee replacements. All of the surgical team have developed expertise in performing partial knee replacement surgery and counselling patients regarding the appropriate type of surgery for their knee.
Partial knee replacement surgery involves removing only the damaged arthritic cartilage from one part of the knee. This worn cartilage is then replaced by a metal cap that is placed on the end of the thighbone (femur) and a second metal plate placed on top of the shin-bone (tibia). A highly engineered and durable plastic bearing is then inserted between the two metal caps to allow them to move smoothly and relieve the arthritic pain.
These are still the subject of extensive investigation. There is evidence in the literature that partial knee replacements are more likely to feel like a “normal knee”, have better patient satisfaction scores and fewer complications including mortality associated with surgery. It is possible to do unicondylar knee replacement as daycase surgery, or with an overnight stay and post-operative recovery is usually quicker.
The benefits are great, but partial knee replacement surgery is not for everyone. Patients need to have cartilage damage isolated to one part of the knee, normal knee ligament function, and a low risk of progression of arthritis in the remainder of the knee. Patients must also understand that partial knee replacements are more likely to require revision surgery, which is commonly due to wearing out other parts of the knee.