The Posterior Internal Impingement Test is designed to evaluate which condition?

• A. Anterior instability
• B. Subacromial impingement
• C. Posterior impingement
• D. Biceps tendinopathy

Answer: (C)

Posterior impingement occurs when the posterior structures of the shoulder—the rotator cuff tendons and the posterior superior glenoid labrum—are pinched between the humeral head and the posterior rim of the socket, especially in positions of abduction with external rotation. The test reproduces this mechanism by placing the arm in a position that loads those posterior structures—typically about 90 to 110 degrees of abduction with maximal external rotation. If this positioning elicits deep posterior shoulder pain or reproduces the patient’s symptoms, it supports posterior impingement as the source of pain.

This is distinct from anterior instability, which centers on instability or pain at the front of the shoulder; subacromial impingement, which is usually provoked during forward flexion and abduction beneath the acromion; and biceps tendinopathy, which tends to present with pain in the bicipital groove and is more related to resisted movements of the elbow and forearm.