140 patients scheduled for total knee arthroplasty with a titanium nitride-coated implant were randomized to either a mobile-bearing (MB) or fixed-bearing (FB) prosthesis. Patients were assessed for knee range of motion, clinical and functional scores, and radiographic alignment over an average of 4.1 years after surgery. Primary outcome was knee range of motion, which demonstrated no significant differences between groups throughout follow-up. In addition, Knee Society Scores, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), mechanical axis, component angles in the coronal and sagittal planes and patellar tilt angle were similar between groups.