Shoulder instability

Introduction to shoulder instability The shoulder joint is the joint of the human body with the largest range of motion, but it is also a joint with relatively low stability. Neither the developmental cause nor the bone structure defect caused by the injury, the labial lesion, the excessive relaxation of the joint capsule or ligament, and the paralysis of the muscles around the shoulder can cause instability of the shoulder joint. basic knowledge The proportion of illness: 0.001% Susceptible people: no special people Mode of infection: non-infectious Complications: shoulder dislocation

Cause of instability of shoulder joint

(1) Causes of the disease

Congenital or developmental factors

Skeletal factors: the development of the scapula is too small, the face is too deep, the scapula is excessively backward (the posterior angle is too large), and the posterior margin of the scapula is an important factor in the instability of the ankle.

Abnormal humeral head development, posterior superior defect (Western axillary malformation), reverse torsion deformity of the humerus, and excessive anteversion of the humeral head are often the basis of recurrent shoulder dislocation.

Soft tissue factors: found in the mesoderal developmental (messoderal) caused by systemic joint capsule and ligament relaxation sign (Ehlers-Danlos syndrome).

2. Paralytic factors

The main muscles of the shoulder and the nerves that innervate the muscles can cause instability of the shoulder joints due to paralysis, brachial plexus injury (including birth injury), radial nerve injury, suprascapular nerve compression, paraneoplastic injury, and neonatal calving sequelae. Both can cause muscle spasm and instability of the shoulder joint.

3. Traumatic factors

The traumatic shoulder dislocation of young adults can cause the avulsion of the joint capsule, the peeling of the labrum and the injury and relaxation of the middle and lower ligaments. It is a common cause of recurrent shoulder dislocation and subluxation. Healing, the abdomen of the anterior and lower abdomen can cause recurrent shoulder dislocation, and the detachment of the front lip is likely to cause recurrent scapular subluxation.

The function of the rotator cuff is not only related to the movement of the proximal end of the humerus, but also to the stability of the ankle joint. The extensive tearing of the rotator cuff makes the ankle joint unstable in the anteroposterior and superior directions, and the shoulder joint dislocation occurs in elderly patients. At the same time, the rotator cuff injury is often combined, resulting in instability of the shoulder joint in the future.

The tear of rotator interval is a special type of rotator cuff injury. The muscle gap between the supraspinatus tendon and the subscapularis muscle splits the synergy of the second muscle when the arm is lifted, and the humeral head is fixed to the shoulder blade. The resultant resultant force is significantly weakened, resulting in joint instability and slapping in the lifting process.

4. Idiopathic shoulder mobilization

Idiopathic shoulder mobilization is a kind of unilateral instability of the shoulder joint with no clear cause and no anatomical abnormality. It can occur on one side or both sides. X-ray examination shows scapular joint slippage in the upper position. When the upper arm is pulled, the humeral head is loosened. This disease is called the multi-directional shoulder instability or the multidirectional unstable shoulder in the British and American literature. It is called in Japan. For the loose shoulder, some scholars believe that the patient has a defect in the posterior inferior scapula and an excessively large scapula, which is strictly limited to instability in the scapular joint.

5. Mental factors

Random ankle dislocation and subluxation are caused by voluntary contraction of muscles. Rowe emphasized in 1973 the importance of mental factors in the etiology of this disease.

(two) pathogenesis

The generalized shoulder joint refers to the ankle joint (the first shoulder joint), the subacromial joint (the second shoulder joint), the shoulder rib wall joint, the shoulder joint lock, the shoulder joint and the sternosacral joint. The joint complex, the first three are the main moving parts of the shoulder joint complex, and the latter three are the fretting parts.

The narrow shoulder joint refers to the ankle joint. The ankle joint is an ankle joint composed of the scapula and the humeral head. The humeral head is large and approximately spherical: the scapular joint surface is approximately oval, and its area is only the humeral head. One third of the articular surface, the sputum is shallow, disc-shaped, surrounded by fibrocartilage around the formation of the labrum, the shoulder joint capsule wall is slack and elastic, forming creases in the front, back and ankle, so that the shoulder joint remains The largest range of motion, shoulder instability is usually the instability of the scapular joint.

The shoulder joint relies on its ligamentous tissue, the joint capsule and the surrounding muscles to maintain its stability. The main stable structure is in addition to the fibrous joint capsule, the scapular ligament, the patellar ligament and the intra-articular stabilization device such as the labrum of the deepened joint. The rotator cuff muscles (the supraspinatus, the infraspinatus, the subscapularis and the small round muscle), the deltoid muscle, the biceps, the triceps, and the muscles that connect the trunk and the scapula (the pectoralis major, the chest small Muscle, rhomboid muscle, scapula levator, latissimus dorsi, trapezius, anterior serratus, etc.), shoulder joint stabilization device, rotator cuff muscles, deltoid muscle, biceps and triceps to scapular joint The stability is of the utmost importance. These muscles are both a stable structure of the shoulder joint and a power device for shoulder joint movement.

Shoulder instability prevention

Early detection and early diagnosis are the key to the prevention and treatment of this disease.

Shoulder instability Complications of shoulder dislocation

Can be used for shoulder subluxation and elastic shoulders.

