Unicondylar- or Total Knee Replacement? Patient Satisfaction, Function and Muscle Mass (UKA or TKA?)

Unicondylar - or Total Knee Replacement in Medial Gonarthritis? A Randomized Study of Patient Related Outcome Measures, Function and Muscle Mass

Patients with medial gonarthritis are randomised to a unicompartmental or a total knee replacement. Primary outcome: Thigh muscle cross sectional area and radiological attenuation measured by CT Secondary aims: functional tests, gait analysis, health related quality of life and patient related outcome.

Objective: The investigators aim with the present study was to compare patient related outcome measurements, knee function and muscle mass in patients operated with an UKR or a TKR for medial gonarthritis. Hypothesis: The investigators hypothesize that a greater number of patients might benefit from a less invasive surgery in terms of increased quality of life, function and muscle mass. Primary Outcome: Thigh muscle cross sectional area and radiological attenuation measured by CT. Secondary outcomes: Functional tests (timed up and go, 30s sit and stand, forward reach, forward step down, 6 min walk and 40 m walk test), knee strength (Biodex isokinetic dynamometer) and patient reported pain on a visual analogue scale (VAS). A number of PROMs: Health related quality of life (EQ-5D), Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS) and Forgotten Joint Score (FJS) as well as 3D movement and gait analysis. Inclusion criteria: Unilateral medial osteoarthritis of the knee (Kellgren 3b-4), aged 50 or above. Exclusion criteria: Insufficient anterior cruciate ligament (ACL). Fixed varus deformity >10°, fixed flexion deformity >10°, flexion <100°. Previous high tibial osteotomy on the same side. Any neurological disease affecting strength or locomotion in any leg. Body mass index (BMI) >35. Rheumatoid disease. Symptomatic osteoarthritis of the contra lateral knee or any hip. Insufficient written or spoken Swedish.

Medial gonarthritis, knee osteoarthritis,, Muscle function, muscle mass, muscle atrophy, Total knee arthroplasty (TKA), Unicondylar knee arthroplasty (UKA), Total knee replacement (TKR), Unicondylar knee replacement (UKR), Health-related quality of life (HRQoL), Patient related outcome measurements (PROMs)

Procedure: Participants are operated with a mobile bearing medial unicompartmental knee arthroplasty (Oxford). They are followed with CT, functional tests and PROM, compared with those operated with TKA.

Procedure: Participants are operated with a cruciate retaining conventional tricompartmental prosthesis (PFC). They are followed with CT, functional tests and PROM, compared with those operated with UKA.

Functional test of quadriceps strength, a stair negotiation test where the patient is asked to perform as many repetitions as possible in 30 seconds.

Inclusion Criteria: medial gonarthritis, (Kellgren 3b-4) correctible varus deformity less than 10 degrees intact ACL proficient in written and spoken swedish Exclusion Criteria: Valgus gonarthritis flexion deformity of 10 degrees knee flexion of less than 100 degrees previous high tibial osteotomy neuromuscular disorders of lower extremities symptomatic osteoarthritis of the contralateral knee or any hip.