The Scarf Test — also called the cross-arm adduction test or horizontal adduction test — is an orthopedic examination technique used to identify pathology of the acromioclavicular (AC) joint. It is most commonly used to assess AC joint osteoarthritis and ligament injury, and earns its name from the arm position required: the patient’s arm crosses the body in the same motion as throwing a scarf over the opposite shoulder.
The test works by compressing the AC joint through horizontal adduction, reproducing localized pain at the joint line when pathology is present.
Quick Reference
| Also Called | Cross-arm adduction test; horizontal adduction test |
| Joint Assessed | Acromioclavicular (AC) joint |
| Common Pathologies | AC joint osteoarthritis; AC joint sprain/separation |
| Positive Sign | Pain localized to the AC joint line |
| Sensitivity | ~77% |
| Specificity | ~79% |
| Best For | Ruling in AC joint pathology when clinical suspicion is moderate to high |
Anatomy: The Acromioclavicular Joint
The acromioclavicular joint is a small, plane synovial joint between the distal clavicle and the acromion process of the scapula. Despite its size, it plays a critical role in shoulder girdle mechanics, transmitting forces between the upper limb and the axial skeleton during overhead reaching, lifting, and contact.
By BodyParts3D is made by DBCLS. (Polygon data is from BodyParts3D) [CC BY-SA 2.1 jp], via Wikimedia Commons
Two ligament systems stabilize the joint:
- Acromioclavicular ligaments (superior and inferior): provide horizontal stability at the joint
- Coracoclavicular ligaments (conoid and trapezoid): provide vertical stability and are the primary restraint against superior displacement of the clavicle
A fibrocartilaginous intra-articular disc is present in most individuals, though it degenerates progressively with age. The joint surfaces are small and incongruent, making the AC joint particularly susceptible to injury from direct impact — most commonly a fall onto the tip of the shoulder or a direct blow in contact sports.
Common AC Joint Pathologies
- AC joint sprain/separation: graded I–VI using the Rockwood classification, based on the degree of ligament disruption and amount of clavicular displacement
- Osteoarthritis: common in older adults and weightlifters; characterized by joint space narrowing, osteophyte formation, and activity-related pain
- Distal clavicle osteolysis: stress-related resorption of the distal clavicle seen in overhead athletes and heavy lifters
- Post-traumatic arthritis: degenerative changes following prior separation or repeated microtrauma
How to Perform the Scarf Test
Patient Position
The patient sits or stands with the arm relaxed at their side. Before testing, palpate the AC joint to identify the exact joint line — this makes interpretation of the pain response more reliable.
Test Procedure
- Passively flex the patient’s shoulder to 90°.
- With the elbow flexed to 90°, guide the arm horizontally across the body into full adduction, bringing the hand toward the opposite shoulder.
- Apply gentle overpressure at end range to further compress the AC joint.
- Ask the patient to identify the exact location and quality of any pain produced.
The test can also be performed with the elbow extended, using the examiner’s arm to guide horizontal adduction. Both variations are clinically acceptable; the elbow-flexed version is more common in practice.
Video Demonstration
Positive Sign and Interpretation
A positive Scarf Test is defined as pain localized to the AC joint line — specifically, at the articulation between the distal clavicle and the acromion.
Pain location is the critical interpretive variable. Horizontal adduction stresses the entire shoulder complex, meaning it can provoke discomfort from multiple structures. The test is only positive when pain is reproduced at the AC joint, not as vague anterior shoulder pain, posterior shoulder discomfort, or deep glenohumeral aching.
What Does Not Constitute a Positive
- Anterior shoulder pain without AC joint localization — may indicate rotator cuff or biceps pathology
- Deep or posterior shoulder pain — suggests glenohumeral or posterior capsule involvement
- General shoulder tightness or a stretch sensation — not a positive finding
- Pain only on active movement, not on passive examiner-applied overpressure
When the pain response is ambiguous, correlate it with direct palpation. If the pain during the Scarf Test corresponds precisely to the point of maximum palpation tenderness at the joint line, the positive is more clinically meaningful.
Sensitivity and Specificity
The diagnostic accuracy of the Scarf Test has been evaluated in patients with suspected chronic AC joint pathology. Published values vary depending on the population studied and the reference standard used.
| Population | Sensitivity | Specificity | LR+ | LR− |
|---|---|---|---|---|
| Isolated chronic AC joint OA | ~77% | ~79% | ~3.7 | ~0.29 |
| Broader AC joint pain population | ~82% | ~28% | ~1.1 | ~0.65 |
The difference between these two rows matters clinically. In patients specifically selected for suspected chronic AC joint OA, the test performs reasonably well — a positive likelihood ratio of ~3.7 is enough to meaningfully shift post-test probability toward AC joint involvement. In a broader, undifferentiated population with shoulder pain, specificity drops substantially and the test adds little diagnostic value on its own.
