Early failures in unicondylar arthroplasty.

Unicondylar arthroplasty has reemerged as an option for isolated compartment knee arthritis. We have noticed an increase in the need for early revision of this construct at our revision center. This study sought to determine if the need for unicondylar revision has increased over time and what factors may have led to early failure. Revision total knee arthroplasties (TKAs) performed between 1990 and 1999 (period 1) were compared to TKAs performed between 2000 and 2008 (period 2). The prevalence of unicondylar revision, time to failure, and reasons for failure were calculated. Between 1990 and 1999, 425 revision TKAs were performed, 7 of which were uni-revisions (1.6%). These had been in place an average of 169 months (range, 12.9-478.6 months). Between 2000 and 2008, 744 revision TKAs were performed, 43 of which were uni-revisions (5.8%). These had been in place an average of only 36 months (range, 4.2-159.5 months). The dominant reasons for failure in period 1 included poly wear and loosening. Reasons for failure in period 2 were variable but included a number of technical errors. Early failure of unicondylar arthroplasty appears to be on the rise. Acknowledging that these patients came from an unknown pool, we are concerned that market pressure may have led to inappropriate patient selection and that surgical inexperience with this procedure may have led to the technical problems noted in period 2. Patients should be apprised of the possibility of early revision with this procedure.