Is MRI adequate to detect lesions in patients with ankle instability?

BACKGROUND: Chondral lesions, peroneal tendon tears, and other disorders in patients with chronic ankle instability may not be detected by preoperative MRI. Also, MRI often is obtained and interpreted at the referring institution, leading to variability in reading. QUESTIONS/PURPOSES: We assessed the accuracy of the radiologists' and orthopaedic surgeon's reading of preoperative MRI for diagnosing ankle lesions in patients with ankle instability warranting surgery. PATIENTS AND METHODS: We retrospectively reviewed 133 patients who underwent 135 surgeries for lateral ankle ligament reconstruction with concomitant ankle arthroscopy and who had preoperative MRI.
RESULTS: We found 72 associated lesions in 66 of the 135 surgeries, including 38 chondral injuries, 18 peroneus brevis tears, seven loose bodies, and nine other miscellaneous abnormalities. Eliminating eight lesions for which the decision to operate was not based on operative findings, there were 127 surgeries with 64 associated lesions that required intraoperative confirmation or were detected intraoperatively. In the original reports, the radiologists identified 39% (15) of the chondral injuries, 56% (10) of the peroneal tears, and 57% (four) of the loose bodies. Radiologists' MRI sensitivity for detecting lesions was 45%. The attending surgeon identified 47% (18) of the chondral injuries, 89% (16) of the loose bodies, 71% (five) of the peroneus brevis tears, and the posterior talus process lesion, with a sensitivity of 63%.
CONCLUSIONS: Our data suggest orthopaedic surgeons should review preoperative MRIs and also suggest the sensitivity of MRI may not be adequate to detect lesions in these patients before surgery. LEVEL OF EVIDENCE: Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.