I. Overview of frozen shoulder
1.Definition Frozen shoulder, also known as the frozen shoulder (scapulohumeral periarthritis), is a chronic aseptic inflammation of the joint capsule and soft tissues around the shoulder joint caused by injury and degeneration of the muscles, ligaments, tendons, bursa and joint capsule. It is a chronic aseptic inflammatory disease of the joint capsule and soft tissues surrounding the joint caused by injury and degeneration of the tendons, bursa and joint capsule. The clinical manifestations of the disease are slow onset and long duration, usually within 1 year, or 1-2 years in longer cases. In Chinese medicine, it is believed that the disease is caused by wind and cold in the shoulder, and it is also called “frozen shoulder” or “shoulder coagulation” because of the stiffness of the chest and shoulder joints and the limitation of movement after the disease.
2. Epidemiology: Frozen shoulder is more common in middle-aged and elderly people between 40 and 70 years old, with a prevalence of 2% to 5%, with more women than men (3:1) and more left shoulders than right shoulders. There are a few cases with bilateral onset, but it is rarely repeated in the same joint. It is characterized by slow onset and no obvious history of trauma or exposure to cold. After the disease progresses to a certain degree, the pain gradually decreases or disappears, and the joint activity can be gradually restored. The entire course of the disease is long, often taking several months to several years. However, there are a few cases that can heal on their own without treatment.
3. Etiology and pathology: There is no unified understanding of the cause of frozen shoulder, but generally the following factors are involved:
(1) Diseases outside the shoulder joint: Shoulder involvement pain from heart, lung, or biliary tract diseases, which is not healed by the original disease for a long time, causes persistent spasm and ischemia in the shoulder muscle and forms inflammatory lesions, which turns into true frozen shoulder.
(2) Bone analysis of the upper limb, cervical spondylosis, etc., which makes it impossible to move for a long time after fixation or joint tear or dislocation reset;
(3) Soft tissue degeneration around the shoulder joint, such as subacromial bursitis, supraspinatus tendonitis, biceps longus tendonitis, etc.
The shoulder joint is the joint with the largest range of motion in the human body, and the humeral head is three times larger than the glenoid, and because the ligaments of the joint are relatively weak, stability is minimal. Therefore, the soft tissues around the shoulder joint are vulnerable to damage; the joint capsule of the shoulder joint is thin and loose, which can increase the flexibility of the joint, but is susceptible to injury and inflammation. The rostral shoulder ligament and the rostro-humeral ligament are like a cap on top of the joint, which are also susceptible to damage and inflammation, as well as degenerative lesions that lead to thinning, calcification, and fracture of the cap. The synovial bursa below the acromion and deltoid helps the humeral head slide under the acromion so that the shoulder joint can be abducted above the horizontal plane. When the arm is frequently abducted or lifted, the greater tuberosity of the humerus and the rostro-capital ligament are constantly rubbing against each other, making this area susceptible to strain.
The pathological process of frozen shoulder can be divided into three stages.
(1) Acute phase or pre-freezing phase: the joint capsule itself is adherent and its lower folds disappear due to mutual adhesions, which restricts shoulder abduction, the biceps tendon sheath is also adherent and sliding is difficult, and shoulder pain becomes progressively worse;
(2) Freezing phase or adhesion phase: the joint capsule and its surrounding structures, such as supraspinatus, infraspinatus, and subscapularis muscles are painful, the rostro-humeral ligament is contracted, the synovial membrane is congested, swollen, and loses elasticity, the joint is almost frozen and cannot move, and the pain persists;
(3) The remission period or recovery period is about half a year to 1~1,5 years, when the inflammation gradually improves, the pain is relieved and the shoulder joint activity is gradually restored, but the range of motion is often not as good as before the disease.
4. Anatomy and physiology: The shoulder joint is the joint with the largest range of motion in the human body. It is a joint complex composed of four parts: the acromioclavicular joint, the acromioclavicular joint, the scapulothoracic wall joint and the sternoclavicular joint. There are many muscles and ligaments attached around the shoulder joint to maintain the stability of the shoulder joint and to move the shoulder joint, including the supraspinatus, infraspinatus, teres minor, subscapularis, deltoid, pectoralis major, pectoralis minor, latissimus dorsi, biceps, triceps, as well as the rostral-shoulder ligament, glenohumeral ligament, and rostro-humeral ligament. At the same time, the shoulder also has a shoulder-humeral joint capsule and numerous synovial bursae, which play a role in lubricating the joint and reducing friction. The blood supply to the acromioclavicular joint mainly depends on the anterior clavicular artery, the suprascapular artery and the posterior rotator humeral artery. The acromioclavicular joint and the surrounding synovial bursa are mainly innervated by the cervical 5 and cervical 6 nerves, namely the suprascapular nerve, the subscapular nerve, the musculocutaneous nerve and the articular branch of the axillary nerve. The acromioclavicular joint is a typical ball and socket joint, and its movements are divided into forward flexion, back extension, abduction, internal retraction, external rotation and internal rotation.
