To our best knowledge this is the first study to assess and compare lower limb biomechanics and gait pattern between patients undergoing total knee arthroplasty with use of fixed-bearing medial-pivot and multi-radius design implants. Results of this study show that there were no statistical differences between both types of implants and even though there was significant improvement in patient-reported outcome and gait pattern, those parameters still differ significantly in comparison to healthy volunteers. The problem with dissatisfaction after operative treatment may not lay in the procedure itself, but many different factors may contribute to it. Next studies comparing other designs of implants, as well as proper rehabilitation protocol should be performed