What Is Subacromial Decompression?

DeSeze and Robinson studied the special structure under the acromion and the movement trajectory of the large nodule, and proposed the name of the second shoulder joint. It is also called the subscapular joint. Because of anatomical or dynamic reasons, the subacromion joint is a clinical symptom of a series of symptoms and signs caused by the impact of the subacromion tissue during shoulder uplift and abduction.

Basic Information

English name

impingement syndrome

Visiting department

orthopedics

Disease site

Bursa, tendon

Disease characteristics

Chronic blunt pain in front of the shoulder, pain or worsening of symptoms in the range of 60 ° 120 ° lifting of the affected arm

Multiple people

10 to seniors

Causes of acromion impingement syndrome

Anterior and lateral acromion morphology, osteophyte formation, osteophyte formation of large humerus nodules, acromioclavicular hyperplasia and hypertrophy, and other reasons that may lead to reduced acromion-humeral head spacing can cause subacromial Squeeze and impact. Most of these impacts occurred before the acromion and under the acromioclavicular joint. Repeated impacts cause damage and degeneration of the bursa and tendons, and even tendon rupture.

Clinical manifestations of acromion impingement syndrome

Acromion impingement syndrome can occur from the age of 10 to the elderly. Some patients have a history of shoulder trauma, and a considerable number of patients are associated with chronic overuse of the shoulder joint. Symptoms are caused by repeated damage to the rotator cuff and bursa, tissue edema, bleeding, degeneration, and even tendon rupture. Early rotator cuff hemorrhage, edema and rotator cuff rupture have similar clinical manifestations, which may confuse the diagnosis. Shoulder impact syndrome should be distinguished from shoulder pain caused by other causes, and the stage of acromion impact syndrome should be distinguished, which is very important for the diagnosis and treatment of this disease.

Common symptoms of acromion impingement syndrome at each stage:

Chronic blunt pain in front of the shoulder

Symptoms may worsen during lifting or outreach activities.

2. Pain arc sign

Pain or aggravation of symptoms occurred when the affected arm was lifted from 60 ° to 120 °. The pain arc sign is only present in some patients, and sometimes it is not directly related to acromion impact syndrome.

3. Gravel rolling sound

The examiner holds the anterior and posterior edges of the acromion of the affected arm with his hand, so that the upper arm can perform internal and external rotation motions and forward flexion and extension motions, and can make gravel rolling sounds. It is easier to hear with a stethoscope. Obvious gravel rolling sounds are more common in acromion impact syndrome stage 2, especially those with complete rotator cuff rupture.

4. Muscle weakness

The obvious weakening of muscle strength is closely related to the advanced acromion impact syndrome with extensive rotator cuff tear. In the early stage of rotator cuff tear, shoulder abduction and external rotation force weakened, sometimes due to pain.

5. Impact test

The examiner presses down the patient's affected scapula with his hand, and raises the affected arm. If the pain occurs due to the impact of the large humerus nodule with the acromion, the impact test is positive. Neer believes that this test is of great clinical significance in identifying acromion impingement syndrome.

6. Impact injection test

10 ml of 1% lidocaine was injected below the acromion into the acromion sac. If there is no shoulder dyskinesia before and after the injection, and the symptoms of shoulder pain disappear completely after the injection, the acromion impact syndrome can be established. If the pain is only partially relieved after the injection, and joint dysfunction still exists, the possibility of "freezing the shoulder" is greater. This method can identify shoulder pain caused by non-shoulder impingement syndrome.

Acromion Impact Syndrome

1. X-ray inspection

X-ray should routinely include anterior and posterior projections of the upper arm neutral position, internal rotation position, external rotation position, and axial position projection, showing acromion, humeral head, glenoid and acromioclavicular joint. Plain radiographs can identify calcium deposits under the acromion, glenohumeral arthritis, acromioclavicular arthritis, dysplasia of acromion epiphysis, and other bone disorders.

X-ray projection (Y position image) of the exit of the Okanagan tendon is very important to understand the structural narrowing of the exit and to measure the acromion-humeral head distance.

X-rays are not specific for the diagnosis of acromion impact syndrome in stages 1, 2, and 3. However, with the following X-ray signs, the diagnosis of acromion impact syndrome is of reference value.

(1) The formation of bone nodule warts. Caused by repeated collisions between large nodules and acromion, usually occurs at the supracondylar muscle stop.

(2) Shoulder peaks are too low and hooked shoulder peaks.

(3) Dense, irregular, or osteophyte formation below the acromion. The beak-shoulder ligament is impacted or repeatedly stretched to form osteophytes under the periosteum before and below the acromion.

(4) Acromioclavicular joints degenerate and proliferate, forming osteophytes that protrude downwards, resulting in narrowing of the superior ganglia muscle outlet.

(5) The acromion-humeral head distance (AH distance) is reduced. The normal range is 1.2 to 1.5 cm, <1.0 cm should be narrow, and 0.5 cm indicates extensive rotator cuff tear. The long head of the biceps brachii rupture completely, lose the function of pressing down the humeral head, or other causes of dynamic imbalance can also cause the AH gap to shrink.

(6) Invasion and absorption of bone under the anterior acromion or acromioclavicular joint; dehumidification of the large humerus tuberosity, invasion and absorption, or dense bone changes.

