The AC Shear Test is a shoulder special test used to provoke symptoms at the acromioclavicular joint by applying a shear or compression force between the clavicle and scapular/acromial region. It is commonly used when AC joint pain, irritation or local instability is part of the assessment reasoning.
A positive finding may include familiar local AC joint pain, abnormal movement, apprehension or clear side-to-side difference. However, diagnostic accuracy evidence for the exact AC Shear Test appears limited, so the result should be interpreted alongside history, trauma mechanism, AC joint palpation, cross-body adduction, Paxinos sign, O’Brien’s active compression test, range of motion, strength and imaging where relevant.
The AC Shear Test is used to assess symptom response around the acromioclavicular joint, commonly called the AC joint. The AC joint is the small joint between the lateral clavicle and the acromion of the scapula. It can be irritated by direct trauma, repetitive loading, falls onto the shoulder, pressing movements, overhead sport or degenerative change.
The test applies a local shear or compression force across the AC joint. If this reproduces familiar pain directly over the AC joint, the finding may support assessment reasoning that the AC joint is relevant to the client’s shoulder symptoms.
However, the AC Shear Test should not be used as a stand-alone diagnostic test. Local shoulder pain can be influenced by AC joint irritation, rotator cuff-related pain, subacromial-region symptoms, cervical referral, glenohumeral symptoms and other contributors.
For Measurz users, the value of the AC Shear Test is in recording a clear response: side tested, local pain location, pain score, whether symptoms were familiar, movement response, side-to-side comparison and related shoulder findings.
Test name: AC Shear Test
Region: Shoulder / acromioclavicular joint
Primary purpose: Provoke local AC joint symptoms or movement response
Commonly associated presentations: AC joint pain, AC sprain, AC joint irritation, shoulder pain after direct trauma, pain with cross-body or pressing movements
Positive finding: Familiar local AC joint pain, abnormal movement, apprehension or clear side-to-side difference
Negative finding: No familiar AC joint pain and no meaningful side-to-side difference
Main limitation: Diagnostic accuracy evidence for the exact test appears limited.
The AC Shear Test is a local shoulder provocation test for the acromioclavicular joint.
The professional places one hand near the clavicle and the other near the scapular spine or acromion region. A compressive or shearing force is applied to stress the AC joint.
The test may be performed in sitting or standing.
The result is based on:
Local AC joint pain
Familiar symptom reproduction
Apprehension
Abnormal movement
Side-to-side difference
Symptom quality
It is best used as part of an AC joint test cluster rather than alone.
The AC Shear Test may be used to support assessment reasoning around:
Local AC joint pain
Shoulder pain after direct trauma
AC joint sprain-type presentations
Pain with cross-body adduction
Pain with pressing or overhead activity
AC joint tenderness
Suspected AC joint irritation
Local shoulder pain mapping
Side-to-side comparison
Baseline and retest documentation
It can help determine whether direct AC joint loading reproduces the client’s familiar symptoms.
The AC Shear Test assesses symptom response to local AC joint shear or compression.
It may provide information about:
Local AC joint tenderness
Familiar pain reproduction
AC joint irritability
Apprehension with AC joint loading
Abnormal local movement
Side-to-side difference
Tolerance to local shoulder loading
It does not directly assess:
AC ligament integrity with certainty
Coracoclavicular ligament integrity with certainty
Radiographic AC separation grade
Rotator cuff integrity
Labral integrity
Cervical contribution
Shoulder strength
Functional capacity
Readiness for sport or work
Treatment need
The AC Shear Test may be useful for clients with:
Local pain over the AC joint
Shoulder pain after a fall onto the shoulder
Pain after contact sport trauma
Pain with cross-body adduction
Pain with push-ups, bench press or dips
Pain with overhead or pressing tasks
Suspected AC joint irritation
Need for baseline and retest documentation
It may also be useful for professionals learning how to differentiate local AC joint symptoms from broader shoulder pain presentations.
Consider using the AC Shear Test when:
Pain is localised near the AC joint
The mechanism involved direct shoulder trauma
AC joint tenderness is present
Cross-body adduction reproduces symptoms
Pressing or overhead activity provokes superior shoulder pain
You want to compare side-to-side AC joint irritability
You are building a broader shoulder assessment profile
The test should be combined with history, palpation, range of motion, strength assessment and other shoulder special tests.
Use caution or avoid the test when:
Recent major trauma suggests fracture or significant AC separation
There is visible deformity after acute injury
Pain is severe before testing
The client cannot tolerate local pressure
Infection, inflammatory flare or systemic red flags are suspected
The professional cannot apply the test safely
The test would not change assessment reasoning
Stop the test if pain increases sharply, the client becomes distressed, or the test reproduces symptoms beyond a useful level.
The AC Shear Test usually requires no equipment.
