Rotator cuff injury

Rotator cuff injury and inflammation is one of the most common causes of shoulder pain. 

The rotator cuff muscles are a group of muscles and tendons that surround the shoulder joint. They are important in shoulder movements by keeping the head of your upper arm bone firmly within the shallow cup of the  shoulder joint, preventing the head from riding up out of the shoulder joint.

The main symptoms are an acute (sudden) onset of pain and painful movement of the shoulder. Pain is worst when you raise your arm above your shoulder level. For example, when you comb your hair or dress yourself. Swimming, tennis, golf, throwing a ball, basketball, painting and hanging clothes on the line can be painful.

Pain often worsens when you sleep on the involved side. 

Rotator cuff injuries most often occur in people who frequently maintain their arm away from their body for extended periods of time.

A complete tear of the rotator cuff muscle or tendon may require surgical repair.