Video 4.1. The O’Brien’s Active Compression Test

The examiner performs the active compression test on a patient. The patient’s shoulder is placed in 90 degrees of forward elevation with the elbow fully extended. The arm is then adducted 10 to 15 degrees. First, the shoulder is internally rotated and the forearm is pronated with the thumb pointing to the floor. In this position, the examiner then exerts an inferiorly directed force to the arm. Next, the shoulder is rotated to neutral external rotation and the forearm is supinated with the thumb pointing to the ceiling. In this position, the examiner again exerts an inferiorly directed force to the arm. A test is considered positive if there is pain in the glenohumeral joint when the forearm is pronated (first position) and the pain is diminished or absent when the arm is supinated (second position). A positive test is suggestive of a superior labrum anterior to posterior (SLAP) tear. Here, the patient has a positive O’Brien’s active compression test. Notably, as with this patient, the pain experienced during the maneuver is located “deep” in the glenohumeral joint.