Low contact stress mobile bearing total knee arthroplasty: results at 5 to 13 years.

A total of 139 mobile bearing knee arthroplasties in 104 patients were evaluated at a mean follow-up of 7.8 years (range, 5-13 years). There were 80 cemented knees, 50 uncemented, and 9 hybrid (cemented tibia, uncemented femur). Ten knees were revised. Four knees were revised for aseptic loosening of an uncemented tibial component, and 1 knee was revised for loosening of an uncemented femoral component. One knee was revised for a recurrent dislocating bearing, and 1 knee was revised for instability. No mechanical loosening occurred in the cemented components. Three knee arthroplasties were revised for infection. A total of 66 patients (92 knees) were evaluated clinically and radiographically. Radiographic evaluation showed a 27% incidence of radiolucent lines for the femur and a 31% incidence of radiolucent lines for the tibia. No components were considered radiographically loose. The survivorship of mobile bearing knee arthroplasties was 93% at an average follow-up of 7.8 years. Aseptic loosening was statistically higher in uncemented components (P=.0051).