Frozen shoulder, also known as frozen shoulder or adhesive capsulitis, is the result of chronic aseptic inflammation of the shoulder capsule, synovial bursa, tendons and soft tissues of the shoulder muscles, which causes adhesions inside and outside the shoulder joint and hinders joint movement. The clinical features are shoulder pain and impaired shoulder movement, especially when the affected arm is abducted, externally rotated, and posteriorly extended, and shoulder muscle atrophy and adhesions can be seen over time. There are many factors that cause shoulder joint adhesions, so let’s make a brief summary of the literature. 1. Age factor. Frozen shoulder is more common in middle-aged people around 50 years old, and most of them are women. This age coincides with menopause in women, and men’s “menopause” is also close to it. Menopause is a disruption of the systemic hormone levels caused by a decline in sex hormones, and leads to changes in various physiological and biochemical indicators of the body, and this change is more pronounced in women. Some studies have found some cases of frozen shoulder that were cured by hormone replacement therapy. In addition, studies have shown that frozen shoulder is associated with changes in proteoglycan composition. Changes in proteoglycan can cause pain and dysfunction secondary to bone growth and aseptic verification around the joint, resulting in ligament and tendon degeneration, adhesions, and calcification. The changes in the composition and metabolism of proteoglycans are most evident around the age of 50. Chinese medicine is called fifty shoulders from this cause. 2, wind, cold and damp invasion. Due to the special position of the shoulder, it is difficult to keep it warm at all times during sleep. As a result, the wind-cold evil is repeatedly felt, causing local tissue blood circulation disorders and tissue metabolism abnormalities, resulting in aseptic inflammation and tissue adhesions in the soft tissues around the shoulder joint, which eventually leads to pain and dysfunction in the shoulder. Therefore, in Chinese medicine, frozen shoulder is also called frozen shoulder. 3. Anatomical factors. The shoulder joint has a complex and flexible structure, which can be easily damaged during activities. Especially in the rostro-humeral space in the front of the shoulder, when the humerus is internally rotated, the rostro-humeral space is narrowed and the soft tissues in the space are compressed, which can lead to ischemic changes and aseptic inflammation of the surrounding tissues, resulting in pain and secondary protective muscle spasm, and causing a vicious circle, which eventually causes local soft tissue degeneration and necrosis. The above etiology is most likely to occur in sleep side lying. In addition, the supraspinatus muscle is attached to the proximal end of the greater tuberosity of the humerus at almost 90°, which generates a huge friction force during upper arm abduction and supination, which can cause chronic injury and secondary inflammatory reaction. 4.Decrease in shoulder activity. As we age, shoulder joint activity gradually decreases, causing local metabolic disorders and degeneration of the joint capsule, rotator cuff tendon, biceps tendon and rostro-humeral ligament, tissue fluid exudation and cell infiltration, eventually causing tissue cell degeneration and causing frozen shoulder. 5. Acute and chronic injuries to the shoulder. Volleyball and gymnastics, chefs, teachers, drivers and computer operators suffer from shoulder strain due to repeated or prolonged abduction, supination and internal rotation of the upper arm. The incidence of frozen shoulder is higher in the above groups. In addition, when an acute injury occurs in the shoulder joint, if the early treatment is not appropriate, it can also induce frozen shoulder. In particular, the long-term lack of movement of the shoulder joint after internal fixation of upper limb fractures leads to shoulder joint adhesions in a few cases. 6. In addition, cervical spondylosis, coronary atherosclerotic heart disease, pneumonia, cholecystitis, upper arm trauma, hemiplegia, long-term intravenous infusion and peri-shoulder surgery can cause a reduction in shoulder joint activity, resulting in joint stiffness due to contracture and adhesion of the joint capsule, which can also induce frozen shoulder. Since patients with early frozen shoulder are afraid to move because of the fear of pain, this aggravates the pathological changes of the tissue and makes frozen shoulder develop to a deeper level. In conclusion, the above factors play an important role in the development of shoulder joint adhesions. However, in view of the complexity of the etiology and pathology of shoulder adhesions, there is no definite conclusion as to which factors are dominant. For example, some scholars have found that histocompatibility antigens and reactive proteins are elevated in the blood of patients with frozen shoulder, and others have found that immune indicators are elevated in patients with frozen shoulder, suggesting that the overall immune status of the body is related to the occurrence and recurrence of frozen shoulder. In recent years, it has been shown that the incidence of frozen shoulder is significantly higher in diabetic patients, and the duration of the disease is longer at a younger age and is more bilateral. Other scholars have found that serum levels of triacylglycerol and cholesterol were significantly higher in patients with frozen shoulder than in controls. Some scholars believe that cervical spondylosis compresses the nerve roots and causes spastic muscle contraction in the neck and shoulder muscles, resulting in scapular displacement and shoulder joint dysfunction. By relaxing the relevant muscles, some of the frozen shoulder is cured. It is worth mentioning that since in our country, many doctors often attribute unexplained shoulder pain and mobility disorders to frozen shoulder. The name periarthritis is actually an extremely vague concept, and it hardly defines the extents of the disease it refers to. The term periarthritis in this article refers mainly to adhesive capsulitis.