Data from the Swedish Knee Arthroplasty Registry were analyzed to compare b
i- and tricompartmental knee arthroplasties carried out in patients operate
d on for arthrosis in 1990-996. Of the 16,607 primary arthroplasties that w
ere carried out there were 5,139 with patellar replacement in the primary p
rocedure and 10,928 without. By April 1998, 280 revisions were performed, 2
50 of these cases were analyzed in this study. Patella-related complication
s were commonly the reason for early revision: in 99 of the 168 knees with
a primary bicompartmental procedure and in 36 of the 82 knees with a primar
y tricompartmental procedure This presentation merely analyzes the extent o
f patellar problems in knee arthroplasty, as a detailed analysis of the cau
ses of this common problem is not possible using data from a national multi
center study.