STERNOCLAVICULAR JOINT INJURIES - ANTERIOR VS POSTERIOR
Posterior = Emergency | Airway Compromise | Mediastinal Structures at Risk
ROCKWOOD CLASSIFICATION
Critical Must-Knows
- Posterior dislocation is an EMERGENCY - can compress trachea, esophagus, great vessels
- SC joint is strongest joint in body - ligaments stronger than bone (physeal injury more common in under 25)
- Serendipity view (40 degree cephalic tilt) best plain film for diagnosis
- CT with contrast is gold standard - assess vascular compression
- Most dislocations are treated conservatively - recurrence well tolerated
Examiner's Pearls
- "Posterior dislocation: Dysphagia, dyspnea, venous congestion in arm/neck
- "Under 25 years - likely physeal injury (SH I/II), not true dislocation
- "Do NOT reduce posterior dislocation without thoracic surgery backup
- "Figure-of-8 reconstruction with hamstring/fascia lata for chronic instability
Critical SC Joint Exam Points
Posterior = Emergency
Posterior dislocation compresses mediastinum. Signs: dysphagia, dyspnea, venous engorgement, diminished pulses. Requires EMERGENT reduction. Have thoracic surgery on standby.
Physeal Injury
SC joint physis closes at age 25 - the last physis to close in the body. In patients under 25, most "dislocations" are actually Salter-Harris fractures through the medial clavicular physis.
Serendipity View
40 degree cephalic tilt X-ray. Anterior dislocation: affected clavicle projects ABOVE opposite side. Posterior: projects BELOW. CT is definitive but serendipity view is exam favorite.
Conservative Treatment
Most SC dislocations managed conservatively. Anterior: sling 6 weeks. Even with residual subluxation, function is usually excellent. Surgery reserved for persistent symptomatic instability.
Quick Decision Guide
| Injury | Findings | Urgency | Treatment |
|---|---|---|---|
| Type I Sprain | Joint tender, stable | Non-urgent | Sling, ice, NSAIDs |
| Anterior dislocation | Clavicle prominent anteriorly | Non-urgent | Closed reduction (optional), sling 6 weeks |
| Posterior (stable patient) | Clavicle depressed, venous distension | Urgent | CT angiogram, closed reduction in OR, thoracic standby |
| Posterior (compromised) | Stridor, hypoxia, arm ischemia | EMERGENCY | Immediate reduction, airway management, thoracic surgery |
| Chronic instability | Recurrent subluxation, pain with activity | Elective | Figure-of-8 reconstruction with graft |
ABCDSC Joint Dislocation Direction
Memory Hook:Anterior is common and cosmetic. Posterior is Perilous - watch for Problems!
STAVEPosterior SC Complications
Memory Hook:Posterior dislocation can STAVE in the mediastinum - structures are compressed!
CICASC Joint Ligaments
Memory Hook:CICA stabilizes the SC joint - Costoclavicular is king!
BUMPReduction Technique
Memory Hook:BUMP the shoulders back and pull the clavicle forward!
Overview and Epidemiology
Incidence and Demographics:
- 3% of all shoulder girdle injuries
- Peak incidence: young adults (15-25 years) - sports, MVA
- Second peak: elderly (falls)
- Male predominance (2:1)
- Anterior dislocations 25 times more common than posterior
Mechanism of Injury:
Anterior Dislocation
- Direct blow to anteromedial clavicle (rare)
- Indirect force with lateral shoulder compression and arm forward
- Medial clavicle displaces anteriorly (lifts up and forward)
Posterior Dislocation
- Direct blow to anterolateral clavicle
- Lateral shoulder compression with arm back and down
- Medial clavicle displaces posteriorly into mediastinum
- High-energy mechanism (MVA, rugby tackle)
Exam Pearl
Age determines pathology: In patients under 25, the medial clavicular physis (last to close at age 22-25) is weaker than ligaments - expect physeal fracture (Salter-Harris I or II) rather than true dislocation.
