O’Brien’s test: How to perform and interpret the result

Key takeaways

O’Brien’s test, also called the active compression test, screens for SLAP lesions and acromioclavicular joint pathology in one two-position maneuver.

Pain deep inside the shoulder that eases in supination points to a SLAP lesion. Pain at the top points to the AC joint.

Reported sensitivity for SLAP detection ranges from 63% to 94% and specificity from 28% to 73%, so the test never confirms a diagnosis alone.

The comparison table below sets O’Brien’s test against Speed’s, Yergason’s, Hawkins-Kennedy, the crank test, and the empty can test.

Practice management software like Pabau keeps shoulder examination findings documented the same way across every practitioner in your team.

Shoulder pain is one of the most common musculoskeletal presentations in practice. Two of its structural causes, SLAP lesions and acromioclavicular joint pathology, produce symptoms that overlap heavily. History alone rarely separates them.

O’Brien’s test was described in 1998 to answer exactly that question. It takes under two minutes, needs no equipment, and separates intra-articular labral pathology from the AC joint in one sequence.

This guide covers the positioning protocol and how to read each result. It also explains what the accuracy figures mean at the bedside, and when to order imaging. A side-by-side table further down compares the maneuver with the other shoulder tests you would run alongside it.

What is O’Brien’s test and what does it detect?

O’Brien’s test, also called the active compression test, screens the shoulder for two distinct problems. Those are superior labrum anterior-to-posterior (SLAP) tears and acromioclavicular (AC) joint disorders. O’Brien and colleagues first described it in 1998. Plenty of textbooks drop the possessive and write it as the O’Brien test, so both spellings describe the same maneuver.

The name active compression test describes the mechanics. The examiner compresses the superior labrum and the AC joint while the patient actively resists a downward force. That is why O’Brien’s special test screens two structures in one sequence, where most shoulder special tests interrogate only one.

The test applies that compressive load in two forearm positions. The first is internal rotation with the thumb down, the second is supination with the palm up. Comparing pain between those two positions is what localizes the source of the complaint.

A reproducible protocol matters most in group practices, where several practitioners assess the same patient over a course of care. Teams running physical therapy practice management software can store that protocol as a shared template. The same works for other regional screens, such as Kemp’s test for the lumbar spine.

The anatomy behind the test

Two structures take the load during O’Brien’s test, and knowing which is which makes the result readable.

The superior labrum is a fibrocartilaginous rim that deepens the glenoid socket. The long head of the biceps tendon originates there, forming the biceps-labral complex. A SLAP lesion tears that labrum forward, backward, or both from the biceps anchor.

When the arm is loaded in internal rotation and forward flexion, compressive force shears across the compromised tissue. That is what provokes the pain you are testing for.

The AC joint sits directly above, where the distal clavicle meets the acromion. Adducting the arm across the body in forward flexion compresses that joint. Pain from here is felt at the top of the shoulder rather than deep inside the glenohumeral joint. That difference drives the whole interpretation.

How to perform O’Brien’s test: Step by step

Every published source converges on the same positioning protocol. Follow it precisely. Small deviations in adduction angle or elbow position change which structures are loaded, and that produces misleading results.

1. Position the patient. The patient stands or sits with their back to the examiner. Standing is more common in practice, but either works.
2. Set the arm at 90° of forward flexion. Bring the arm to 90 degrees of forward flexion with the elbow fully extended. Partial elbow flexion reduces the compressive force on the superior labrum.
3. Adduct 10-15° across the midline. From that flexed position, bring the arm roughly 10 to 15 degrees across the body’s midline. This maximally compresses both the superior labrum and the AC joint.
4. Internally rotate the forearm, thumb down. Ask the patient to pronate fully so the thumb points at the floor. This is the first test position.
5. Apply a downward force. Place one hand on the patient’s forearm and stabilize the scapula with the other. Apply a steady downward force while the patient resists. Note whether pain or clicking appears, and exactly where.
6. Repeat in supination, palm up. Without moving the arm, ask the patient to supinate fully so the palm faces up. Apply the same downward force. Ask whether the pain has changed, disappeared, or stayed the same.

