Since the research on frozen shoulder has revealed different pathological changes from different angles and put forward numerous etiological theories, it proves that frozen shoulder is a syndrome of shoulder joint pain and motor dysfunction, but in fact, like low back pain, it is a vague concept and not a single disease. In order to improve the efficacy of treatment. Due to the accumulation of anatomical, pathological, biochemical, immunological and etiological knowledge, the term “periarthritis” has gradually been replaced by “biceps longus tendinitis”, “rostral synovitis”, “supraspinatus tendinitis”, and “supraspinatus tendinitis”. “supraspinatus tendinitis and supraspinatus tendon calcification”, “subacromial bursitis or subdeltoid bursitis”, “frozen shoulder”, “shoulder impingement syndrome These terms are replaced by specific qualitative terms such as “frozen shoulder” and “shoulder impingement syndrome”, which are described below. (a) Classification and diagnosis of frozen shoulder 1. Biceps long head tendinitis The biceps long head tendon starts from the superior glenoid ridge and penetrates the shoulder capsule via the interungual groove and the deep surface of the interungual ligament. The synovial sheath of this tendon is located in the interungual groove segment. Any chronic inflammation of the shoulder joint or repeated mechanical stimulation during daily life activities can cause congestion, edema, cellular infiltration, or even fibrosis of the tendon sheath, thickening of the tendon sheath, and formation of adhesions, making the biceps tendon sliding function impaired and sometimes unable to slide. It is a common cause of shoulder pain, often with no obvious cause. Shoulder pain sometimes radiates to the upper arm and forearm, and the pain increases at night or after exercise. On examination, pain is also seen when pressure is applied to the inter-nodal groove or tendon, and the tendon is pushed to the sides. Expansion test (elbow extension, shoulder abduction and posterior extension) causes pain. The external shoulder rotation test (natural dropping of the upper limb, external rotation of the humerus after passive flexion of the elbow) is not limited and painless, and the shoulder does not freeze. x-ray examination is more negative, and the tangential position of the interunited sulcus can be photographed to determine whether the interunited sulcus has unevenness or osteophytic changes. 2, rostral synostosis The rostral synostosis is the main attachment point for the tendons and ligaments of the shoulder. The rostral collar ligament, rostral shoulder ligament, rostro-humeral ligament, biceps short head tendon, rostro-humeral muscle, and pectoralis minor muscle are all attached to the rostral eminence. When the tendons, ligaments and synovial bursa are injured, degenerated and inflamed, they can involve their attachment points – rostral prominence, causing pain and pressure in the rostral prominence. It is a common cause of anterior shoulder pain in young adults. In addition to painful symptoms, passive external rotation is limited, but supination and abduction are generally normal. The disease is often misdiagnosed as biceps longus tenosynovitis, and painful point closure at the rostral process has a significant pain-relieving effect. 3.Supraspinatus tendinitis and supraspinatus tendon calcification The supraspinatus muscle starts from the suprascapular fossa, passes under the acromion, above the acromion and above the humeral head, and attaches to the proximal side of the greater tuberosity of the humerus. The supraspinatus muscle is an important component of the rotator cuff and plays an important role in upper arm abduction, upward motion and stabilization of the glenohumeral joint. Therefore, supraspinatus is the muscle with the highest incidence of muscle fiber rupture and the earliest degeneration among rotator cuff muscles. The supraspinatus tendon is in the 1 cm area proximal to the greater tuberosity stop, which is the lack of blood vessels in the tendon and has the worst blood supply and is most affected by stress. Supraspinatus tendonitis is a degenerative change of the tendon gradually caused by strain and minor trauma, while supraspinatus tendon calcification is a calcific tendonitis based on the degeneration of the supraspinatus tendon with calcium salt deposition. On x-ray, there are irregular, variable-sized calcified shadows near the greater tuberosity of the humerus, which corresponds to the supraspinatus tendon. The disease is more common in middle-aged and older manual workers, housewives and young athletes. It gradually causes degenerative changes in the tendon after strain and minor trauma. Initially, the pain is felt over the anterior shoulder and fatigue, and the pain may radiate in the direction of the trapezius muscle or the upper arm and forearm. In the acute phase, the pain is severe and can affect sleep and diet. Painkillers or sedatives cannot relieve the pain. The pain generally decreases or disappears after a few weeks, but the shoulder muscle spasm and movement restriction are still obvious. Sometimes there is limited pressure pain in the subacromial space and proximal side of the greater tuberosity, and intra-articular gravelly sounds can be detected during continuous extension and flexion of the shoulder joint. In addition to anterior shoulder pain and pressure pain in the subacromial space and proximal aspect of the greater tuberosity, clinical examination shows significant limitation of shoulder joint motion and positive pain arc syndrome (i.e., pain within 60° to 120° of the affected arm elevation.) Calcification of the supraspinatus tendon. X-ray orthopantomographs of the shoulder joint show small, inconsistent, irregular calcified shadows within the supraspinatus tendon above the greater tuberosity. In some cases, there are varying degrees of bone sparing in the greater tuberosity area of the humerus, but they must be differentiated from free bodies within the shoulder joint. 