X-ray of the hand of a 60-year-old male patient with osteorthritis of the trapeziometacarpal joint (at the base of the thumb) and the fingers. 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.