Acromioclavicular (AC) Shear Test

The Acromioclavicular Shear Test (also known as the AC Joint Compression Test) is a manual orthopedic assessment used to evaluate the integrity of the acromioclavicular (AC) joint in the shoulder. It is particularly helpful for detecting AC joint separation, sprains, osteoarthritis, or post-traumatic injury.

How the Test is Performed

  • Position: The client sits comfortably, arms at the side.

  • The therapist places the heel of one hand over the clavicle and the heel of the other over the spine of the scapula, cupping the hands over the top of the shoulder and the deltoid muscle region.

  • The therapist squeezes the hands together, applying a compressive (shearing) force across the AC joint.

  • Observation: The test is positive if pain is reproduced at the AC joint or there is palpable abnormal movement (laxity, “give,” or “shift”) during compression.

Clinical Significance

  • A positive AC Shear Test suggests pathology at the AC joint, including separation (grades I-III), sprain, degenerative changes (osteoarthritis), or inflammation.

  • The test is especially useful for differentiating AC joint involvement from other causes of shoulder pain, but should be interpreted in combination with history and other shoulder tests to rule out rotator cuff injury and bursitis.

  • Abnormal motion during the test may indicate significant ligamentous injury to the AC joint.

Assessment

  • Use the AC Shear Test when clients report localized pain, tenderness, or history of injury directly over the top of the shoulder.

  • If positive, document findings and avoid deep tissue work, friction, or aggressive movement directly over the AC joint, as these could aggravate the injury.

  • Monitor response to therapy over time and recheck as needed with medical clearance.

Treatment Planning

  • For confirmed or suspected AC joint pathology:

    • Focus massage on supporting musculature (deltoid, upper trapezius, rotator cuff), avoiding direct pressure on the joint itself.

    • Gentle techniques and pain-free range of motion therapy are appropriate; avoid forced abduction or elevation.

    • Encourage clients to seek further medical assessment if pain, swelling, or instability is significant or if trauma was involved.

Safety and Contraindications

  • Avoid aggressive manual therapy to a painful or unstable AC joint. Refer out for medical assessment and possible imaging if instability is significant or accompanied by acute trauma.

  • If swelling, bruising, or deformity is present, or if symptoms worsen with the test, defer hands-on work and facilitate prompt medical evaluation.

  • Remain cautious in chronic cases of osteoarthritis or old separations; treatment may still provide relief for compensatory muscular tightness but should avoid aggravating the joint.