High-yield overview
6 typesI to VI, escalating ligament disruption and displacement
I–II non-operativesling, early mobilisation, expect good outcome
III controversialmost treated non-operatively; surgery for select high-demand patients
IV–VI operativefixation or reconstruction of the CC ligament complex
Critical Must-Knows
- The Rockwood classification grades AC joint injuries from I to VI based on which ligaments are disrupted (AC, CC) and the direction and severity of clavicle displacement on imaging.
- Types I and II involve the AC ligaments only — the CC ligaments are intact or sprained, and the clavicle is minimally displaced or not displaced at all. These are always treated non-operatively.
- Type III is the controversy zone. Both AC and CC ligaments are torn, and the clavicle is displaced superiorly by 25 to 100 per cent of clavicle width. Non-operative treatment produces satisfactory results for most patients, but surgery is offered to overhead athletes, manual labourers, and acute high-demand cases where anatomical reduction and CC reconstruction may restore function.
- Types IV, V, and VI are operative. The CC ligaments are torn and the clavicle is displaced posteriorly (IV), severely superiorly (V), or inferiorly beneath the coracoid (VI). These require anatomical or modified Weaver-Dunn reconstruction, hook plate fixation, or arthroscopic coracoclavicular stabilisation.
- The axillary lateral view is essential for detecting posterior displacement (type IV) and subcoracoid displacement (type VI), which are missed on the standard anteroposterior film.
The threshold examiners want
Examiners expect you to classify the injury on imaging, describe the ligament disruption pattern, and justify your management based on the type. The two high-yield pressure points are: (1) why type III is controversial — name the factors that push you toward surgery (overhead sport, dominant arm, manual occupation, acute injury less than three weeks, high cosmetic concern, and bilateral comparison for asymmetry), and (2) why types IV to VI are operative — the posterior or inferior displacement represents structural failure that will not remodel and risks skin breakdown, neurovascular compromise, or painful non-union if left unreduced. Always mention the axillary lateral view — an AP film alone misses type IV and VI injuries.
The Rockwood Classification System
The patient typically presents after a direct fall onto the point of the shoulder — common in cycling, rugby, skiing, and contact sports. Pain is localised to the AC joint; the arm is held adducted close to the body to relieve strain on the injured ligaments.
Examination sequence:
- Look: Inspect both shoulders from behind. Compare the clavicle contour — a type III or V injury shows a prominent superior step at the AC joint. Type IV may show a posterior bulge. Type VI shows the shoulder sitting inferiorly with a shortened clavicular profile. Check for skin tenting, abrasions, and swelling over the AC joint.
- Feel: Palpate directly over the AC joint — point tenderness is present in all types. Palpate along the clavicle for tenderness extending to the CC ligament interval. In type IV, the posterior edge of the clavicle may be palpable behind the acromion.
- Move: Active forward flexion and abduction are painful, particularly in the mid-range. Cross-body adduction compresses the AC joint and reproduces pain in all types. Assess scapular dyskinesis — early fatigue and abnormal scapulohumeral rhythm may indicate trapezius dysfunction in higher-grade injuries.
- Special tests: Cross-body adduction test — forward flex the arm to 90 degrees then forcibly adduct across the chest. Pain over the AC joint is positive and highly sensitive for AC joint pathology. AC joint compression (Paxinos) test — downward force on the proximal humerus with the arm adducted. Active compression (O'Brien) test — sensitive but less specific for AC joint disorders.
The classification describes six grades of acromioclavicular separation based on the structures disrupted and the magnitude and direction of clavicular displacement.
| Type | AC Ligaments | CC Ligaments | Clavicle Displacement | Key Clinical Feature |
|---|---|---|---|---|
| I | Sprained | Intact | None | Point tenderness over AC joint; normal radiographs; no instability on stress views |
| II | Torn | Sprained (partial) | Slight superior (less than 50 per cent of clavicle width) | Palpable step-off; mild upward subluxation on Zanca view; mild instability |
| III | Torn | Torn | Superior, 25–100 per cent of clavicle width above acromion | Prominent deformity; CC distance increased; deltoid-trapezius fascia detached from distal clavicle |
| IV | Torn | Torn | Posterior — clavicle displaced behind acromion into trapezius | Posterior prominence; pain on cross-body adduction; may have skin tenting; visible on axillary view only |
| V | Torn | Torn | Severe superior, 100–300 per cent of clavicle width | Gross deformity; deltoid and trapezius completely detached from distal clavicle; high-energy mechanism |
| VI | Torn | Torn | Inferior — clavicle displaced under coracoid process | Rare; very high-energy; associated neurovascular injury and rib or scapula fractures; shoulder looks shortened and inferior |
Mnemonic
UBVD \u2014 Up, Behind, Very high, DownDirection defines the high-grade types
Clinical Pearl
The axillary lateral view is non-negotiable for AC joint injuries. An anteroposterior radiograph alone cannot detect posterior (type IV) or inferior subcoracoid (type VI) displacement. In the viva, if you describe the classification without mentioning the axillary view, the examiner will ask you what you are missing.
