An AC shear test is a physical examination maneuver used to assess the stability and integrity of the acromioclavicular (AC) joint in the shoulder. The following explanation incorporates details from the provided YouTube video:
How is the AC Shear Test Performed?
The AC shear test is performed by applying opposing forces to the scapula and clavicle to evaluate movement or pain at the AC joint. Here is how it is typically performed:
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Hand Placement:
- One hand is placed against the patient's scapular spine.
- The heel of the other hand is positioned against the clavicle, near the AC joint.
- The hands should cup around the shoulder.
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Applying Pressure:
- The examiner then applies pressure by squeezing the heels of both hands together. This creates a shearing force at the AC joint.
What Does a Positive AC Shear Test Indicate?
A positive AC shear test is usually indicated by:
- Pain: Provocation of pain at the AC joint is a common finding in AC joint pathology.
- Movement: Excessive movement or clicking of the AC joint may be felt or noted by the examiner, suggesting instability.
This test is helpful in detecting:
- AC Joint Sprains/Separations: These injuries involve damage to the ligaments supporting the AC joint, causing pain and instability.
- Arthritis: Degenerative changes in the AC joint can also lead to pain and a positive shear test.
Example in Practical Terms
Imagine someone has fallen on their shoulder. An AC shear test can help a doctor quickly assess if the AC joint has been injured. If pushing the shoulder in a specific way causes significant pain at that joint, it suggests an issue with the AC joint.
Key Takeaways
- Purpose: The AC shear test is designed to assess the stability and health of the acromioclavicular joint.
- Method: It involves applying opposing forces to the scapula and clavicle.
- Positive Result: Pain and/or movement at the AC joint indicate a possible injury or pathology.