Clinical manifestations of frozen shoulder
1. Symptoms
(1) Pain: Mild shoulder pain at first, gradually aggravated. Most of them are chronic, and later on the pain gradually increases or stabbing pain, and it is persistent, but reduces when pressed. In severe cases, the pain is unbearable at the slightest touch. Most patients often complain of waking up with pain in the second half of the night and cannot sleep, especially when lying on the affected side, and the pain can involve the neck, scapula, deltoid, upper arm or dorsal forearm. Usually the patient is in a self-defense posture, holding the affected limb close to the side of the body and using the healthy limb to protect the affected limb.
(2) Restricted activity: The shoulder joint activity can be restricted in all directions. The shoulder joint activity is gradually restricted, and the abduction, supination, external rotation and internal rotation are obviously restricted. In severe cases, the function of the elbow joint may also be affected, and the hand cannot touch the ipsilateral shoulder when flexing the elbow, especially when the arm is posteriorly extended.
(3) Fear of cold: The affected shoulder is afraid of cold, and many patients use cotton pads to wrap their shoulders throughout the year, and even in the summer, the shoulder does not dare to blow.
2. Physical signs
(1) Pressure pain: Mostly in the rostral process, subacromial crest, interscapular sulcus, deltoid stops, infraspinatus muscle group and its joint tendons. Stiff striations can be palpated at the infragonal fossa, outer edge of the scapula, and supragonal fossa, and there is obvious pressure pain. The pressure pain in the infragonal fossa can radiate to the medial side of the upper arm and the dorsal side of the forearm.
(2) Muscle atrophy: Spasm of deltoid, supraspinatus and other muscles around the shoulder may appear in the early stage, and disuse muscle atrophy may occur in the late stage, with typical symptoms such as shoulder peak protrusion, inconvenience in lifting and unfavorable backbend, etc. At this time, pain symptoms are reduced instead. The shoulder joint is most obviously restricted in abduction, external rotation and posterior extension, and in a few people, internal retraction and internal rotation are also restricted, but less restricted in forward flexion.
(3) Muscle resistance test: The muscle with the main lesion not only has obvious pressure pain at its starting and ending points, muscle belly and ventral tendon articulation but also has a positive resistance test.
Ultrasound can detect a shoulder mass. In some cases, in order to exclude cervical spine pathology, X-ray frontal, lateral and oblique cervical spine films, or CT or MRI examination are required.
Clinical treatment principles of frozen shoulder
There are many treatment methods for frozen shoulder, but the treatment principle is to take appropriate measures for different periods of frozen shoulder or the severity of its symptoms. Generally speaking, if the diagnosis is timely and the treatment is appropriate, the course of the disease can be shortened and the motor function can be restored early.
1. In the early stage of frozen shoulder, the patient’s pain symptoms are heavy. Therefore, the main purpose of treatment is to relieve pain and prevent joint dysfunction. Generally, you can take some active exercises to maintain the mobility of the shoulder joint, and only after the acute period, you can use massage to improve blood circulation and promote local inflammation.
2. Joint dysfunction is the main problem during the frozen phase of frozen shoulder, and pain is often caused by joint movement disorders. The treatment focuses on restoring the joint movement function. The treatment can be done by physical therapy, massage and acupressure to release the adhesions, expand the range of motion of the shoulder joint and restore the normal joint movement. For the symptoms of dysfunction, patients with severe frozen shoulder can use the method of large massage under anesthesia to tear the adhesions if necessary. During this phase, functional exercises of the shoulder joint should be adhered to. In addition to passive exercises, the patient should actively cooperate and carry out functional training of active exercises, which is an extremely important part of the whole treatment process.
3. During the recovery period of frozen shoulder, the elimination of residual symptoms should be the main focus, and the main principle is to continue to strengthen functional exercises to enhance muscle strength, restore the scapular band muscles that have undergone waste atrophy in the earlier stage, and restore the normal elasticity and contraction function of deltoid muscles and other muscles, in order to achieve comprehensive recovery and prevent recurrence.