Adhesive capsulitis of the shoulder: MR diagnosis

Adhesive capsulitis is a clinical syndrome of pain and severely decreased joint motion ("frozen shoulder") caused by thickening and contraction of the joint capsule and synovium. Although arthrographic criteria for the diagnosis have been described, to our knowledge, the MR characteristics have not been reported. Accordingly, we studied the MR findings in 10 patients with this syndrome.

MR images of 25 subjects were included in the study. Nine had adhesive capsulitis documented by arthrography, and one had adhesive capsulitis proved at surgery. The MR findings in these patients were compared with those of 15 asymptomatic volunteers. Images were assessed for thickness of the joint capsule and synovium, for thickness of the coracohumeral ligament, and for volume of articular fluid. Capsule and synovium thickness was measured adjacent to the axillary recess. The volume of intraarticular fluid was calculated from direct measurements of the axillary recess and biceps tendon sheath. The rotator cuff interval was qualitatively evaluated for the presence of abnormal tissue.

Thickening of capsule and synovium on MR images was characteristic of adhesive capsulitis, with a significant difference between mean thickness in patients with adhesive capsulitis (5.2 mm) and in asymptomatic volunteers (2.9 mm) (p < .01). Capsule and synovium thickness greater than 4 mm was a specific (95%) and sensitive (70%) criterion for the diagnosis of adhesive capsulitis. There was no significant difference in volume of articular fluid or thickness of the coracohumeral ligament between patients with adhesive capsulitis and asymptomatic volunteers (p > .5). The rotator cuff interval was not useful for assessing changes of adhesive capsulitis.

Joint capsule and synovium thickness greater than 4 mm is a useful MR criterion for the diagnosis of adhesive capsulitis. The volume of articular fluid seen on MR images is not significantly diminished in patients with adhesive capsulitis.