Legs of a 77 year old female patient with severe osteoarthritis of the knees. Osteoarthritis (or arthrosis) is a common degenerative disease characterised by a loss of the cartilage that lines the joints between bones. This leads to pain, swelling and occasionally may result in the loss of function of the affected joint. Symptoms may be relieved with analgesic drugs and physiotherapy. Joint-replacement surgery may be performed in severe cases.