In the O'Brien test, pain with the arm in pronation that is relieved in supination suggests which diagnosis?

• A. SLAP tear
• B. AC joint pathology
• C. Biceps tenosynovitis
• D. Rotator cuff tear

Answer: (A)

The test targets the superior labrum and the biceps anchor inside the shoulder joint. When the arm is flexed to about 90 degrees, adducted, and the forearm is pronated, a SLAP tear makes the intra-articular structures more likely to hurt. If you then supinate the forearm, the tension on the biceps anchor decreases and the pain often improves. That pronation-agonist pain relieved by supination points to intra-articular labral pathology rather than extra-articular issues. Rotator cuff tears typically show weakness or pain with specific resisted motions rather than a rotation-dependent pain pattern; biceps tenosynovitis tends to produce tenderness along the bicipital groove and different tendon-specific tests; AC joint pathology produces pain localized to the AC joint and with cross-body adduction. So the pronation pain relieved by supination pattern is most consistent with a SLAP tear.