Magnetic resonance arthrography in the assessment of anterior instability of the shoulder: comparison with double-contrast computed tomography arthrography.

Forty-seven shoulders with traumatic anterior instability were studied by magnetic resonance arthrography (MRA) and computed tomography arthrography (CTA) to compare the diagnostic performance of these examinations in the evaluation of Bankart lesions. All shoulders were examined by arthroscopy to verify the lesions. Labral damage evaluated by MRA and by CTA correlated significantly with arthroscopic findings (MRA, r = 0.55, p < 0.0001; CTA, r = 0.45, p = 0.0050). MRA possessed higher sensitivity in detecting torn labra (MRA, sensitivity = 87%, specificity = 75%; CTA, sensitivity = 33%, specificity = 88%). In detecting displaced labra, sensitivity and specificity were 65% and 94% for MRA and 75% and 69% for CTA. The inferior glenohumeral ligament was depicted as a lax structure in 74% by MRA but in only 21% by CTA. We conclude that MRA is superior to CTA in detecting lesions associated with shoulder instability.