Anatomy and Biomechanics
Bony Anatomy:
- SC joint is the only true articulation between upper limb and axial skeleton
- Saddle-type synovial joint (incongruous surfaces)
- Medial clavicular epiphysis is the LAST physis to close (age 22-25)
- Intra-articular disc (fibrocartilage) divides joint and acts as shock absorber
Key Stabilizers:
SC Joint Stabilizers
| Structure | Function | Clinical Significance |
|---|---|---|
| Costoclavicular ligament | PRIMARY stabilizer - limits elevation, anterior/posterior translation | Short and very strong - origin of physis injury concept |
| Anterior capsular ligament | Strongest capsular component - resists posterior displacement | Must be disrupted for posterior dislocation |
| Posterior capsular ligament | Weaker - resists anterior displacement | Disrupted in anterior dislocation |
| Interclavicular ligament | Connects medial clavicles across sternum | Limits excessive clavicular depression |
| Articular disc | Intra-articular shock absorber | Can tear with subluxation |
Posterior Mediastinal Relations:
Danger Zone
The following critical structures lie only 1-2cm behind the SC joint:
- Trachea (directly posterior)
- Esophagus
- Subclavian artery and vein
- Carotid artery
- Internal jugular vein
- Innominate (brachiocephalic) artery and vein
- Brachial plexus
- Lung apex
Posterior dislocation can compress, lacerate, or thrombose any of these structures, making this a surgical emergency.
Biomechanics:
- The clavicle acts as a strut - transmits forces from upper limb to axial skeleton
- SC joint permits 35 degrees elevation, 35 degrees anterior/posterior movement, 50 degrees rotation
- True dislocation requires high energy to overcome very strong ligaments
Classification Systems
Most commonly used - based on direction and severity:
| Type | Description | Pathology | Treatment |
|---|---|---|---|
| I | Sprain | Ligaments intact, microscopic tears | Sling, ice, conservative |
| II | Subluxation | Capsule torn, costoclavicular intact | Sling 4-6 weeks |
| III | Anterior dislocation | Complete ligament rupture, anterior displacement | Usually conservative |
| IV | Posterior dislocation | Complete ligament rupture, posterior displacement | Urgent reduction required |
Exam Pearl
Types I-III are generally managed conservatively with good outcomes. Type IV (posterior) is the only true emergency requiring urgent intervention.
Clinical Assessment
History:
- High-energy mechanism (MVA, sports collision, fall onto shoulder)
- Direct blow vs indirect (lateral shoulder compression)
- Arm position at time of injury
- Symptoms suggesting vascular/airway compromise (dyspnea, dysphagia, arm swelling)
Physical Examination:
Anterior Dislocation
- Medial clavicle prominence (palpable anteriorly)
- Pain with arm movement, especially cross-body
- Swelling at SC joint
- Full shoulder ROM typically preserved
- Cosmetic deformity is main concern
Posterior Dislocation
- Medial clavicle less prominent or hollow (depressed posteriorly)
- Venous congestion in neck or ipsilateral arm
- Dysphagia (esophageal compression)
- Dyspnea, stridor (tracheal compression)
- Hoarseness (recurrent laryngeal nerve)
- Diminished upper limb pulses (subclavian compression)
- Brachial plexus symptoms (rare)
Red Flags for Posterior Dislocation
Examine every SC joint injury for:
- Stridor or respiratory distress
- Dysphagia or odynophagia
- Venous engorgement (neck, face, ipsilateral arm)
- Diminished or absent radial pulse
- Neurological deficit (brachial plexus)
- Supraclavicular hematoma
If any present - treat as posterior dislocation until proven otherwise!
