AC JOINT SERIES (2/5): AC SHEAR TEST / AC RESISTED EXTENSION TEST Another test for the AC joint is the acromioclavicular joint is the AC Shear Test also known as the AC Resisted Extension test. According to Chronopoulos et al. (2004) this test has a high sensitivity of 72% and specificity of 85%, which makes it a moderately accurate test to diagnose the AC joint as source of nociception. Chronopoulos et al. (2004): https://www.ncbi.nlm.nih.gov/pubmed/15090381 | Physiotutors