Thirty patients undergoing total knee arthroplasty for the treatment of medial knee osteoarthritis were randomized to receive a mobile bearing or fixed bearing prosthesis. The outcomes of interest included the Oxford Knee Score (OKS), mean flexion/extension angle in the stance and swing phase, knee axial rotation during the gait cycle, internal/external rotation and the range of motion of the 6 degrees of freedom of the knee joint. Outcomes were assessed pre-operation and 7.5 months post-operation. Results showed significantly a favourable mean flexion/extension angle in the stance and swing phases in the mobile bearing group compared to the fixed bearing group. No significant differences in OKS scores were observed between the two groups.