ACJ Injury (Acute)

History:

• •Direct blow to the point of the adducted shoulder
• •Contact sport, cycling, or fall
• •Localised pain over the ACJ
• •Difficulty lifting or adducting the arm across the chest

Examination:

• •Tenderness over the ACJ
• •Visible step deformity: subtle in I-II, obvious in III and beyond
• •Skin tenting, blanching, or dusky discolouration in type V
• •Palpable defect behind the clavicle in type V (deltotrapezial fascia disruption)
• •Posterior clavicular prominence trapped under trapezius in type IV
• •Positive scarf test (cross-body adduction reproduces ACJ pain) - the ACJ-specific test
• •Neurovascular assessment, particularly in types IV-VI
• •Assess for floating shoulder (ipsilateral scapular neck fracture) and any open injury

Rockwood classification:

• •Type I: AC sprain only. Radiographs normal
• •Type II: AC ligaments torn, CC intact. ACJ widened but CC distance change <25%
• •Type III: AC and CC torn. Clavicle 25-100% superiorly displaced. Deltotrapezial fascia intact. Modern UK practice recognises IIIA (horizontally stable) and IIIB (horizontally unstable)
• •Type IV: AC and CC torn with posterior displacement of the clavicle through or into trapezius. Detected on axillary view
• •Type V: AC, CC, and deltotrapezial fascia all torn. Clavicle 100-300% superiorly displaced. Skin tenting and palpable posterior defect characteristic
• •Type VI: AC and CC torn with inferior displacement (subacromial or subcoracoid). Rare; high-energy

Red flags:

• •Open injury
• •Neurovascular compromise
• •Skin tenting, blanching, or dusky skin
• •Type IV, V, or VI injury
• •Dysphagia, dyspnoea, stridor, vascular symptoms, or medial clavicular tenderness should prompt reconsideration of the diagnosis (exclude posterior SCJ injury or associated thoracic injury)

Plain radiographs (first-line):

• •Zanca view (AP of both ACJs with 10-15° cephalic tilt) - the canonical view; compare CC distance to the contralateral side
• •Axillary view: essential for detecting posterior displacement (type IV); a Zanca view alone can miss it

Additional imaging:

• •Alexander view (bilateral scapular AP with patient pushing shoulders forward): useful for assessing horizontal instability in suspected type IIIB
• •Dynamic ultrasound: increasingly used by UK shoulder specialists to assess horizontal translation in equivocal type III injuries
• •CT: rarely required acutely; consider for complex cases or pre-operative planning
• •MRI: not first-line; useful in equivocal cases or pre-operative planning of chronic injuries
• •Stress (weighted) radiographs: largely obsolete

CC distance measurement: compare injured to contralateral on the Zanca view. 25-100% increase suggests type III; 100-300% increase suggests type V.

Management is driven by the Rockwood classification.

Type I and II (low-grade):

• •Non-operative: broad arm sling for comfort 1-2 weeks (does not alter healing); analgesia per general fracture pathway; early ROM and progressive strengthening
• •Most improve over 2-6 weeks; cosmetic prominence may persist longer
• •Often managed via self-care or virtual fracture clinic pathways

Type III (controversial):

• •UK practice favours initial non-operative trial with reassessment at ~3 months; surgery for persistent symptoms, high-demand athletes, or significant cosmetic concerns
• •IIIA (horizontally stable): respond well to non-op
• •IIIB (horizontally unstable): more likely to fail non-op and progress to surgery
• •Long-term functional outcomes broadly similar between operative and non-operative for most type III

Type IV, V, VI (high-grade):

• •Urgent orthopaedic assessment; commonly operative
• •Acute repair within ~3 weeks is the golden window: native CC ligaments primarily repaired with augmentation. Beyond 3 weeks ligaments retract and scar, requiring more complex reconstruction (Weaver-Dunn modification or tendon allograft)
• •Operative options (awareness): hook plate (temporary); suspensory button constructs (Tightrope, Dog Bone); direct ligament repair with CC augmentation; graft reconstruction for delayed presentations
• •Consent: supraclavicular nerve injury (chest wall numbness inferior to scar)

Referral:

• •Urgent: types IV-VI; open injury; neurovascular compromise; threatened skin
• •Routine (often via fracture clinic): type III for shared decision; type I-II with persistent symptoms beyond 6 weeks

Type I and II:

• •Sling for comfort, weaned as tolerated
• •Early ROM from day 1-3, progressive strengthening from week 1-2
• •Return to non-contact activity ~3-4 weeks; contact sport ~4-6 weeks

Type III (non-operative):

• •Progressive ROM and strengthening with scapular stabilisation
• •Return to non-contact ~4-6 weeks; contact sport ~8-12 weeks
• •Elite contact athletes often require 3-4 months for full clearance

Post-operative (any type):

• •Sling 4-6 weeks
• •Gradual ROM under physiotherapy supervision
• •Strengthening from 6-8 weeks
• •Return to contact sport ~4-6 months, guided by the operating team

Modifiable factors: smoking slows healing - advise cessation. Address fear-avoidance and graded return-to-work planning for manual workers.

• •Rockwood classification (I-VI) - The framework that drives ACJ injury management; Types I-II non-operative, III controversial (UK favours initial non-operative trial), IV-VI commonly operative.
• •IIIA vs IIIB (modern UK refinement) - Horizontally stable IIIA respond well to non-operative care; horizontally unstable IIIB are more likely to fail and progress to surgery.
• •Operative golden window - Acute high-grade injuries (IV-VI) optimally repaired within ~3 weeks; native CC ligaments retract and scar beyond this, mandating more complex reconstruction.
• •BOAST guidance on virtual fracture clinics - Most low-grade ACJ injuries are appropriately managed via VFC pathways without routine in-person orthopaedic follow-up.
• •Imaging - Zanca view is canonical; axillary view is essential to exclude type IV; Alexander view and dynamic USS assess horizontal instability.

• •Type III management is the classic controversy. UK shared decision-making with initial non-operative trial is the current answer; long-term outcomes broadly similar between operative and non-operative paths.
• •IIIA (horizontally stable) vs IIIB (horizontally unstable) is an increasingly tested distinction. IIIB is more likely to fail non-operative management and progress to surgery.
• •Skin tenting with a palpable posterior defect characterises type V (deltotrapezial fascia disruption). Posterior clavicular displacement trapped under trapezius defines type IV.
• •The golden window for acute high-grade repair is approximately 3 weeks; beyond this the native CC ligaments retract and more complex reconstruction is required.
• •Supraclavicular nerve injury (chest wall numbness inferior to scar) is a specific consent point for ACJ surgery.
• •Dysphagia or dyspnoea should prompt reconsideration - exclude posterior SCJ injury or associated thoracic injury.