Comparison of the in Vivo Stability of 2 Cementless TKA Designs

The goal of this randomized controlled trial is to analyze the stability of a cementless Total Knee Arthroplasty (TKA) over time and compare it to a well-documented implant in patients with knee osteoarthritis. The main aim is to answer if there is a difference in stability over time as a measure of long time survivorship in these 2 implants.50 participants will be randomly allocated to receive either the Triathlon Tritanium (Stryker) or the Global Medacta Knee Sphere (GMK Sphere, Medacta) 3D printed cementless TKAs.

Inclusion Criteria:• Patients referred to Kristiansund Hospital for primary total knee replacement surgery for osteoarthritis with Kellgren & Lawrence grade 3 or 4Exclusion Criteria:Preoperative severe deformity (Hip-Knee-Ankle angle of >5 (valgus) or <-15 degrees (varus) on a full-length leg image at weight bearingPreoperative flexion contracture more than 15°Less than 50 and more than 75 years of age at the time of surgeryUse of walking aids because of other musculoskeletal and neuromuscular problemsPreoperative diagnosis other than osteoarthritis or avascular necrosis (e.g. rheumatoid arthritis, tumours)Revision arthroplastyObesity with BMI>35 g/m2Lateral collateral ligament deficient kneePrevious knee joint infectionCognitive dysfunction or severe psychiatric disorders.