Fractures

The most commonly injured bone in the shoulder girdle in adults is the proximal end of the humerus (114 per 100,000 population), followed by the clavicle (30 to 50 per 100,000 population), with middle third fractures making up the majority (80%), followed by the lateral third (15%) and middle third (5%). The next most common fractures in adults involve the humeral shaft. Scapular fractures are uncommon (10 to 12 per 100,000 population) and result from significant force (e.g., high speed motor vehicle crashes, falls from heights). Supracondylar distal humeral fractures rarely occur after the age of 15 years.

Dislocations

The most common dislocations are glenohumeral (85% being anterior), followed by acromioclavicular, sternoclavicular, and the very rare dislocation of the entire shoulder girdle from the thorax.

Soft Tissue Injuries

The most common soft tissue injuries are the shoulder impingement syndromes, including subacromial tendinitis and bursitis with rotator cuff tears (95% are chronic and 5% acute), as well as tendinitis and rupture of the long head of the biceps tendon.

Sternoclavicular Joint Sprains and Dislocations

These injuries are graded as type I, a simple sprain of the joint; type II, subluxation of the joint, either anterior or posterior; and type III, complete dislocation of the joint. Dislocation usually results from a lateral force applied to the shoulder and an indirect force applied to either a rolled-back shoulder (anterior dislocation) or a rolled-in shoulder (posterior dislocation). Posterior dislocations are potentially life-threatening because the dislocated medial head of the clavicle may cause pneumothorax or injuries to the great vessels, esophagus, or trachea (all structures in the superior mediastinum).¹

The patient complains of severe pain in the affected sternoclavicular joint. In anterior dislocations, the protruding medial end of the clavicle is visible, easily palpable, and tender. In posterior dislocations, there is often a cavity where the medial end of the clavicle would normally lie, which is especially noticeable when compared with the uninjured side. Patients with posterior dislocations may also have signs and symptoms of pneumothorax, vascular occlusion, and esophageal or tracheal injury.² Routine radiographs may not be diagnostic, and computed tomography (CT) is usually required to make the diagnosis. This should always be performed with intravenous (IV) contrast media when a posterior sternoclavicular dislocation is suspected to rule out injuries to the superior mediastinal vascular structures³ (Fig. 87.3).

Fig. 87.3 Computed tomography scan of the right sternoclavicular joint revealing posterior dislocation of the right proximal aspect of the clavicle into the posterior mediastinum.

(Courtesy Donald Sauser, MD.)

Acromioclavicular Joint Dislocation or Separation

Acromioclavicular separations are generally caused by a fall onto the point of the shoulder or acromioclavicular joint with the arm adducted (thus the lay term shoulder pointer to describe this injury). It is caused less frequently by a fall onto the outstretched arm in extreme abduction, which drives the acromion below the clavicle. Acromioclavicular separations are classified as six types, although only the first three (I to III) are commonly seen. Types IV to VI are very uncommon and usually require surgical repair.¹ In type I acromioclavicular separations, the acromioclavicular ligaments are partially torn and the coracoclavicular ligaments are intact, which results in less than 50% superior dislocation or separation of the clavicle from the acromion (Fig. 87.4, A to C). In type II injuries, the acromioclavicular ligaments are completely torn and the coracoclavicular ligaments are stretched or partially torn, which results in at least 50% superior dislocation or separation of the clavicle from the acromion. In type III injuries, both the acromioclavicular and coracoclavicular ligaments are completely torn, with complete superior dislocation or separation of the clavicle from the acromion.

Fig. 87.4 A, First-degree acromioclavicular (AC) sprain. B, Second-degree AC sprain. C, Third-degree AC sprain.

The patient complains of severe pain in the acromioclavicular joint. Type I dislocations are characterized by tenderness and some swelling over the acromioclavicular joint, with little or no tenderness over the distal end of the clavicle and coracoid process. With type II dislocations, patients have tenderness and more swelling over the acromioclavicular joint and some tenderness over the coracoid process. In type III dislocations, the clavicle is obviously dislocated superiorly when the patient is sitting or standing, with less deformity noted when the patient is supine. Shoulder radiographs may miss an acromioclavicular separation if the radiograph is taken with the patient supine. Acromioclavicular views (a single radiograph that includes both acromioclavicular joints) should be taken with patients in the sitting or standing position and the arms unsupported. In type I injuries there is less than 50% cephalad dislocation of the clavicle on the acromion of the affected shoulder. Type II injuries are marked by greater than 50% cephalad displacement of the clavicle on the acromion on the affected side. In type III dislocations, complete dislocation is seen on sitting or standing films. Use of weight-bearing films (the patient holds weights with the affected arm) is of no benefit.⁴

Clavicle Fractures

The most common mechanism of injury is a medially directed blow to the shoulder, usually from a ground-level fall. Children frequently have a bowing deforming or a greenstick fracture, whereas in adults the fracture fragments are often significantly displaced. Clavicle fractures are divided into proximal third, middle third, and lateral third. Lateral third fractures are divided into types I, II, and III (Fig. 87.5). Type II lateral third fractures are relatively unstable because the coracoclavicular ligament has been disrupted.

Fig. 87.5 A-C, Three types of lateral third clavicle fractures.

Patients complain of severe pain at the site of the fracture. They may support the adducted arm on the injured side with the other hand. A deformity is usually obvious, and the fracture site is tender. The diagnosis is made by radiography of the injured clavicle. If a type II distal third clavicle fracture is suspected, both supine and upright films will reveal the degree of instability of the fracture.

