Detection of the Tram Track Lesion in the Ankle Joint: Comparing 3.0-Tesla Magnetic Resonance Imaging and Arthroscopy

Purpose: To show the effectiveness of magnetic resonance imaging (MRI) for the detection of tram track lesions in the ankle compared with ankle arthroscopy. Methods: We retrospectively assessed all patients who underwent arthroscopic ankle surgery between January 2013 and July 2015. Patients with anterior impingement spurs were included, but those with an osteochondral lesion or arthritis were excluded. Anterior ankle bony spurs on preoperative weight-bearing radiographs were scored using an impingement classification system. The 3.0-tesla MRIs were reviewed for tram track lesions (defined as focal high signal intensity along the talar dome cartilage surface on coronal views) and compared with arthroscopic findings. The cartilage defect grade at arthroscopy was stratified according to the International Cartilage Repair Society (ICRS) grading system. Results: Overall, 175 ankles in 170 patients were evaluated. Tram track lesions were identified on MRI in 14 ankles (8.0%) and at arthroscopy in 16 ankles (9.1%). The overall sensitivity of MRI for the detection of tram track lesions was 87.5% and the specificity was 100%. On plain weight-bearing radiographs, of the 16 patients with confirmed tram track lesions on arthroscopy, 4 patients had grade 1, 2 had grade 2, and 10 had grade 3 impingement spurs. Under the ICRS grading system, 4 patients had grade II, 4 had grade III, and 8 had grade IV cartilage defects at arthroscopy. On MRI, 2 patients had grade II (50% of arthroscopy), 4 had grade III (100% of arthroscopy), and 8 had grade IV defects (100% of arthroscopy). The impingement spur grade showed no significant correlation with the arthroscopic ICRS grade of the tram track lesion (P =.609). Conclusion: Tram track lesions can be confidently detected on MRI with high sensitivity and specificity. The impingement spur grade did not correlate with the severity of cartilage injury of the talar dome. Level of Evidence: Level III, diagnostic evaluation study.