Comparison of the in Vivo Stability of 2 Cementless TKA Designs

Inclusion Criteria: • Patients referred to Kristiansund Hospital for primary total knee replacement surgery for osteoarthritis with Kellgren \& Lawrence grade 3 or 4 Exclusion Criteria: * Preoperative severe deformity (Hip-Knee-Ankle angle of \>5 (valgus) or \<-15 degrees (varus) on a full-length leg image at weight bearing * Preoperative flexion contracture more than 15° * Less than 50 and more than 75 years of age at the time of surgery * Use of walking aids because of other musculoskeletal and neuromuscular problems * Preoperative diagnosis other than osteoarthritis or avascular necrosis (e.g. rheumatoid arthritis, tumours) * Revision arthroplasty * Obesity with BMI\>35 g/m2 * Lateral collateral ligament deficient knee * Previous knee joint infection * Cognitive dysfunction or severe psychiatric disorders.