[Computerized tomography of osteochondral diseases of the talus dome]

The definition "osteochondritis dissecans" of the talus improperly includes a variety of diseases involving the chondral surface of the talus dome and the relative subchondral bone. To investigate the CT diagnostic potentials in the study of these conditions, 35 patients complaining of a "painful ankle" were examined with plain radiography and axial and direct paracoronal CT over a 2-year period. Twelve patients were then examined with double contrast CT arthrography with air and iodated contrast agents. CT diagnostic accuracy was assessed evaluating the following parameters: the presence and extent of the subchondral bone fragment, the presence of residual bone fragment attachment at the lesion base or its intraarticular dislocation, the presence of subchondral bone cysts, of chondral surface lesions and, finally, of capsular and ligamentous damage. All the patients with CT findings of osteochondral conditions of the talus dome were submitted to arthroscopic examination/treatment and/or surgical arthrotomy. Baseline CT exams accurately depicted all the lesions, except for early (grade I) lesions. Moreover, the administration of intraarticular contrast agent (CT arthrography) increased the diagnostic accuracy in articular cartilage studies. Therefore, the authors believe baseline CT on the orthogonal planes to represent an effective tool for the staging of osteochondral talar lesions and for accurate treatment planning.