Special Tests:
- Adson test: May assess subclavian artery compression
- Pulse comparison: Compare radial pulses bilaterally
- Venous distension: Look at jugular veins and arm veins
Investigations
Imaging Modalities
| Modality | Findings | Indication |
|---|---|---|
| Standard X-rays (AP) | Often inconclusive - structures overlap | Initial screening only |
| Serendipity view (40 degree cephalic) | Anterior: clavicle UP; Posterior: clavicle DOWN | Classic exam view - good for direction |
| CT scan | Gold standard for fracture/dislocation assessment | All suspected dislocations |
| CT angiography | Vascular injury assessment | All posterior dislocations |
| MRI | Soft tissue, physeal injury in young patients | Subacute/chronic cases, physeal injury |
Exam Pearl
Serendipity view technique: Patient supine, X-ray beam angled 40 degrees cephalad centered on sternum. Compare both SC joints on same film. Anterior dislocation: affected clavicle projects ABOVE the normal side. Posterior: projects BELOW. This is a classic exam question!
CT Findings:
- Definitive for direction of displacement
- Identifies associated fractures
- With contrast - assesses vascular compression/injury
CT Angiography
All posterior SC dislocations require CT angiography to assess for vascular compression or injury. Even after successful reduction, delayed vascular complications can occur.
Management Algorithm
Conservative Management:
Treatment Protocol
- Ice, sling for comfort
- NSAIDs for pain and inflammation
- Avoid aggravating activities
- Protected range of motion
- Wean from sling as pain allows
- Progressive ROM exercises
- Gentle strengthening
- Avoid contact sports/heavy lifting
- Full ROM should be achieved
- Sport-specific rehabilitation
- Gradual return to full activity
Prognosis: Excellent - near 100% return to full function
Surgical Technique
Indications:
- Chronic symptomatic anterior or posterior instability
- Failed conservative management
- Recurrent dislocation affecting function
Contraindications:
- Active infection
- SC joint arthritis (consider resection instead)
Surgical Steps:
- Positioning and Approach - Supine with bump under shoulders, transverse skin incision over SC joint, protect supraclavicular nerves, expose SC joint and medial clavicle
- Tunnel Preparation - Create 5-6mm tunnel through medial clavicle (anterior to posterior), create 5-6mm tunnel through manubrium or 1st rib, protect mediastinal structures with retraction and finger guard
- Graft Passage - Pass doubled graft through clavicular tunnel, cross graft in figure-of-8 pattern, pass through sternal/rib tunnel, return to clavicular tunnel
- Tensioning and Fixation - Reduce SC joint anatomically, tension graft with arm in neutral position, secure graft with interference screw or suture over bone bridge, confirm stability with stress
This technique provides stable reconstruction without metal hardware.
Complications
Complications by Injury Type and Treatment
| Complication | Anterior Dislocation | Posterior Dislocation |
|---|---|---|
| Vascular injury | Rare | Common - subclavian/innominate compression or laceration |
| Airway compromise | No | Yes - tracheal compression can be fatal |
| Dysphagia | No | Yes - esophageal compression |
| Mediastinitis | No | Risk with open reduction |
| Chronic instability | Common (usually cosmetic) | Rare if adequately reduced |
| Post-traumatic arthritis | 5-10% | 5-10% |
| Hardware migration | If metal used - can be fatal | If metal used - can be fatal |
Hardware Migration - Fatal Complication
Multiple case reports document fatal migration of pins, screws, and plates from the SC joint into:
- Heart (cardiac tamponade)
- Aorta (hemorrhage)
- Pulmonary vessels
- Subclavian vessels
Migration can occur months to years after surgery. Metal hardware is absolutely contraindicated at the SC joint.
