Mastering Sternoclavicular Dislocation Acute Repair & Reconstruction

Comprehensive Introduction and Patho-Epidemiology

Sternoclavicular (SC) joint dislocation represents one of the rarest yet most formidable clinical entities encountered in orthopedic traumatology. Accounting for approximately 3% of all injuries to the shoulder girdle, as classically delineated in the foundational series of 1,603 shoulder injuries by Cave et al., the SC joint is infrequently disrupted due to the immense strength of its surrounding ligamentous envelope. Despite its rarity, the modern shoulder surgeon or traumatologist will inevitably confront this pathology, particularly within practices that manage a high volume of high-energy polytrauma. The true epidemiological ratio of anterior to posterior dislocations remains a subject of academic debate, largely due to the disproportionate clinical and literary focus on the more morbid posterior variant. Historical estimates have varied significantly; Nettles and Linscheid reported a staggering 20:1 ratio of anterior to posterior dislocations in their cohort of 60 patients, whereas Rockwood’s extensive series of 185 traumatic sternoclavicular injuries demonstrated a narrower ratio of approximately 3:1.

The pathogenesis of sternoclavicular dislocations is almost exclusively predicated on high-energy traumatic forces. Motor vehicle collisions, equestrian accidents, and high-impact contact sports (such as rugby and American football) are the predominant etiologies. The mechanism of injury is typically an indirect force applied to the lateral aspect of the shoulder girdle. Biomechanically, if the shoulder is subjected to a massive compressive force and simultaneously rolled forward (anteriorly), the medial clavicle is levered backward, resulting in a posterior dislocation. Conversely, if the lateral shoulder is compressed and rolled backward (posteriorly), the medial clavicle is levered forward, producing an anterior dislocation. Less commonly, a direct blow to the anteromedial aspect of the clavicle can drive the bone posteriorly into the mediastinum, creating a life-threatening surgical emergency.

Understanding the natural history of these injuries is paramount for appropriate clinical decision-making. Mild to moderate sprains, where the joint remains stable or only slightly subluxated, typically resolve with conservative management, though they may remain persistently symptomatic for weeks. Acute anterior dislocations, while visually striking due to the prominent medial clavicular deformity, are notoriously unstable following closed reduction. However, the orthopedic consensus heavily favors nonoperative management for anterior dislocations, as the residual deformity is generally well-tolerated and the inherent risks of operative fixation—particularly hardware migration—far outweigh the aesthetic concerns. In stark contrast, posterior dislocations carry a profoundly different natural history. The retrosternal displacement of the medial clavicle places the vital structures of the mediastinum at immediate risk. Unreduced posterior dislocations are associated with devastating complications, including thoracic outlet syndrome, acute vascular compromise, pneumothorax, and delayed erosion into the great vessels or trachea.

Furthermore, a critical demographic nuance must be acknowledged: the medial clavicular epiphysis is the last ossification center in the human body to appear and the last to fuse. Ossification typically commences between the 18th and 20th years of life, with complete physeal fusion delayed until 23 to 25 years of age. Consequently, a vast majority of presumed "sternoclavicular dislocations" in adolescents and young adults are, in anatomical reality, Salter-Harris physeal fractures. This distinction is not merely semantic; physeal injuries possess a robust osteogenic potential due to the intact periosteal sleeve, allowing for remarkable remodeling and often obviating the need for aggressive surgical intervention even in the presence of significant initial displacement.

Detailed Surgical Anatomy and Biomechanics

The sternoclavicular joint is a diarthrodial, saddle-type articulation that boasts the least amount of bony congruence and inherent osseous stability of any major joint in the human body. The articular surface of the medial clavicle is distinctly bulbous, presenting a concave profile in the anteroposterior plane and a convex profile vertically. This articulates with the relatively shallow, curved clavicular notch of the manubrium sterni. In approximately 2.5% of the population, a small articular facet on the inferior aspect of the medial clavicle also articulates with the superior aspect of the first rib. Because less than half of the medial clavicle actually articulates with the sternum at any given time, the structural integrity of the SC joint is almost entirely dependent upon its complex, multidirectional ligamentous restraints.

The ligamentous anatomy is divided into four primary structures: the intra-articular disc ligament, the costoclavicular (rhomboid) ligament, the interclavicular ligament, and the capsular ligaments. The intra-articular disc ligament is a dense, fibrocartilaginous structure that arises from the synchondral junction of the first rib and sternum, passing superiorly through the SC joint to attach onto the superior and posterior aspects of the medial clavicle. This disc effectively divides the joint into two separate synovial cavities and acts as a robust checkrein against medial displacement of the proximal clavicle. The costoclavicular ligament, often referred to as the rhomboid ligament, anchors the inferior surface of the medial clavicle (at the rhomboid fossa) to the superior surface of the first rib. Averaging 1.3 cm in length and 1.9 cm in width, it is a formidable secondary stabilizer, though biomechanical sectioning studies have demonstrated that it is relatively unimportant for gross stability provided the capsular ligaments remain fully intact.

