Capsular elongation in shoulders with recurrent anterior dislocation: Quantitative assessment with magnetic resonance arthrography

Background: Elongation of the shoulder capsule is often noticed on arthrograms or during surgery in shoulders of patients who have experienced recurrent anterior dislocations. Hypothesis: We can quantify the elongation of the capsule in shoulders with recurrent anterior dislocations by using magnetic resonance arthrography. Study Design: Retrospective review of prospectively collected data. Methods: Twelve patients with unilateral recurrent anterior shoulder dislocations were enrolled in this study. Magnetic resonance images in the axial and coronal oblique planes were obtained from both shoulders (involved and uninvolved sides) after 10 mi of gadolinium/saline solution was injected into the glenohumeral joint. The length of the anteroinferior, inferior, and posteroinferior portions of the capsule was measured by using image analyzing software and normalized to the humeral head diameter. Results: The anteroinferior capsule was significantly elongated in the involved shoulder at 4 mm (16% elongation) and 10 mm (19% elongation) superior to the inferior margin of the glenoid. The inferior capsule was also significantly elongated in the involved side both at the center (12% elongation) and at 4 mm anterior to the center of the glenoid (29% elongation). The posteroinferior capsule did not show any significant elongation. Conclusions: The anteroinferior and inferior portions of the shoulder capsule are elongated an average of 19% in shoulders with recurrent anterior dislocation.