Osteochondral talar defects (OCDs) are sometimes located so far posteriorly that they may not be accessible by anterior arthroscopy, even with the ankle joint in full plantar flexion, because the talar dome is covered by the tibial plafond. It was hypothesized that computed tomography (CT) of the ankle in full plantar flexion could be useful for preoperative planning. The dual purpose of this study was, firstly, to test whether CT of the ankle joint in full plantar flexion is a reliable tool for the preoperative planning of anterior ankle arthroscopy for OCDs, and, secondly, to determine the area of the talar dome that can be reached by anterior ankle arthroscopy. In this prospective study, CT-scans with sagittal reconstructions were made of 46 consecutive patients with their affected ankle in full plantar flexion. In the first 20, the distance between the anterior border of the OCD and the anterior tibial plafond was measured both on the scans and during anterior ankle arthroscopy as the gold standard. Intra- and interobserver reliability of CT as well as agreement between CT and arthroscopy were assessed by intraclass correlation coefficients (ICCs) and a Bland and Altman graph. Next, the anterior and posterior borders of the talar dome as well as the anterior tibial plafond were marked on all 46 scans. Using a specially written computer routine, the anterior proportion of the talar dome not covered by the tibial plafond was calculated, both lateral and medial, indicating the accessible area.PURPOSE
METHODS
