Comparing a unicompartmental implant to a total knee replacement (TKR) is a little like comparing apples to oranges. These are both implants used for joint destruction caused by osteoarthritis. Patients who only have one side of the joint damaged are better candidates for the unicompartmental implant.
Studies show the unicompartmental implant requires less invasive surgery. There's a more rapid rehabilitation and a better chance for more normal knee motion and function.
On the downside is the fact that wear and durability may be less for the unicompartmental implant. It is suggested that the TKR has a 15 (up to 20 year) span, whereas the durable life of the unicompartmental is closer to 12 years.
The condition and longevity of both implants depends on your activity level. The more active you are, the greater the stress and load on the implant leading to wear and tear. In the case of the unicompartmental implant, the condition of the other side of the joint at the time of procedure can make a difference. If there are any signs of arthritic changes, there may be progression of the disease leading to joint failure in time.
Overall, results show that for some patients, the unicompartmental implant is a good way to save money while improving quality of life, motion, and function. Later, you can convert from a unicompartmental to a total knee if needed.