[Ankle impingement syndrome].
OBJECTIVE
The ankle impingement syndrome depends on many factors (fiber or bone production changes) manifested with pain and limited range of movement of the tibiotarsal joint. We tried to classify the various causes and sites of impingement syndromes with MRI.


METHODS
A cohort of 42 selected patients underwent a 2-year orthopedic follow-up. All patients were examined with MRI using both a low field permanent dedicated magnet at 0.2 Tesla (Artoscan, Esaote Biomedica, Genoa, Italy) and a high field General Electric unit at 1.0 T; sequences and views were chosen according to the condition studied. Gd-DTPA was administered in 26/42 patients. All patients underwent arthroscopy.


RESULTS
Twenty-one patients had positive symptoms in the anterolateral region of the ankle and 14 of them had lateral changes. In 13 patients we found fibrous tissue (meniscoid lesion) or hypertrophy of the synovial tissue. An intra-articular body was observed in one patient. An osteophyte was found in 5 patients at the level of the anterior margin of the tibia, with the presence of reactive synovial tissue. Three of 18 patients with posterior pain had a traumatic injury of the posterior exterior tubercle of the astragalus, 7 had a fracture of the os trigonum and 2 had small sclerotic foci formations in calceneal site; chondropathy with sclerosis of subchondral bone was diagnosed in 2 patients. Posterior bone impingement was observed in the remaining 4 patients. Two patients had synovial impingement in posterolateral site. A posterior plica synovialis was seen in 1 patient. Fibrotic-scar tissue was observed in one case, in the subtalus region (impingement synovialis subtalaris). The administration of intra-articular Gd-DTPA provided better definition of the fibrous tissue and the intra-articular free bodies. Modest vascular enhancement of the tissues was seen in 9 of 8 patients receiving the contrast agent. In the other two cases, where signal tissue was low, no signal enhancement was observed after the contrast agent administration.


CONCLUSIONS
Based on integrated MR, clinical and arthroscopic findings we classified tibiotarsal joint impingement syndromes into three types, namely: 1) bone impingement; 2) fibrous impingement where both site and grade are considered; 3) impingement synovialis subtalaris.


CONCLUSIONS
MRI appears to be a fundamental diagnostic imaging tool in depicting and detailing the various patterns and sites of the impingement syndrome of the tibiotarsal joint thus allowing an objective classification.
Dipartimento di Radiologia, Azienda Ospedaliera, Centro Traumatologico Ortopedico, Centro Rieducazione Funzionale, Maria Adelaide, Via Zuretti, 29, 10126 Torino TO.
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Faletti
D000328:Adult; D000843:Ankle Joint / Q000473:pathology*; D005260:Female; D006801:Humans; D007592:Joint Diseases / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D013577:Syndrome