Practice Essentials
The sternoclavicular (SC) joint is a saddle-shaped, synovial joint that provides the primary skeletal connection between the axial skeleton and the upper limb. Sternoclavicular joint (SCJ) dislocations may follow direct trauma to the anteromedial aspect of the clavicle that drives it backward and causes a posterior dislocation. [1, 2] Patients typically present with their head tilted toward the affected side and hold the affected arm across the trunk with the uninjured arm. More commonly, dislocations arise from an indirect force applied to the anterolateral or posterolateral shoulder that compresses the clavicle down toward the sternum. The direction the shoulder is driven determines the type of dislocation. [2, 3]
The affected shoulder usually appears shortened and thrust forward. Generally, edema and tenderness are present over the SCJ. Pain manifests with any range of motion testing that affects the SCJ and becomes more severe when a lateral compressive force is applied to the shoulders.
During a sporting event, an athlete lying on his or her back may be jumped on with the knee of the jumper landing directly on the medial end of the clavicle. A kick delivered to the front of the medial clavicle can also produce dislocation. In a "pile-on" in football or other sports, the shoulder off the ground may be rolled backward, causing an anterior dislocation, or rolled forward, causing a posterior dislocation. Direction of displacement is particularly important due to risk of injury to intrathoracic structures, which has the potential to result in fatal outcomes. [4]
Falls (eg, a person falling on an outstretched abducted arm, driving the shoulder medially) are also responsible. Dislocations of the sternoclavicular joint also may result from congenital, degenerative, and inflammatory processes.
Ligamentous laxity, more common in young girls, is associated with recurrent atraumatic anterior dislocations of the sternoclavicular joint. This tends to be a self-limited condition. In a study of 23 patients with atraumatic sternoclavicular dislocation, in which the clavicle subluxates earlier in abduction than in forward flexion, the average at diagnosis was 18.6 years. [5]
A freely moveable synovial joint links the upper extremity to the torso, with the sternoclavicular joint (SCJ) participating in all movements of the upper extremity. The SCJ is a saddle-type joint that provides free movement of the clavicle in nearly all planes. The ability to thrust the arm and shoulder forward requires sound function of the SCJ. Because only about 50% of the medial end of the clavicle articulates with the manubrium, the SCJ has little inherent stability. Most of the SCJ's strength and stability originates from the joint capsule and supporting ligaments. The capsule surrounding the joint is weakest inferiorly, while it is reinforced on the superior, anterior, and posterior aspects by the various ligaments, including the interclavicular, anterior and posterior sternoclavicular, and costoclavicular ligaments.
Classification
On the basis of severity of the injury, SCJ injuries can be classified into 3 types, as follows [2] :
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Type 1: sprain of SCJ without laxity or pain.
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Type 2: rupture of SCJ ligaments; costoclavicular ligaments stay intact.
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Type 3: rupture of SCJ and costoclavicular ligaments, resulting in dislocation of the joint.
SCJ instability can be classified according to direction (anterior, posterior, superior), cause (traumatic, atraumatic), and duration (acute, chronic). [2]
Diagnosis
Routine radiographs of the sternoclavicular joint are often difficult to interpret and may falsely appear normal. [6, 7, 8] A specialized view, known as the serendipity view and described by Rockwood, may reveal the medial clavicle position. [9] The serendipity view is a radiographic projection centered on the SCJ with 40° cranial angulation and should include the medial third of both clavicles. The medial ends of the clavicles are normally equidistant from the sternum and in the same horizontal plane; however, in posterior dislocation, the clavicle is projected caudally to the mean horizontal plane of the SCJ, and in anterior dislocation, it is projected cranially. [2]
CT scanning is an excellent technique to study problems of the sternoclavicular joint. [10] Request inclusion of both sternoclavicular joints and the medial half of both clavicles on the CT scan so that the injured side can be compared with the noninjured side.
In a study to assess digital tomography in SCJ pathology, of 102 patients who had digital tomography as their initial investigation, the most common diagnoses identified included osteoarthritis, fracture, and dislocation, and only 18 patients required further investigation by CT or MRI to make the diagnosis. [11]
Depending on the mechanism of injury (eg, motor vehicle crash) and the close proximity of the sternum and clavicle to the vital structures of the neck and chest, patients with sternoclavicular joint injuries may incur severe and life-threatening injuries. [12] Foremost, therefore, the ABCs should be addressed during prehospital care, with rapid transport to an appropriate trauma care facility if indicated. For patients with seemingly isolated SJI, immobilization of the affected upper extremity with a sling stabilizes the joint and minimizes pain.
Treatment
Patients with posterior SCJ dislocations frequently sustain associated potentially serious injuries that may take treatment precedence over the dislocation. Sprains of the SCJ require only symptomatic treatment (eg, immobilization with a sling, ice for 24-48 hr, analgesics, and anti-inflammatory medications). [12] (See Treatment.)
Reductions performed in the ED require stabilization of the affected shoulder with a soft figure-of-eight dressing, a commercial clavicular harness, or secure sling. Maintain immobilization for at least 4 weeks. [13, 14]
To ensure adequate healing of sprains, arrange for a follow-up visit to the appropriate physician after stabilization of the affected shoulder and analgesia.
