Clavicle Fractures and Acromioclavicular Joint Dislocations: High-Yield Medical Student Notes
Clavicle Fractures
Epidemiology and Anatomy
- The clavicle is the most commonly fractured bone in the body, accounting for 2.6-5% of all fractures 1, 2
- Midshaft fractures (middle third) are the most frequent location 2
- The typical deformity is a "Z" configuration due to pull of the pectoralis major and weight of the arm 3
Classification by Location
- Midshaft (middle third): Most common, typically displaced
- Distal (lateral) third: Unstable if coracoclavicular ligaments disrupted
- Proximal (medial) third: Least common
Clinical Assessment Pearls
- Always obtain upright or stress radiographs—supine films underestimate true displacement 4
- Look for >2 cm shortening, which predicts 15% nonunion rate with conservative management 4
- Examine for emergent surgical indications: open fracture, skin tenting, neurovascular compromise, hemopneumothorax, brachial plexus injury 5
Treatment Decision Algorithm
For Displaced Midshaft Fractures in Adults:
Surgical fixation provides higher union rates and better early functional outcomes than conservative management, though long-term outcomes are similar 3
Strongly favor surgery when:
- Displacement >2 cm shortening 4
- Active laborers or athletes requiring rapid return to work/sport 4
- Tobacco users (increased nonunion risk with conservative care) 4
- Patients prioritizing cosmetic outcome 4
- Patients unable to tolerate prolonged immobilization 4
Either approach is reasonable when:
- Patient accepts 15% nonunion risk and slower recovery with conservative care 3
- Long-term functional goals are the priority (outcomes equivalent at 1+ years) 3
For Minimally Displaced Fractures:
- Conservative management with simple sling immobilization for 4 weeks 2
- Begin range-of-motion exercises at 4 weeks 2
- Full return to activities by 12 weeks 2
For Adolescents (≤18 years):
Surgery shows NO advantage over conservative care—union rates are comparable 4
- Surgical management carries notable revision surgery rates for implant removal 4
- Same emergent indications as adults still mandate urgent referral 4
For Distal (Lateral) Clavicle Fractures:
- Unstable fractures with coracoclavicular ligament disruption require surgical evaluation 4
- Type II distal fractures are prone to nonunion—consider operative fixation 6
Surgical Techniques
- Plate osteosynthesis (superior or anterior positioning, single or dual plating) 3
- Intramedullary fixation 3
- No consensus on optimal technique 3
Complications to Counsel Patients About
- Nonunion: Up to 15% with conservative management of displaced fractures 3
- Symptomatic malunion: Affects shoulder strength and function 3
- Vascular injury: Subclavian vessels 5
- Neurologic injury: Brachial plexus paresis 5
- Thoracic complications: Hemopneumothorax, scapulothoracic dissociation 5
Acromioclavicular (AC) Joint Dislocations
Mechanism and Epidemiology
- Result from direct blow to superolateral shoulder with arm in adduction 2
- Account for up to 12% of shoulder girdle injuries, up to 50% in sports-related injuries 7
Rockwood Classification (Types I-VI)
Based on ligaments injured and degree of displacement 2:
- Type I: AC ligament sprain, no displacement
- Type II: AC ligament torn, coracoclavicular (CC) ligaments intact, <25% vertical displacement
- Type III: Both AC and CC ligaments torn, 25-100% displacement
- Type IV: Posterior displacement of clavicle into trapezius
- Type V: >100% superior displacement (>300% increase in CC distance)
- Type VI: Inferior displacement of clavicle (rare)
Key Diagnostic Pitfall
Weighted stress radiographs (10 kg axial load) can both overestimate and underestimate injury severity—routine use should be questioned 8
- In one study, 13 patients shifted Rockwood classification between weighted and non-weighted views 8
- May lead to unnecessary surgery for overestimated injuries or inadequate conservative treatment for underestimated ones 8
Vertical Displacement Patterns
AC joint injury does NOT exclusively cause scapular depression or clavicular elevation 8
- Five displacement patterns exist: isolated clavicle elevation, isolated scapula depression, both elevated, both depressed, or combined elevation/depression 8
- Most commonly, BOTH structures elevate due to muscle spasm and pain 8
Treatment Algorithm
Low-Grade Injuries (Types I-II):
- Conservative management is standard 2
- Activity modification, NSAIDs, sling for comfort 2
- General agreement on nonoperative approach 6
Type III Injuries:
Treatment remains controversial—no distinct advantage of surgery over conservative care 6, 9
- Consider patient factors: overhead athlete, manual laborer, cosmetic concerns
- Both approaches yield acceptable outcomes 6
High-Grade Injuries (Types IV-VI):
Chronic AC Joint Pain:
- Surgery reserved for persistent symptoms despite conservative care 1
- Options include distal clavicle excision, AC joint reconstruction 2
Surgical Considerations
No gold standard technique exists—multiple options available 10, 9:
- Mechanical fixation devices
- Synthetic ligaments
- Biologic anatomic reconstructions (tendon autograft/allograft)
- Open vs. arthroscopic approaches 9
- Coracoclavicular ligament reconstruction techniques 10
Surgical Complications
- Iatrogenic coracoid fracture: Significant complication when passing sutures/grafts through or around coracoid 7
- Recurrent dislocation 7
- Hardware complications requiring removal 7
- No consensus on optimal technique reflects uncertainty in this field 10
Associated Conditions
Distal clavicle osteolysis 2:
- Pathologic bone resorption from repetitive overhead activities
- Managed conservatively with activity modification, NSAIDs, injection
- Surgical options available if conservative fails
AC joint osteoarthrosis 2:
- May be posttraumatic or idiopathic
- Similar management to distal clavicle osteolysis
Critical Teaching Points
When to Refer Urgently
- Open fracture 4
- Neurovascular compromise 4, 5
- Skin tenting 4
- Hemopneumothorax 5
- Scapulothoracic dissociation 5