The Drop Arm Test is used for diagnosing rotator cuff tendon tears, specifically the supraspinatus tendon tear. The test helps in determining if there is a tear in the supraspinatus tendon and the can be done by many techniques. The patient should be instructed to fully abduct the arm. Then, the patient should slowly lower the arm to the side. If there is a tear in the rotator cuff tendon, the arm will drop from a position of about 90° of abduction. 
Even if the patient attempts this several times, the patient with a supraspinatus tendon tear cannot lower the arm smoothly and slowly. If the patient with the supraspinatus tendon tear is able to hold the arm in abduction, a small amount of pressure on the forearm will cause the arm to fall to the side.
Another method of performing the test begins with the physician instructing the patient to fully abduct the arm and the examiner supporting the arm so that it is able to be tested in 90° of abduction. The patient is asked to actively lower the arm from abduction to the side, slowly and
smoothly in a controlled way. A positive test occurs when the patient is unable to hold the arm in 90° of abduction or is unable to control lowering the arm to the side. The practical way of performing the test is when the examiner holds the arm fully abducted by the side of the patient and then will release it. If the arm drops, this will mean that there is a large rotator cuff tear present. The test is positive when pain and weakness causes the arm to drop to the side.
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