Magnetic resonance imaging (MRI) is a way of viewing the tissues of your knee without using any radiation but using strong magnets. This involves your knee being placed in a special holder and then your whole body moving into the scanner. The scan takes about 25 minutes and the machine makes loud noises as is scans. You can even listen to some music to pass the time if you wish. The scan picks up many things including damage to cartilage, menisci, ligaments, bone bruising, any areas of the bone that have an absent blood supply (spontaneous osteonecrosis) and arthritis.