The most common cause leading to a shoulder replacement is osteoarthritis, or wear and tear arthritis. Osteoarthritis can occur without any injury to the shoulder, but it is uncommon. This is in large part because the shoulder is not a weight-bearing joint. Wear and tear arthritis is more common in the hip and knee. More commonly, osteoarthritis occurs many years after an injury to the shoulder. A shoulder dislocation can result in instability of the shoulder that leads to chronic instability. Repeated dislocations over many years damage the joint leading to arthritis. Some fractures of the shoulder can also lead to arthritis. The problem with aseptic necrosis described above can also lead to osteoarthritis.