Periarthritis, or “frozen shoulder”, is a relatively common disease among the general population, and any pain and limited movement in the shoulder joint area is blamed on “frozen shoulder”. Since there are many diseases that cause shoulder pain and limited movement, some diseases can be treated well with conservative treatment, while others require surgery, the term “periarthritis” is too general and can cause confusion in the diagnosis and treatment process. This term has been abandoned in the specialty of shoulder surgery. In fact, the term “frozen shoulder” or “fifty shoulder” is generally synonymous with frozen shoulder in Chinese medicine. It belongs to the category of frozen shoulder and leaking shoulder wind in Chinese medicine. In Western medicine, it is called “frozen shoulder”; the clinical manifestation is shoulder joint pain and joint contracture caused by various causes. The etiology is not well understood, but some studies suggest that it is associated with autoimmune diseases and infections, and a history of diabetes is also a risk factor. Its pathology is characterized by severe adhesions of the joint capsule within the shoulder joint. The symptoms are progressive limitation of shoulder movement without cause, especially limitation of external rotation, and pain in the shoulder joint, which can affect sleep in severe cases. The pain and limitation of motion peak 3-6 months after the onset of the disease, after which the symptoms gradually resolve. Sometimes the onset of symptoms in one shoulder joint may be followed by an attack in the other shoulder joint some time later. The diagnosis of frozen shoulder is a diagnosis of exclusion, which means that all diseases that may cause shoulder pain and limited movement, such as rotator cuff injury, post-traumatic adhesions, and osteoarthritis of the shoulder joint, need to be excluded before a conclusion can be made. Due to the self-limiting course of the disease, the treatment of most frozen shoulders does not require surgery, but strict and active functional exercises must be performed under the guidance of a physician. The goal is to maintain a certain degree of shoulder mobility as much as possible during the period of restricted shoulder movement, so that normal shoulder movement can be maintained even after the joint adhesions recover on their own. For a small number of patients who cannot relieve themselves, surgical treatment is required. In recent years, with the development of arthroscopic surgery, we can perform arthroscopic release of the joint capsule and supplement it with pushing and releasing under anesthesia, which can achieve satisfactory results. Here we have to mention another concept, “stiff shoulder”, which is actually secondary to frozen shoulder, a periarthritis of the shoulder joint that occurs secondary to other diseases. The most common form of frozen shoulder is secondary to acute trauma to the shoulder or upper extremity. Shoulder trauma, including shoulder fractures and dislocations, such as clavicle fractures, scapula fractures, proximal humerus fractures, etc.; rotator cuff ruptures, ligament ruptures, etc. all require prolonged immobilization of the shoulder joint. Upper extremity trauma, especially humeral fractures, also require prolonged immobilization of the shoulder joint. Long-term immobilization of the shoulder joint can cause adhesions and contractures in the shoulder capsule, resulting in periarthritis. Other conditions such as ankylosing spondylitis, cervical spondylosis, and low back disorders can also affect the shoulder joint movement and lead to secondary frozen shoulder, causing adhesions and contractures in the soft tissues around the shoulder, resulting in severely restricted shoulder movement and stiffness of the shoulder joint. In most cases, surgical treatment is required. The rotator cuff can be repaired through arthroscopy, and the adhesions can be released. After surgery, we can improve the function of the shoulder joint to improve the quality of life of the patient.