The capsular ligaments themselves represent focal thickenings of the joint capsule and are unequivocally the most critical stabilizers of the SC joint. The anterior fasciculus arises anteromedially on the sternum, courses superiorly and laterally, and resists both lateral displacement and upward rotation of the clavicle. However, it is the posterior fasciculus that is biomechanically paramount. Shorter and thicker than its anterior counterpart, the posterior capsule arises laterally, runs medially and superiorly, and is the primary restraint against both anterior and posterior translation, as well as resisting medial displacement and excessive downward rotation. The interclavicular ligament connects the superomedial aspects of both clavicles across the jugular notch, integrating with the capsular ligaments and upper sternum. Functioning similarly to the wishbone of an avian skeleton, it provides "shoulder poise," actively holding the lateral aspect of the shoulder girdle aloft against the constant pull of gravity.

From an applied surgical perspective, the anatomy immediately posterior to the SC joint is fraught with peril. A thin "curtain" of strap muscles—comprising the sternohyoid, sternothyroid, and scaleni—is the only physical barrier separating the posterior joint capsule from the superior mediastinum. Directly behind this muscular curtain lie the innominate artery, the innominate vein, the internal jugular vein, the vagus and phrenic nerves, the trachea, and the esophagus. Furthermore, the anterior jugular vein, which can be up to 1.5 cm in diameter and lacks competent valves, traverses the operative field between the clavicle and the strap muscles. Inadvertent laceration of this vessel during surgical exposure results in torrential hemorrhage. The intimate proximity of the aortic arch, superior vena cava, and right pulmonary artery absolutely contraindicates the use of unthreaded pins or K-wires directed from the clavicle into the sternum, as catastrophic and fatal hardware migration into these structures is a well-documented historical tragedy.

Exhaustive Indications and Contraindications

The decision-making algorithm for surgical intervention in sternoclavicular joint pathology requires a meticulous balancing of the patient's symptoms, the direction of instability, and the inherent risks of operating in the anatomical "danger zone" of the superior mediastinum. Nonoperative management remains the gold standard for mild to moderate sprains, atraumatic spontaneous subluxations (often seen in ligamentously lax young females), and the vast majority of acute anterior dislocations. Attempted closed reduction of an anterior dislocation is reasonable, but the surgeon must be prepared to accept the resultant deformity when the joint inevitably redislocates, as the functional outcomes of unreduced anterior dislocations are paradoxically excellent. Operative intervention for anterior dislocations is strictly reserved for chronic, exquisitely painful instability that has failed extensive conservative management, or in the exceedingly rare instance where the medial clavicle threatens the integrity of the overlying skin.

Conversely, acute posterior dislocations represent a potential orthopedic and vascular emergency. The primary indication for immediate intervention is a posterior dislocation associated with any signs of mediastinal compression, such as dyspnea, dysphagia, dysphonia (hoarseness), or venous congestion of the ipsilateral upper extremity. An urgent closed reduction under general anesthesia should be attempted in the operating room, ideally with a cardiothoracic surgeon readily available. If closed reduction fails, or if the joint remains grossly unstable and falls back into the mediastinum, open reduction and ligamentous reconstruction are absolutely indicated. Chronic posterior dislocations that present late with insidious mediastinal impingement also necessitate operative intervention, typically in the form of a medial clavicle resection combined with costoclavicular ligament reconstruction, as primary capsular repair is no longer viable.

Physeal injuries in the adolescent population present a unique set of indications. Because the medial clavicular physis possesses massive remodeling potential, most displaced physeal fractures can be managed nonoperatively. Anteriorly displaced physeal fractures that cannot be reduced closed should be left alone, as the periosteal tube will generate new bone and remodel the deformity over time. Posteriorly displaced physeal fractures should undergo an attempt at closed reduction. If irreducible but completely asymptomatic (lacking mediastinal compression), they may also be observed. However, severely displaced posterior physeal fractures that cause mechanical symptoms or severe deformity warrant open reduction and heavy suture fixation through the medial shaft and epiphysis.

