Acromioclavicular (AC) joint separation

A 20-year-old female presents with pain in her right shoulder after a fall during a soccer match. On examination, there is decreased range of motion, and the shoulder appears dropped. X-rays show an acromioclavicular joint separation. What is the most likely cause of this injury?

A) Rotator cuff tear
B) Clavicular fracture
C) Acromioclavicular joint separation
D) Glenohumeral dislocation
E) Scapular fracture

Correct Answer:

C) Acromioclavicular joint separation

Explanation:

• Acromioclavicular (AC) joint separation is typically caused by direct trauma or falling onto the shoulder, leading to ligamentous injury and separation of the clavicle from the acromion.
• Rotator cuff tear (A) presents with shoulder weakness and pain with overhead activities, not usually with a dropped shoulder appearance.
• Clavicular fracture (B) is common in falls but would not cause a dropped shoulder unless associated with a severe AC joint injury.
• Glenohumeral dislocation (D) presents with a deformed shoulder and limited range of motion, typically caused by trauma, but not by a dropped shoulder.
• Scapular fracture (E) is less common and would present with severe trauma to the back.

Key Tips for PLAB 1:

✅ Shoulder injury with dropped appearance = AC joint separation
✅ X-ray findings = Separation of the acromion and clavicle
✅ Management = Conservative for mild cases, surgery for severe cases