Which examination test is used to assess acromioclavicular joint injury by placing the arm across the chest?

• A. O'Brien test
• B. Apprehension test
• C. Cross-arm (horizontal adduction) test
• D. Apley grind

Answer: (C)

The main idea is to assess the acromioclavicular joint by bringing the arm across the chest to provoke pain at the AC joint. In the cross-arm (horizontal adduction) test, the patient places one arm across the chest and the examiner gently adducts the arm horizontally, applying light pressure to stress the AC joint. If an AC joint injury or separation is present, this maneuver reproduces localized pain over the AC joint, indicating pathology in that joint.

This test is specifically about the AC joint, unlike other common shoulder maneuvers. For example, the apprehension test evaluates anterior shoulder instability in the glenohumeral joint, not the AC joint. The Apley grind tests the knee joint, not the shoulder. The O'Brien test is used for intra-articular shoulder pathology such as a SLAP lesion, though it can provoke AC joint pain in some contexts, the cross-arm approach remains the most direct test for AC joint injury.