Characterization of Lesions of the Talus and Description of Tram-Track Lesions

Abstract

Background: The ankle joint, although not prone to primary osteoarthritis (OA), is known to be susceptible to secondary OA as a result of sports injuries and other trauma. Unlike the knee joint, a thorough investigation of talar cartilage lesions has not been previously reported. Methods: One hundred and five human tali from 67 donors were used to determine the type and location of the most common lesions through gross examination, radiography, diffraction enhanced imaging, and histology. “tram-track lesions” also are described. Results: The most anterior and posterior regions of the talar dome, along with the medial and lateral borders of the dome were most affected by cartilage degeneration. These are regions that appear to be most subjected to frictional forces from their articulating counterparts during high stress activities that move articulating surfaces slightly out of congruence with each other. One particularly striking cartilage degeneration pattern that, to our knowledge, has not been described histologically, is the tram-track lesion. These lesions displayed a longitudinally oriented groove in the cartilage, running from anterior to posterior, in which the deepest portion of the groove was located in the middle of the anterior-posterior axis of the talus. Several of these cartilage grooves had a bony ridge beneath, mirroring the cartilage groove whereas others did not. This suggests that the cartilage groove develops before the interruption of the tidemark (border between the calcified and uncalcified cartilage). In specimens for which the articulating tibial articular surface was available, (17) it was found that the tibia displayed small osteophytes on the anterior articular margin that exactly corresponded to their articulation with the talar cartilage grooves as the ankle articulated through plantar flexion and dorsiflexion. Conclusion: This study provides an in-depth histologic and gross anatomic look at the most common lesions of the talus of the ankle joint. In particular, the “tram-track” lesion was shown to be a consequence of its tibial articulation and to include both subchondral bone and articular cartilage changes.