The knee must meet strict criteria to qualify for this – namely the knee must have good movement, not be too bent or deformed and have intact ligaments. The medial knee compartment is replaced far more that the lateral knee compartment or knee cap joint.

The partial knee versus total knee debate

Doing a knee replacement is a compromise. It is the best solution engineers and surgeons can provide to mimic the anatomy and function of the knee. Certainly there are positives and negatives when comparing a partial knee replacement to a total knee replacement.

Positives to partial knee replacement

Smaller ‘minimally invasive’ incision, lower levels of post operative pain, lower chance of needing a blood transfusion, lower infection rate, feels more like a normal knee as ligaments are preserved, earlier recovery, more movement, can be revised relatively easily to a total knee replacement if needed.

Negatives to partial knee replacement

The rest of the knee may wear over time and thus need replacing and a partial knee replacement has higher revision rates than total knee replacements (revision rate – the rate of needing to remove the implants and replace with another total knee replacement). I think that historically the revision rates were higher because of implant design / technique / low numbers performed and certainly when people had ‘pain’ after a partial knee they were revised to a total knee quickly… sadly many of the ‘painful’ partial knees continued to have a ‘painful’ total knee replacement. Surgeons have learned that revising implants for ‘pain’ with no cause found tends to lead to more misery for the patient and the surgeon. Another reason they are revised sooner is because they are put in physiologically younger, more active patients who get on and use them!

How long will my knee replacement last?

We know from research that the younger the patient has a joint replacement the higher the chance of it needing revising.  If you have a total knee replacement under the age of 55 then you have a 12% revision rate at 10 years compared to a 2% revision rate if you are over the age of 80 (clearly very significant thus patients will need to be aware and counselled about the likelihood of needing another knee replacement in the future). Pooled national data suggests that the failure rate for a partial knee replacement is 5% at 5 year and for a total knee is 2% at 5 years.