Do Bankart lesions heal better in shoulders immobilized in external rotation? A randomized single-blind study of 55 patients examined with MRI

Background and purpose Immobilization in external rotation (ER) for shoulder dislocation has been reported to improve the coaptation of Bankart lesions to the glenoid. We compared the position of the labrum in patients treated with immobilization in ER or internal rotation (IR). A secondary aim was to evaluate the rate of Bankart lesions. Patients and methods 55 patients with primary anterior shoulder dislocation, aged between 16 and 40 years, were randomized to immobilization in ER or IR. Computer tomography (CT) and magnetic resonance imaging (MRI) were performed shortly after the injury. After the immobilization, MRI arthrography was performed. We evaluated the rate of Bankart lesions and measured the separation and displacement of the labrum as well as the length of the detached part of the capsule on the glenoid neck. Results Immobilization in ER reduced the number of Bankart lesions (OR = 3.8, 95% CI: 1.1-13; p = 0.04). Separation decreased to a larger extent in the ER group than in the IR group (mean difference 0.6 mm, 95% CI: 0.1-1.1, p = 0.03). Displacement of the labrum and the detached part of the capsule showed no significant differences between the groups. Interpretation Immobilization in ER results in improved coaptation of the labrum after primary traumatic shoulder dislocation.