The whole maneuver takes under two minutes and needs nothing but your hands. Getting every practitioner to record it the same way is the harder part. Digital intake forms with a built-in shoulder examination template solve that.

How to interpret the results

A positive O’Brien’s test needs two findings together. The first is pain or clicking in pronation. The second is a clear reduction of that symptom in supination. Where the patient feels the pain then separates SLAP pathology from AC joint pathology.

The table below sets out all four scenarios, cross-checked against Cleveland Clinic and standard physical therapy references:

Pain that appears in both positions, or that does not change between them, is not a positive O’Brien’s test. What you are looking for is the change between positions.

SLAP lesion: Deep shoulder pain that changes with rotation

A SLAP-positive result means the patient reports pain or clicking deep inside the shoulder during the pronated phase. That symptom eases meaningfully once the arm moves into supination. Rotating the forearm changes tension on the biceps-labral complex, which offloads the damaged tissue. That mechanism is why the maneuver works as a labral test, rather than a general pain provocation test.

Treat the result as clinically significant rather than confirmatory. It carries most weight in three groups:

• Overhead athletes, especially throwers with a painful late cocking phase
• Patients who felt a pop during a fall on an outstretched hand
• Anyone reporting deep shoulder pain on resisted biceps loading

Surgical planning still waits for imaging, and return-to-sport protocols after a SLAP repair are built around the confirmed lesion type.

AC joint pathology: Pain at the top of the shoulder

An AC joint-positive result uses the same position-change criterion, but the pain localizes to the superior shoulder rather than deep inside the glenohumeral joint. The adducted, forward-flexed arm compresses the distal clavicle against the acromion, and supination partly unloads it.

Patients usually point to the very top of the shoulder when asked to locate the pain. A SLAP response sends the finger inward, or toward the axilla. When imaging confirms an acromioclavicular dislocation, the code depends on how far the joint has displaced. A follow-up visit for a 200% displacement injury is coded as S43.139D. Lesser separations take a different code in the S43.1 series.

Sensitivity and specificity: How accurate is the test?

Accuracy varies widely, and that variation is itself the clinically useful finding. Reported sensitivity spans 63% to 94%, and specificity spans 28% to 73%. A test behaves very differently at either end of those ranges.

The figures depend on the patient population, the examiner’s technique, and the reference standard used for comparison. Read the numbers before you lean on them in a treatment decision.

For the AC joint the pattern reverses. Sensitivity is low, so a negative result misses plenty of AC pathology. Specificity is high, so pain that localizes to the top of the shoulder carries weight when it appears. That makes the maneuver useful for ruling AC pathology in, and poor at ruling it out.

The 1998 original paper reported sensitivity of 100% and specificity of 98.5%. No independent study has reproduced those figures. Later systematic reviews report more modest and more variable numbers. Examiner technique, patient selection, and the choice of arthroscopy or MRI arthrogram as the gold standard all move the result.

As with other clinical decision rules in musculoskeletal practice, context matters as much as the result. A positive test in a 22-year-old thrower means something different from the same result in a 60-year-old with degenerative AC change.

Limitations and common pitfalls

Several limitations reduce the test’s reliability in day-to-day practice. Know them before you draw a conclusion from a positive result.

• False positives from rotator cuff pathology. Cuff tears and supraspinatus tendinopathy provoke pain in the same arm position. A drop arm test helps separate the two.
• Biceps tendinopathy overlap. The maneuver loads the biceps-labral complex, so long head tendinopathy can mimic a SLAP response. Speed’s test and Yergason’s test help differentiate.
• Examiner technique varies. Small differences in adduction angle, forearm rotation, or force direction change which structures are compressed. Tests with a measured endpoint, such as the knee-to-wall test, are less exposed to this. Standardizing technique across the practice is the closest equivalent here.
• Pain reporting is subjective. The test depends on the patient locating their own pain. Diffuse shoulder pain or radiation from the cervical spine muddies that answer. Every provocation test shares that weakness, including the windlass test at the foot.
• Combined pathology is common. Plenty of patients have AC joint degeneration and labral pathology at once, which makes clean differentiation impossible from this test alone.

Professional standards expect every clinical decision to be justified by the evidence available at the time. Record why a positive result led to a particular management pathway, and note which limitations you weighed. That habit is what turns a treatment note into safer clinical notes that hold up under review.

