Special Tests: Acromioclavicular (AC) Joint Pathology
by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS
For an introduction to Special Tests including definitions of specific terminology, what special tests measure, how we chose the tests in these lessons, and best use, check out:
Special Tests Covered in this Lesson:
- Acromioclavicular (AC) Joint Test-item Cluster
- Screening Tool
- Palpation (High Sensitivity)
Special Notes on AC Joint Special Tests:
Two or more positive tests in the AC Joint Test-item cluster increases the likelihood ratios a small amount over the Resisted Extension Test alone (25). In general, apprehension tests are slightly more specific than sensitive (1-2, 4-5, 7, 14, 17, 25-27, 30). Performing Obrien's Active Compression Test first represents the use of this test as a "pivot" from the Instability/Labrum Composite Test-item Cluster, as pain in or on top of the AC joint may indicate AC joint pathology (7, 14, 22). Pain with palpation of the AC joint may be an effective screen. One study showed 96% sensitivity (better than any other test) and 10% specificity, implying that a negative test results in a high likelihood of not having AC joint pathology, where as a positive test suggests further testing is needed (11).
O'Brien's Active Compression Test
- The patient is standing with involved shoulder flexed to 90° and internally rotated to end-range in the scapular plane, with elbow extended.
- The examiner stands on the side of the involved shoulder and asks the patient to resist a downward force applied to the wrist.
- The patient is asked to report any pain and the location of that pain. Top of the shoulder may indicate acromioclavicular (AC) joint pathology, and