This study is a follow-up of a previous randomized trial performed by the same authors. The previous study compared a mobile-bearing total knee prosthesis (TMK) with a fixed-bearing device (ACG) over a 1-year follow-up period. The current study provides an assessment at the 3-year follow-up period. A separate multi-centre cohort receiving the same intervention will also be examined. 40 patients underwent bilateral total knee replacement. Each patient received a mobile-bearing prosthesis (TMK) on one knee and a fixed-bearing prosthesis (ACG) on the other knee. A cohort of 172 patients undergoing unilateral arthroplasty with the TMK was also evaluated for frequency of complications. The results found no significant differences in the clinical assessments between the implant types.