Shoulder dislocation

Introduction to shoulder dislocation Dislocation of the shoulder joint is the most common, accounting for about 50% of the dislocation of the whole body. This is related to the anatomical and physiological characteristics of the shoulder joint. For example, the humeral head is large, the joint is shallow and small, the joint capsule is slack, and the front and lower tissues are weak. Big, there are many opportunities to suffer from external forces. Dislocation of the shoulder joint occurs mostly in young adults and more men. Dislocation of the shoulder joint can be divided into anterior dislocation and posterior dislocation. The former is more common. The joint consists of the shoulder blade and the humeral head. The shoulder blade is small and shallow. The humeral head is hemispherical and its area is 4 times that of the iliac crest. The shoulder joint capsule is weak and slack, and the range of motion is large, which is prone to dislocation. When falling, the palm or elbow is on the ground, and the upper limb is rotated inside and out. Due to the effect of conduction violence or leverage, the size of the violence can cause dislocation under the armpit, condyle or subclavian. basic knowledge The proportion of illness: 0.03% Susceptible people: young adults Mode of infection: non-infectious Complications: fractures, surgical neck fractures of the humerus

Cause of shoulder dislocation

Caused by violence (30%):

Dislocation of the shoulder joint is divided into anterior dislocation and posterior dislocation according to the position of the humeral head. The anterior dislocation of the shoulder joint is common. It is often caused by indirect violence. For example, the upper extremity abducts and external rotation, the palm or elbow touches the ground, and the external force is along the humerus. In the axial direction, the humeral head avoids the joint capsule from the weak part between the subscapularis muscle and the large plexus, and dislodges forward and downward to form a anterior dislocation. The humeral head is pushed under the scapula condyle to form a dislocation under the condyle, such as The violence is relatively large, and the humeral head moves forward to the lower part of the clavicle, forming a dislocation of the subclavian bone. The posterior dislocation is rare, and the hand is affected by the violent action from the front to the back or the internal rotation of the shoulder joint. Caused by the ground, the posterior dislocation can be divided into the shoulder scapula and the subacromial dislocation. If the shoulder dislocation is improperly treated at the initial stage, habitual dislocation can occur.

Leverage (30%):

When the upper limbs are lifted, the outer drawers, and the external rotations, the large bone nodules are closely connected with the shoulder bees and form a fulcrum of the lever force. If the palm of the hand violently uploads or violently causes the upper limbs to overexpose, the humeral head will slip off the front and lower parts after being stressed, and become a dislocation of the armpit. Due to the pulling of the pectoralis major and the subscapular muscles, the humeral head slides to the shoulder to become a dislocation under the condyle.

Trauma (30%):

The patient fell laterally, and the affected limb landed on the palm or elbow. The violence spread along the fat bone to the rib head, causing the rib head to break through the weaker anterior wall of the joint capsule and slide to the submental space to form a dislocation under the invagination. Dislocation is more common. If the violence is too large, the ribs can be pushed to the lower part of the clavicle to become dislocated under the clavicle, but it is rare in clinical practice.

Shoulder dislocation prevention

The disease is caused by traumatic factors, no special preventive measures, the focus of clinical prevention and treatment is early and clear diagnosis, early treatment, the treatment is simple, the patient suffers little, and the treatment result is good. Missed diagnosis and misdiagnosis will turn fresh dislocation into old dislocation, the treatment is complicated, the treatment is long, the patient suffers greatly, and the treatment result is poor. Therefore, the clinical orthopaedic surgeon should be alert to the possibility of dislocation of the shoulder joint, and should take a photo or wear a suspicious case. X-ray of the thoracic position, CT scan of the shoulder joint if necessary.

Complications of shoulder dislocation Complications fractures of the humerus surgical neck

There are often comorbidities in the dislocation of the shoulder joint, about 30 to 40% of cases with dislocation of the shoulder joint and large nodular fractures, or a surgical neck fracture of the humerus, or a compression fracture of the humeral head, sometimes with a joint capsule or scapular margin from the front. Adhesive avulsion, poor healing can cause habitual dislocation, biceps brachii tendon can slip backward, causing joint reduction disorder, the medial bundle of phrenic nerve or brachial plexus can be compressed or pulled by the humeral head, causing nerve Dysfunction can also damage the radial artery.

Symptoms of shoulder dislocation Common symptoms The feeling of the lateral side of the shoulder arm... Scapular sore shoulder joint activity limited shoulder test positive shoulder deformity shoulder and back pain

1. Swelling of the injured shoulder, pain, limited active and passive activities.

2. The affected limb is elastically fixed in the mild outreach position, and the arm is often held by the hand, and the head and the trunk are inclined to the affected side.

3. The shoulder deltoid muscle collapses, showing a square shoulder deformity. Under the armpit, under the condyle or under the collarbone, the displaced humeral head can be touched.

4. The shoulder test (Dugas) is positive. When the affected side is leaning against the chest, the palm cannot be placed on the opposite shoulder.

Examination of shoulder dislocation

X-ray radiographs of the conventional anterior and posterior shoulder joints are often negative when the shoulder joint is dislocated, because the subacromial posterior dislocation is the most common, and the general positional relationship between the humeral head and the glenoid and shoulder peaks during the X-ray of the anterior and posterior shoulder. Still exists, so the film report is often negative, but you can still find the following abnormal features after careful reading:

1 Because the humeral head is in the forced internal rotation position, even if the forearm is in the neutral position, the humeral neck can be found to be shortened or disappeared, and the images of the nodules overlap.

2 The gap between the inner edge of the humeral head and the leading edge of the scapula is widened. It is generally considered that the gap is greater than 6 mm, and the abnormality can be diagnosed.

3 The elliptical overlapping shadow of the normal humeral head and the shoulder blade disappears.

4 The relationship between the humeral head and the scapula is asymmetrical, showing high or low, and not parallel with the anterior border of the iliac crest.

It is highly suspected that when the shoulder joint is dislocated, the sacral or the thoracic lateral radiograph should be added. The humeral head can be found on the posterior side of the scapula. If necessary, the shoulder CT scan can clearly show that the humeral head joint face is backward. And take off the trailing edge of the joint. Sometimes a sacral fracture of the humeral head can be found and a compression occurs with the posterior margin of the glenoid to affect the reduction, or the fracture of the posterior border of the glenoid.

Diagnosis of shoulder dislocation

Diagnose based on:

1. Have a history of shoulder or upper limb trauma.

2. According to the above symptoms and signs.

3. X-ray film can identify the type of dislocation and the presence or absence of fracture.

Differential diagnosis

The disease needs to be differentiated from frozen shoulder. Both shoulder and shoulder dislocation have severe pain in the shoulder and shoulder function is obviously limited, but periarthritis of shoulder is a kind of degenerative inflammation of chronic shoulder soft tissue. Mainly with severe pain, dysfunction in the middle and late stage, and a history of acute injury in the dislocation of the shoulder joint, such as pulling or colliding with excessive force or sudden violence, landing on the palm and elbow when falling, due to sudden violence The impact along the humerus causes the humeral head to disengage from the joint.

In addition, the type of dislocation needs to be identified. After dislocation, it can be divided into 3 types according to the position of the humeral head:

1 type: The humeral head is located below the glenoid, which is rare.

2 Undergrowth type: The humeral head is located under the scapula, which is also rare.

3 Shoulder type: The humeral head is still under the shoulder, but the joint face is facing backwards, behind the shoulder blade. This type is most common.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.