The rotator cuff is the four muscles that surround the shoulder joint and play an important role in the normal physiological activities of the shoulder joint. When the rotator cuff is injured or degenerates due to trauma or bone spur growth, the tendons may become edematous and inflammatory, or even rupture, causing friction between the rotator cuff tendons and the acromion during shoulder abduction, resulting in pain, weakness and limited movement of the shoulder joint. This type of condition is called acromioclavicular impingement syndrome. If not treated in a timely manner, the lesion will worsen and the impingement and rotator cuff tendon wear will become a vicious circle, severely impairing the function of the shoulder joint. The treatment of impingement and rotator cuff injuries should be tailored to the patient’s specific condition. If the patient does not have acute onset features and has a short history, and there are no signs of huge subacromial spurs or rotator cuff tears on X-ray and MRI, conservative treatment, including subacromial seal injections and physical therapy, can be considered first. If conservative treatment is ineffective or if the patient has a sudden progression of shoulder pain and force weakness within a short period of time and there is clear evidence of tendon tear on imaging, surgery is recommended. Similar to the treatment of habitual shoulder dislocation, the main treatment is currently performed by shoulder arthroscopy, which involves removing the hyperplastic subacromial bone spur and applying suture anchors to repair and reconstruct the ruptured rotator cuff tendon tissue. Since shoulder arthroscopy does not require the destruction of the deltoid stop on the acromion, the postoperative recovery process is fast and the chance of adhesions in the shoulder joint is significantly reduced, resulting in a smoother functional recovery. Another common clinical cause of acromioclavicular impingement syndrome is calcific rotator cuff tendinitis, in which calcium deposits are ectopically deposited in the rotator cuff tendon. Patients often present with severe pain in the shoulder joint of a sudden nature, and any slight movement of the shoulder joint can exacerbate the painful symptoms. A radiograph may reveal a mass of calcified foci of varying size near the large nodules of the shoulder joint. If left untreated, this type of patient will have recurrent shoulder pain. Arthroscopic surgery to locate the calcified foci and remove them, as well as repairing the remaining tears in the tendon, can greatly reduce the duration of the patient’s pain and prevent future degenerative rotator cuff injuries.