Drs. Baker et al in the April 17th issue of the Journal of Bone and Joint Surgery reported on a registry-based study evaluating outcomes of medial unicompartmental knee replacements. This study was performed in the United Kingdom and utilized the National Joint Registry of England and Wales data base. They evaluated 23,400 medial Oxford unicompartmental knee replacements performed in the UK between 2003 and 2010. Revision rates from centers with the lowest volume were greater than revision rates from centers with higher volume. They also noted that the incidence of revisions with surgeons who performed a lower volume were significantly higher than surgeons with a higher volume.
The 5 year survival rate was also higher in the higher volume sites/surgeons. Low volume surgeons had a 90 percent 5 year survival rate which is inferior to total knee replacement. The authors based on the evaluation of this data suggested that surgeons should perform a minimum of 13 or more unicompartmental replacements per year to yield results that are similar to those of higher volume surgeons. This points out the importance of evaluating not only the implant or technique, but the surgeon experience with the particular implant and/or technique.
There has been a lot of media coverage and advertising about certain types of partial knee replacements, as well as certain techniques i.e., robotically assisted techniques. Until individual centers and surgeons publish their data it is important to note that in this study surgeons who performed less than 13 partial knee replacements per year had a higher revision rate than surgeons who performed a greater number and also a significantly higher revision rate than patients who underwent complete knee replacement.
- When considering what option is best for you I think you should:
Find out your diagnosis and whether or not a partial or complete knee replacement would be better for you. - Determine the volume of these procedures a surgeon does.
- Whether or not there is any peer reviewed published data regarding a particular technique and/or implant to help you make a sound shared decision with your surgeon.
—Willliam P Barrett, MD
As Malcom Gladwell wrote about in Outliers, the 10,000 hour rule applies to surgeons. It takes 10,000 hours of practice at a skill to achieve proficiency.