Sensitivity and specificity of noncontrast magnetic resonance imaging reports in the diagnosis of type-II superior labral anterior-posterior lesions in the community setting.

BACKGROUND: Magnetic resonance imaging (MRI) has been suggested to be of high accuracy at academic institutions in the identification of superior labral tears; however, many Type-II superior labral anterior-posterior (SLAP) lesions encountered during arthroscopy have not been previously diagnosed with noncontrast images. This study evaluated the accuracy of diagnosing Type-II SLAP lesions in a community setting with use of noncontrast MRI and analyzed the effect that radiologist training and the scanner type or magnet strength had on sensitivity and specificity. METHODS: One hundred and forty-four patients requiring repair of an arthroscopically confirmed Type-II SLAP lesion who had a noncontrast MRI examination performed within twelve months before the procedure were included in the sensitivity analysis. An additional 100 patients with arthroscopically confirmed, normal superior labral anatomy were identified for specificity analysis. The transcribed interpretations of the images by the radiologists were used to document the diagnosis of a SLAP lesion and were compared with the operative report. The magnet strength, type of MRI system (open or closed), and whether the radiologist had completed a musculoskeletal fellowship were also recorded. RESULTS: Noncontrast MRI identified SLAP lesions in fifty-four of 144 shoulders, yielding an overall sensitivity of 38% (95% confidence interval [CI] = 30%, 46%). Specificity was 94% (95% CI = 87%, 98%), with six SLAP lesions diagnosed in 100 shoulders that did not contain the lesion. Musculoskeletal fellowship-trained radiologists performed with higher sensitivity than those who had not completed the fellowship (46% versus 19%; p = 0.009). CONCLUSIONS: Our results demonstrate a low sensitivity and high specificity in the diagnosis of Type-II SLAP lesions with noncontrast MRI in this community setting. Musculoskeletal fellowship-trained radiologists had significantly higher sensitivities in accurately diagnosing the lesion than did radiologists without such training. Noncontrast MRI is not a reliable diagnostic tool for Type-II SLAP lesions in a community setting.

Preoperative magnetic resonance imaging diagnosis of the floating anterior inferior glenohumeral ligament.

Approximately a century ago, labral avulsion from the glenoid was described as a source of recurrent anterior shoulder dislocation. Since then, the significance of other origins of shoulder instability has been a controversial issue. Cadaveric dissection, biomechanical evaluation, and surgical observation have led to the discovery of additional pathologic conditions associated with glenohumeral instability that must be properly identified and addressed for operative success. Recently, several authors have emphasized the importance of lesions of the glenohumeral ligament as a cause of post-traumatic shoulder instability. One such condition is bipolar avulsion of the anterior inferior glenohumeral ligament (AIGHL), or floating AIGHL. In previous reports, this finding has only been identified during surgery. We present a case of traumatic anterior shoulder dislocation in which a preoperative diagnosis of floating AIGHL was made by magnetic resonance imaging. Recognition of this rare lesion before surgical intervention is advantageous for appropriate preoperative planning and management of patients with posttraumatic anterior glenohumeral instability.