This disclosure relates to a method and system for diagnosing the extent of degeneration of a knee joint, and determining a suitable prosthesis for use in knee arthroplasty as indicated by the extent of joint degeneration. According to the disclosure there is provided a method of determining a corrective surgical procedure for the treatment of degeneration of a joint, including the steps of comparing a set of radiological images, and in particular a set of x-ray images of the joint, to a set of degenerative joint conditions to determine a diagnosis； and correlating the diagnosis with a grading system which prescribes a corrective surgical procedure. The prescribed procedure may be a total knee arthroplasty, a partial knee arthroplasty, a patellofemoral arthroplasty or an anterior cruciate ligament reconstruction.
