O’Brien’s Test, also known as the Active Compression Test, is a common physical examination technique used in orthopedics to assess shoulder pain. Healthcare professionals often employ it as part of a broader evaluation to pinpoint the source of a patient’s shoulder symptoms.
What O’Brien’s Test Identifies
O’Brien’s Test primarily helps diagnose specific shoulder conditions, particularly labral tears and acromioclavicular (AC) joint issues. The labrum is a ring of cartilage lining the shoulder’s socket, providing stability. A Superior Labrum Anterior to Posterior (SLAP) tear, an upper labrum tear, can cause pain and clicking, often from repetitive overhead motions or acute trauma. The test also evaluates the AC joint, where the collarbone meets the shoulder blade. Problems like inflammation or injury in this joint can cause shoulder pain.
Performing the Test
A healthcare professional performs O’Brien’s Test with the patient seated or standing. The patient extends the affected arm forward to 90 degrees of shoulder flexion, keeping the elbow straight. The arm moves slightly across the body (10-15 degrees), and the hand rotates inward with the thumb pointing downward. In this position, the examiner applies a downward force, and the patient resists. The test repeats with the hand rotated outward, palm up, as the patient resists another downward force.
Interpreting Test Findings
A positive O’Brien’s Test occurs when the patient experiences pain or clicking in the shoulder during the first position (thumb down) that decreases or disappears in the second (palm up). Deep shoulder pain or a clicking sound may suggest a labral tear. Conversely, pain felt closer to the surface, at the top of the shoulder, may indicate an AC joint problem. A negative test result means the specific pain pattern was not reproduced. A positive test indicates a potential issue, but further diagnostic steps are needed.
Important Considerations for the Test
O’Brien’s Test is one component of a thorough shoulder examination, not a standalone diagnostic tool. Its diagnostic accuracy, including sensitivity (ability to correctly identify those with the condition) and specificity (ability to correctly identify those without the condition), varies across studies. For SLAP lesions, sensitivities range from 20% to 96%, with specificities from 38% to 100%. For AC joint lesions, sensitivities can be as low as 14%, while specificities may be around 92%. Due to this variability, the test is combined with other physical examination maneuvers, a detailed patient history, and often imaging studies like MRI scans for a more definitive diagnosis. Orthopedic surgeons and physical therapists commonly perform this test.