4.Subacromial bursitis or subdeltoid bursitis The subacromial bursa is also known as the subdeltoid bursa, which is separate in children and often intersects with each other in adults. The bursa is located below the acromion and rostral shoulder ligament and above the rotator cuff and greater tuberosity of the humerus. The top of the bursa is attached to the underside of the acromion and rostroscapular ligament and to the deep surface fibers of the deltoid from the acromion, and the bottom of the bursa is attached to the upper and lower 2 cm of the greater tuberosity of the humerus and to the rotator cuff. When the shoulder joint is abducted or internally rotated, this bursa slides with the greater tuberosity into the underside of the acromion and cannot be touched. The characteristics of this bursitis are not primary, but secondary to lesions in the adjacent tissues, especially in the supraspinatus muscle, which is most affected by injury, degeneration, calcium salt deposition and rupture of the tendon cuff, such as calcific supraspinatus tendonitis, which can break down into the bursa in the acute phase and cause acute bursitis, called calcific bursitis. Of course, it can also be caused by direct or indirect trauma. Pain, limited motion and limited pressure pain are the main symptoms of subacromial bursitis. The pain gradually increases, and is more prominent at night, often waking up in pain, especially when the shoulder is abducted and externally rotated. When the bursa is swollen or fluid accumulates, there is pressure pain in the shoulder joint area or within the deltoid muscle. In order to relieve the pain, the patient often puts the shoulder in the internal retraction and internal rotation position. With the thickening and adhesion of the bursa wall, the range of motion of the shoulder joint is gradually reduced to completely disappeared. Occasionally, calcium deposits in the supraspinatus muscle may be seen on x-ray. In acute trauma, acute bursitis of the subdeltoid bursa often appears only a few days after the injury. A puncture of the subacromial bursa can help diagnose the nature and extent of the lesion based on the amount and nature of the fluid. 5.Frozen shoulder Freezing shoulder is also known as painful shoulder contracture, which is a sudden onset of shoulder pain and joint contracture after middle age, and it usually occurs around the age of 50, so it is also called “fifty shoulder”. Leaky Shoulder Wind”. It is a self-limiting disease with a tendency to heal itself. After several months or even years, the inflammation gradually subsides and the symptoms are relieved. In the past, it was collectively referred to as frozen shoulder, but in 1934 Codman first used the diagnostic term “frozen shoulder” to distinguish it from other frozen shoulder conditions. The exact etiology of the disease is unknown, but the pathology is a multi-bursal, multi-site lesion involving the subacromial or subdeltoid bursa, the subscapularis bursa, the long head of the biceps tendon sheath, and the glenohumeral synovial cavity, as well as the supraspinatus, subscapularis, and long head of the biceps tendon, rostral shoulder, and rostro-humeral ligament. In the early stage, the synovial membrane is edematous, congested, and hypertrophied with exudate, and in the later stage, the synovial cavity is occluded with adhesions and fibrin-like material is deposited. Huang Gongyi et al. divided the clinical pathogenesis of frozen shoulder into three phases. (1) Acute phase, also known as the freezing progression phase: the onset of the disease is acute, with severe pain, muscle spasm, and limited joint movement. The pain is severe at night, and the pressure pain is widespread, including the rostral process, rostro-humeral ligament, inferior acromion, supraspinatus, biceps longus tendon, and quadrilateral foramen. The acute phase can last for 2 to 3 weeks. (2) Chronic phase, also known as the freezing phase: The pain is relatively reduced at this time, but the pressure pain is still widespread, and the functional limitation of the joint develops into joint contracture disorder. The soft tissue around the shoulder joint is “frozen”. On arthrography, the intracavitary pressure increases and the volume decreases to 5-15 ml (20-30 ml in normal subjects), the subscapularis subacromial bursa is atretic and does not appear, the subacromial crease gap disappears, and the biceps long head tendon sheath is incompletely filled or atretic. Arthroscopic examination: fibrosis of the glenohumeral capsule, thickening of the capsule wall, adhesions in the joint cavity, atresia of the subacromial folds of the shoulder glenoid, reduction of the joint volume, fibrous strips and floating debris visible in the cavity. This period can last for several months or even more than a year. (3) Functional recovery period: The inflammation in the glenohumeral joint cavity, periapical bursa and tendon sheath is gradually absorbed, the blood supply is normalized, adhesions are absorbed, the joint volume is gradually normalized, and the blood supply and neurotrophic function of the muscles are improved during the gradual recovery of motor function, and the function of the shoulder joint can be restored to normal or close to normal in most patients. 