The incidence of revision of the metal component of total knee arthroplasties in different tibial-insert designs.

Seventy-one revisions of knee arthroplasty due to wear of modular tibial polyethylene inserts undertaken from May 1990 to May 1999 were reviewed. In 38 cases (53.5%), severe damage was noted that necessitated replacement of the metal components. This proportion was less than in a previous study (88.7%). All the cases were further divided into two groups based on the design of the tibial component, one group having mobile bearings and the other fixed. In only 17.7% of the mobile group was there a need to replace metal parts at revision, whereas 83.8% of the fixed group required such replacement, which is much more comparable to the previous study. Therefore, the incidence of revision of the metallic component of a total knee arthroplasty depends greatly on the design of the tibial components.