Optional equipment includes:
Measurz app
Pain rating scale
Notes field for pain location and comparison side
Shoulder range of motion record
Strength testing record
Video or image record only where appropriate
Referral or imaging notes if relevant
Ask the client to sit or stand comfortably.
Explain the test:
“I am going to apply gentle pressure around the top of your shoulder to see whether it reproduces your familiar symptoms around the AC joint.”
Expose or identify the top of the shoulder enough to locate the clavicle, acromion and scapular spine.
The client sits or stands upright with:
Shoulder relaxed
Arm resting by the side
Neck relaxed
No active bracing
Both shoulders visible for comparison if possible
The professional stands behind or slightly beside the client.
They should be able to place one hand over the clavicular region and the other over the scapular spine/acromion region.
A common method is:
One hand contacts the clavicle/anterior shoulder region.
The other hand contacts the scapular spine/posterior shoulder region.
The hands are positioned to apply a compressive or shearing force across the AC joint.
Avoid direct excessive pressure on sensitive tissue.
The client remains relaxed.
Do not force the shoulder into elevation or cross-body position unless using a different AC joint test.
Apply a gentle compressive or shearing force through the AC joint region.
The force should be:
Controlled
Gradual
Symptom-limited
Compared with the other side where appropriate
Tell the client:
“Tell me if this reproduces your familiar shoulder pain. Point to where you feel it and rate the discomfort.”
A positive finding may include:
Familiar local pain directly over the AC joint
Reproduction of the client’s usual superior shoulder pain
Apprehension with local AC loading
Abnormal local movement compared with the other side
Clear side-to-side difference
Pain that matches other AC joint findings
Record whether the finding was pain, movement, apprehension or a combination.
A negative finding may include:
No familiar AC joint pain
No meaningful side-to-side difference
No local apprehension
No relevant symptom reproduction
Only mild non-familiar pressure discomfort
A negative finding does not fully exclude AC joint involvement.
Stop the test if:
Pain increases sharply
The client asks to stop
There is visible acute deformity or concerning instability
The test is too irritable to interpret
The professional feels further testing is inappropriate
The test should be gentle. Avoid aggressive compression, especially after recent trauma or suspected AC separation.
A positive AC Shear Test may increase suspicion that the AC joint is relevant when it reproduces familiar local pain directly over the AC joint. The finding is more meaningful when it matches the history, local tenderness, cross-body symptoms, pressing pain and other AC joint tests.
However, a positive AC Shear Test does not confirm AC joint pathology. Local pain may be influenced by soft tissue sensitivity, recent trauma, shoulder irritability, cervical referral or broader shoulder conditions.
A negative AC Shear Test may reduce suspicion that direct local AC joint shearing is a major symptom driver in that session. However, a negative result does not fully exclude AC joint involvement, particularly if other AC joint tests are positive or symptoms occur only during higher-load tasks.
The result is more meaningful when interpreted with:
Mechanism of injury
Pain location
AC joint palpation
Cross-body adduction
Paxinos sign
O’Brien’s active compression test
Shoulder range of motion
Resisted AC joint extension
Rotator cuff tests
Cervical assessment where relevant
Imaging or referral findings where appropriate
At the time of writing, high-quality diagnostic accuracy evidence for the exact AC Shear Test variation appears limited.
This means the AC Shear Test should be used as a local symptom provocation and assessment reasoning tool rather than as a stand-alone diagnostic test.
Related AC joint diagnostic accuracy evidence includes:
Condition or presentation: Acromioclavicular joint pain
Population: People with shoulder pain in diagnostic accuracy studies
Test variation: AC tenderness, Paxinos test, O’Brien’s active compression and related AC joint clinical tests
Reference standard: AC joint diagnostic injection in key studies
Reported values: In Walton et al., AC tenderness had high sensitivity at approximately 96%, while the Paxinos test had sensitivity around 79%, but many tests had low specificity
Cluster evidence: A systematic review by Krill et al. reported that clinical test combinations may improve reasoning compared with individual tests, but diagnostic accuracy remains limited
Key limitation: These values are not specific to the AC Shear Test and should not be applied directly as its sensitivity or specificity.
Plain-language interpretation:
A positive AC Shear Test may support AC joint assessment reasoning when symptoms are local and familiar.
The exact test does not have strong diagnostic accuracy evidence.
Related AC joint tests are more useful as a cluster than individually.
A negative AC Shear Test does not fully exclude AC joint involvement.
The result should be recorded descriptively rather than treated as diagnostic confirmation.
Reliability evidence for the exact AC Shear Test appears limited.
Reliability may be affected by:
Hand placement
Force direction
Amount of compression
Client irritability
Recent trauma
Local tenderness
Definition of a positive result
Whether pain or movement is recorded
Professional experience
Validity is limited as a stand-alone diagnostic test. The AC Shear Test has practical face validity as a local AC joint provocation test, but it does not directly verify ligament injury, joint degeneration or radiographic separation.
