What condition is tested by the Lift-Off Sign?

The Lift-Off Sign specifically assesses the function of the subscapularis muscle, which is one of the four rotator cuff muscles. This test is designed to evaluate whether the subscapularis is functioning properly, as it is responsible for internal rotation of the shoulder.

When a patient is instructed to lift their hand off their back while the arm is positioned behind them, an inability to do so indicates a potential dysfunction of the subscapularis. This impairment could be due to a tear or inflammation affecting the muscle or its tendon.

Understanding the mechanics of this test clarifies why it is closely associated with subscapularis dysfunction and not primarily with the other conditions listed. For instance, while rotator cuff injuries encompass a range of issues with multiple muscles, the Lift-Off Sign is more specific and directly surveys the subscapularis. Similarly, anterior shoulder instability and glenohumeral arthritis involve different diagnostic tests and considerations that do not center on the isolated evaluation of the subscapularis muscle's function.