Labral-ligamentous complex of the shoulder: evaluation with MR arthrography.

PURPOSE: To determine the usefulness of magnetic resonance (MR) arthrography in assessment of the labral-ligamentous complex and test the hypothesis that the inferior glenohumeral ligament (IGHL) is an important anatomic feature of clinical instability. MATERIALS AND METHODS: Forty-eight shoulders with labral diagnoses proved with arthroscopy or open surgery were prospectively examined with MR arthrography after intraarticular injection of gadopentetate dimeglumine. RESULTS: Surgical findings showed that 14 labra were normal, 29 were torn, and six were deficient. (One labrum was torn and deficient in separate locations.) MR arthrographic findings had a diagnostic sensitivity of 91% and specificity of 93%. In 32 patients with proved labral abnormalities, 30 lesions involved the labral-bicipital junction, origins of the glenohumeral ligaments, or both. In 22 of 23 shoulders considered clinically unstable, a labral abnormality involved the origin of the IGHL. CONCLUSION: MR arthrography accurately shows the relationship of labral lesions to the origins of the glenohumeral ligaments and helps in distinction between stable and unstable lesions.