Which test would most likely yield a positive result in a patient with posterior labral involvement presenting with instability?

• A. Jerk Test
• B. Pull Test
• C. Tinel's sign (elbow)
• D. Cozen's test

Answer: (A)

Posterior shoulder instability from a posterior labral tear is best teased out with a test that specifically loads the posterior aspect of the glenoid and watches for a sudden shift of the humeral head. The jerk test does exactly this: with the arm brought across the body and a posterior-directed load transmitted through the arm, the humeral head is stressed against the posterior glenoid rim. If a posterior labral pathology is present, the humeral head will subluxate posteriorly and then reduce, often producing a sudden clunk or reproduced pain. This clunk or abrupt movement is a hallmark of a positive test and points toward posterior labral involvement with instability.

The other signs and tests target different issues. Tinel’s sign at the elbow checks for ulnar nerve irritation, not shoulder labral pathology. Cozen’s test is used for lateral elbow tendinopathy, not the shoulder. The pull maneuver described in some instability screens isn’t specifically designed to provoke posterior labral tears, so it wouldn’t be the most sensitive choice for posterior labral involvement with instability.