The clavicle forms from two primary centers of ossification that fuse in utero, making the clavicle among the first long bones to become radiographically visible.1,2 The medial claviclar epiphysis, however, does not ossify until approximately 18 to 20 years of age; the medial clavicular physis does not close until 22 to 25 years of age. Awareness of these anatomic points is important in the evaluation and treatment of SCJ injuries, as many radiographic “dislocations” may indeed represent physeal fractures of the medial clavicle, although the medial epiphysis is not yet radiographically apparent. In addition, the medial physis contributes to approximately 80% of the longitudinal growth of the clavicle. On account of the proximity of the SCJ to the medial physis, there may be remodeling potential of bony deformities in young patients with remaining skeletal growth.
The medial clavicle is surrounded by a number of anatomic structures that influence treatment decisions and surgical approaches. The sternocleidomastoid, pectoralis major, and sternohyoid muscles all have their origins or attachments in the medial clavicle. More important, however, is the close proximity of the SCJ to the mediastinal structures, including the trachea, esophagus, brachiocephalic veins, aorta, common carotid arteries, and brachial plexus. Concern regarding acute or chronic compromise to these structures in part drives orthopaedic decision making.3
The SCJ is a true diarthrodial joint between the medial clavicle and clavicular notch of the sternum.2 The joint is saddle-shaped; however, the medial head is concave in the anterior-posterior dimension and convex in the superior-inferior dimension. Furthermore, less than 50% of the bulbous clavicular head articulates with the clavicular notch of the sternum, resulting in little bony congruity. As Grant has pointed out in his anatomy writings, “The two (make) an ill fit.”1,4 On account of the lack of inherent bony restraint, the SCJ relies upon a number of ligamentous structures to provide both motion and stability. The intraarticular disk is a flat, circular fibrocartilaginous structure attached both to the superoposterior aspect of the clavicular articular surface and inferiorly to the costocartilaginous junction of the first rib. Unlike its counterpart in the acromioclavicular joint, the intraarticular disk is complete in most people. There are both anterior and posterior sternoclavicular joint ligaments, which are broad and reinforce the thickened anterior and posterior SCJ capsule. The interclavicular ligament connects the medial ends of both clavicles, running along the superior border of the sternal manubrium. Finally, the costoclavicular ligament arises from the inferior aspect of the medial clavicle and attaches to the superior costal cartilage of the adjacent rib.
Biomechanical studies have documented significant motion in the SCJ with shoulder activities.5 Indeed, the SCJ contributes to 35 degrees of forward flexion, 35 degrees of flexion and extension, and 45 degrees of rotation around its longitudinal axis. Most of SCJ motion occurs between the articular disk and the clavicle. Earlier cadaveric studies have shown that the posterior capsule and posterior SCJ ligaments provide the greatest restraint to anterior translation of the clavicle, whereas the posterior capsule alone confers restraint to posterior translation.6,7 The interclavicular and costoclavicular ligaments provide relatively little stability with SCJ motion.
Sternoclavicular joint fracture-dislocations are uncommon injuries, representing less than 5% of shoulder girdle injuries.1,8 Usually arising from high-energy mechanisms of injury (eg, falls from a height, motor vehicle collisions, sports-related injuries), both direct and indirect trauma to the ipsilateral shoulder may result in SCJ injuries. Obtaining a history of earlier trauma is critical, as atraumatic cases of SCJ instability do occur—particularly in children and adolescents—and the natural history and results of treatment are quite different than in traumatic cases.5,9 Displacement of the medial clavicle can either be anterior, typically resulting from direct lateral blow to the shoulder with the shoulder extended; or, posterior, usually resulting from indirect forces imparted to the shoulder girdle with the shoulder adducted and flexed or with direct posterior blow to the medial clavicle.
Varying clinical presentations may be seen depending on the direction of clavicular displacement. With anterior displacement, the patient will often have pain localized to the SCJ, tenderness, ecchymosis, and an obvious bony prominence of the clavicular head. Ranging the shoulder causes pain and/or sensation of instability. Typically, there is no associated neurovascular compromise. Conversely, physical examination findings in patients with posterior SCJ injuries may be subtle. Although swelling and tenderness may be seen, often there is no obvious deformity. Posterior displacement increases the risk of mediastinal compression, and some patients may have dyspnea, dysphagia, or hoarseness of voice.10 In rare situations, signs of venous congestion, arterial insufficiency, or brachial plexopathy may be seen. A high index of suspicion is critical for accurate diagnosis and timely intervention.