For anterior/posterior dislocations, a follow-up visit is indicated to determine the need for further treatment (eg, elective reduction, internal fixation) and to evaluate subsequent functional capacity. Patients should restrict activity and follow up as instructed. Patients with posterior dislocations who are discharged home should return for medical care if they exhibit symptoms of mediastinal injury.
Consider consultation of an orthopedic surgeon for reduction and possible operative stabilization of SCJ dislocations. Suspicion of additional injuries secondary to a posterior SCJ dislocation may necessitate consultation by additional specialties, such as a vascular or thoracic surgeon.
Most patients have adequate upper extremity function following sternoclavicular joint injuries. The prognosis depends on such factors as extent and type of joint damage, activity level, and concomitant medical illness of the patient.
Pathophysiology
Usually only through the application of significant force do the ligaments supporting the SCJ become completely disrupted, enabling dislocation of the joint. Whether the SCJ subluxes or dislocates depends on the extent of the damage to the supporting ligaments and capsule. Sternoclavicular joint injuries (SJIs) are graded into 3 types.
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A first-degree injury, or simple sprain, constitutes an incomplete tear or stretching of the sternoclavicular and costoclavicular ligaments. Discomfort is mild, and no instability is present. This is the most common type of SJI.
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With a second-degree injury, the clavicle undergoes an anterior or posterior subluxation from its manubrial attachment, signifying a complete breach of the sternoclavicular ligament but at most, only a partial tear of the costoclavicular ligament.
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With a third-degree injury, complete rupture of the sternoclavicular and costoclavicular ligaments permits the clavicle to completely dislocate from the manubrium.
A significant direct or indirect force to the shoulder region can cause a traumatic dislocation of the SCJ. [15] Anterior dislocations of the SCJ are much more common (by a 20:1 ratio), usually resulting from an indirect mechanism such as a blow to the anterior shoulder that rotates the shoulder backward and transmits the stress to the joint. [16] Traumatic contact driving the shoulder forward can cause posterior dislocations of the SCJ, as can direct impact to the superior sternal or medial clavicular surfaces.
Epidemiology
The ligaments and capsule of the SCJ contribute enough stability to make this one of the least dislocated joints in the body. Posterior dislocations are considerably less common than anterior dislocations. However, the proportion of reported mediastinal complications seems to have risen. This may be due to either reporting bias or due to detection bias with the increased use of CT scanning and its increased sensitivity.
Mortality/Morbidity
Mortality and significant morbidity occur infrequently with anterior dislocations of the SCJ. [17, 18, 19, 20] Problems are usually related to issues of physical appearance as well as pain and functional limitations for persons with an active lifestyle.
However, a posterior SCJ dislocation (PSCD) has the potential for severe and even life-threatening complications. Neurovascular complications occur in up to 30% of patients with PSCD, with a mortality between 3 and 4%. [21, 22] Case reports of such complications have included the following:
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Lung injury (eg, hemothroax, pneumothorax)
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Tracheal injury
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Vascular injury, such as compression, laceration, fistula formation, thrombosis, and pseudoaneurysm formation of the adjacent blood vessels (including the aorta, superior vena cava, subclavian artery or vein, brachiocephalic artery or vein, mammary artery, and jugular vein)
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Nerve injury (including cerebrovascular accident, phrenic nerve, and brachial plexus injury)
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Esophageal injury
These and other complications can cause significant disability, including even cerebrovascular accident and death. [17, 18, 23]
Overall incidence of sternoclavicular joint injury is higher in males than in females, probably because of the activities (eg, motor vehicle crash, contact sports) associated with the injury. However, recurrent atraumatic anterior subluxation of the SCJ (usually associated with overall joint laxity), though rare, occurs more frequently in young girls.
In patients younger than age 25 years, a true sternoclavicular separation may not occur. A physeal disruption causing clavicular displacement may present with similar signs and symptoms [24] .
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This 80-year-old woman presented 1 week after a fall because of persistent pain and discoloration in the anterior part of her chest. Certain movements of her right arm were especially painful though not incapacitating. Note the extensive ecchymosis of the anterior part of her thorax and the swelling of the right upper parasternal/lower anterior neck area. The right sternoclavicular joint area was tender and edematous to palpation.
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Superior mediastinal contents may be threatened in posterior dislocations of the sternoclavicular joint.
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CT scan of a left sternoclavicular dislocation demonstrates anterior and superior displacement of the clavicle from its normal articulation with the manubrium. The right sternoclavicular joint is normal.
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CT scan of a left sternoclavicular dislocation demonstrates anterior and superior displacement of the clavicle from its normal articulation with the manubrium. The right sternoclavicular joint is normal.
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CT scan of a left sternoclavicular dislocation demonstrates anterior and superior displacement of the clavicle from its normal articulation with the manubrium. The right sternoclavicular joint is normal.
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The right sternoclavicular joint appears edematous on lateral inspection. Palpation confirms the apparent anterior dislocation.
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Comparison of the normal left sternoclavicular joint emphasizes the abnormalities.
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The patient refused further workup and treatment beyond a temporary sling, stating that the injury had not significantly affected her lifestyle. She was discharged home in the company of her daughter with over-the-counter analgesics.
