Subacromial impingement syndrome

　　One, Etiology

　　Abnormal morphology of the anterior and lateral end of the acromion, osteophyte formation, osteophyte formation of the greater tubercle of the humerus, hypertrophy of the acromioclavicular joint, and other causes that can reduce the distance between the acromion and the humeral head can all cause compression and impingement of the subacromial structure. This kind of impingement mostly occurs in the anterior 1/3 of the acromion and below the acromioclavicular joint. Repeated impingement promotes the injury and degeneration of the synovium and tendons, and even the rupture of the tendons.

　　Two, Pathogenesis

　　Pathological manifestations: According to the pathological manifestations of the impingement syndrome, it can be divided into 3 stages:

　　1. The first stage:Also known as the edema and hemorrhage stage, it can occur at any age. Common causes include activities that require overhead arm movement, such as painting and decorating walls, as well as sports such as gymnastics, swimming, tennis, and baseball throwing, which can cause excessive use of the shoulder joint and cumulative injury. In addition, this stage also includes a history of a single shoulder injury, such as edema and hemorrhage of the supraspinatus tendon, long head of the biceps brachii, and subacromial bursa after contact sports or severe falls. Although muscle strength is weakened due to pain during this period, there are no typical symptoms of rotator cuff tears, and physical examination is not easy to find signs such as pain arc sign, crepitus, and positive chronic impingement test. Subacromial lidocaine injection can completely relieve pain. X-ray examination generally does not show any abnormalities, and arthrography cannot detect the presence of rotator cuff rupture.

　　2. The second stage:The chronic tendinitis and synovial fibrosis stage, more common in middle-aged patients. Repeated impingement under the acromion leads to synovial fibrosis, thickening of the囊壁, and repeated tendinous injury presenting as chronic tendinitis, which is usually characterized by the coexistence of fibrosis and edema. The thickened synovium and tendons occupy the subacromial space, the outlet of the supraspinatus muscle is relatively narrow, which increases the opportunity and frequency of impingement, and the pain symptoms can last for several days. Even during the pain relief period, shoulder fatigue and discomfort can still be felt. Physical examination can easily find the pain arc sign and positive impingement test. If there is tendinitis of the long head of the biceps brachii, the Yergason sign is positive, and the biceps brachii long head extension traction test can also cause pain. Subacromial lidocaine injection can temporarily relieve pain.

　　3. The third stage:The period of tendon rupture, mainly characterized by partial or complete rupture of the supraspinatus tendon and the long head of the biceps brachii tendon, which occur on the basis of repeated injury and degeneration. The incidence of rotator cuff tear with impingement syndrome is more common after the age of 50. Neer II reported that the average age of patients with partial tendon rupture was 52 years, and the average age of patients with complete rupture was 59. The degree of tendon degeneration and the ability to repair are related to age factors. It should be pointed out that not all impingement syndromes lead to rotator cuff rupture, and not all rotator cuff injuries are caused by impingement syndromes. The rotator cuff rupture caused by impingement syndrome accounts for only about 1/2 of those with a history of trauma, among whom only a few have a relatively obvious or severe history of trauma. In most cases, the actual force causing injury is actually less than the force required to cause complete rotator cuff rupture, indicating the importance of intrinsic degenerative factors of the tendons.

　　1. Treatment of internal impingement:Dabidson et al. described an internal impingement that occurs when the upper arm is abducted 90° and the elbow is hyperextended, compressing the supraspinatus muscle between the humeral head and the superior posterior aspect of the glenoid. Arthroscopy can find wear of the posterior superior labrum of the affected shoulder and lesions of the rotator cuff joint surface. While performing rotator cuff debridement under arthroscopy, the degenerative labrum should also be debrided. Postoperative rehabilitation can achieve good efficacy.

　　2. Concurrent glenohumeral joint:The treatment of instability is difficult to diagnose because the significant symptoms and signs of the rotator cuff often mask the subtle manifestations of glenohumeral joint instability. Therefore, it is difficult to diagnose the glenohumeral joint instability concurrent with impingement, and ignoring the treatment of instability only to perform subacromial decompression surgery or rotator cuff debridement surgery results in poor surgical outcomes. Therefore, it is necessary to clarify whether the cause of subacromial impingement is structural or dynamic before surgery. If there is a dynamic cause, it is necessary to strengthen muscle strength training simultaneously, and if necessary, surgery to strengthen the stability of the glenohumeral joint.

　　3. Concurrent acromioclavicular joint:Osteoarthritis of the acromioclavicular joint below the acromion is also the common site of subacromial impingement. Missed diagnosis of acromioclavicular osteoarthritis is a common cause of surgical failure in subacromial impingement. Lozman et al. reported that subacromial decompression and partial resection of the lateral end of the clavicle can be performed simultaneously under arthroscopy. After an average follow-up of 32 months, the function, strength, and range of motion of 18 patients improved, 16 patients experienced pain relief, and the overall excellent and good rate of surgery was 89%.

