 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. 