Chapter 271: Shoulder and Humerus Injuries

STERNOCLAVICULAR SPRAINS AND DISLOCATIONS

ANATOMY

The sternoclavicular joint contains an intra-articular fibrocartilaginous disc and has the least amount of bony stability of any major joint because less than half of the medial end of the clavicle articulates with the upper sternum. However, the joint is remarkably stable, due to the strong surrounding ligaments. As a result, most injuries are simple sprains, while dislocations and fractures are uncommon.^1-4

The medial clavicular epiphysis is the last epiphysis of the body to appear radiographically (age 18 years old) and the last to close (age 22 to 25 years old). Because of this, an apparent sternoclavicular joint dislocation in children and young adults is typically a Salter-Harris type I or II fracture, with either anterior or posterior displacement of the clavicular metaphysis that requires orthopedic consultation and follow-up for optimal healing and remodeling.^1,5

CLINICAL FEATURES AND DIAGNOSIS

The major symptom of dislocation is severe pain, exacerbated by arm motion and lying supine. A posterior dislocation results from a direct blow or from an indirect force to the shoulder, causing the shoulder to roll forward at the time of impact. The shoulder may appear shortened and rolled forward. In posterior dislocations, the medial clavicle end is less visible and often not palpable, and the patient may have signs and symptoms of impingement of the superior mediastinal contents, such as stridor, dysphagia, and shortness of breath (Figure 271-1).^3,4 An anterior dislocation may result from a similar indirect force if the shoulder is rolled backward at the moment of impact. On examination, anterior dislocations have a prominent medial clavicle end that is visible and palpable anterior to the sternum, although swelling and tenderness may impede diagnosis.

Minor trauma may result in a sprain to the sternoclavicular joint with only pain and swelling localized to the joint. Sprains of the sternoclavicular joint are treated with ice, sling, and analgesics. In a nontrauma patient, pain at the sternoclavicular joint should raise suspicion for septic arthritis, especially in injection drug users. US can detect effusion and aid in joint aspiration.

Routine radiographs have a low sensitivity for the detection of dislocation, but an immediate chest radiograph is needed to exclude a pneumothorax, pneumomediastinum, and hemopneumothorax. Special views and comparison with the other clavicle may be helpful.¹ CT is the imaging procedure of choice (Figure 271-2) and is recommended in any posterior dislocation with concern for injury to the mediastinal structures. IV contrast may be administered to further delineate injury. Point-of-care US can identify sternoclavicular joint effusions and may been used to rapidly diagnose ...