Norwegian Cartilage Project - Microfracture

114 patients between 18 and 50 years with an isolated focal cartilage defect in the knee will be randomized to either receive arthroscopic microfracture or arthroscopic debridement. Both groups will then undergo a systematic physiotherapy training regime for 6-9 months. The groups will then be compared for results, after 3, 6, 12 and 24 months, by using validated patient reported outcome scores (Lysholm, KOOS, Tegner) and EQ5D as well as clinical examination and radiological findings at 2 years (MRI).