MR arthrographic depiction of tears of the rotator cuff: benefit of abduction and external rotation of the arm.

PURPOSE: To show the effectiveness of positioning the arm in abduction and external rotation (ABER) during magnetic resonance (MR) arthrography for depiction of tears of the rotator cuff. MATERIALS AND METHODS: Five throwing athletes with shoulder pain were prospectively imaged with standard MR imaging, MR arthrography, and ABER MR arthrography. The status of the rotator cuff was recorded; arthroscopic correlation was obtained. RESULTS: One partial tear of the distal infraspinatus tendon was detected with ABER MR arthrography only. One full-thickness tear was detected with both MR arthrography and ABER MR arthrography, but the component of the tear that extended into the infraspinatus tendon was depicted with ABER MR arthrography only. One partial tear was detected with both MR arthrography and ABER MR arthrography; no additional information was provided by either technique alone. CONCLUSION: The ABER position may be useful in detection and characterization of tears of the rotator cuff, especially partial tears of the undersurface. This information would be useful in selection of patients for conservative therapy, arthroscopy, or arthrotomy.