Which movement during Codman's Drop Arm Test assesses rotator cuff function?

The movement associated with controlled lowering from shoulder height during Codman's Drop Arm Test is significant in assessing rotator cuff function, particularly the integrity of the supraspinatus muscle. This test is designed to evaluate the ability of a patient to stabilize the arm in an abducted position, usually at 90 degrees.

When the arm is raised to shoulder height and then the patient is instructed to lower it in a controlled manner, it provides insight into their rotator cuff strength and function. If the patient can control the descent without the arm dropping rapidly, it suggests that the rotator cuff, particularly the supraspinatus, is functioning properly. Conversely, difficulty in controlling the arm's descent or a rapid drop may indicate a tear or weakness in the rotator cuff, demonstrating the test's effectiveness in identifying potential injuries in that area.

The other movements do not accurately reflect the assessment of rotator cuff function as effectively. Rapid drops may indicate instability but are not as indicative of controlled strength, while immediate lifting or stabilizing the shoulder during abduction do not directly assess the muscle's ability to manage descent, which is critical for an accurate evaluation of rotator cuff integrity.