False-colour x-ray of the pelvis & upper legs of a person suffering from severe osteoarthritis of the right hip (left of image). Osteoarthritis is an inflammatory disease of joint cartilage, associated with secondary changes in underlying bone. It causes pain & impaired function of the joint. The disease is most common in elderly persons. The damage to the hip joint is evident in the uneven appearance of the ball-&-socket joint (compare with the smoother appearance of the left hip joint on the right of the image). Initial treatment involves use of analgesics & dieting to reduce pressure on the joint; more advanced cases may require a prosthetic (artificial) hip joint.