Scapula Fractures

Scapular fractures are typically associated with high-energy force and are thus often associated with significant life-threatening injuries, especially injuries to the ipsilateral ribs, pleura, and lungs. Most scapular fractures are caused by a direct blow, although fractures of the glenoid and scapular neck may occur as a result of a fall on an outstretched arm.⁵

The patient complains of pain at the site of the fracture. Any movement of the ipsilateral arm will exacerbate the pain, especially with fractures of the glenoid. Fractures of the scapular spine are usually seen clearly on plain films. However, fractures of the neck and the glenoid may not be seen, and if suspected, a CT scan of the scapula should be obtained.

Glenohumeral Dislocations

Dislocations of the glenohumeral joint are divided into anterior, posterior, and inferior (luxatio erecta). Most glenohumeral dislocations are anterior and are caused by an indirect force such as abduction, extension, and external rotation; however, they are occasionally caused by a direct blow to the proximal end of the humerus.

Patients generally have severe pain in the glenohumeral joint and hold the affected arm in adduction and internal rotation. There is lack of the normal contour, with a depression where the humeral head would normally reside. Patients report extreme pain in the joint with any attempted movement of the arm. Anteroposterior (AP) and axillary or transthoracic lateral radiographic views should be obtained in all patients with suspected dislocations, even if the patient has a history of multiple dislocations, because occasionally an associated fracture of the proximal end of the humerus or a posterior dislocation will be present.^6,7 If displaced fractures of the glenoid or proximal end of the humerus are suggested on plain radiographs, CT scans of the shoulder should be obtained. Although the AP film usually shows the “light bulb” appearance of the humeral head, it is not always present (Fig. 87.6). Though rare, with luxatio the patient has the classic picture of holding the arm in marked adduction and over the head (Fig. 87.7). The radiograph reveals the humeral head to lie inferior to the glenoid and the humeral shaft adducted superiorly (Fig. 87.8).

Fig. 87.6 Anteroposterior shoulder radiograph of a patient with a posterior glenohumeral dislocation.

Fig. 87.7 Photograph of a patient with luxatio erecta.

(From Thomsen T, Setnick G, editors. Procedures consult—emergency medicine module.

Fig. 87.8 Radiograph of the shoulder of a patient with luxatio erecta.

(From Thomsen T, Setnick G, editors. Procedures consult—emergency medicine module.

Proximal Humerus Fractures

The two mechanisms that most commonly cause fractures of the proximal end of the humerus are (1) a direct blow to the lateral aspect of the upper part of the arm and (2) indirect forces generated by a fall on an outstretched arm. The position of the humeral shaft in relation to the proximal fragments depends on whether the fall is onto an abducted or adducted arm.

The Neer fracture classification is most commonly used and is based on the position of the articular segment, the greater and lesser tuberosities, and the humeral shaft. According to the Neer classification, a fracture is considered displaced if any major fracture fragment is displaced 1 cm or more or is angulated greater than 45 degrees.⁸ Fractures are classified as one-, two-, three-, or four-part fractures and are usually differentiated along the classic epiphyseal lines (anatomic neck, surgical neck, greater tuberosity, and lesser tuberosity) (Fig. 87.9).

Fig. 87.9 Neer classification of proximal humerus fractures.

The patient has severe pain in the proximal end of the humerus. An obvious deformity may be present, as well as swelling and extreme tenderness over the proximal end of the humerus. The trauma radiographic series recommended by Neer,⁸ as well as an AP internal rotation view and an axillary lateral view, provides the most complete diagnostic information. A CT scan of the shoulder may be necessary to better define the extent of injury.

Humeral Shaft Fractures

Humeral shaft fractures are almost always caused by a direct blow to the bone, and this mechanism usually results in a transverse fracture. Occasionally, a fall onto an outstretched hand or a severe twisting force brought about by supination or pronation or by twisting of the entire arm may result in spiral fractures.

Symptoms include pain and deformity at the fracture site. In addition, the fracture is usually very unstable. If the radial nerve is injured, the patient will not be able to extend the wrist or fingers and generally has decreased sensation on the dorsum of the hand. The diagnosis is based on radiographs of the humerus. As with all long-bone fractures, the joints above and below the fracture—in this case the shoulder and elbow—should also be radiographed.

Distal Humerus (Supracondylar) Fractures

Supracondylar fractures are classified as either flexion or extension fractures and occur almost exclusively in children, usually between the age of 4 and 10 years. More than 95% of these fractures are the extension type and occur when the child falls onto an outstretched arm with the elbow in full extension or hyperextension. In the flexion-type fracture, the child falls onto the arm with the elbow flexed.

The patient is generally seen holding the injured arm in extension with the unaffected hand. Swelling, as well as tenderness to palpation over the distal end of the humerus, is typical. An S-shaped deformity may be present if significant displacement of the fracture fragments has occurred. The patient resists any attempt to flex or extend the elbow. Elbow radiographs (AP and lateral views) should be obtained. The fracture will often be visible only on the lateral view unless fracture fragments are significantly displaced. Normally, the anterior humeral line should pass through the capitellum (Fig. 87.10, A and B). If the capitellum is anterior to the anterior humeral line, it is diagnostic of a flexion-type supracondylar fracture in a child. If the capitellum is posterior to the anterior humeral line, it is diagnostic of an extension-type supracondylar fracture. Based on radiographic findings, extension fractures are often classified into three types: type I has minimal or no displacement; type II is a displaced fracture with the posterior cortex intact; and type III is a completely displaced fracture, with both the anterior and posterior cortices disrupted.

Fig. 87.10 A, Normal anterior humeral line alignment. B, Supracondylar fractures.

(From Simon R, Koenigsknecht S. Emergency orthopaedics: the extremities. 2nd ed. Norwalk, Conn.: Appleton & Lange; 1987.)

Rotator Cuff Tendinitis/subacromial Bursitis, Rotator Cuff Tears, and Impingement Syndromes