The Scarf Test is better at ruling in AC joint pathology than ruling it out. A negative result does not exclude AC joint involvement.
Clinical Considerations
- The test does not differentiate pathology type. A positive Scarf Test indicates AC joint involvement — it does not distinguish between osteoarthritis, ligament injury, distal clavicle osteolysis, or post-traumatic arthritis. History, imaging, and clinical context are required for that distinction.
- Combine with O’Brien’s Test. The active compression test also stresses the AC joint when pain is localized superficially. Using both tests together increases diagnostic confidence: when both are positive with pain at the AC joint line, the likelihood of significant AC joint pathology is high.
- Distinguish AC joint pain from SLAP. Both the Scarf Test and O’Brien’s Test can produce positive findings in SLAP tears. The key differentiator: in AC joint pathology, pain is superficial and located at the joint line; in SLAP lesions, pain is typically deeper, more posterior, or described as inside the shoulder.
- Diagnostic injection as confirmation. When clinical tests are inconclusive, a small-volume local anesthetic injection into the AC joint is a reliable confirmatory tool. Meaningful pain relief following injection strongly supports the AC joint as the primary pain source.
- Overhead athletes and weightlifters. These populations have higher rates of distal clavicle osteolysis and AC joint OA. A positive Scarf Test in these patients warrants imaging — plain X-ray with weighted views as a first step; MRI if soft tissue detail is needed.
Related Tests
- O’Brien’s Active Compression Test — tests the AC joint and superior labrum (SLAP); positive for AC pathology when pain is superficial and at the joint line in the pronated position
- Paxinos Test — examiner applies superior pressure to the lateral clavicle while supporting the acromion; particularly useful for posterior AC joint pathology
- AC Joint Palpation — direct palpation tenderness at the joint line is not a formal test but remains a clinically meaningful finding when correlated with provocative tests
- Yergason’s Test — used to evaluate biceps tendon integrity when anterior shoulder pain is present and the AC joint needs to be differentiated
Frequently Asked Questions
What does a positive Scarf Test mean?
It means the patient reports pain localized to the AC joint during passive horizontal adduction. It suggests AC joint pathology — most commonly osteoarthritis or ligament injury — but does not confirm a specific diagnosis on its own. Further testing and imaging are usually needed.
How is the Scarf Test different from O’Brien’s Test?
Both tests stress the AC joint, but O’Brien’s requires active muscle contraction and also tests the superior labrum (SLAP). The Scarf Test is passive and isolates horizontal joint compression more directly. Using both together gives more diagnostic information than either alone.
Can the Scarf Test be positive without AC joint pathology?
Yes. Horizontal adduction stresses multiple shoulder structures, so false positives occur — particularly in patients with posterior shoulder tightness, rotator cuff pathology, or glenohumeral instability. This is why pain must be localized specifically to the AC joint line, not just anywhere in the shoulder.
Is the Scarf Test accurate enough to use on its own?
No. With sensitivity around 77% and a positive likelihood ratio of ~3.7 in the most favorable studies, the test works best as part of a clinical battery. A negative result does not rule out AC joint pathology. Use it alongside O’Brien’s Test, direct palpation, and a thorough history.
What should I do if the Scarf Test is positive?
Confirm with O’Brien’s Test and AC joint palpation, then correlate with history and mechanism of injury. Plain X-ray with weighted views is a reasonable first imaging step. If the diagnosis remains unclear, a diagnostic AC joint injection is reliable and straightforward.
Why is it called the Scarf Test?
The name comes from the arm position during the test. With the elbow flexed and the arm brought across the body toward the opposite shoulder, the movement resembles the gesture of throwing a scarf over the opposite shoulder.
References
- Chronopoulos E, Kim TK, Park HB, Ashenbrenner D, McFarland EG. Diagnostic value of physical tests for isolated chronic acromioclavicular lesions. Am J Sports Med. 2004;32(3):655–661.
- Walton J, Mahajan S, Paxinos A, et al. Diagnostic values of tests for acromioclavicular joint pain. J Bone Joint Surg Am. 2004;86(4):807–812.
- Hegedus EJ, Goode AP, Cook CE, et al. Which physical examination tests provide clinicians with the most value when examining the shoulder? Update of a systematic review with meta-analysis of individual tests. Br J Sports Med. 2012;46(14):964–978.
- Rockwood CA, Williams GR, Young DC. Disorders of the acromioclavicular joint. In: Rockwood CA, Matsen FA, eds. The Shoulder. 2nd ed. Philadelphia: WB Saunders; 1998.