The decision between a unicompartmental knee arthroplasty (UKA) and total knee replacement (TKA) may boil down to patient preference based on one or two factors. But let us outline the differences as reported in the literature so you can make an informed choice.
The difference between a total knee replacement (TKR) and unicompartmental knee arthroplasty (UKA) is more than just the implant itself but let’s review that first. As the name suggests, with a total knee replacement (TKR), the surgeon removes the entire damaged knee joint and replaces both the upper and lower sides of the joint.
The unicompartmental arthroplasty (UKA) involves just replacement of the inner or outer half of the joint. Most patients having a UKA have problems with knee alignment and have worn out just the medial joint surface. Medial refers to the side closest to the other knee.
The idea behind a UKA is that there’s no need to replace the entire joint when only one-half is compromised. Other advantages of the UKA include a shorter hospital stay, fewer infections, and faster recovery. Studies show patients having a UKA are at lower risk for blood clots. They also have less pain after surgery compared with a total knee replacement (TKR).
The major stumbling block with a unicompartmental knee arthroplasty (UKA) is the revision rate (second surgery). It is twice as high for UKA compared with a total knee replacement (TKR).
There are several reasons for the higher failure rate of the UKA. The unicompartmental implant is more likely to come loose. Bone fractures around the implant are also more common in this group. Patients seem to have more pain after a unicompartmental implant compared with a total knee replacement. And more patients with a UKA developed arthritis severe enough to require further surgery (usually conversion from a UKA to a TKR).
According to some experts, with equal results but higher revision rates associated with the unicompartmental arthroplasty (UKA), it may be better to go with a total knee replacement (TKR). Only patients needing more knee flexion might find the UKA a better choice.
Your surgeon is the best one to advise you on this point. Based on all of your own personal factors, goals, and anatomy, there may be a clear winner when comparing one type of implant over another for you.