Shoulder Impingement
Shoulder impingement occurs when the tendons of rotator cuff muscles become "impinged" or compressed as they pass underneath the top of the shoulder socket (the acromion). The tendons become inflamed and irritated, and this causes pain and usually stiffness. Golfers who have this condition most often complain of increased pain at the top of the backswing or at the end of the follow through, or they may be weak at the initial takeaway.
AC Joint Disease
Acromioclavicular or AC joint disease affects the space where the collarbone attaches to the front of the shoulder blade. There can either be a separation of these two bones due to injury, or more commonly, the development of degenerative arthritis. This area is stressed during the backswing as the front arm comes across the body.
Shoulder Instability
Shoulder Instability occurs when the capsule and ligaments of the shoulder joint are too loose, putting people at increased risk for dislocation or subluxation (partial dislocation). This can affect golfers when they are trying to maximize the shoulder turn to generate power, which requires a great deal of flexibility. The effort to increase power in their swing may cause the structures supporting the shoulder to stretch out too much, resulting in instability.
The back of the shoulder can be unstable at the top of the backswing when the lead arm moves across the body. The front of the shoulder can be unstable at the end of the follow through phase as the arm is rotated and lifted away from the body.
Arthritis
Arthritis is characterized by the wearing down of the articular cartilage or cushioning between two bony surfaces in a joint. Golfers over 50 are more prone to developing this wear and tear condition, known as osteoarthritis. When the cartilage in the shoulder joint becomes damaged, it leads to increased contact between the bony surfaces, which can cause pain with movement. It can limit range of motion, flexibility and strength.