Complication Prevention:
- Use only soft tissue reconstruction
- CT angiogram for all posterior dislocations
- Thoracic surgery standby for reduction
- Careful tunnel placement during reconstruction
Management of Complications:
- Vascular injury: Immediate thoracic/vascular surgery
- Chronic instability: Figure-of-8 reconstruction
- Arthritis: Medial clavicle resection (rare)
Postoperative Care
After Closed Reduction:
- Figure-of-8 brace or sling for 6 weeks
- NSAIDs for pain
- Ice to reduce swelling
- Serial X-rays to confirm maintained reduction
- Progressive ROM after immobilization
After Figure-of-8 Reconstruction:
Rehabilitation Protocol
- Sling immobilization
- Elbow, wrist, hand ROM maintained
- Pendulum exercises at 2 weeks
- No lifting, pushing, or pulling
- Wean from sling
- Active-assisted shoulder ROM
- Gentle isometric strengthening
- No resistance exercises
- Progressive resistance exercises
- Full ROM should be achieved
- Return to light activities
- Sport-specific training
- Gradual return to contact (if applicable)
- Functional testing before clearance
Outcomes and Prognosis
Natural History:
- Most SC injuries have excellent outcomes with conservative treatment
- Even with residual deformity, function is typically normal
- Posterior dislocations require intervention but outcomes good if promptly treated
Outcome by Injury Type
| Injury Type | Treatment | Good/Excellent Outcome | Return to Full Activity |
|---|---|---|---|
| Type I-II (Sprain) | Conservative | 95-100% | 4-6 weeks |
| Anterior dislocation | Conservative | 85-95% | 6-12 weeks |
| Posterior dislocation | Closed reduction | 80-90% | 6-12 weeks |
| Chronic instability | Figure-of-8 reconstruction | 75-85% | 4-6 months |
Prognostic Factors:
- Time to treatment (especially posterior)
- Age (younger patients do better)
- Associated injuries
- Compliance with rehabilitation
Evidence Base
SC Joint Physeal Closure Age
- Medial clavicular physis closes between 22-25 years, making it the last physis to fuse in the human body
- Physis visible on CT until age 20-25
- Complete fusion by age 25 in most individuals
- Female closure slightly earlier than male
Posterior SC Dislocation Reduction Techniques
- Closed reduction is usually successful for acute posterior dislocations when performed with adequate muscle relaxation and proper technique
- Reduction with arm abduction and extension most effective
- Towel clip technique effective for resistant cases
- Thoracic surgery backup reduces risk of adverse events
Conservative Treatment Outcomes
- At long-term follow-up (mean 10 years), conservatively treated SC dislocations had 88% good or excellent results despite residual deformity
- Functional results excellent in 88% of patients
- Cosmetic deformity does not correlate with symptoms
- Surgery rarely needed for anterior dislocations
Figure-of-8 Reconstruction Outcomes
- Figure-of-8 tendon graft reconstruction for chronic SC joint instability provides reliable stability with low complication rates
- Both autograft and allograft effective
- No cases of hardware migration (soft tissue only)
- One case of iatrogenic vascular injury during tunnel creation
Hardware Migration Fatalities
- Review of case reports documenting migration of metal hardware from SC joint into mediastinum with multiple fatalities
- Migration can occur months to years post-operatively
- Heart, aorta, and pulmonary vessels at risk
- Fatalities from cardiac tamponade, hemorrhage reported
Viva Scenarios
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Posterior SC Dislocation - Emergency
"A 28-year-old male presents to the emergency department after a motorcycle accident. He complains of difficulty swallowing and shortness of breath. You note venous engorgement in his right neck and arm. The right medial clavicle appears less prominent than the left."
Thank you. This clinical picture is highly concerning for a posterior sternoclavicular dislocation, which is a surgical emergency.
Immediate assessment: I would perform an ATLS primary survey focusing on airway given the dyspnea. If the patient is stable, I would assess radial pulses bilaterally to evaluate for subclavian compression.
Diagnosis: The triad of dysphagia (esophageal compression), dyspnea (tracheal compression), and venous engorgement (venous obstruction) with a less prominent medial clavicle strongly suggests posterior SC dislocation.
Investigations: If hemodynamically stable, I would obtain an urgent CT angiogram of the chest to confirm the diagnosis and assess for vascular injury. A chest X-ray and ECG should be done while awaiting CT.