6.Shoulder impingement syndrome is a painful condition of the subacromial joint caused by the impingement of the subacromial tissues during shoulder supination and abduction movements due to structural or dynamic reasons. /It can occur at any age and is one of the causes of rotator cuff rupture and long head biceps tendon degeneration and injury. Clinical symptoms include shoulder pain, limited shoulder supination, positive pain arc sign, positive impingement test, abnormal shape of the acromion, reduced acromion-humeral head spacing, excessively long acromion, excessively low acromion, and formation of large nodular bones on X-rays. (2) Differential diagnosis of frozen shoulder 1. Rotator cuff injury: Rotator cuff is the general name of the tendon tissue covering the subscapularis, supraspinatus, infraspinatus and infraspinatus muscles in the front, top and back of the shoulder. Its common function is to keep the humeral head and shoulder pelvis stable in any movement or resting state, so that the glenohumeral joint becomes the axis and fulcrum of movement, maintaining the upper arm in all kinds of unrestrained positions and completing various motor functions. If the hand lands abducted during a fall, or if the shoulder joint is suddenly abducted and lifted while holding a heavy object, or if it is sprained, this disease is likely to occur. The greater the external force, the more severe the rotator cuff tear. A complete rotator cuff rupture should be distinguished from a partial rupture. A partial supraspinatus tendon rupture has an abduction pain arc of 60° to 120°, but can still lift the upper arm automatically; whereas a complete rotator cuff rupture severely affects the abduction function of the shoulder and cannot lift the upper arm. 2.Thoracic outlet syndrome: It refers to the syndrome caused by the compression of the brachial plexus nerve and subclavian artery and vein at the thoracic outlet and the rostral attachment of the pectoralis minor muscle. It can be caused by cervical rib, congenital hypertrophy of the attachment of the anterior oblique muscle, congenital incomplete separation of the anterior and middle oblique muscles, which reduces the outlet and squeezes the subclavian artery and brachial plexus nerve. This includes what used to be called cervical rib syndrome, anterior rhomboid syndrome, clavicular rib syndrome, and hyperextension syndrome. A positive Adson’s test (head rotation to the back or simultaneous supination of the upper extremity, with diminished to absent radial artery pulsation) is usually complained of. Special physical signs can be distinguished from frozen shoulder. 3. Cervical spondylosis: The sensory nerves in the skin of the shoulder come from C3 and C4 nerve roots, and the lateral cutaneous nerves in the upper arm come from C5 and C6, while the sensory nerves in the deep sensory area, including the joint capsule and ligament distribution, come from C5 to C8 nerve roots. Therefore, nerve root damage caused by cervical degeneration or cervical disc herniation can involve the shoulder. The main symptoms are neck pain, neck stiffness, pain in one shoulder, upper limb or radiating pain in the upper arm and forearm. 4.Pulmonary sulcus tumor (Pancoast tumor): Lung cancer occurs in the apical part of the lung, which may infiltrate the nerve vessels in the neck and cause shoulder pain, abnormal sensation and vascular compression symptoms in the upper extremity, sometimes easily misdiagnosed as frozen shoulder. 5. Shoulder-hand syndrome: This is a pain syndrome caused by abnormalities in the vegetative nerve function of the upper extremity of unknown origin, which belongs to the same category of lesions as Sudeck’s atrophy. The main symptoms are pain in the shoulder, upper extremity and hand, and dyskinesia with vasomotor disorders. The limbs are swollen, puffy, with elevated skin temperature, fever, and congestion, and the fingers prefer to be in an extended position. Shoulder joint movement is often limited, but there is no restrictive pressure pain. Antipyretic and analgesic drugs and vasodilator drugs can be used to strengthen the functional exercise of the affected hand. 6. Endocrine diseases: Diabetic patients often have frozen shoulder, which may be related to disorders of glucose metabolism, and on the basis of this, strain and cold may cause the shoulder joint resistance to decrease and cause the disease. Hyperthyroidism is an autoimmune disease, due to excessive secretion of thyroid hormones, accelerated protein catabolism and negative nitrogen balance, resulting in pain around the shoulder, muscle weakness and muscle atrophy. Therefore, the few cases of frozen shoulder that are not cured may be caused by endocrine disorders, so we should look for the cause carefully and give treatment to the original disease while treating frozen shoulder so that frozen shoulder can be cured.