bubble_chart Overview

Shoulder dislocation is the most common, accounting for about 50% of all joint dislocations in the body. This is related to the anatomical and physiological characteristics of the shoulder joint, such as the large humeral head, shallow and small glenoid cavity, loose joint capsule, weak anterior and inferior tissues, large range of motion, and frequent exposure to external forces. Shoulder dislocation mostly occurs in young adults, with males being more affected.

bubble_chart Etiology

Shoulder dislocation is classified into anterior dislocation and posterior dislocation based on the position of the humeral head. Anterior shoulder dislocation is very common and often caused by indirect violence, such as falling with the upper limb abducted and externally rotated, with the palm or elbow hitting the ground. The force impacts upward along the longitudinal axis of the humerus, causing the humeral head to tear through the joint capsule between the subscapularis and teres major muscles, dislocating forward and downward, resulting in anterior dislocation. The humeral head is pushed beneath the coracoid process of the scapula, forming a subcoracoid dislocation. If the force is greater, the humeral head may shift further forward under the clavicle, causing a subclavicular dislocation. Posterior dislocation is rare and usually occurs due to a force acting from front to back on the shoulder joint or falling with the arm adducted and internally rotated while the hand hits the ground. Posterior dislocation can be divided into infrascapular and subacromial dislocation. If shoulder dislocation is improperly treated in the initial stage, habitual dislocation may occur.

bubble_chart Clinical Manifestations

Traumatic anterior shoulder dislocation all have a clear history of trauma, with shoulder pain, swelling, and dysfunction. The injured limb is elastically fixed in a grade I abduction and internal rotation position, with the elbow flexed and the forearm supported by the contralateral hand. The appearance shows a "square shoulder" deformity, with a prominent acromion and emptiness beneath it. The humeral head can be palpated in the axilla, below the coracoid process, or beneath the clavicle. The injured limb is in grade I abduction and cannot be pressed against the chest wall. When the elbow is placed against the chest, the palm cannot simultaneously touch the contralateral shoulder (Dugas sign, indicating a positive shoulder abduction test). A straight ruler placed along the lateral side of the upper arm can simultaneously contact the acromion and the lateral epicondyle of the humerus (straight ruler test). X-ray examination can confirm the type of dislocation and determine the presence of any fractures.

Attention should be paid to checking for complications. In cases of shoulder dislocation, approximately 30–40% are associated with greater tuberosity fractures. Fractures of the surgical neck of the humerus or compression fractures of the humeral head may also occur. Sometimes, the joint capsule or the anterior attachment of the glenoid labrum may be avulsed, and poor healing can lead to habitual dislocation. The long head tendon of the biceps brachii may slip backward, obstructing joint reduction. The axillary nerve or the medial cord of the brachial plexus may be compressed or stretched by the humeral head, causing neurological dysfunction, and the axillary artery may also be injured.

The clinical symptoms of posterior dislocation are less obvious than those of anterior dislocation. The main manifestations include a prominent coracoid process, flattening of the anterior shoulder, and a palpable humeral head in the lower scapular region. The upper arm is slightly abducted and markedly internally rotated. An anteroposterior X-ray of the shoulder can clearly show the posterior dislocation of the humeral head.

bubble_chart Treatment Measures

1. Manual Reduction

Dislocation should be reduced as soon as possible. Appropriate anesthesia (brachial plexus block or general anesthesia) should be selected to relax the muscles and allow the reduction to be performed painlessly. Elderly patients or those with weak muscle strength can also undergo reduction under analgesics (e.g., 75–100 mg of pethidine). Habitual dislocation may not require anesthesia. The reduction technique should be gentle, avoiding forceful maneuvers to prevent additional injuries such as fractures or nerve damage. There are three commonly used reduction techniques.

(1) Foot-Step Method (Hippocrate's Method)

The patient lies supine, and the surgeon stands on the affected side. The surgeon grasps the patient’s wrist with both hands and places the heel in the axilla of the affected side. With steady and continuous traction, the heel pushes the humeral head outward while rotating and adducting the arm to achieve reduction. A clicking sound may be heard during reduction.

(2) Kocher's Method

This method is more likely to succeed under muscle relaxation. Avoid excessive force to prevent excessive torsion on the humeral neck, which could lead to fracture. Steps: Hold the wrist with one hand and flex the elbow to 90 degrees to relax the biceps brachii. With the other hand holding the elbow, apply continuous traction, gradually abduct the arm (Grade I), externally rotate the upper arm, then adduct the elbow toward the midline of the chest wall, and finally internally rotate the upper arm. Reduction can then be achieved, often accompanied by a clicking sound.