While important for establishing the diagnosis of an SCJ injury, radiographic evaluation can be difficult, owing to the anatomy of the SCJ and overlying or adjacent skeletal structures. An anteroposterior chest radiograph may show asymmetry of clavicular length and abnormalities in the SCJ articulation, though these findings may be subtle. Dedicated radiographs of the clavicle are centered on the clavicular diaphysis and often lack the detail needed to make the diagnosis. For this reason, a number of dedicated views have been proposed to image the SCJ. Heinig11 has proposed earlier a tangential radiograph of the SCJ, taken with the patient in a supine position and the cassette placed behind the opposite shoulder. The beam is angled in the coronal plane, parallel to the longitudinal axis of the opposite clavicle, providing a profile of the affected SCJ. Hobbs12 has proposed a 90-degree cephalocaudal lateral, taken with the patient seated and flexed over a table. The cassette is placed on the table, against the chest wall, and the beam is directed through the cervical spine. Finally, Rockwood1 has reported on the use of the “serendipity view,” so-called because of the fact that its utility was discovered quite by accident. With the cassette placed behind the chest, the radiographic beam is angled 40 degrees cephalic centered on the sternum, allowing for the visualization of both SCJs (Fig. 1). In cases of anterior dislocation, the affected clavicular head will appear superiorly displaced compared with the unaffected side. Conversely, with posterior displacement, the medial clavicle will appear inferior.
Given the difficulties in plain radiography in imaging the SCJ, 3-dimensional imaging with the use of computed tomography has increasingly become the standard of care for radiographic diagnosis (Fig. 2). With improved resolution and imaging techniques, the distinction between physeal fractures and true joint dislocations may be made. Furthermore, simultaneous assessment of compression or injury to the adjacent soft tissue structures (eg, esophagus, trachea, brachiocephalic vessels) may be made.
In general, a number of principles guide the treatment of SCJ fracture-dislocations. First, the acuity or chronicity of an injury must be considered, as nonoperative or surgical treatment options are influenced by the time from initial injury. Second, the direction of displacement must be taken into consideration. Although anterior injuries may cause little pain or functional compromise, posteriorly displaced injuries may result in compression of the adjacent mediastinal structures. Third, the severity of symptoms, if any, must be noted to weigh the risks and benefits of intervention. Finally, patient demands play an important role in the decision-making process, particularly in laborers or overhead athletes.
Unfortunately, there is a paucity of information regarding the natural history of untreated SCJ injuries. For this reason, treatment recommendations and results of surgical intervention have not been carefully compared with the natural history of the condition. As a result, symptomatic relief and avoidance of acute or late complications remain the factors driving treatment recommendations.
In general, treatment options may be divided according to acuity and direction of displacement. There is tremendous controversy regarding the optimal treatment of acute anterior SCJ fracture-dislocations. Symptomatic management alone with sling immobilization followed by gradual return to activities has been advocated with the expectation of return of shoulder motion and strength.13 Patients should be counseled about the likelihood of a persistent bony prominence in the region of the clavicular head. In young patients with physeal fractures, remodeling of bony deformity may be seen with continued skeletal growth. Others have recommended closed reduction under conscious sedation or general anesthesia. Reduction maneuvers involve scapular retraction and posteriorly directed pressure over the medial clavicle, followed by application of a figure-of-eight strap. While reduction may often be achieved, recurrent instability is commonplace. Surgical techniques of open reduction and ligament repair or reconstruction are not routinely used in acute anterior, traumatic cases. Again, closed reduction maneuvers or surgical reconstructions should be generally avoided in patients with atraumatic or voluntary anterior SCJ instability.
