Can ultrasound replace MRI in diagnosing causes of ankle impingement in different compartments?

This prospective study aims to determine the role of ultrasound (US) in diagnosing different types of ankle impingement due to osseous and soft tissue pathologies and to compare the results with magnetic resonance imaging (MRI), which is considered our gold standard.

The study population included 90 patients with unilateral ankle pain who presented with symptoms and signs suggestive of ankle impingement. Their age ranged from 17 to 57 years, with a mean age of 33.7 years. Using US and MRI, our cases were classified into bony and soft tissue ankle impingement. They were further classified according to the anatomical compartments affected, into anteromedial, anterior, anterolateral, posteromedial, and posterior.

90 patients were enrolled in this study: 51 males and 39 females. In our study, posterior ankle impingement was the commonest impingement type, while anteromedial ankle impingement was the rarest type, followed by posteromedial impingement. The accuracy of US in diagnosing osseous impingement was found to have the following: sensitivity 70.37%, specificity 100%, PPV 100%, NPV 75%, accuracy 84.31%, and p value < 0.001; meanwhile, the accuracy of US in diagnosing soft tissue impingement was found to have the following: sensitivity 83.33%, specificity 100%, PPV 100%, NPV 87.10%, accuracy 92.16%, and p value < 0.001.

US is a good diagnostic tool in bone and soft tissue impingements, with a significant p value of 0.001 for both. US cannot replace MRI as a diagnostic tool, but as a widely available imaging modality, it can save time and cost and allows dynamic imaging.