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Causes. The shoulder joint is the most frequently dislocated joint of the body. Because it moves in several directions, your shoulder can dislocate forward, backward or downward, completely or partially, though most dislocations occur through the front of the shoulder. dislocated shoulder may be caused by: 1  Sports injuries. 2  Shoulder dislocation is a common injury in contact sports, such as football and hockey, and in sports that may involve falls, such as downhill skiing, gymnastics and volleyball. 3  Trauma not related to sports.
Osteoarthritis (OA), which is also known as osteoarthrosis or degenerative joint disease (DJD), is a progressive disorder of the joints caused by gradual loss of cartilage and resulting in the development of bony spurs and cysts at the margins of the joints.steoarthritis is caused by disintegration of the cartilage that covers the ends of the bones. As the cartilage wears away, the roughened surface of the bone is exposed, and pain and stiffness result. In severe cases the center of the bone wears away and a bony ridge is left around the edges.