Treatment by Classification Grade
| Type | Recommended Management | Key Indication | Expected Outcome |
|---|---|---|---|
| I | Non-operative | Sling for comfort (1 to 2 weeks), ice, analgesia; early active-assisted ROM | Excellent; full return to sport at 2 to 6 weeks |
| II | Non-operative | Sling 2 to 3 weeks, gradual ROM then strengthening; return to sport at 6 to 8 weeks | Good; mild residual step-off common but pain-free in most |
| III | Controversial — non-operative first line | Non-operative: sling, rehab, activity modification. Surgery for select patients — overhead athletes, manual labourers, dominant arm, acute presentation less than three weeks | Non-operative: satisfactory in 85 to 90 per cent of patients at medium-term follow-up. Surgical: better cosmesis and strength but higher complication rate; no clear superiority in outcome scores |
| IV | Operative | Open or arthroscopic CC ligament reconstruction (modified Weaver-Dunn, anatomical CC reconstruction with allograft or autograft, hook plate) | Restored anatomy and stability; address posterior buttonholing |
| V | Operative | CC ligament reconstruction with deltoid-trapezius repair; fixation options include hook plate, double-button (TightRope), or coracoclavicular screw (temporary) | Functional restoration; risk of loss of reduction if deltoid repair fails |
| VI | Operative — urgent | Open reduction, CC ligament reconstruction, repair of surrounding soft tissues; assess for neurovascular injury | Satisfactory outcome with prompt reduction; delay risks neurovascular compromise |
Caution
Type VI injuries can compromise the brachial plexus and subclavian vessels because the clavicle is driven inferiorly beneath the coracoid and into the thoracic outlet. Examine distal pulses, radial nerve function, and upper limb neurology urgently. These are high-energy injuries — screen for associated pneumothorax, scapular fracture, and sternoclavicular disruption. Operative reduction and stabilisation is urgent.
Mnemonic
Non, Non, Discuss, Operate, Operate, OperateTreatment decision by type
Controversies and Limitations
- The type III debate is the single biggest exam topic. The evidence does not support routine operative fixation for acute type III injuries. Multiple level-1 and level-2 trials and systematic reviews show that non-operative treatment produces comparable functional outcome scores, return-to-work rates, and patient satisfaction at two to five years. Surgery offers better cosmetic appearance and marginally stronger isometric strength, but carries a complication rate of 20 to 40 per cent including hardware failure, wound infection, loss of reduction, and the need for re-operation. Most guidelines recommend non-operative treatment as first line with surgery reserved for specific patient factors (overhead athletes, manual labourers, dominant arm, acute injury less than three weeks, high cosmetic demands).
- Inter-observer reliability is only moderate. Studies using both plain radiographs and CT show fair to moderate agreement between surgeons when classifying the same injury, particularly distinguishing between type III and V injuries and between III and IV when the axillary view is suboptimal. The CC distance measurement threshold between types varies between institutions.
- Weighted stress views are debated. Some centres use bilateral weighted views (5 to 10 kg per hand) to demonstrate dynamic CC instability and help differentiate type II from III. Critics argue that the test is painful, non-standardised, and that all patients with complete CC disruption show widening under stress regardless of treatment implications.
- The classification does not capture chronicity. A type III injury treated non-operatively that remains painful and unstable at six months is a chronic type III — this is functionally a different clinical entity from an acute type III, and the treatment algorithm shifts toward late reconstruction.
- Rockwood type VI is rare and poorly studied. Most published series have fewer than five cases. The classification was described before widespread adoption of CT, and the true incidence and optimal surgical technique are not well established.
