Frozen shoulder is the result of chronic aseptic inflammation of the shoulder capsule, synovial bursa, tendons and soft tissues of the periacetabular muscles, causing adhesions inside and outside the shoulder joint and impeding joint movement. The clinical characteristics are shoulder pain and shoulder joint movement disorders, especially when the affected arm abduction, external rotation and posterior extension are significantly restricted, and over time, shoulder muscle atrophy, adhesion and square shoulder deformity can be seen. There are many factors that cause square shoulder deformity, which may be related to the following factors: 1. Shoulder dislocation: When the shoulder joint is dislocated, the appearance of square shoulder deformity, shoulder swelling, loss of the bulging and plump shape; when the elbow joint is flexed, the tip of the elbow is not close to the thoracic ribs, and the affected side cannot hitch behind the healthy side (i.e. positive shoulder hitch test) and there is an obvious history of trauma. 2.Humeral surgical neck fracture: local swelling and bruising ecchymosis, loss of functional activity of the shoulder joint, the affected limb is slightly shorter than the healthy side, there is pressure pain at the fracture site, when the left upper arm is tapped longitudinally, there is sharp pain at the fracture site, when touched, there can be bone rubbing sound at the fracture site, and there is obvious history of trauma. 3.Other diseases: such as heart disease, lung disease, cervical spine syndrome, septic arthritis of shoulder joint, tuberculous arthritis of shoulder joint, bone tumor and other diseases can lead to square shoulder deformity.