Acromioclavicular Joint Injury
Basics
Description
Description
- The acromioclavicular (AC) joint is formed by the articulation of the distal clavicle and the scapular acromion
- It is stabilized by the AC ligament, coracoclavicular (CC) ligament, and attachments from deltoid and trapezius muscles
- AC ligament is responsible for horizontal stability
- CC ligament is responsible for vertical stability
- Rockwood classification (sequential injury pattern):
- Type I:
- No visible deformity
- Sprained AC ligament (AC joint tender)
- Intact joint capsule
- No CC ligament injury (nontender)
- No deltoid or trapezius injury
- No radiographic abnormality (clinical diagnosis)
- Type II:
- Ruptured AC ligament (AC joint tender) (distal clavicle horizontally unstable)
- Ruptured joint capsule
- Sprained CC ligament (CC ligament tender)
- Minimal deltoid and trapezius injury
- Radiographs show slight widening of AC joint (normal <5 mm)
- Normal CC space (11–13 mm)
- Type III:
- Ruptured AC ligament (AC joint tender) (distal clavicle horizontally unstable)
- Ruptured joint capsule
- Ruptured CC ligament (CC ligament tender) (distal clavicle vertically unstable)
- Detached deltoid and trapezius
- Complete AC dislocation
- Radiographs show widening of AC joint
- Increased CC space, with distal clavicle above superior aspect of acromion (100% displaced)
- Types IV, V, and VI:
- Cause more significant pain than types I, II, and III
- Best visualized on lateral/axillary radiographs
- All require operative treatment
- Greater risk for prolonged disability
- Type IV:
- Identical ligamentous/muscular injury pattern to type III
- Clavicle is displaced posteriorly into trapezius muscle
- Posteriorly displaced clavicle may be palpable on exam
- May cause tenting of skin posteriorly
- Type V:
- Rare
- Identical ligamentous/muscular injury pattern to type III
- Clavicle is displaced superiorly above the trapezius (100–300% increase in CC space)
- Shoulder droops severely
- Clavicle may be palpated subcutaneously
- May cause tenting, ischemia, or disruption of skin
- Type VI:
- Usually associated with severe trauma with multiple injuries
- Identical ligamentous/muscular injury pattern to type III
- Clavicle is displaced inferiorly into subacromial or subcoracoid location
- Shoulder appears flattened
- Associated neurovascular injury is common
- Type I:
Etiology
Etiology
- Injury most commonly seen in young, active males during contact sports
- Most common mechanism is direct trauma to superior or lateral shoulder while arm is adducted, usually in the setting of a fall:
- Acromion is displaced inferomedially
- Clavicle remains stabilized by sternoclavicular ligaments
- May also occur indirectly via a fall on an outstretched hand or elbow, with transmission of force to the AC joint
Diagnosis
Signs and Symptoms
HistorySigns and Symptoms
- Pain to anterior or superior aspect of the shoulder following trauma
- Pain exacerbated by moving arm across the chest, behind the back, or overhead
- Mechanism/force will dictate suspicion for and pattern of injury
- Associated neurovascular symptoms
- Cervical spine symptoms
Physical Exam
- Exam in standing or sitting position, as supine position negates force of gravity which can mask joint instability
- Inspection: Ecchymosis, abrasion, swelling, symmetry, deformity of AC joint, skin tenting, or laceration
- Prominence of clavicle with sagging of the acromion indicates rupture of AC joint (Rockwood type II injury or greater)
- Palpation: Sequential exam of sternoclavicular joint, length of clavicle, AC joint, CC ligament, coracoid process, scapular spine, and proximal humerus
- Tenderness over AC joint indicates AC ligament injury (Rockwood type I injury or greater)
- Horizontal instability of distal clavicle indicates AC ligament rupture (Rockwood type II injury or greater)
- Tenderness over CC ligament indicates CC ligament injury (Rockwood type II injury or greater)
- Vertical instability of distal clavicle indicates CC ligament rupture (Rockwood type III injury or greater)
- Special tests:
- Cross-body adduction test:
- Arm elevated to 90 degrees with elbow flexed at 90 degrees, and adducted across chest
- Pain confirms AC injury by specifically compressing the joint
- Sensitivity 77%, specificity 79%
- O'Brien test:
- Arm elevated to 90 degrees with elbow in extension, adduction of 10–15 degrees and maximum forearm pronation
- Examiner applies downward force against resistance
- Pain over top of shoulder confirms AC injury
- Sensitivity 16–93%, specificity 90–95%
- Cross-body adduction test:
- Complete distal neurovascular exam, including brachial plexus
- Careful cervical spine exam
Essential Workup
Essential Workup
- History to seek mechanisms that commonly cause AC joint injury and associated force
- Physical exam to evaluate for injury pattern, neurovascular compromise and exclude other causes of pain
- Radiographic evaluation as outlined below
Diagnostic Tests and Interpretation
ImagingDiagnostic Tests and Interpretation
- Specific AC joint radiograph:
- Recommended if AC injury suspected
- Should include bilateral AC joints (for comparison)
- Standard shoulder views will over penetrate AC joint and may obscure subtle injuries
- Stress views no longer recommended
- Zanca view (10–15 degrees cephalic tilt to remove scapula from field) for limited initial views
- Axillary view for type III–VI injuries to determine position of distal clavicle
- CT or MRI for further evaluation of surgical cases (Rockwood types IV–VI)
