The rotator cuff is a complex of four muscles of the shoulder joint, they start from the scapula and their tendons end at the small and large tuberosity of the humeral head, also called the rotator cuff, which is composed of the tendons of the subscapularis, supraspinatus, infraspinatus and teres minor muscles together, in a cuff shape around the humeral head, during shoulder abduction, the rotator cuff muscle presses down on the humeral head, allowing the upper limb to lift or rotate. Tearing of these tendons is called rotator cuff injury; cadaveric and epidemiological studies have found that the incidence of rotator cuff injury is 20-30% in people over the age of 60, 50% in people over the age of 70, and nearly 80% in people over the age of 80. With the progress of aging, rotator cuff disease will gradually become an important social health problem in the future. Its clinical manifestations are mainly pain plus shoulder joint weakness, or the shoulder joint cannot actively abduct, lift, or rotate internally or externally, and the pain becomes more obvious at night due to quietness. The diagnosis mainly relies on physical examination and MRI by a specialist. Early diagnosis and treatment are recommended. Complete rotator cuff tears do not heal on their own and require surgery to restore the function of the shoulder joint.