(3) Traction-Tuina Method

The patient lies supine. One assistant uses a cloth sling to pull the chest toward the healthy side, a second assistant uses a sling under the axilla to pull the affected limb upward and outward, and a third assistant holds the wrist of the affected limb, applying downward traction while externally rotating and adducting. All three assistants apply slow, continuous traction simultaneously. The surgeon pushes the humeral head outward from the axilla to achieve reduction. Alternatively, two assistants can perform traction reduction.

After reduction, the shoulder regains its normal rounded and full contour, and the dislocated humeral head can no longer be palpated in the axilla, below the coracoid process, or under the clavicle. The shoulder abduction test becomes negative, and X-ray confirms the humeral head is in the correct position. If accompanied by an avulsion fracture of the greater tuberosity of the humerus, the fracture fragment is often connected to the humeral shaft by periosteum, so in most cases, the avulsed fragment reduces along with the shoulder dislocation.

Post-Reduction Management: After reduction of an anterior shoulder dislocation, the affected limb should be kept in adduction and internal rotation, with a cotton pad placed in the axilla. A triangular bandage, elastic bandage, or plaster is then used to immobilize the arm against the chest. After three weeks, gradual shoulder swinging and rotation exercises can begin, but excessive abduction and external rotation should be avoided to prevent recurrent dislocation. For posterior dislocations, the limb should be immobilized in an antagonistic position (i.e., abduction, external rotation, and extension).

2. Surgical Reduction

A few shoulder dislocations require surgical reduction. Indications include: anterior shoulder dislocation complicated by posterior slippage of the long head of the biceps tendon, obstructing manual reduction; avulsion fracture of the greater tuberosity with the fragment trapped between the humeral head and glenoid, hindering reduction; combined humeral surgical neck fracture that cannot be manually reduced; combined fractures of the coracoid process, acromion, or glenoid with significant displacement; or combined injury to major axillary blood vessels.

3. Treatment of Old Shoulder Dislocation

A shoulder dislocation left unreduced for more than three weeks is considered an old dislocation. The joint cavity becomes filled with scar tissue, adhering to surrounding tissues, and the surrounding muscles contract. If accompanied by a fracture, callus formation or malunion may occur, all of which impede reduction of the humeral head.

Management of old shoulder dislocation: For cases where the dislocation is within three months, the patient is young and physically strong, the dislocated joint still retains some range of motion, and X-rays show no osteoporosis or intra- or extra-articular ossification, manual reduction may be attempted. Before reduction, traction through the olecranon of the ulna on the affected side may be performed for 1–2 weeks; if the dislocation duration is short and joint mobility impairment is mild, traction may be omitted. Reduction is performed under general anesthesia, preceded by shoulder tuina and gentle rocking movements to release adhesions, alleviate muscular rigidity, and facilitate reduction. The reduction procedure employs traction tuina or the foot-stomp method, with post-reduction management identical to that for fresh dislocations. It is crucial to avoid forceful manipulation to prevent fractures and neurovascular injuries in the axillary region. If manual reduction fails or the dislocation has persisted for over three months, surgical reduction may be considered for young and robust patients. If severe damage to the humeral head articular surface is observed, shoulder arthrodesis or artificial joint replacement should be considered. Postoperative mobility after shoulder joint reduction is often unsatisfactory; for elderly patients, surgical treatment is not advisable, and they should be encouraged to strengthen shoulder exercises.

4. Treatment of habitual anterior shoulder dislocation

Habitual anterior shoulder dislocation is commonly seen in young adults. The cause is generally attributed to injury sustained during the initial traumatic dislocation, which, despite reduction, did not receive proper and effective immobilization and rest. Due to inadequate healing of the torn or avulsed joint capsule, labral and glenoid rim injuries, as well as pathological changes such as flattening of the posterolateral depression fracture of the humeral head, the joint becomes lax. Subsequently, dislocation may recur with minimal force or during certain movements, such as abduction, external rotation, and extension of the upper limb. Diagnosis of habitual shoulder dislocation is relatively straightforward. In addition to standard anteroposterior radiographs of the shoulder, X-rays should also be taken with the arm internally rotated 60-70° to clearly demonstrate any posterior humeral head defects.

For habitual shoulder dislocation, surgical treatment is recommended if dislocations occur frequently. The goal is to reinforce the anterior joint capsule, limit excessive external rotation and abduction, and stabilize the joint to prevent recurrent dislocation. Several surgical techniques are available, with the most commonly used being the Putti-Platt procedure (subscapularis and capsular overlap repair) and the Magnuson procedure (lateral transfer of the subscapularis insertion).