GUEPAR unicompartmental Lotus prosthesis for single-compartment femorotibial arthrosis. A five- to nine-year follow-up study.

The results of 52 Groupe d'utilisation et d'expérimentation des prosthèses articulaires (GUEPAR) unicompartmental Lotus knee prostheses implanted for osteoarthritis of the knee are analyzed with a follow-up time exceeding five years (five to nine years). Thirty-five knees had no weight-bearing pain, six knees had slight pain, three knees had moderate pain, and eight knees had revisions. Except for one complication from infection, all the poor results (eight revisions and three knees with moderate pain) in terms of pain can be explained by mechanical causes, i.e., femorotibial subluxation, loosening of the tibial component, or narrowing of the nonprosthetic femorotibial space. Because the cause of these poor results appears to be due to malposition of the prosthesis component, or to components that are too thick with an inadequate mechanical axis, the precision of the surgical procedure is important.