- Imaging limitations. Plain radiographs underestimate CC distance compared with CT or MRI. The Zanca view is technically dependent on beam angulation (10 to 15 degree cephalic tilt). MRI can directly visualise the ligaments but is not routine in acute injury management. Normal CC distance is 1.1 to 1.3 cm; a difference greater than 50 per cent compared with the contralateral side suggests complete CC disruption.
- The classification does not account for associated injuries. Concomitant rotator cuff tears, superior labral anterior-posterior (SLAP) lesions, and coracoid fractures can occur with any type and change the treatment plan independently of the Rockwood grade.
Mnemonic
ZAW \u2014 Zanca, Axillary, WeightedImaging views for AC joint injury
Evidence Base
Evidence
Surgical versus conservative management of Type III acromioclavicular dislocation: a systematic review
Longo UG, Ciuffreda M, Rizzello G, et al. • Br Med Bull (2017)
Key Findings:
- 14 studies / 646 shoulders comparing operative vs non-operative Rockwood type III AC dislocation
- No significant difference in post-treatment osteoarthritis or persistent pain (pain trended lower with surgery)
- Insufficient evidence to favour surgery for functional outcome — type III remains controversial
Clinical implication: Rockwood I-II are managed non-operatively and IV-VI operatively; type III is the genuinely controversial grade where evidence does not clearly favour surgery.
Limitation: Heterogeneous, mostly low-level studies; no high-quality RCTs.
Evidence
Operative versus nonoperative management of high-grade acromioclavicular injuries: a systematic review and meta-analysis
Adra M, Mohamed Haroon A, Milchem H, et al. • Cureus (2024)
Key Findings:
- 13 studies / 729 patients with Rockwood III-V AC injuries
- Operative treatment gave better Constant scores and radiological (ACJ width, redislocation) outcomes
- More non-operative patients rated their subjective result 'good'; operative complications ~18 percent
Clinical implication: For higher Rockwood grades (especially IV-VI), operative reconstruction improves functional/radiological outcomes, balanced against surgical complication risk.
Limitation: Grades pooled (III-V); subjective satisfaction favoured non-operative.
Exam Viva
Practise clinical reasoning and management decisions out loud
Viva scenarioStandard
Clinical prompt
“A 28-year-old professional cricketer presents with a painful left shoulder after a diving catch two days ago. Examination reveals a prominent AC joint step-off with tenderness. Radiographs show the clavicle displaced about 75 per cent of its width above the acromion on the Zanca view, with an increased CC distance. How would you classify and manage this?”
Practical approach
I would classify this as a Rockwood type III AC joint separation. The AC and CC ligaments are torn, and the clavicle is displaced superiorly by roughly 75 per cent of clavicle width — consistent with type III. The management of type III is controversial and patient-specific. For this patient, I would lean toward operative management: he is a professional overhead athlete, the injury is acute and within three weeks, it involves his dominant bowling arm, and anatomical reduction may give him the best chance of returning to high-level sport with full shoulder mechanics. I would discuss the options with him — the evidence shows non-operative treatment is satisfactory for 85 to 90 per cent of general patients, but the complication rate of surgery (20 to 40 per cent) and the lack of clear superiority in outcome scores mean this must be a shared decision. If he proceeds to surgery, I would perform an arthroscopic-assisted CC ligament reconstruction using a double-button fixation system supplemented by biological augmentation, with repair of the deltoid-trapezius fascia.
Key clinical points
Correctly classify as Rockwood type III based on ligament disruption and displacement
Recognise and explain the type III controversy — non-operative for most, operative for select patients
List the patient-specific factors favouring surgery: overhead athlete, dominant arm, acute injury less than three weeks, high functional demand
Mention the evidence: systematic reviews show comparable outcomes; surgery has higher complications but may offer better strength and cosmesis in athletes
Common pitfalls
Automatically saying non-operative without discussing the controversy or patient-specific factors
Forgetting to ask about handedness, occupation, sport, and timing of injury
Not mentioning the complication rate of surgery or offering a shared decision
Operating without confirming the classification on an axillary lateral view first
Further questions
“What is your preferred surgical technique and why?”
“How would you counsel him about return to sport and what is the expected timeline?”
“What complications would you warn him about specifically?”