Management: This requires urgent closed reduction in the operating room. I would alert the thoracic surgery team for standby, arrange blood products, and prepare for general anesthesia. The reduction technique involves placing a bump between the scapulae to extend the shoulders, applying longitudinal traction with the arm abducted 90 degrees. If unsuccessful, I would use the towel clip technique to grasp the medial clavicle percutaneously and apply anterior traction.
Post-reduction: CT to confirm reduction, figure-of-8 brace for 6 weeks, and close monitoring for delayed vascular complications.
Scenario 2: Anterior SC Dislocation
"A 22-year-old rugby player presents with a prominent lump over his right sternoclavicular joint following a tackle. He has full range of motion of the shoulder but pain with overhead activities. Plain X-rays are inconclusive. What is your assessment and management?"
Thank you. This presentation is consistent with an anterior sternoclavicular joint injury, most likely a Type III anterior dislocation or subluxation in the Rockwood classification.
Assessment: I would first examine for any signs of posterior dislocation (dysphagia, dyspnea, venous engorgement, diminished pulses) to rule out the more dangerous alternative. Given his age (22), I would also consider that this may represent a Salter-Harris physeal injury rather than a true dislocation, as the medial clavicular physis doesn't close until age 25.
Investigations: Serendipity view (40-degree cephalic tilt) would help confirm anterior displacement. If there's any doubt, CT scan is definitive and would also show physeal injury patterns.
Management: For anterior SC dislocation, I would recommend conservative treatment. Closed reduction can be attempted but often does not stay reduced - this is acceptable. I would treat with a sling for 6 weeks, ice, and NSAIDs. I would counsel him that residual prominence is cosmetic only and function is typically excellent.
Return to sport: He can return to non-contact training at 4 weeks and full rugby at 6-8 weeks once pain-free and with full strength.
Scenario 3: Chronic SC Instability
"A 35-year-old female office worker presents with chronic pain at her right SC joint. She had an anterior dislocation 2 years ago treated conservatively. Now she has a prominent medial clavicle that subluxes with arm elevation and causes pain affecting her work. She requests surgical treatment."
Thank you. This patient has symptomatic chronic anterior SC joint instability that has failed conservative management and is affecting her function.
Assessment: I would confirm the instability is the source of symptoms by examining for provocative maneuvers that reproduce her pain and subluxation. I would also assess for signs of arthritis which may require a different approach.
Investigations: CT scan to assess joint morphology, any arthritic changes, and to plan surgery. MRI if there's concern about soft tissue pathology.
Non-operative optimization: Before surgery, I would ensure she has tried activity modification, physiotherapy focusing on scapular stability and posture, and possibly a local anesthetic/corticosteroid injection for diagnostic and therapeutic purposes.
Surgical indication: If she has failed 6+ months of conservative treatment with persistent symptomatic instability affecting her work, she is a reasonable surgical candidate.
Surgical technique: I would perform a figure-of-8 reconstruction using autograft (semitendinosus) or allograft. This involves creating tunnels through the medial clavicle and first rib/manubrium, passing the graft in a figure-of-8 pattern, and tensioning to restore stability. I would use only soft tissue - NO METAL HARDWARE due to the well-documented risk of migration into the mediastinum.
Post-operative: Sling for 6 weeks, progressive ROM, return to full activity at 4-6 months.
MCQ Practice Points
Anatomy Question
Q: What is the last epiphyseal plate to close in the human body?
A: The medial clavicular physis closes at age 22-25 years. This is clinically important because in patients under 25, SC joint injuries often represent Salter-Harris physeal fractures rather than true ligamentous dislocations, with better healing potential.
Imaging Question
Q: On a serendipity view, how does an anterior SC dislocation appear compared to the contralateral normal side?
A: The affected medial clavicle projects ABOVE the normal side in anterior dislocation. In posterior dislocation, it projects BELOW. The serendipity view is obtained with a 40-degree cephalic tilt X-ray beam centered on the sternum.
Emergency Question
Q: A patient with a posterior SC dislocation presents with stridor and dysphagia. What mediastinal structures are being compressed?
