RESUMO
PURPOSE: To retrospectively determine the accuracy of direct magnetic resonance (MR) arthrography of the shoulder in patients with recurrent or residual signs and/or symptoms of instability after prior instability repair, with surgical findings as the reference standard. MATERIALS AND METHODS: After institutional ethics review board approval was obtained and informed consent was waived, 40 patients (31 men, eight women; mean age, 28 years) with recurrent instability after previous instability repair who underwent direct shoulder MR arthrography before repeat surgery were studied. Two musculoskeletal radiologists reviewed direct MR arthrographic studies by using consensus agreement in a blinded fashion. MR assessment included evaluation of the labrum (overall, superior, anterior and anteroinferior, posterior and posteroinferior), rotator cuff, biceps tendon, articular cartilage, and presence or absence of a Hill-Sachs lesion. Mean interval between MR arthrography and repeat surgery was 6.2 months (range, 6 days to 36 months). Surgical reports were compared with MR arthrographic results, and accuracy, sensitivity, and specificity of direct MR arthrography were determined. RESULTS: Accuracy, sensitivity, and specificity, respectively, of direct MR arthrography in diagnosis of overall labral tears (n = 26) were 91.9%, 96.2%, and 81.8%; those of superior labral tears (n = 16) were 89.2%, 93.8%, and 85.7%; and those of anteroinferior tears (n = 17) were 91.9%, 100%, and 85%. Overall accuracy for detecting rotator cuff injury (n = 17) was 87.2% (sensitivity, 94.1%; specificity, 81.8%); accuracy for biceps injury (n = 7) was 95.7% (sensitivity, 85.7%; specificity, 100%); accuracy for glenoid and/or humeral articular cartilage abnormality (n = 15) was 76.2% (sensitivity, 73.3%; specificity, 83.3%); and accuracy for Hill-Sachs lesion (n = 14) was 93.3%. CONCLUSION: Direct MR arthrography is accurate (91.9%) for assessing labral pathologic conditions and other internal derangements of the shoulder in patients with recurrent or residual signs and/or symptoms after prior shoulder instability repair.