Rotator cuff injuries are caused by several factors: first, subacromial impingement, where the greater tuberosity of the humerus impinges on the anterior 1/3 of the acromion and the rostrocarpal ligament during forward flexion and abduction of the shoulder, resulting in subacromial bursa inflammation and even rotator cuff injury. This impingement is called primary impingement. Changing the shape of the acromion and cutting the rostral shoulder ligament can eliminate the impingement of the rostral shoulder arch on the rotator cuff tissue; secondly, internal impingement, when abducting 90 degrees and extremely externally rotating, the lateral part of the rotator cuff joint near the stop and the posterior superior glenoid labrum impinges, leading to rotator cuff injury, this impingement is called posterior internal impingement; thirdly, local degeneration, rotator cuff tears most often occur in the area 1 cm from the humeral stop, this This area is exactly where the branches of the superior and inferior scapular arteries from the muscle belly and the branches of the anterior rotator humeral artery from the greater tuberosity meet, lacking blood supply and prone to degeneration; fourth, trauma, trauma is an external factor causing rotator cuff injury, and severe trauma can cause normal rotator cuff injury and tear.