What is shoulder impingement?

• A. Dislocation of the acromioclavicular joint.
• B. Fracture of the clavicle.
• C. Frozen shoulder unrelated to impingement.
• D. Compression of the rotator cuff tendons or subacromial bursa between the humeral head and acromion during overhead activities.

Answer: (D)

Shoulder impingement is the pinching of the rotator cuff tendons and the subacromial bursa between the humeral head and the acromion that occurs when the arm is raised overhead. As the arm elevates, the available space above the rotator cuff narrows, so repetitive or forceful overhead movements irritate or compress these structures, leading to pain, weakness, and limited motion. This description matches the idea of compression of the rotator cuff tendons or subacromial bursa between the humeral head and the acromion during overhead activities.

Dislocation of the acromioclavicular joint is a separation at the joint between the clavicle and the acromion, not a pinch under the acromion. Fracture of the clavicle is a bone break in the collarbone. Frozen shoulder (adhesive capsulitis) involves global shoulder stiffness and reduced range of motion, not primarily compression under the acromion during elevation.