In an article published in the December 15, 2010, Journal of Bone Joint Surgery, Dr. Lygre et al reviewed the findings from a study utilizing patients from the Norwegian arthroplasty registry. They selected a group of 372 patients who had undergone a unicompartmental knee replacement (partial knee) and compared them to 972 patients who had undergone a total knee arthroplasty. The implants used in this study all had relatively long proven track records. The authors found no statistically significant difference between the patients with the unicompartmental versus total knee replacement with regard to pain, function, and ability to carry out activities of daily living. The unicompartmental patients did have a tendency towards less pain and better function, but did not reach the level of statistical significance.
This data further enlightened surgeons regarding the options for partial and complete knee replacement. Previous studies using registry data from Scandinavian countries have shown a higher revision rate for unicompartmental or partial knee replacement. There are several confounding factors that make interpretation of this data somewhat challenging, but in general patients who are ideal candidates for unicompartmental replacement do enjoy some of the benefits of this procedure.
There have been several different types of technology introduced over the last decade to improve the results of both unicompartmental and total knee replacement. Computer-assisted surgery has been shown to decrease the number of outliers in both types of procedures. More recently, companies have introduced computer-assisted robotic surgery. The Makoplasty procedure is a robotic assisted unicompartmental procedure. This is relatively new and there is no long-term data regarding this type of procedure. Of concern, some of these more recent robotic-type procedures utilize implants without proven track record, and therefore an uncertain future.
As has been noted in my previous blogs, the greatest influence on outcome and complications seems to be surgeon volume. Therefore, from a patient’s perspective, you would like to seek a surgeon who has significant experience with a particular procedure or device.
William P. Barrett, MD