　　Impingement can occur at any age from 10 years old to old age. Some patients have a history of shoulder trauma, and a considerable number of patients are related to long-term excessive use of the shoulder joint. Symptoms are caused by repeated injury to the rotator cuff, bursa, tissue edema, hemorrhage, degeneration, and even tendon rupture. Early rotator cuff hemorrhage, edema, and clinical manifestations of rotator cuff rupture are similar, which can easily lead to confusion in diagnosis. It is important to differentiate impingement from shoulder pain caused by other causes and to distinguish which stage the impingement belongs to. This is very important for the diagnosis and treatment of the disease.

　　The affected joint should be protected, the joint load reduced, weight loss, adequate rest, and avoid long-term heavy loads and poor posture. Use canes, walkers, and other aids. Pay attention to keeping the affected joint warm in daily life, and use hot water bottles, hot towels, and other heat therapy. Try to avoid air conditioning and fans blowing directly on the joint during hot days. Appropriate exercise can help protect and improve joint mobility, and relieve pain greatly.

　　One. Rheumatoid factor uric acid arthroscopy

　　1. X-ray films have no specificity for the diagnosis of stage 1, 2, and 3 impingement signs, but they have reference value for the diagnosis of subacromial impingement when the following X-ray signs are present.

　　2. Formation of osteophytes on the greater tuberosity, caused by repeated impacts between the greater tuberosity and the acromion, usually occurring at the insertion of the supraspinatus muscle.

　　3. The acromion is too low and hook-shaped.

　　4. The subacromial area becomes dense, irregular, or osteophytes form, the coracohumeral ligament is impacted, or bone spurs are formed subperiosteally below the anterior acromion due to repeated stretching.

　　5. Degeneration, hyperplasia of the acromioclavicular joint, formation of downward protruding osteophytes, leading to narrowing of the superior glenohumeral ligament outlet.

　　6. The distance between the acromion and the humeral head (A-H distance) decreases, with a normal range of 1.2 to 1.5 cm.

　　7. Erosion and absorption of bone below the anterior acromion or acromioclavicular joint, decalcification of the greater tuberosity of the humerus, erosion and absorption, or dense bone formation.

　　8. The rounded钝ening of the greater tuberosity of the humerus, the disappearance of the boundary between the articular surface of the humeral head and the greater tuberosity, and the deformation of the humeral head.

　　Secondly, indications for shoulder arthrography in impingement syndrome

　　1. Patients over 40 years old with clinical manifestations supporting impingement syndrome and shoulder cuff injury, who have been ineffective with non-surgical treatment for more than 3 months.

　　2. Subacromial impaction injury accompanied by sudden loss of abduction and external rotation strength.

　　3. Chronic anterior shoulder pain accompanied by rupture of the long head of the biceps brachii tendon.

　　4. Persistent shoulder pain accompanied by instability of the glenohumeral joint.

　　5. During shoulder arthrography, if the contrast agent is found to leak from the glenohumeral joint into the subacromial bursa or the subdeltoid bursa, it can be diagnosed as a complete shoulder cuff rupture. It can observe the morphology and filling degree of the long head of the biceps brachii tendon to determine whether there is a rupture. Small and incomplete shoulder cuff ruptures are difficult to display during arthrography. Subacromial bursal arthrography also helps in the diagnosis of complete shoulder cuff tears, but due to the variation in the shape of the subacromial bursa and the overlapping of imaging, its practical value is limited. Non-invasive diagnostic method MRI has a high sensitivity for soft tissue lesions, and with the accumulation of experience, the specificity of MRI in diagnosing shoulder cuff injuries is also increasing, and it has gradually become one of the routine diagnostic methods.

　　6. Ultrasound diagnosis is a non-invasive examination method with repeatability and certain diagnostic value for shoulder cuff edema, hemorrhage, and both partial and complete tendon ruptures. Currently, there is no unified standard for ultrasound diagnosis of shoulder cuff injury, and there are still certain difficulties in interpreting ultrasound images, which requires further exploration and summary. Ultrasound examination may be a direction that should be paid attention to in the future for the identification and diagnosis of partial tendinous rupture within the shoulder cuff.

　　7. Arthroscopic examination is a direct diagnostic method that can detect the range, size, and shape of tendon rupture, and it also has diagnostic value for partial rupture of the superior glenohumeral ligament at the joint surface and pathologies of the long head of the biceps brachii tendon. It can also observe the lesions of the bursa beneath the acromion and the rupture of the superior glenohumeral ligament at the bursal surface. In addition, treatment can be performed simultaneously, such as debridement and decompression of the subacromial space, resection of the anterior acromial osteophytes, and acromioplasty. Arthroscopic examination is an invasive method that requires anesthesia and certain experience and technical equipment, making it difficult to be widely implemented.

　　What kind of food is good for the body with subacromial impingement syndrome:

　　It is advisable to eat light, eat more vegetables and fruits, and rationally match the diet. The diet of patients should be light and easy to digest, eat more vegetables and fruits, and rationally match the diet, and pay attention to adequate nutrition. In addition, patients need to pay attention to avoid spicy, greasy, and cold foods.