Reliability improves when the professional standardises:
Client position
Hand placement
Force direction
Force intensity
Symptom questions
Side-to-side comparison
Pain location recording
Positive-test criteria
Common errors include:
Applying too much pressure
Not identifying the AC joint clearly
Not recording symptom location
Counting general shoulder pain as a clear positive
Not comparing sides
Using the test after significant trauma without caution
Not combining with other AC joint tests
Assuming positive pain confirms AC pathology
Ignoring cervical or rotator cuff contribution
Limitations include:
Exact diagnostic accuracy evidence is limited
Local pressure can provoke non-specific pain
It does not grade AC separation
It does not confirm ligament integrity
Acute trauma may require further assessment
It should not be used alone for decision-making
Shoulder pain sources often overlap
The AC Shear Test may be useful for:
Local AC joint symptom provocation
Shoulder pain mapping
Comparing sides
Recording AC joint irritability
Supporting broader AC joint assessment reasoning
Baseline and retest documentation
Client education
Deciding whether further shoulder assessment is needed
In Measurz, it can be recorded alongside AC tenderness, Cross-Body Adduction Test, Paxinos Sign, O’Brien’s active compression test, Resisted AC Joint Extension Test, shoulder range of motion, rotator cuff testing and cervical screening.
Record:
Test name: AC Shear Test
Side tested
Result: positive, negative, unclear or unable to test
Pain score
Symptom location
Whether pain was directly over the AC joint
Whether symptoms were familiar
Apprehension
Abnormal movement if present
Force direction
Client position
Comparison side
Irritability
Guarding or compensations
Reason for stopping if relevant
Related findings
Confidence in interpretation
Further assessment or referral notes if appropriate
Retest date if relevant
Recording these details improves repeatability, communication, client education, assessment reasoning, monitoring over time, team consistency and reporting quality.
Cross-Body Adduction Test
Paxinos Sign
O’Brien’s Active Compression Test
Resisted AC Joint Extension Test
AC Joint Palpation
Shoulder Range of Motion
Drop Arm Test
Internal Rotation Lag Sign
Scapular Assistance Test
Cervical Quadrant Test
It assesses local symptom response to shear or compression across the acromioclavicular joint.
A positive finding may include familiar local pain over the AC joint, apprehension, abnormal movement or a clear side-to-side difference.
No. It may support suspicion, but it does not confirm AC joint injury or pathology on its own.
High-quality diagnostic accuracy evidence for the exact AC Shear Test appears limited.
Pain directly over the AC joint is more meaningful than vague general shoulder pain.
Use caution. Significant trauma, deformity or severe pain may require further assessment before provocative testing.
Yes, side-to-side comparison can improve interpretation when safe and appropriate.
History, local palpation, cross-body adduction, Paxinos sign, O’Brien’s active compression test, resisted AC joint extension and broader shoulder assessment.
The AC Shear Test provokes local AC joint symptoms using shear or compression.
A positive finding is most meaningful when it reproduces familiar local pain over the AC joint.
Diagnostic accuracy evidence for the exact AC Shear Test appears limited.
Related AC joint tests are usually more useful as a cluster than individually.
The test does not confirm AC joint pathology, ligament injury or separation grade on its own.
Measurz recording should include side, pain location, pain score, symptom familiarity, movement response and comparison side.
Chronopoulos, E., Kim, T. K., Park, H. B., Ashenbrenner, D., & McFarland, E. G. (2004). Diagnostic value of physical tests for isolated chronic acromioclavicular lesions. The American Journal of Sports Medicine, 32(3), 655–661. https://doi.org/10.1177/0363546503261723
Krill, M. K., Rosas, S., Kwon, K., Dakkak, A., Nwachukwu, B. U., & McCormick, F. (2018). A concise evidence-based physical examination for diagnosis of acromioclavicular joint pathology: A systematic review. The Physician and Sportsmedicine, 46(1), 98–104. https://doi.org/10.1080/00913847.2018.1413920
Walton, J., Mahajan, S., Paxinos, A., Marshall, J., Bryant, C., Shnier, R., Quinn, R., & Murrell, G. A. C. (2004). Diagnostic values of tests for acromioclavicular joint pain. The Journal of Bone and Joint Surgery. American Volume, 86-A(4), 807–812.
Cadogan, A., McNair, P. J., Laslett, M., Hing, W. A., & Taylor, S. (2013). Shoulder pain in primary care: Diagnostic accuracy of clinical examination tests for non-traumatic acromioclavicular joint pain. BMC Musculoskeletal Disorders, 14, 156. https://doi.org/10.1186/1471-2474-14-156
