AC Joint Separation: Rockwood Classification, Treatment & Recovery MCQs

Acromioclavicular (AC) Joint Injuries

Often called a "Shoulder Separation," AC joint injuries are common in contact sports. The injury ranges from a simple sprain to a complete displacement involving both the AC and Coracoclavicular (CC) ligaments.

1. Relevant Anatomy

• AC Ligaments: Control horizontal stability (AP direction).
• Coracoclavicular (CC) Ligaments: Control vertical stability. Composed of Conoid and Trapezoid ligaments.

2. Rockwood Classification

• Type I: Sprain of AC ligament. CC normal. No deformity.
• Type II: Tear of AC ligament. Sprain of CC. Slight step-off.
• Type III: Tear of BOTH AC and CC ligaments. 100% displacement (Complete dislocation).
• Type IV: Clavicle displaced posterior into Trapezius.
• Type V: Severe superior displacement (>100-300%).
• Type VI: Inferior displacement (subcoracoid). Rare.

3. Management

• Conservative (Type I & II): Ice, Sling (1-2 weeks), NSAIDs. Rehab starts early.
• Controversial (Type III): Most treated conservatively initially. Surgery for laborers/overhead athletes.
• Surgical (Type IV, V, VI): Reconstruction of ligaments (e.g., Weaver-Dunn procedure, Dog-bone button).

Clinical Sign: "Piano Key Sign"
Pressing down on the distal clavicle causes it to depress and then spring back up (like a piano key), indicating a ruptured CC ligament.

25 Practice MCQs

Q1. Which ligaments are torn in a Rockwood Type III injury?

Answer: C). Complete disruption of both sets of ligaments.

Q2. The "Piano Key Sign" indicates vertical instability due to rupture of:

Answer: B). The CC ligaments prevent the clavicle from springing up.

Q3. Which view is best to visualize AC joint pathology?

Answer: A). It removes superimposition of the scapular spine.

Q4. Type I AC injury is managed by:

Answer: B). Symptomatic relief only.

Q5. The two parts of the Coracoclavicular ligament are:

Answer: A). Conoid is medial/posterior, Trapezoid is lateral/anterior.

Q6. In Type IV injury, the clavicle is displaced:

Answer: B). A key distinguishing feature of Type IV.

Q7. The most common mechanism of AC joint injury is:

Answer: A). Drives the acromion down, away from the clavicle.

Q8. Weaver-Dunn procedure involves transferring which ligament?

Answer: A). The CA ligament is transferred to the distal clavicle to mimic the CC ligament.

Q9. Which Rockwood type involves >100% superior displacement with skin tenting?

Answer: C). Severe superior displacement.

Q10. Painful Arc Syndrome associated with AC joint pathology occurs at:

Answer: B). High painful arc is specific to the AC joint.

Q11. The Cross-Body Adduction test (Scarf Test) is positive for:

Answer: A). Compresses the AC joint surfaces.

Q12. Osteolysis of the distal clavicle is common in:

Answer: A). Due to repetitive microtrauma (bench press).

Q13. The primary restraint to horizontal translation of the AC joint is:

Answer: A). AC ligaments control AP stability.

Q14. Which type of displacement is Type VI?

Answer: B). The clavicle is lodged under the coracoid.

Q15. Chronic AC joint instability often results in:

Answer: A). The scapula is not stable, affecting cuff mechanics.

Q16. "Step deformity" is visible in which grades?

Answer: B). Requires rupture of CC ligaments to drop the scapula significantly.

Q17. The AC joint is what type of joint?

Answer: A). Allows gliding movement.

Q18. Immediate management of Type III on the field involves:

Answer: A). Reduction is not possible/stable on the field.

Q19. Heavy weight lifting should be avoided for how long in Type II injuries?

Answer: B). To allow ligament scarring and healing.

Q20. What view was historically used to check AC instability (stress view)?

Answer: A). Weights pull the arm down; if AC is unstable, the gap widens. (Less common now).

Q21. Mumford procedure is:

Answer: A). For painful AC arthritis, the end of the bone is removed.

Q22. Which muscle reinforces the superior AC joint?

Answer: A). Their fascia blends with the AC ligaments.

Q23. Taping for AC joint injury usually aims to:

Answer: A). To approximate the joint surfaces.

Q24. O'Brien's test is primarily for Labrum, but can indicate AC pain if:

Answer: A). Differentiating superficial (AC) vs deep (Labral) pain is key.

Q25. Post-op rehab for Weaver-Dunn usually restricts active flexion for:

Answer: B). To protect the transferred ligament healing.