Pre-Operative Planning, Templating, and Patient Positioning

Thorough pre-operative planning is the cornerstone of safe and effective sternoclavicular joint surgery. The clinical evaluation must begin with a high index of suspicion for concomitant life-threatening injuries, given the high-energy mechanisms typically responsible for these dislocations. The physical examination must explicitly document the presence or absence of hoarseness, difficulty swallowing, shortness of breath, and venous engorgement of the neck or upper extremity, as these are cardinal signs of retrosternal compression. Palpation of the joint may reveal an obvious anterior prominence or a palpable void indicating posterior displacement, though severe localized swelling can frequently mask a posterior dislocation, making it appear as anterior fullness.

Radiographic evaluation historically relied upon specialized plain films, most notably the "Serendipity view." This 40-to-45-degree cephalic tilt view is obtained with the patient supine, the x-ray tube centered directly on the manubrium, and a large non-grid cassette placed under the upper shoulders and neck. This projection throws the medial clavicles upward, allowing for side-to-side comparison; an anteriorly dislocated clavicle will project superior to the normal side, while a posteriorly dislocated clavicle will project inferiorly. While historically significant, plain radiography and conventional tomography have been entirely superseded by computed tomography (CT).

A high-resolution CT scan is the unequivocal gold standard and an absolute pre-operative requirement for any suspected SC joint dislocation. The scan must encompass both sternoclavicular joints and the medial halves of both clavicles to allow for precise contralateral comparison. CT imaging definitively differentiates true dislocations from medial physeal fractures and provides exact three-dimensional spatial orientation of the displaced clavicle relative to the mediastinal structures. If the patient exhibits any signs of vascular compromise, or if the posterior displacement is severe, a CT angiogram (intravenous contrast) is mandatory to delineate the proximity of the medial clavicle to the innominate artery, innominate vein, and superior vena cava.

Patient positioning in the operating room must facilitate both adequate surgical exposure and rapid access for a sternotomy should catastrophic vascular injury occur. The patient is placed in the supine position on a radiolucent table. A rolled towel or small bump is placed vertically between the scapulae to allow the shoulders to fall posteriorly, which aids in reducing anterior dislocations and provides better access to the anterior chest wall. The head is slightly extended and rotated away from the operative side. A reverse Trendelenburg tilt of 15 to 20 degrees is often utilized to decrease venous engorgement in the head and neck. Both arms must be prepped and draped free to allow for intraoperative manipulation of the shoulder girdle, which is critical for achieving and maintaining reduction during fixation.

Step-by-Step Surgical Approach and Fixation Technique

The surgical repair and reconstruction of the sternoclavicular joint demand meticulous dissection and profound respect for the underlying anatomy. The procedure should ideally be performed with a cardiothoracic surgeon either scrubbed or immediately available on standby. The approach begins with a curvilinear or T-shaped incision centered over the medial clavicle and extending down over the manubrium. The subcutaneous tissues are divided, and meticulous hemostasis is achieved. The surgeon must immediately identify and protect the anterior jugular vein, which courses vertically in this region; if it cannot be safely retracted, it should be formally ligated and divided to prevent torrential bleeding.

The deltotrapezial fascia is incised in line with the clavicle. In the setting of a true dislocation, the capsular ligaments will be completely avulsed, often exposing the articular surface. In the setting of a physeal fracture, the periosteal sleeve will be split, and the metaphyseal bone will be protruding while the epiphysis remains attached to the sternum. Subperiosteal dissection is carried out carefully. A malleable retractor or a broad periosteal elevator must be placed posterior to the medial clavicle and manubrium at all times during drilling or passing of instruments to physically shield the pleura and great vessels from iatrogenic injury.

Reduction of a posterior dislocation is achieved by grasping the medial clavicle with a robust towel clip or bone tenaculum and applying lateral and anterior traction, while an assistant applies lateral traction to the abducted arm. Once reduced, the joint is evaluated for stability. If primary repair of the capsular ligaments is impossible due to tissue maceration, a robust biological reconstruction is required. The gold standard for acute instability that cannot be primarily repaired, or for chronic instability, is the figure-of-eight reconstruction utilizing a semitendinosus autograft or allograft, as popularized by Spencer and Kuhn.

To perform the figure-of-eight reconstruction, paired drill holes are created in both the medial clavicle and the manubrium. Using a 3.2 mm or 4.0 mm drill bit, two holes are placed in the anterior cortex of the manubrium, exiting superiorly into the clavicular notch. Similarly, two holes are drilled in the medial clavicle, from anterior to superior/inferior. It is absolutely critical that the posterior cortices of the sternum and clavicle are NOT breached by the drill, to avoid plunging into the mediastinum. The graft is then meticulously passed through these osseous tunnels in a figure-of-eight configuration.

