Which test is performed by the examiner applying compression across the AC joint with the patient seated?

• A. Cross body adduction
• B. AC shear test
• C. Yergason's test
• D. Adson's test

Answer: (B)

The test being described is designed to stress the acromioclavicular (AC) joint directly to detect pathology there. When the examiner places a hand on the clavicle and the other on the acromion (or the spine of the scapula) and applies a compressive force across the AC joint while the patient is seated, a shearing force is created at the joint surfaces. If this reproduces pain localized to the AC joint or reveals abnormal movement, it suggests an AC joint sprain or other AC joint pathology. This approach specifically targets the AC joint itself, unlike other tests listed which assess different structures (for example, the Yergason’s test for the biceps tendon, the Adson’s test for thoracic outlet syndrome). The cross-body adduction test also stresses the AC joint but the described mechanism—compression directly across the AC joint with the patient seated—most closely matches the AC shear test.