Adhesive capsulitis of the shoulder: Dimensions of the rotator interval measured with magnetic resonance arthrography

Background: This study was performed to define the dimensions of the rotator interval (RI) in adhesive capsulitis using magnetic resonance (MR) arthrography preoperatively to clarify and evaluate pathology. Methods: We performed a retrospective review of a series of 73 Shoulders that underwent MR arthrography. The shoulders were grouped according,to their diagnosis: group I comprised 47 shoulders without adhesive capsulitis; group II comprised 26 shoulders with adhesive capsulitis. Using MR arthrography, we estimated the height, base, RI area, width, RI index, and RI ratio. Results: The group II shoulders differed significantly in height, base, RI area, RI index,and RI ratio from the group I shoulders. There were statistically significant differences in RI dimensions between patients with and without adhesive capsulitis of shoulder. Conclusions: Estimating the dimensions of the RI in adhesive capsulitis using MR arthrography may prove to be valuable for assessing patients preoperatively. Level of evidence: Basic science study. (C) 2009 Journal of Shoulder and Elbow Surgery Board of Trustees.