The rotator cuff is a group of muscles and tendons that surround the shoulder joint, keeping the upper arm bone securely within the shoulder socket.

Rotator cuff injuries can come from overuse, and cause a dull ache in the shoulder, which may become worse when sleeping.

Treatments generally start conservatively, with ice and rest. A steroid injection to relieve pain may be used if rest, ice, and physical therapy do not relieve pain.

Surgery may become an option for severe rotator cuff injuries. Arthroscopic and open tendon repair are common surgical procedures.