Common Causes

Rotator cuff tendonitis, an irritation or inflammation of the tendons in the rotator cuff, (2:5) is the most common cause of shoulder pain. (5:13) (2:10) This inflammation can occur due to overuse of the shoulder, (2:8) particularly if you’ve recently played sport in which you throw a ball or lift heavy weights. (2:7) It could also be because of a specific injury to the shoulder. This pain will get worse if you lift your arm above your head and may disrupt sleep. (8:3)

Any serious injury to the shoulder, such as a dislocation or separation of the shoulder, can cause serious pain. (1:4)

A condition called frozen shoulder makes movement of the shoulder very restricted, it is characterized by stiffness and pain in the shoulder joint. The condition occurs when the ligaments and tendons that comprise the shoulder joint thicken and tighten, thereby restricting movement. (2:12) (7:3)

Some of the causes of frozen shoulder are: (7:3)

Lack of use due to chronic pain.
Rheumatic disease that is getting worse.
Bands of tissue that grow in the joint and restrict motion.
Lack of the fluid that helps the shoulder joint move.