Anatomy Muscles and tendons. It can be divided into two layers. The outer layer is the deltoid muscle and the inner layer is the four short muscles of supraspinatus, infraspinatus, subscapularis and teres minor and their joint tendons. The joint tendon is closely connected to the joint capsule and attached to the upper humerus like a cuff, which is called rotator cuff. The pathogenesis of this disease is still unclear. In 1946, Neviaser found a contracture of the shoulder capsule, chronic inflammation and fibrosis of the subsynovial layer of the capsule, also known as “adhesive capsulitis”. Many studies suggest that the early stage of the disease consists of synovial fibroblast aggregation, fibrous tissue and capillary hyperplasia, followed by synovial congestion, synovial villus hypertrophy, intra-articular plasma exudate and spread to the joint capsule and surrounding synovium; the later stage consists of fibrinous exudate in the synovial cavity, intra-articular and surrounding bursal adhesions, joint capsule and ligament contracture, resulting in shoulder joint pain and decreased mobility. The disease is divided into three phases: the acute phase (also known as the freezing phase), the chronic phase (also known as the freezing phase), and the functional recovery phase. The acute phase is characterized by acute onset, severe pain, muscle spasm, and limited motion. During the freezing phase, pain is relatively reduced, but pressure pain is still widespread, and protective muscle spasm leads to contractile dysfunction and reduced joint stiffness and volume. During the functional recovery period, the joint inflammation is gradually absorbed, blood flow returns to normal, synovial fluid secretion is gradually restored, adhesions are absorbed, and the joint volume returns to normal. Diagnosis The diagnosis of frozen shoulder can be confirmed by the following criteria: the patient has no cause for the onset of the disease; the patient has pain in the affected shoulder joint with nocturnal pain; the active and passive activities of the shoulder joint are significantly limited, with supination <100 degrees and external rotation less than half of that of the healthy side; the diagnosis can be confirmed by the positive and lateral X-rays of the shoulder joint showing normal joints, while excluding traumatic fractures, rheumatoid arthritis, tumors and other secondary frozen shoulders. Treatment 1.Regardless of the duration of the disease, and whether the symptoms are mild or severe, active activities of the shoulder joint should be performed daily, and the activities should not cause severe pain. 2. If conservative treatment is ineffective, then minimally invasive arthroscopic surgery is recommended.