Computerized assessment of Bankart lesions under tension with magnetic resonance arthrography

Abstract

Accurate anatomic depiction of Bankart lesions based on magnetic resonance imaging (MRI) is crucial for the treatment of posttraumatic recurrent dislocation of the glenohumeral joint. MR arthrography, the intraarticular injection of dilute gadolinium before MR imaging, improves sensitivity in the detection of shoulder pathology. Abduction and external rotation (ABER) of the shoulder places dynamic stress on the inferior capsular pouch and anterior labroligamentous complex, important structures for anterior shoulder stability. This study sought to determine whether MR arthrography, by use of computerized image analysis, can visualize Bankart lesions better with the shoulder in the neutral position or in ABER. We evaluated 12 shoulders after traumatic anterior dislocation. The MR images were analyzed with image-analyzing software. We compared 3 parameters at 5 levels of the glenoid in the neutral position and in ABER: detachment (the length of detachment between the anterior glenoid rim and the anterior periosteal attachment), displacement (the distance between the anterior glenoid rim and the tip of the displaced labrum), and Bankart area (the area bounded by the detachment line, the displacement line, and the anterior aspect of the Bankart lesion). MR images revealed that Bankart lesions were under tension in ABER and lax and redundant with the shoulder in the neutral position. All 3 parameters were greater in ABER than in the neutral position in all cases (P = .012, P = .0006, and P = .012). Computerized image assessment of MR arthrography with the shoulder in ABER provides excellent visualization and evaluation of Bankart lesions.