Diagnostic x-rays of persons with osteoarthritis demonstrate collapse of the knee joint, indicating destruction of the cartilage and meniscus (fibrous tissue). Magnetic resonance imaging (MRI) may be used for evaluation of knee pain, in addition to x-rays. Knee arthroscopy, a surgical procedure, examines the inner surfaces of the knee joint. Knee arthroscopy allows for evaluation and treatment of the ligaments, tendons, and cartilage involved in the knee joint, as well as debridement (removing damaged tissues) within the joint. Patients have a medical evaluation by their primary doctor (or specialists, if needed for their specific medical conditions) before knee replacement, since joint replacements are major surgery. This may include cardiac (heart) testing, evaluation of lung function, or improving control of high blood pressure and diabetes in order to reduce the chance of complications.