(7) The humerus nodules are rounded, the boundary between the humeral head articular surface and the nodules disappears, and the humeral head deforms.

The above 1 to 3 point X-ray manifestations combined with clinical anterior shoulder pain symptoms and positive impact test should consider the existence of acromion impact syndrome. X-ray signs from 4 to 7 belong to the late manifestation of acromion impact syndrome.

In addition to using static X-ray filming and measurement at different positions, dynamic observation under X-ray monitoring should also be done. In the direction and angle of acromion impingement syndrome, the affected arm was subjected to repeated forward lifting and abduction, and the relative anatomical relationship between the large humerus nodule and the acromion beak and shoulder arch was observed. Dynamic observation is particularly important for the diagnosis of dynamic acromion impact syndrome.

2. Shoulder arteriography

For rotator cuff rupture in the late stage of acromiform impact syndrome, angiography is still the most specific diagnostic method for complete rotator cuff rupture.

Should shoulder contrast be found when the contrast medium overflows from the glenohumeral joint into the acromioclavicular bursa or deltoid bursa, a complete rotator cuff rupture can be diagnosed. The shape of the biceps brachii tendon and the fullness of the tendon sheath can be observed to determine whether the biceps brachii tendon is broken. Small rotator cuff ruptures and incomplete rotator cuff ruptures are difficult to show during imaging. Acromion bursal angiography is also helpful for the diagnosis of complete rotator cuff tear, but its practical value is limited due to the morphology of acromion bursa and the overlap of imaging.

3.MRI examination

Non-invasive diagnostic method MRI has a high sensitivity to soft tissue lesions. With the accumulation of experience, the specificity of MRI for the diagnosis of rotator cuff injury is also increasing, and it has gradually become one of the conventional diagnostic methods.

4. Arthroscopy

Arthroscopy is an intuitive diagnostic method. It can find the range, size and shape of tendon rupture. It is also useful for diagnosis of partial ruptures of the articular surface of the superior tendon and biceps longus tendon lesions. The bursal lesions and the rupture of the bursa surface of the supraspinatus tendon were observed in the peak bursa. In addition, treatment can be performed at the same time as the diagnosis, such as planing and reducing pressure in the subacromial space, removing lesions, and resecting the anterior acromion osteophyte, and performing anterior acromion surgery. Arthroscopy is a traumatic test and needs to be performed under anesthesia.

Acromion Impact Syndrome Diagnosis

The diagnosis can be established based on medical history, clinical symptoms and signs and tests, X-rays, magnetic resonance, ultrasound, arthrography, etc.

Acromion Impact Syndrome Treatment

1. Treatment options for acromion impact syndrome

The choice of treatment depends on the etiology and duration of the acromion impingement syndrome.

(1) Non-surgical treatment for acromion impingement syndrome . Early use of a triangle towel or sling to brake, injection of corticosteroids and lidocaine in the space under the acromion can achieve significant pain relief. Oral non-steroidal anti-inflammatory analgesics can promote edema subsidence, relieve pain, and can be treated with physical therapy.

(2) Acromion Impact Syndrome Stage 2 Entering the stage of chronic supraspinatitis and chronic bursitis, non-surgical treatment is still the main treatment. Physical therapy and physical therapy are mainly used to promote the rehabilitation of joint function, and to change the working posture and operating habits to avoid the recurrence of acromion impact syndrome.

(3) Stage 3 acromion impingement syndrome is accompanied by pathological changes such as supraspinatus tendon rupture and biceps long tendon rupture, which are indications for surgical treatment. Mclaughlin repair is generally used for the supraspinatus tendon rupture. For extensive rotator cuff tears, subscapular muscle transposition or supramastral muscle shift repair can be used to reconstruct the function of the rotator cuff. , Cut the anterior and lateral part of the acromion, and cut off the coracoid shoulder ligament to prevent the repaired tendon from being hit again. After surgery, the affected limb should be fixed with zero-degree traction or shoulder herringbone plaster. After 3 weeks, the fixed limb is removed for rehabilitation training.

2. Non-surgical treatment of acromion impact syndrome

The duration of non-surgical treatment ranges from 12 to 18 months. The application of arthroscopy in subacromial decompression reduces the complications of surgical operation, so the time of non-surgical treatment may be appropriately shortened. The duration of non-surgical treatment depends on the specific circumstances of the patient, but most reports suggest that the duration of non-surgical treatment should not be less than 6 months.

3. Surgical treatment of acromion impact syndrome

Indications for surgical treatment are patients with stage 2 and 3 acromion impingement syndrome who have failed surgical treatment. Surgery includes two parts: subacromial decompression and rotator cuff repair. Subacromial decompression is the first choice. It includes cleaning the acromioclavicular sac with inflammation, resection of the coracoid ligament, the anterior inferior part of the acromion, and Osteophyte or even the entire joint. Removal of the acromioclavicular joint is not routine. It is indicated only when the acromioclavicular joint is tender and the osteophyte of the acromioclavicular joint is determined to be part of the cause of the acromiform impact syndrome. Today, the subacromial decompression surgery can be performed with traditional open techniques or Ellman's arthroscopy.

Acromiform impact syndrome prognosis

Shoulder impact syndrome can be diagnosed in a timely manner, the etiology and pathological changes can be clarified, and proper treatment can generally achieve satisfactory results.