Subacromial impingement causes pain in the shoulder. Mostly, the pain is related to movement of the shoulder, particularly when the hand is raised above shoulder height.
Subacromial impingement is often related to sport, especially swimming and racquet sports. It can also be related to domestic tasks such as ironing and gardening. The pain often affects daily tasks including sleeping and dressing.
The pain is related to four tendons that move the shoulder, called the rotator cuff. The rotator cuff is attached to the shoulder blade at one end and to the top of the upper arm bone, the humerus, at the other. The tendons pass through a narrow space before attaching to the top of the humerus. This gap can become narrowed over time due to a bony spike developing or a thickened ligament. This creates increased pressure on the rotator cuff tendons causing the pain of subacromial impingement.