The sternoclavicular joint is the most frequently moved, nonaxial
joint of the body. It also 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. Therefore, joint stability
depends on the integrity of the surrounding ligaments, which give
the sternoclavicular joint surprising strength. As a result, the
majority of injuries to this area are simple sprains, and dislocations
and fractures are uncommon.
Forcing the shoulder forward suddenly, or applying a medially
directed force to the shoulder, may result in a sprain to the sternoclavicular
joint. Pain and swelling are localized to the joint, and treatment
is symptomatic with ice, sling, and analgesics. Differential diagnosis
in the nontrauma patient should include consideration of septic
arthritis, especially in injection drug users.
Dislocations are unusual and typically result from motor vehicle
crashes or sports injuries. If the shoulder is rolled forward at
the time of impact, a posterior dislocation may result from a direct
blow or from an indirect force to the shoulder. An anterior sternoclavicular
joint dislocation may result from the same indirect force if the
shoulder is rolled backward at the moment of impact. Posterior sternoclavicular
joint dislocations are much less common than anterior dislocations.
Patients with a sternoclavicular joint dislocation have severe
pain that is exacerbated by arm motion and lying supine. The shoulder
appears 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 (Figure 268-1), and the patient may have signs and
symptoms of impingement of the superior mediastinal contents.
Right posterior dislocation shows less visible right
medial clavicle. (Courtesy of John Rudzinski, MD.)
Routine radiographs may not be diagnostic. Special views and
comparison with the other clavicle may be helpful. CT is the imaging
procedure of choice (Figures 268-2 and 268-3), and IV contrast may be administered
to further delineate injury to adjacent mediastinal structures (Figure 268-4).
Clavicle radiograph shows asymmetry of the clavicles. Arrow
indicates asymmetric and inferiorly displaced medial clavicle. (Courtesy
of Rockford Health System.)
CT scan shows right posterior sternoclavicular dislocation.
Arrow indicates disrupted sternoclavicular joint with posterior
displacement of clavicle and compression of adjacent lung. (Courtesy
of Rockford Health System.)
Sternoclavicular joints. The relationship of the sternoclavicular
joint to adjacent structures.