Ankle impingement syndromes.

The ankle impingement syndrome is a frequent condition in both athletes and the normal population. We investigated this painful syndrome from both a clinical and a diagnostic viewpoint. Depending on what ankle tissue impinges on the other, it is possible to distinguish bone impingement, soft tissue impingement and peripheral nerve entrapment. For each of these pathologic conditions we investigated the diagnostic role of conventional radiography, Computed Tomography and Magnetic Resonance Imaging. The evidence of osteophytes, exostosis and presence of the os trigonum on plain films make clinical diagnosis easy in both anterior and posterior bone impingement. CT can provide useful information about the component of the posterior ankle. MRI always adds important information about chondral or subchondral bone injuries, synovial reaction and adjacent soft tissue involvement. The anterolateral impingement syndrome is caused by repeated injuries in plantar flexion and ankle intrarotation. MRI well detects the meniscoid injury thanks to high contrast sequences; it can also distinguish this syndrome from painful chondral and/or bony lesions at this level. MRI is also the method of choice to study sinus tarsi impingement, especially thanks to fat suppression sequences which increase MR diagnostic capabilities in this important anatomic area. Deep peroneal nerve entrapment, the medial plantar nerve entrapment syndrome and the tarsal tunnel syndrome are the most important entrapment neuropathies of the ankle. US and MRI are very useful to study the tendon and soft tissue abnormalities causing the anterior tarsal tunnel syndrome. CT and particularly MRI can easily detect many pathologic conditions causing the medial plantar nerve entrapment and the tarsal tunnel syndromes.