Viva scenarioAdvanced
Clinical prompt
“A 45-year-old construction worker fell from scaffolding onto his right shoulder. He has a grossly deformed shoulder with the clavicle sitting very high — radiographs show it displaced more than twice the clavicle width above the acromion with an empty CC space. The axillary view confirms the clavicle is superiorly displaced, not posterior. How do you classify this, what is your surgical plan, and what are the key steps?”
Practical approach
I would classify this as a Rockwood type V AC joint separation. Both AC and CC ligaments are torn, and the clavicle is displaced superiorly by more than twice the clavicle width — the severe displacement and stripping of the deltoid and trapezius from the distal clavicle define type V. This is an operative injury. My surgical plan is open reduction and CC ligament reconstruction with repair of the deltoid-trapezius fascia. I would use a technique that provides stable initial fixation and reliable biological healing — my preference is a coracoclavicular double-button fixation (TightRope system) combined with an anatomical AC ligament reconstruction using a semitendinosus allograft. The key steps are: first, a sabre-type incision over the distal clavicle extending to the coracoid; second, debridement of the AC joint scar tissue; third, reduction of the clavicle to the acromion with provisional K-wire fixation; fourth, drilling tunnels through the clavicle and the base of the coracoid; fifth, passing the double-button construct and reducing the CC distance anatomically; sixth, augmenting with the allograft woven through bone tunnels to reconstruct the AC and CC ligaments; seventh, repairing the deltoid and trapezius back to the distal clavicle with non-absorbable sutures; and eighth, closing in layers with the arm in a sling. Post-operatively, I would protect in a sling for four to six weeks, commence passive ROM immediately, progress to active-assisted then active by six weeks, and start strengthening from three months. I would warn him about the risks of loss of reduction, hardware irritation requiring removal, infection, and delayed or non-union of the AC joint.
Key clinical points
Correctly classify as type V based on severe superior displacement (greater than 100 per cent of clavicle width) and deltoid-trapezius stripping
State that types IV, V, and VI are operative — the structural failure does not remodel with non-operative treatment
Describe a specific, step-by-step surgical technique with named implants
Include post-operative rehabilitation protocol and specific complications
Common pitfalls
Classifying as type III — the severe displacement and soft-tissue stripping distinguish V from III
Describing non-operative treatment for any type V injury
Not describing deltoid and trapezius repair — the soft-tissue envelope is key to outcome
Giving a vague surgical plan without named steps or fixation method
Further questions
“How does your plan differ for a type IV injury?”
“What are the biomechanical differences between hook plate fixation and double-button reconstruction?”
“What would you do if the reduction is lost post-operatively?”
Exam day cheat sheet
Rockwood Classification \u2014 Exam Cheat Sheet
Classification — ligament disruption and displacement
- I: AC sprained, CC intact, no displacement
- II: AC torn, CC sprained, slight superior displacement (less than 50 per cent of clavicle width)
- III: AC and CC torn, superior displacement 25 to 100 per cent of clavicle width, deltoid-trapezius detached
- IV: AC and CC torn, posterior displacement into trapezius — detect on axillary view
- V: AC and CC torn, severe superior displacement (100 to 300 per cent), deltoid-trapezius stripped
- VI: AC and CC torn, inferior subcoracoid displacement — rare, high-energy, screen neurovascular status
Imaging essentials
- Zanca view (10 to 15 degree cephalic tilt AP centred on AC joint) — primary grading view
- Axillary lateral — essential to detect type IV (posterior) and type VI (inferior) displacement
- Weighted stress views — 5 to 10 kg per hand; distinguishes type II from III by unmasking CC instability
- Normal CC distance is 1.1 to 1.3 cm; a difference greater than 50 per cent compared with the contralateral side suggests complete CC disruption
Treatment rules
- I and II: non-operative — sling, ice, analgesia, early ROM; expect excellent outcome
- III: controversial — non-operative first line (85 to 90 per cent satisfactory); surgery for overhead athletes, manual labourers, dominant arm, acute less than three weeks
- IV, V, VI: operative — CC ligament reconstruction, deltoid-trapezius repair; type VI is urgent
- Type III surgery factors: sport, occupation, dominance, timing, cosmetic concern, and bilateral comparison
Exam traps
- Forgetting the axillary view — you cannot classify without it
- Classifying a type V as type III — the displacement and soft-tissue stripping are different
- Saying all type III injuries are non-operative without mentioning the controversy or patient factors
- Not mentioning complications of surgery (20 to 40 per cent rate: hardware failure, infection, loss of reduction, re-operation)