- Angiography may be used to evaluate associated neurovascular injuries
- US if CT/MRI is not available
Differential Diagnosis
Differential Diagnosis
- Shoulder dislocation
- Fractures of acromion or clavicle
- Rotator cuff injury
- Tendinitis
- Capsulitis
- Cervical radiculopathy
- Osteoarthritis
- Osteomyelitis
Pediatric Considerations
- Pediatric clavicle encased in periosteal tube:
- CC ligament within tube
- AC ligament external to tube (more vulnerable)
- AC joint injury rarely occurs in isolation in the pediatric population
- When injury does occur, it is more often type I or II
- Distal clavicular fractures through physis are more common than type III AC joint dislocations
Treatment
Pre Hospital
Pre Hospital
- Ice packs
- Sling immobilization
- Cervical spine immobilization if indicated
Initial Stabilization/Therapy
Initial Stabilization/Therapy
- Ice packs
- Sling immobilization
- Cervical spine immobilization if indicated
- Analgesia (NSAIDs, other analgesics)
Ed Treatment/Procedures
Ed Treatment/Procedures
- Types I and II:
- Rest, ice, analgesics
- Brief sling immobilization (typically 3–7 d)
- Range of motion (ROM) and strengthening exercises as soon as can be tolerated
- Resume normal activities once painless ROM and strength have returned (2–4 wk)
- Type III:
- Rest, ice, analgesics
- Sling immobilization and early (within 72 hr) orthopedic referral
- Treatment plan is controversial as insufficient evidence exists to favor one management strategy over the other (conservative vs. surgical)
- Which approach is chosen may depend on general health of patient, level of activity, occupation, hand dominance, and risk for reinjury
- Current trend is toward nonoperative management except for those with persistent symptoms and functional limitations after 6–12 wk
- Types IV, V, and VI:
- Rest, ice, analgesics
- Sling immobilization and immediate orthopedic referral
- Require early surgical intervention
- Special circumstance: Potential future complication of AC joint injury is arthritis of the joint
Pediatric Considerations
- Types I and II:
- Conservative management (rest, ice, analgesics, sling)
- Should heal without major sequelae
- Type III:
- Age <15 yr, conservative management
- Age ≥15 yr may require more aggressive treatment
- Types IV, V, and VI:
- Operative repair
Medication
Medication
- Ibuprofen: 600 mg (peds: 4–10 mg/kg) PO q.i.d
- Ketorolac: 30 mg (peds: 0.5 mg/kg up to 30 mg if >6 mo) IM/IV q6h (15 mg IM/IV q6h if >65 yr or <50 kg)
Ongoing Care
Disposition
Admission CriteriaDisposition
- Open injury
- Types IV, V, and VI require admission for operative repair
Discharge Criteria
- Types I and II can be discharged with orthopedic referral
- Type III should have urgent orthopedic referral
Follow-Up Recommendations
Follow-Up Recommendations
- Type I and II: Orthopedic follow-up within 2–4 wk
- Type III: Early (within 72 hr) orthopedic follow-up
- Type IV–VI: Immediate orthopedic referral
- All pediatric injuries should have prompt orthopedic follow-up, with type IV–VI injuries requiring immediate referral
Pearls and Pitfalls
- Type I and II AC injuries:
- No increase in CC space
- Conservative management with rest, ice, sling, and ROM/strength exercises
- Type III injuries:
- 100% superior displacement of distal clavicle
- Management somewhat controversial
- Require early orthopedic follow-up
- Type IV–VI injuries:
- Identical ligamentous and muscular injuries to type III
- Difference according to position of distal clavicle
- Operative management is standard of care
Additional Reading
- Bossart PJ, Joyce SM, Manaster BJ, et al. Lack of efficacy of weighted radiographs in diagnosing acute acromioclavicular separation. Ann Emerg Med. 1988;17:47–51.
- Bussieres AE, Peterson C, Taylor JA. Diagnostic imaging guideline for musculoskeletal complaints in adults—an evidence-based approach-part 2: Upper extremity disorders. J Manipulative Physiol Ther. 2008;31(1):2–32.
- Hegedus EJ, Goode A, Campbell S, et al. Physical examination tests of the shoulder: A systematic review with meta-analysis of individual tests. Br J Sports Med. 2008;42:80–92.
- Mazzocca AD, Arciero RA, Bicos J. Evaluation and treatment of acromioclavicular joint injuries. Am J Sports Med. 2007;35(2):316–329.
- Simovitch R, Sanders B, Ozbaydar M, et al. Acromioclavicular joint injuries: Diagnosis and management. J Am Acad Ortho Surg. 2009;17:207–219.
- Stucken C, Cohen SB. Management of acromioclavicular joint injuries. Orthop Clin N Am. 2015;46(1):57–66.
- Tamaoki MJS, Belloti JC, Lenza M, et al. Surgical versus conservative interventions for treating acromioclavicular dislocation of the shoulder in adults. Cochrane Database of Sys Rev. 2010;(8):CD007429.
See Also
See Also
Authors
Gina T. Waight
Aleksandr M. Tichter
© Wolters Kluwer Health Lippincott Williams & Wilkins
Citation
Schaider, Jeffrey J., et al., editors. "Acromioclavicular Joint Injury." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307671/all/Acromioclavicular_Joint_Injury.
Acromioclavicular Joint Injury. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307671/all/Acromioclavicular_Joint_Injury. Accessed December 11, 2024.
Acromioclavicular Joint Injury. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307671/all/Acromioclavicular_Joint_Injury
Acromioclavicular Joint Injury [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2024 December 11]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307671/all/Acromioclavicular_Joint_Injury.
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