Treatment considerations are starkly different in acute posterior SCJ fracture-dislocations. Unrecognized or untreated acute posterior traumatic SCJ injuries may lead to a host of complications. Tracheal stenosis, esophageal compression, pneumothorax, great vessel compromise, brachial plexopathy, thoracic outlet syndrome, sepsis, and even death have been reported in these instances.1,10,14–17 Furthermore, many of these complications can be seen in initially asymptomatic patients.10 For these reasons, reduction of acute posterior SCJ fracture-dislocations is recommended. Closed reduction has been proposed by many as definitive, particularly given the remodeling potential of the medial clavicle and thus the ability to accept a nonanatomic reduction.1,18 Closed reduction is typically performed under general anesthesia through the manipulation of the shoulders with abduction traction, adduction traction, or scapular retraction. Furthermore, percutaneous techniques of controlling the medial clavicle (eg, towel clip or screw) during reduction maneuvers have been advocated. More recent information, however, suggests that while an initial reduction may be achieved, recurrent instability is very common, if not universal.10,19
For these reasons, formal open reduction and suture fixation, with or without ligament repair or reconstruction, are advocated for acute posterior SCJ injuries (Fig. 3). Under general anesthesia and with appropriate general surgery or thoracic surgery back-up, patients are placed in the modified beach chair position. The affected upper limb and entire hemithorax is prepped and draped into the surgical field. A transverse incision centered on the SCJ is used, and the platsyma is divided in line with the surgical incision. Subperiosteal elevation is performed in a lateral-to-medial direction over the clavicle, allowing for both clavicular head and SCJ exposure. Diagnosis of a true joint dislocation versus physeal fracture is made on inspection of the zone of injury. Using gentle manipulation, the dislocation or fracture may be anatomically reduced. Awareness of the normal anatomy is critical, as the clavicular head is normally only partially seated into the clavicular notch of the manubrium. In cases of physeal fractures, drill holes are created into both the medial clavicular metaphysis and epiphysis, and heavy nonabsorbable sutures are passed in a figure-of-eight fashion to provide stability. In cases of SCJ dislocations, repair is similar to above with sutures from the anterior sternum into the epiphysis in a figure of eight positions. Smooth pins, screws, and Dacron tape are avoided to prevent complications of implant migration and osteolysis.20–22 Stability can be assessed intraoperatively with ranging the ipsilateral shoulder and upper limb. Postoperatively, patients are immobilized with sling-and-swathes for 4 to 6 weeks, followed by range-of-motion exercises. Contact sports are restricted for 3 to 6 months postoperatively. Using these techniques, SCJ stability and return to all activities may be anticipated.10,19 In a series of 13 patients treated with open reduction and suture fixation for acute posterior SCJ fracture-dislocations published earlier, all patients had restoration of SCJ stability and shoulder motion with full return to activities.10 Rockwood scores were perfect at mean 22-month follow-up, and no respiratory or vascular complications were seen.
Symptomatic chronic anterior instability is an uncommon problem. Patients will present with pain, “clicking” or “popping” with shoulder motion, and limitations with away from body or overhead activities. Treatment options in these situations are listed in Table 1. Joint reduction and ligament reconstruction, medial clavicular resection with ligament reconstruction or soft tissue interposition have been advocated (Fig. 4).23–27 The degree of articular cartilage damage determines ligament reconstruction alone versus medial clavicle resection and ligament reconstruction. Through a curvilinear incision centered on the SCJ, the joint capsule is incised. Most often in chronic conditions, the articular cartilage is thinned down to exposed bone. In these cases, approximately 1 cm of the prominent medial clavicle is resected obliquely, preserving the inferior ligamentous attachments. The intraarticular disk is identified, and while preserving its attachment to the sternum, the superior end is passed into the intramedullary canal of the clavicle and subsequently secured with sutures tied over drill holes. Stability is supplemented by sutures passed from the preserved costoclavicular ligament to the clavicle. Although some investigators have reported satisfactory results with resection arthroplasty following the principles listed above, others have reported suboptimal outcomes.24,25,28 Although indications continue to evolve, resection arthroplasty should be considered in the setting of bony changes and joint arthrosis, or if a ligament reconstruction cannot be performed.
A number of techniques have been proposed for more anatomic ligament reconstruction in cases of chronic anterior instability. Tenodesis using the subclavius tendon, intraarticular disk ligament reconstruction, and figure-of-eight tendon reconstructions using hamstring tendon autograft or allograft have all been advocated.7,29 Earlier biomechanical testing has confirmed that figure-of-eight tendon graft reconstructions provide the strongest restraints to anterior and posterior loading of the SCJ. Through a transverse skin incision and after exposure of the SCJ, drill holes may be created in the medial clavicle and manubrium while protecting the adjacent mediastinal structures. Semitendinosis, palmaris longus autograft, or allograft, is then passed through the drill holes in a figure-of-eight fashion, ensuring that the parallel fibers lie on the side of instability and the crossed tendon lies opposite the direction of instability. After satisfactory joint reduction, the graft limbs may be secured to one another with nonabsorbable sutures, avoiding overtightening of the reconstruction. Patients are sling-and-swathe immobilized for 4 to 6 weeks, followed by therapy for range-of-motion and strengthening. Contact sports are again avoided for 3 to 6 months postoperatively. In a published report of 15 patients treated with either resection arthroplasty or ligament reconstruction for chronic SCJ instability, greater than 85% achieved complete SCJ stability and the majority had complete resolution of pain.28 Functional outcomes as assessed by the American Shoulder and Elbow Surgeons score and Simple Shoulder Test were near normal, and no complications were reported. However, 13 of the 15 patients had mild persistent limitations with overhead athletic or recreational activities. Although no statistical differences were seen among the surgical techniques, a trend for better outcomes was noted with ligament reconstruction.
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Keywords:© 2010 Lippincott Williams & Wilkins, Inc.
sternoclavicular joint; fracture; dislocation