A: Trachea (causing stridor) and esophagus (causing dysphagia). Other structures at risk include the subclavian vessels, innominate artery/vein, carotid artery, internal jugular vein, and brachial plexus. This constitutes a surgical emergency.
Treatment Question
Q: What is the primary concern if metal hardware (plates/screws) is used for SC joint fixation?
A: Migration into the mediastinum. Hardware can migrate into the heart, great vessels, or lungs, causing fatal complications including cardiac tamponade and hemorrhage. Only soft tissue reconstruction (figure-of-8 with tendon graft) should be used for SC joint stabilization.
Ligament Question
Q: Which ligament is the primary stabilizer of the SC joint?
A: The costoclavicular ligament is the primary stabilizer. It runs from the first rib/costal cartilage to the inferior medial clavicle and limits elevation, anterior translation, and posterior translation of the clavicle.
Classification Question
Q: In the Rockwood classification of SC joint injuries, which type requires emergent treatment?
A: Type IV (posterior dislocation) requires urgent/emergent reduction due to risk of mediastinal structure compression. Types I-III (sprains and anterior dislocation) are generally managed conservatively.
Australian Context and Medicolegal Considerations
Australian Epidemiology
- SC injuries common in MVA (high-speed rural roads)
- Contact sports: Rugby union/league, AFL
- Transfer protocols for posterior dislocations to major trauma centers
- Access to thoracic surgery varies by center
RACS Guidelines
- Transfer posterior dislocations to Level 1 trauma center
- Thoracic surgery consultation mandatory
- Document neurovascular status before and after intervention
Private vs Public
- Posterior dislocations: Public hospital with thoracic surgery capability
- Elective reconstruction: Can be done privately with appropriate facilities
- Ensure CT angio capability at operating facility
Medicolegal Considerations
Key documentation requirements:
- Complete neurovascular examination before and after any intervention (document pulses, sensation, motor function)
- Imaging confirming direction of dislocation before reduction
- Documented thoracic surgery consultation for posterior dislocations
- Informed consent discussing hardware migration risk if any fixation planned
- CT post-reduction to confirm anatomic position
Common litigation issues:
- Delayed diagnosis of posterior dislocation leading to vascular injury
- Vascular injury during reduction without surgical backup
- Hardware migration causing cardiac/vascular injury
- Inadequate documentation of neurovascular status
STERNOCLAVICULAR JOINT INJURIES
High-Yield Exam Summary
Key Statistics
- •3% of all shoulder girdle injuries
- •Anterior : Posterior ratio = 25:1
- •Medial clavicular physis closes at 22-25 years (LAST physis)
- •Under 25 = likely physeal injury, not true dislocation
Rockwood Classification
- •Type I: Sprain - ligaments intact - conservative
- •Type II: Subluxation - capsule torn - conservative
- •Type III: Anterior dislocation - usually conservative
- •Type IV: Posterior dislocation = EMERGENCY
Posterior Dislocation Signs (STAVE)
- •Subclavian vessel compression
- •Trachea compression (stridor/dyspnea)
- •Artery (carotid) compression
- •Vein (jugular) engorgement
- •Esophagus compression (dysphagia)
Management Principles
- •Anterior: Conservative - sling 6 weeks, accept prominence
- •Posterior: URGENT reduction - thoracic surgery standby
- •Chronic: Figure-of-8 reconstruction with tendon graft
- •NEVER use metal hardware - migration into mediastinum
Key Imaging
- •Serendipity view: 40 degree cephalic tilt
- •Anterior = clavicle projects ABOVE normal
- •Posterior = clavicle projects BELOW normal
- •CT/CTA mandatory for posterior (assess vascular)
Must Know for Exam
- •Posterior SC dislocation is a surgical emergency
- •Thoracic surgery backup mandatory for reduction
- •No metal hardware at SC joint (fatal migration)
- •Costoclavicular ligament is primary stabilizer
- •Last physis to close = medial clavicle (22-25y)