 Isolated patellofemoral osteoarthritis can be a disabling condition of the knee necessitating knee arthroplasty. It is debated whether total knee replacement or isolated patellofemoral replacement is the better treatment option. This randomized trial attempts to give a qualified answer to the debate by comparing clinical outcome range of movement, stability, effusion, patellofemoral tracking, tenderness, stair climbing, patient self assessment scores EQ-5D, Oxford Knee Score, KOOS, SF-36, AKS, complications infections, revisions, longevity survival analysis and cost direct and indirect for the two implant types. 