The graft is tensioned while the clavicle is held in its anatomic, reduced position. The limbs of the graft are then sutured to themselves and to the remaining native capsular tissue using heavy non-absorbable sutures. This construct provides excellent multiplanar stability, recreating the vital checkrein effect of the anterior and posterior capsular ligaments. In cases of chronic posterior dislocation where the articular surface is severely degenerated, a medial clavicle resection (excision of the medial 1 to 1.5 cm of the clavicle) is performed. However, this must be accompanied by a reconstruction of the costoclavicular ligament to prevent the remaining clavicle from migrating superiorly and causing intractable pain.

For physeal fractures that require operative intervention, heavy non-absorbable transosseous sutures are utilized. Drill holes are placed through the metaphyseal bone, and the sutures are passed through the retained epiphysis and strong posterior capsular tissues. The use of any smooth or threaded Kirschner wires, Steinmann pins, or other rigid intramedullary devices across the sternoclavicular joint is universally condemned due to the catastrophic risk of hardware migration.

Complications, Incidence Rates, and Salvage Management

The complication profile of sternoclavicular joint dislocations and their surgical management is uniquely severe among orthopedic pathologies. Complications can arise from the injury itself, from delayed diagnosis, or from surgical misadventure. The most feared complication of an unreduced posterior dislocation is delayed erosion of the medial clavicle into the great vessels, trachea, or esophagus, which can lead to fatal hemorrhage or mediastinitis. Acute vascular compromise, thoracic outlet syndrome, and pneumothorax are also well-documented sequelae of posterior displacement.

Surgically, the historical use of Kirschner wires and Steinmann pins for SC joint stabilization resulted in one of the most infamous complication profiles in modern orthopedics. Due to the immense multiplanar forces across the SC joint during normal respiration and upper extremity movement, rigid metal pins inevitably fatigue, break, and migrate. Literature is replete with case reports of pins migrating into the aorta, pulmonary artery, heart chambers, and spinal canal, frequently resulting in patient death. Consequently, the use of pins across this joint is considered a definitive violation of the standard of care.

Even with modern biological reconstructions, complications exist. Recurrent instability or subluxation occurs in approximately 5% to 10% of reconstructed joints, often due to premature return to activity or graft attenuation. Infection, particularly deep space infection extending into the mediastinum, is a rare but devastating complication requiring aggressive debridement, hardware/graft removal, and prolonged intravenous antibiotics. Iatrogenic neurovascular injury during exposure or drilling is mitigated by the strict adherence to the use of posterior malleable retractors.

Salvage management for a failed primary reconstruction, or for severe post-traumatic arthrosis, typically involves a medial clavicle excision. It is imperative that no more than 1.5 cm of the medial clavicle is resected to preserve the insertion of the costoclavicular ligament. If the costoclavicular ligament is incompetent or inadvertently resected, the remaining clavicle will become grossly unstable, requiring a complex secondary reconstruction utilizing a semitendinosus graft to tether the clavicular stump to the first rib.

Phased Post-Operative Rehabilitation Protocols

The post-operative rehabilitation following a sternoclavicular joint reconstruction is deliberately conservative, reflecting the massive biomechanical forces transmitted across the joint even during seemingly benign activities. The clavicle rotates upwards of 50 degrees along its long axis during full shoulder elevation, placing immense torsional strain on any healing graft or capsular repair. Therefore, strict adherence to a phased rehabilitation protocol is critical for a successful outcome.

Phase I: Maximum Protection (Weeks 0 to 6)
Immediately following surgery, the patient is placed in a custom orthosis or a rigid sling with a swath. The primary goal of this phase is the absolute protection of the biological reconstruction to allow for initial soft tissue healing and graft incorporation. Absolute immobilization of the shoulder girdle is maintained. Active and passive range of motion of the elbow, wrist, and hand are encouraged to prevent distal stiffness. Pendulum exercises are strictly prohibited, as they generate significant traction and rotational forces across the SC joint.

Phase II: Controlled Mobilization (Weeks 6 to 12)
At the six-week mark, clinical and radiographic evaluations are performed. If healing is progressing satisfactorily, the sling is gradually weaned. Passive range of motion (PROM) of the shoulder is initiated, strictly limiting forward flexion and abduction to 90 degrees to minimize clavicular rotation. Scapular retraction and protraction exercises are begun in a protected range. By week 8, active-assisted range of motion (AAROM) is introduced, progressing to full active range of motion (AROM) by week 10 to 12. Isometric strengthening of the deltoid and rotator cuff may commence late in this phase, provided it does not provoke pain at the SC joint.

Phase III: Advanced Strengthening and Return to Function (Weeks 12 to 24+)
Beyond 12 weeks, the focus shifts to restoring full dynamic stability of the shoulder girdle. Progressive resistive exercises are introduced for the rotator cuff, deltoid, and periscapular musculature