Anterolateral Ankle Impingement: Diagnostic Performance of MDCT Arthrography and Sonography

OBJECTIVE. The purpose of our study was to compare the diagnostic performance of CT arthrography and sonography in the diagnosis of anterolateral ankle impingement. SUBJECTS AND METHODS. Fifty-one patients with clinically suspected anterolateral ankle impingement prospectively underwent ankle sonography and CT arthrography, immediately followed by an additional ankle sonography examination to evaluate a potential joint effusion impact on diagnostic performance. CT arthrographic findings as well as sonographic findings before and after arthrography were correlated to subsequent arthroscopic appearance in 41 patients. The diagnostic performance of CT arthrography and sonography before and after joint injection was calculated using arthroscopy as the reference standard and compared using McNemar tests. RESULTS. The sensitivity and specificity of sonography were respectively 77% and 57% before joint injection and 85% and 71% after joint injection. Positive Doppler masses were found to be anterolateral impingements at arthroscopy in all cases (10/10), and masses of hyperechoic appearance were found not to be anterolateral impingements in all cases (3/3). The sensitivity and specificity of CT arthrography in the diagnosis of anterolateral impingement were respectively 97% and 71%. The performances of CT arthrography and ankle sonography in the diagnosis of anterolateral ankle impingement were significantly different (p = 0.006). CONCLUSION. CT arthrography is quite accurate and superior to ankle sonography in the diagnosis of anterolateral impingement. The diagnostic performance of sonography is limited, but positive Doppler appearance and hyperechogenicity, when present, could help to exclude or confirm the diagnosis.