Osteoarthritis: Coloured X-ray of the human pelvis showing destruction of the right hip (left on image) due to osteoarthritis. Osteoarthritis is a disease of the joint cartilage that is associated with changes in the underlying bone. It is recognized on X-rays by a reduction in the joint space (due to loss of cartilage), by the presence of osteophytes (bony projections) and a ragged, irregular appearance of the remaining joint. Osteoarthritis is associated with mechanical wear and most commonly affects the elderly.