O'Brien Test: Purpose, Performance, Interpretation, and Clinical Significance

What is the O-Brien Test?

The O'Brien test, also known as the Active Compression Test, is a clinical orthopedic examination used primarily to assess for superior labral anterior-posterior (SLAP) lesions and acromioclavicular (AC) joint pathology in the shoulder.

Introduction and Purpose

The O'Brien test is a widely utilized special test in physical examination for the shoulder, designed to help clinicians differentiate between various sources of shoulder pain, particularly those originating from the superior labrum or the acromioclavicular joint. Developed by Dr. Stephen J. O'Brien, it is a provocative test, meaning it attempts to reproduce the patient's symptoms by placing stress on specific anatomical structures. Its primary utility lies in aiding the diagnosis of SLAP tears, which involve the cartilage rim (labrum) at the top of the shoulder socket where the biceps tendon attaches, and osteoarthritic changes or sprains within the AC joint.

Anatomy and Biomechanics Involved

Understanding the structures involved is crucial for appreciating the O'Brien test's mechanism. The test primarily stresses:

• Superior Labrum: The fibrocartilaginous rim surrounding the glenoid fossa (shoulder socket). SLAP tears typically occur in the superior aspect of this labrum, often extending into the biceps tendon anchor.
• Biceps Tendon (Long Head): This tendon originates from the superior labrum and supraglenoid tubercle. Stressing the labrum can also place tension on the biceps anchor.
• Acromioclavicular (AC) Joint: The articulation between the acromion of the scapula and the clavicle. This joint is susceptible to injury and degenerative changes.
• Glenohumeral Joint: While not the primary target, the overall mechanics of the shoulder joint are involved in the movement.

The specific positions of shoulder flexion, adduction, and rotation during the test are designed to compress and shear these structures, making existing pathology symptomatic.

How to Perform the O'Brien Test (The Active Compression Test)

The O'Brien test involves two distinct phases, each designed to provoke symptoms in different ways. The patient should be seated or standing, with the examiner positioned to observe and apply resistance.

• Patient/Client Positioning: The patient is seated or standing comfortably with their shoulder exposed.
• Examiner Positioning: The examiner stands beside or in front of the patient, ready to apply resistance and observe responses.

Phase 1: Internal Rotation and Adduction

1. Shoulder Flexion: The patient actively flexes their affected shoulder to 90 degrees.
2. Horizontal Adduction: The arm is then adducted horizontally across the body by approximately 10-15 degrees.
3. Internal Rotation: The patient fully internally rotates their shoulder, so the thumb points downwards (like emptying a can).
4. Resistance Application: The examiner applies a downward resistance to the distal forearm, while the patient resists the movement. The patient is asked to report any pain or clicking.

Phase 2: External Rotation and Abduction

1. Shoulder Flexion and Adduction (Same as Phase 1): The arm remains in 90 degrees of flexion and 10-15 degrees of horizontal adduction.
2. External Rotation: The patient externally rotates their shoulder, so the palm faces upwards (like holding a can).
3. Resistance Application: The examiner again applies a downward resistance to the distal forearm, while the patient resists the movement. The patient is asked to report any pain or clicking.

Throughout both phases, the examiner carefully monitors for the reproduction of pain, clicking, or a sense of "giving way."

Interpreting the Results

Interpretation of the O'Brien test relies on the patient's reported symptoms and the comparison between the two phases.

• Positive Test Indicators for SLAP Lesion:

  • Pain reported deep within the glenohumeral joint during Phase 1 (internal rotation).
  • A reduction or complete elimination of this pain during Phase 2 (external rotation).
  • A painful clicking or catching sensation may also be reported.
  • This "painful arc" suggests irritation or damage to the superior labrum and/or biceps anchor, which is maximally stressed in the internally rotated position.

• Positive Test Indicators for AC Joint Pathology:

  • Pain reported specifically over the AC joint (on top of the shoulder) during both Phase 1 and Phase 2.
  • The pain does not significantly change or is not relieved between the two phases.
  • This indicates compression or shear stress on the AC joint.

• Negative Test Indicators:

  • No pain or discomfort reported in either phase.
  • Pain is reported in both phases, but it is not localized to the AC joint or deep glenohumeral joint, or it does not follow the specific pattern for a SLAP lesion.

Clinical Significance and Limitations

The O'Brien test is a valuable tool, but its results must be interpreted within the context of a comprehensive physical examination and patient history.

• Reliability and Validity: Studies have shown variable sensitivity and specificity for the O'Brien test in diagnosing SLAP lesions, ranging from moderate to high. It is generally considered more sensitive for SLAP II lesions. Its specificity for AC joint pathology is also considered good.
• Differential Diagnosis: A positive O'Brien test for a SLAP lesion should prompt further investigation, as other conditions (e.g., biceps tendinopathy, rotator cuff pathology) can sometimes mimic its presentation. Similarly, AC joint pain can be caused by various factors, and the test helps to confirm the joint as a source of symptoms.
• Limitations:
  • It is not a standalone diagnostic test; imaging (MRI) is often required for definitive diagnosis.
  • False positives can occur, especially in individuals with non-specific shoulder pain or other shoulder pathologies.
  • Patient apprehension or inability to fully relax can affect results.
  • The test may be less reliable in older populations due to higher prevalence of degenerative labral changes that may not be symptomatic.

Who Should Perform This Test?

The O'Brien test should only be performed by qualified healthcare professionals who are trained in orthopedic physical examination, such as:

• Orthopedic Surgeons
• Physical Therapists (Physiotherapists)
• Chiropractors
• Sports Medicine Physicians
• Athletic Trainers

These professionals have the anatomical knowledge and clinical expertise to perform the test correctly, interpret the findings accurately, and integrate them into a broader diagnostic and treatment plan. It is not intended for self-assessment or for individuals without clinical training to perform on others.

Conclusion

The O'Brien test, or Active Compression Test, stands as a critical component in the diagnostic toolkit for shoulder pathologies, particularly SLAP lesions and AC joint dysfunction. By systematically stressing specific structures of the shoulder through precise movements and resistance, it provides valuable clinical information to guide diagnosis. However, like all special tests, its findings must be carefully weighed against the patient's full clinical picture, history, and potentially confirmatory imaging to ensure an accurate and comprehensive understanding of the patient's condition.