Total Versus Robotic Assisted Unicompartmental Knee Replacement

Inclusion Criteria: * Listed for elective primary TKA for end stage medial compartment osteoarthritis * Intact anterior cruciate ligament * Full thickness and good quality lateral cartilage * Correctable intra-articular varus deformity and intact medial collateral ligament * American Society of Anesthesiologists (ASA) grades 1 and 2 * Male or female, age 50 - 75 at the time of listing for surgery * Suitable candidate for a cruciate retaining TKA (Triathlon prosthesis) and a UKA Exclusion Criteria: * Varus deformity of \> 20 degrees * Fixed flexion of \>10 degrees * Patient is unable to comply with the study protocol (incl. refusal for CT scan) or functional assessments * Female participants who are pregnant, lactating or planning pregnancy during the course of the study * Requires patella resurfacing or lateral compartment has significant OA * Inability to understand the patient information for the study, provide written informed consent or answer study questionnaires for cognitive or language reasons * Inflammatory disorder e.g. rheumatoid arthritis * Symptomatic foot, hip or spine pathology * Prior surgery (other than arthroscopy) or septic arthritis of the knee * Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the study,