Assessment of capsular laxity in patients with recurrent anterior shoulder dislocation using MRI

The purpose of our study was to investigate the usefulness of MRI in assessing capsular laxity in patients with recurrent shoulder dislocation.

The records of 64 consecutive patients (the study group consisted of 58 patients, 45 male and 13 female; average age, 39.3 years; range, 13-82 years) who underwent MR arthrography between October 2002 and May 2008 were retrospectively reviewed. The patients were divided into three groups: group A, no shoulder dislocation; group B, first dislocation; and group C, recurrent dislocation. The maximum capsular widths at the anterior, anteroinferior, and inferior regions in the neutral and abducted and externally rotated (ABER) positions were measured on oblique sagittal images. The relationship of capsular width with the number of dislocations, type of capsular attachment, presence of anteroinferior labral tear, and patient sex were evaluated. The sensitivity and specificity of MRI and clinical tests in detecting capsular laxity were also calculated.

Among all three patient groups, there were significant differences (p < 0.05) in the widths with the shoulder in the ABER position and the degree of capsular tightening at the anterior region. The average maximum width was largest in group C and smallest in group A. There was a significant difference in the degree of anterior capsular tightening in groups B and C. A moderate correlation of capsular width and anterior tightening (R = -0.45) with number of shoulder dislocations was found. There was a significant difference in capsular width and capsular tightening in relation to the presence of an anteroinferior labral tear. The sensitivity and specificity to detect capsular laxity were 92% and 100%, respectively, for clinical tests and 85% and 96% for MRI.

MRI is a useful and objective method to assess capsular laxity in patients with recurrent shoulder dislocation.