STERNOCLAVICULAR SPRAINS AND DISLOCATIONS
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, it is remarkably stable, due to the strong surrounding ligaments, and as a result, most injuries are simple sprains, while dislocations and fractures are uncommon.1,2,3
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). 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.1,4
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. An anterior dislocation may result from a similar indirect force if the shoulder is rolled backward at the moment of impact.
The major symptom is severe pain, exacerbated by arm motion and lying supine. The shoulder may appear shortened and rolled forward. 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. 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 Minor trauma, on the other hand, may result in a sprain to the sternoclavicular joint with only pain and swelling localized to the joint.
Posterior sternoclavicular joint dislocation impinging on the mediastinal structures.
Routine radiographs have a low sensitivity for the detection of dislocation, but immediate chest x-ray 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. US can identify sternoclavicular joint effusions.
CT scan of right posterior sternoclavicular dislocation. Arrow indicates disrupted sternoclavicular joint with posterior displacement of clavicle and compression of adjacent lung.