Which AC joint sprain type features inferior displacement of the distal clavicle under the conjoined tendon with rib fractures and neurovascular injury?

Which AC joint sprain type features inferior displacement of the distal clavicle under the conjoined tendon with rib fractures and neurovascular injury?

• A. Type 6
• B. Type 4
• C. Type 2
• D. Type 5

Answer: (A)

This question hinges on recognizing the most severe pattern of AC joint injury in the Rockwood classification, which describes how the clavicle shifts after ligament disruption. The key descriptor here is the distal clavicle being displaced inferiorly beneath the conjoined tendon (the short head of the biceps with the coracobrachialis) and accompanied by rib fractures and neurovascular injury. That combination signals a high-energy, complete disruption of the AC and CC ligaments with the clavicle driven downward under the conjoined tendon, a pattern that is rare and represents the extreme end of the spectrum. Other patterns involve different directions of displacement (posterior in some cases, superior in others) and do not include this specific inferior under-tendon position with associated thoracic injuries. Hence, this description corresponds to the most severe, rarely seen form of AC joint disruption.

This question hinges on recognizing the most severe pattern of AC joint injury in the Rockwood classification, which describes how the clavicle shifts after ligament disruption. The key descriptor here is the distal clavicle being displaced inferiorly beneath the conjoined tendon (the short head of the biceps with the coracobrachialis) and accompanied by rib fractures and neurovascular injury. That combination signals a high-energy, complete disruption of the AC and CC ligaments with the clavicle driven downward under the conjoined tendon, a pattern that is rare and represents the extreme end of the spectrum. Other patterns involve different directions of displacement (posterior in some cases, superior in others) and do not include this specific inferior under-tendon position with associated thoracic injuries. Hence, this description corresponds to the most severe, rarely seen form of AC joint disruption.