The cross arm test, also known as the cross-body adduction test, is a physical examination maneuver used to assess for acromioclavicular (AC) joint pathology. It involves adducting the patient's arm across their chest.
How the Cross Arm Test Works
The test is performed by having the patient raise their arm to 90 degrees and then adducting (bringing it across) their body. The examiner typically applies gentle overpressure to maximize the adduction. A positive test is indicated by pain localized to the AC joint.
Sensitivity of the Cross Arm Test
According to a study by Chronopoulos et al. in 2004, the cross-body adduction test has a sensitivity of 77% for detecting AC joint pathology. This means that the test will correctly identify 77% of individuals who have a problem with their AC joint.
Purpose of the Cross Arm Test
The primary purpose of the cross arm test is to help diagnose AC joint injuries or conditions such as:
- AC joint osteoarthritis: Degeneration of the cartilage in the AC joint.
- AC joint separation: Injury to the ligaments that support the AC joint, often caused by a fall or direct blow.
- AC joint sprain: A less severe injury to the AC joint ligaments.
Limitations of the Cross Arm Test
While the cross arm test is a useful diagnostic tool, it is important to note that it is not always accurate. False positives (the test is positive, but the patient does not have an AC joint problem) and false negatives (the test is negative, but the patient does have an AC joint problem) can occur. Therefore, the results of the cross arm test should be interpreted in conjunction with other clinical findings and imaging studies, such as X-rays.