When to combine it with other shoulder tests

No single shoulder special test is accurate enough to diagnose SLAP or AC pathology on its own. A 2018 systematic review of acromioclavicular examination reached the same conclusion. It recommended clustering tests rather than trusting any one of them.

The table below sets O’Brien’s test beside the five maneuvers most often paired with it. Read it by arm position first. Each test loads a different structure, and that is what a combination buys you.

The empty can test sits in that table as the contrast case. It is the only maneuver here that loads neither the labrum nor the AC joint. Running it alongside O’Brien’s is the quickest way to see whether the cuff is generating the pain you just provoked.

Pair the tests by what they rule out, not by how many you can fit into a session. Two positives that load the same structure tell you little more than one does.

Recording all of them as one assessment episode is what makes the combination useful later. Sports medicine software that stores examination templates against the patient timeline makes that practical.

When to escalate to MRI after a positive result

A positive O’Brien’s test raises suspicion. It does not confirm a structural diagnosis, and the decision to image is a separate judgment.

Refer for shoulder MRI or MRI arthrogram when any of the following applies:

• Multiple shoulder tests are positive for SLAP pathology, such as O’Brien’s plus a positive crank or Yergason’s test
• Symptoms persist beyond 6 to 8 weeks of targeted conservative management
• The patient is an overhead athlete whose symptoms limit sport participation and a return-to-sport decision is due
• Surgical planning is on the table, since Snyder Type I to IV classification needs an MRI arthrogram
• The picture is unclear, with pain in both pronation and supination, suggesting a cuff component or combined pathology

Standard shoulder MRI has moderate sensitivity for SLAP tears. MRI arthrogram, using intra-articular contrast, improves both sensitivity and specificity, so it is the better choice when surgery is being planned. Neither replaces the clinical examination in the initial assessment.

Screening with O’Brien’s test and reserving imaging for the indicators above matches guidance from the American Academy of Orthopaedic Surgeons (AAOS).

Practices that keep structured patient records can show the reasoning from positive test to imaging request. That trail matters for audit and for insurance documentation.

How Pabau standardizes shoulder assessment documentation

Most physical therapy and sports medicine practices still record special tests in free-text notes. One practitioner writes “O’Brien’s positive”. Another writes out the pain location and the supination response. Six weeks later, nobody can tell whether the finding changed.

Practice management software like Pabau replaces that with a structured form. You build a shoulder examination template once, with fields for arm position, pain location, and the pronation-to-supination change. Every practitioner then answers the same questions in the same order.

The findings attach to the patient record, so the next clinician sees what was tested and what it showed. Our physical therapy EMR also triggers the follow-up task when a positive result needs an imaging referral. That means fewer patients waiting on a scan request nobody chased.

Document shoulder findings the same way across your team

Pabau captures structured examination findings, attaches them to the patient record, and triggers the follow-up automatically. See how physical therapy and sports medicine practices use it.

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Conclusion

The value of O’Brien’s test is speed and direction. In under two minutes it points you at the superior labrum or the AC joint. History alone rarely does that. It will not give you the diagnosis. Treating a positive result as one leads to unnecessary imaging and misdirected treatment.

So run it as a screening step inside a battery. Record the pain location as carefully as the pain itself. Let the change between positions carry the weight. Do that consistently and your imaging referrals get easier to justify, because the reasoning is already written down.

Consistency across a whole team is a documentation problem more than a clinical one. Book a demo to see how Pabau standardizes shoulder examination records and connects them to follow-up care.

Continue your research

Setting up a physical therapy practice? Opening a physiotherapy clinic walks through the compliance, staffing, and software decisions you face before the first patient.

Need to rule the biceps in or out? Bicep tear test compares the hook test and Yergason’s, and says when each one earns its place.

Building a wider special-test battery? Lateral pivot shift test shows how grading works when a special test has more than a yes-or-no answer.

Want normative values to compare against? Deep neck flexor endurance test gives the timings that separate a normal result from a deficit.

Clearing an athlete to return to sport? Drop jump test covers the protocol and the metrics that support a return-to-play decision.

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