Imaging of osteochondral lesions of the talus.

A review of the literature reveals that all studies have been performed retrospectively. These studies have included limited numbers of low-grade lesions and no prospective, randomized, comparison studies have been performed to suggest the superiority of CT scanning over MR imaging. The following conclusions, however, can be made. Plain radiographs are useful in the initial evaluation of patients with acute or chronic complaints of ankle pain and swelling. These initial studies, however, may not identify all osteochondral lesions of the talus, particularly lower grade lesions. CT scanning can accurately identify and localize a lesion while defining its extent. It has been suggested that CT scanning can be used to assess whether bony healing has occurred at follow-up. MR imaging can also precisely identify, localize, and define an OLT with the advantage of assessing the integrity of the overlying cartilage. It can detect lower grade lesions with improved sensitivity and may aid in the differentiation of Stage II and Stage III lesions. Using the preceding observations, the following approach is recommended in the evaluation and work-up of an osteochondral lesion of the talus (Fig. 7). The patient who presents with ankle pain and swelling should have weight-bearing radiographs of the ankle obtained. If these films demonstrate an osteochondral lesion of the talus, staging of the lesion should be performed. In lesions that appear nondisplaced on plain radiography (low grade; stable), MR imaging is recommended so the clinician can evaluate the integrity of the overlying cartilage and assess the true stability of the lesion. In lesions that appear displaced on plain radiography (high grade; unstable), the CT scan is the preferred modality in order to provide accurate assessment of lesion size and location. It should be noted, however, that no study has prospectively [figure: see text] compared the efficacy of these two modalities in the evaluation of osteochondral lesions. If a symptomatic patient presents with negative plain films, then an initial period of immobilization using a cast or boot brace is recommended. This is followed by joint mobilization and range of motion exercises. If the patient remains symptomatic at the 4 to 6 week followup period, then an MR image should be performed. This study provides information regarding soft-tissue impingement, proliferative synovitis, and other bony and soft-tissue pathology. The authors have found that despite the results of bone scintigraphy, an MR image is invariably obtained. Because of this the authors do not recommend bone scintigraphy in the evaluation and diagnosis of OLT.