Which test involves resisting the arm while it is positioned in internal rotation?

The test that involves resisting the arm while it is positioned in internal rotation is O'Brien's test. This examination primarily assesses for labral tears and acromioclavicular joint (ACJ) pathology. During this test, the patient raises their arm to 90 degrees of flexion with the thumb pointing down (internal rotation). The therapist applies downward resistance against the arm, and if there is pain or clicking during this position but relief occurs when the arm is placed in external rotation, it suggests a potential labral tear or issue with the AC joint.

The specific resistance of the arm while it's held in internal rotation is crucial to the test as it simulates the loading of the shoulder in a way that enhances the sensitivity for detecting these specific injuries. This makes O'Brien's test a valuable assessment tool in diagnosing shoulder pathologies, particularly those related to the labrum and AC joint.