Purpose: To analyze a series of postoperative magnetic resonance (MR) images obtained in patients with recurrent signs or symptoms of instability in whom subsequent surgical correlation was performed to determine the accuracy in diagnosing recurrent injury.
Materials and methods: The authors identified 24 patients who underwent MR imaging after shoulder instability surgery and had recurrent instability requiring repeat surgery. Twelve nonenhanced MR images and six indirect and six direct MR arthrograms were retrospectively reviewed with consensus to determine the presence or absence of recurrent labral or rotator cuff tear. Operative reports were reviewed to confirm the presence or absence of labral or rotator cuff tear. The mean interval between initial surgery and MR imaging was 10 months. The mean interval until repeat surgery was 2 months.
Results: Overall, the accuracy of postoperative MR imaging was 79% in depicting recurrent labral tear and 88% in depicting recurrent rotator cuff tear. Indirect MR arthrography had 100% accuracy for recurrent labral tear detection, whereas direct MR arthrography and nonenhanced MR imaging had accuracies of 67% and 75%, respectively. Direct MR arthrography was more sensitive, 100% versus 71%, but less specific, 60% versus 80%, than nonenhanced MR imaging in depicting recurrent labral tears. Direct MR arthrography had 100% accuracy in depicting rotator cuff tear, whereas both indirect MR arthrography and nonenhanced MR imaging had 83% accuracy.
Conclusion: MR imaging, indirect MR arthrography in particular, appears to be an accurate means of evaluating the shoulder following instability surgery.