　　First, the treatment of subacromial impingement syndrome

　　1. Impingement syndrome stage 1:Non-surgical treatment is adopted. In the early stage, the shoulder is braced with a triangular bandage or sling. Injections of corticosteroids and lidocaine into the subacromial space can achieve significant pain relief. Oral non-steroidal anti-inflammatory analgesics can promote edema subsidence, relieve pain, and can also be used in physical therapy. Generally, after about 2 weeks of treatment, when the symptoms are basically relieved, the functional exercises of the shoulder should be started, that is, bending forward to make the affected arm swing in the anterior and posterior, left and right directions under the protection of the triangular bandage (Codman clock exercise). After 3 weeks, start to practice lifting the upper arm, and in the initial stage, it should be selected to lift the arm in the non-painful direction. It is advisable to engage in original labor or sports activities after 6 to 8 weeks of complete relief of symptoms, as early recovery of physical activity and sports activities may lead to recurrence of impingement syndrome.

　　2. Impingement syndrome stage 2:Enter the stage of chronic supraspinatus tendinitis and chronic bursitis, and non-surgical treatment is still the main approach. Physical therapy and sports therapy are mainly used to promote joint function recovery, and changes in working posture and operational habits, adjustment of job types, and avoidance of recurrence of subacromial impingement syndrome. If the lesion progresses to the late stage of the second period, the thickening of the fibrous bursa has caused narrowing of the rotator cuff outlet, causing repeated impingement, and non-surgical treatment is ineffective, and the patient has lost the ability to work for more than half a year, then subacromial fibrous bursa resection (or bursa resection can also be performed under arthroscopy) and coracohumeral ligament transection should be considered. For all patients with stage 2 impingement syndrome accompanied by clear anatomical abnormalities in the subacromial structure, it is necessary to remove the cause of impingement syndrome, such as acromionoplasty, resection of the greater tuberosity osteophyte, partial resection of the acromioclavicular joint, and coracohumeral ligament transection, to eliminate impingement factors. For impingement syndrome caused by dynamic imbalance, reconstruction of dynamic balance and joint stability device should be considered according to the nature of the lesion, such as tenotomy or transplantation, glenohumeral joint arthroplasty, and artificial joint replacement.

　　3. Impingement syndrome stage 3:Accompanied by pathologies such as rotator cuff tears and biceps brachii long head tendons, it is an indication for surgical treatment. Generally, McLaughlin repair is adopted for rotator cuff tears, and subscapularis transfer or supraspinatus advancement repair can be used for extensive rotator cuff tears to reconstruct the function of the rotator cuff. At the same time, it is routine to perform anterior acromionoplasty, resect the anterior lateral part of the acromion, and cut the coracohumeral ligament to avoid re-injury to the repaired tendons. After surgery, the affected limb should be tractioned in zero position or fixed with a shoulder figure-of-eight cast, and rehabilitation training should be started after 3 weeks of fixation removal.

　　Second, non-surgical treatment

　　1. Non-surgical treatment for subacromial impingement syndrome:Non-surgical treatment is applicable to 1st and most 2nd stage patients with subacromial impingement syndrome. Early use of triangular bandages or slings for immobilization, and injecting hormones into the space under the acromion can achieve significant pain relief. Oral non-steroidal anti-inflammatory drugs can promote the resolution of edema, relieve pain, and at the same time, physical therapy can be performed. After 2 weeks of treatment, symptoms begin to improve, and functional exercises (Codman clock exercises) can be started. After 3 weeks, practice lifting the upper arm. After 6 to 8 weeks of complete relief of symptoms, physical activities or sports exercises can be resumed. Morrison et al. reported 616 cases of subacromial impingement syndrome treated with non-surgical treatment (oral NSAIDs, muscle isometric and isokinetic exercises). After 27 months of follow-up, 413 cases (67%) were satisfied with the efficacy; 172 cases (28%) underwent surgery due to poor efficacy, and the postoperative results were satisfactory; 31 patients had poor efficacy but refused surgery. He noted that patients with type 1 acromion (flat type) were more likely to achieve better efficacy than those with type 2 (curved type) and type 3 (hooked type) acromion.

　　2. Non-surgical treatment:The duration of non-surgical treatment varies from 12 to 18 months. The application of arthroscopy in subacromial decompression has reduced the complications of surgical manipulation, so the duration of non-surgical treatment may be appropriately shortened. The duration of non-surgical treatment depends on the specific condition of the patient, but most reports suggest that the duration of non-surgical treatment should not be less than 6 months.

　　3. Surgical treatment for subacromial impingement syndrome:Indications for surgical treatment are the 2nd and 3rd stage patients with subacromial impingement syndrome who have failed non-surgical treatment. The surgery includes two parts: subacromial decompression and rotator cuff repair. Subacromial decompression is the first choice, which includes cleaning the inflamed subacromial bursa, excising the coracohumeral ligament, the anterior lower part of the acromion, and the osteophytes of the acromioclavicular joint, or even the entire joint. Excision of the acromioclavicular joint is not routine and is indicated only when there is tenderness in the acromioclavicular joint and the osteophytes of the acromioclavicular joint are determined to be part of the cause of the impingement syndrome. Now, subacromial decompression surgery can be performed by traditional open techniques or Ellman's arthroscopic techniques.