ANTEROLATERAL IMPINGEMENT OF THE ANKLE - EFFECTIVENESS OF MR-IMAGING

PURPOSE: To determine the effectiveness of magnetic resonance (MR) ima ging in the diagnosis of anterolateral impingement of the ankle. MATER IALS AND METHODS: MR images were reviewed in 12 patients (12 ankles) w ith arthroscopically proved anterolateral impingement and in 19 contro l subjects (20 ankles) with diagnoses other than impingement. MR image s were scored by means of consensus of two musculoskeletal radiologist s and independently by a third radiologist. Patients underwent imaging at 1.5 T, with use of standard imaging sequences and a dedicated extr emity coil. RESULTS: For the consensus reading, the sensitivity, speci ficity, and accuracy of MR imaging for the diagnosis of impingement we re 42%, 85%, and 69%, respectively. The frequency of lateral gutter fu llness and anterior talofibular ligament thickening on MR images was h igher in the 12 ankles with impingement (seven [58%] and seven [58%] a nkles, respectively) than in the 20 control ankles (seven [35%] and fi ve [25%] ankles, respectively), but these trends did not reach statist ical significance. Interobserver agreement for anterior talofibular li gament thickening was high, whereas that for lateral gutter fullness w as fair. CONCLUSION: Conventional MR imaging of the ankle is insensiti ve for anterolateral impingement. Anterior talofibular ligament thicke ning and soft-tissue fullness in the lateral gutter may be suggestive of the diagnosis, but the reliability of the latter finding is questio nable.