Which test is used to assess posterior shoulder instability?

• A. Posterior Apprehension Test
• B. Sulcus Sign
• C. Moving Valgus Test
• D. Tinel's sign (elbow)

Answer: (A)

Posterior shoulder instability is best evaluated by provoking posterior translation of the humeral head within the glenoid to reproduce apprehension or pain, indicating that the joint can become unstable in the posterior direction. The Posterior Apprehension Test specifically places the arm in a position that stresses the posterior capsule and labrum and then applies a posterior directed force on the humeral head. A positive result—patient apprehension or discomfort consistent with instability—signifies posterior instability or a posterior labral lesion.

The other tests target different structures or joints: the Sulcus Sign assesses inferior/laxity of the shoulder capsule rather than posterior stability; the Moving Valgus Test checks for elbow medial collateral ligament injury; and Tinel's sign at the elbow evaluates ulnar nerve irritation, not the shoulder joint.