Symptoms of shoulder joint instability Common symptoms fatigue fatigue nodules muscle atrophy joint relaxation shoulder strain

Congenital or developmental shoulder instability occurs in children or adolescents, Ehlers-Danlo patients may have a genetic history or a positive family history, and idiopathic shoulder mobilization (loose shoudler) is more common in the age of 20 Young women, women are significantly more than men, recurrent shoulder dislocation after trauma and bankar lesions (Bankart lesion) are more common in young adults, and have a history of acute trauma, also need to shoulder subluxation caused by sports or work injuries in young adults. Except for rotator cuff injury, the instability of the injured ankle in the elderly should also consider the possibility of rupture of the rotator cuff on the basis of degeneration.

Symptom

Pain: manifested as dull shoulder pain, increased weight during exercise or weight bearing, joint instability and squeaking; 70% of patients feel conscious of ankle instability and squeaking, often lifting or abduction to an angle There is a sense of instability, and the symptoms are more obvious when weight-bearing, about half of the patients have fatigue and fatigue, especially not for lifting heavy objects for a long time, about 1/3 of patients have numbness around the shoulder.

In the recurrent anterior dislocation of the ankle joint, there are typical malformations and dysfunctions in the occurrence of dislocation. It is easy to occur in the external rotation and extension of the outreach position, and the reduction is easier, but the symptoms are not as obvious as the acute shoulder dislocation.

2. Signs

During the examination, the patient is fully exposed to the shoulders and sitting opposite the examiner. The examination contents should include:

(1) Whether the muscles are atrophied: such as the deltoid muscle, the supraspinatus muscle, the infraspinatus muscle, the small round muscle and the upper limb with other muscles.

(2) Range of joint activities: including the range of lifting, abduction, extension and passive, and external rotation (simultaneously with the healthy side for comparison), during passive flexion and extension exercises and active abduction, press when lifting Touch the front of the joint to detect the presence or absence of a ringing or unstable vibration. If the shoulder joint is overactive in all directions, the other joints of the limbs should be further examined.

(3) Joint stability check: push the humeral head in the anteroposterior direction to detect the presence or absence of excessive loosening. The upper arm and the outer rotation position respectively pull the upper arm down, such as the humeral head moving down obviously, the shoulder and the humeral head. Apparent depressions indicate a downward loosening, idiopathic shoulder mobilization and rotator cuff tears have the above-mentioned manifestations. Instability in front of and below the shoulder is the most common type, rare recurrence. Dislocation of the back of the shoulder, there is instability in the back, and the humeral head is easily pushed to the rear.

(4) tenderness site: recurrent shoulder anterior dislocation or Bankart lesion anterior and inferior anterior and posterior tibia may have tenderness; rotator cuff injury tenderness is often located under the shoulder and near the large nodules, rotator cuff space splits on the outer edge of the condyle Pain, pain in passive external rotation, congenital dysplasia and paralysis, scapular instability caused by random shoulder subluxation often has no fixed tenderness.

Shoulder joint instability check

X-ray inspection

The anterior and posterior humeral head defects (Western axe deformity) were found on the conventional X-ray anterior and posterior slices to support the diagnosis of recurrent shoulder dislocation. If the anterior and posterior radiographs of the upper arm position of the affected arm are slippery, the lateral side is not Stable existence, such as when the arm is pulled down, the humeral head has a significant downward movement, which is an unstable X-ray under the shoulder joint.

Axial X-rays can help to detect poor or poor posterior margin and understand the relationship between the humeral head and the scapula (whether the center of the humeral head deviates from the central axis of the scapula), and the axial position can also measure the shoulder. The posterior opering angle and the glenoid tiling angle can be used to determine the free articular surface of the humeral head and the free surface central angle of humeral head. The measurement of 80° is unstable and the ratio of the scapular index (the ratio of the long diameter of the scapula and the long diameter of the humeral head) are useful for the diagnosis of the cause of instability of the shoulder joint.

Arthrography is still a reliable method for diagnosing rotator cuff tear and rotator cuff gap. The former can be seen from the shoulder scapula cavity through the rotator cuff rupture into the shoulder sac sac, the latter see contrast agent in the sputum The anterior superior and superior scapular muscles and the subscapularis muscles form an abnormal image of the papillary or band. In the arthrography, the axial or posterior tangential position of the scapular joint can be observed. Lip image.

In the arthrography of the joint capsule dislocation and subluxation caused by subluxation and idiopathic shoulder mobilization, the contrast agent is pulled down the inner arm and the contrast agent accumulates above the humeral head to form a "snow cap." "snow cap shadow".

2. Special inspection

(1) CT examination: scapular sleeve injury and humeral head anteversion caused by abnormal rotation of the humeral shaft can be found to be too large. For example, combined with low concentration double contrast angiography can help to find the front joint Hill Sachs lesion and Bankart lesion.

(2) B-ultrasound examination: it is helpful for the diagnosis of complete rotator cuff fracture and severe tear.

(3) Electromyography examination and shoulder joint motion analysis method: It has diagnostic value for shoulder joint instability caused by paralysis, and has certain reference significance for the diagnosis of idiopathic shoulder mobilization and rotator cuff space division.

(4) Arthroscopy: some pathological factors of instability in the joints, such as rotator cuff injury, avulsion of the labrum and relaxation of the scapular ligament, relaxation of the joint capsule wall, and secondary cartilage exfoliation of the humeral head It is an intuitive diagnostic method.

Diagnosis of shoulder instability

It is not difficult to diagnose the instability of the shoulder joint with systemic joint and ligament relaxation or obvious paralysis. However, the clinical diagnosis of subluxation and idiopathic shoulder stagnation caused by ankle relaxation is difficult. The diagnosis of joint instability should be based on the age of onset, medical history, clinical symptoms, detailed physical examination, X-ray examination, arthrography, CT examination and arthroscopy to determine the cause and degree of instability.

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