Local compressive strength of the superolateral and sueromedial aspects of the anterior half of the talar dome: A biomechanical and histological study.

ABSTRACT

One cause of osteochondritis dissecans of the talar dome is related to trauma. The lesion occurs at the anterior half of the talar dome. The lateral osteochondritis dissecans is located at the superolateral aspect, while the medial lesion is located at the superomedial aspect. The lateral lesion is more common and its crater is shallower than that of the medial lesion. This study was therefore carried out to determine the local compressive strength of the superolateral and superomedial aspects of the anterior half of the talar dome. Ten pairs of fresh normal cadaveric tali were obtained. Using a universal testing machine, a compressive load was applied through a metal indenter at the superolateral and superomedial aspects of the talar dome until the maximal load was obtained. The maximal load and depth of depression were recorded. Histological studies of the compressive lesion was done using decalcified hematoxylin eosin stain. The results of the study showed that the superolateral aspect of the talar dome could withstand 1.27 times less compression load than could the superomedial aspect without a significant difference in stiffnesses. Moreover, the depth of depression of the superolateral compressive lesion was shallower than that of superomedial. Histological studies showed that the compressive lesion was a depression fracture. The depression fracture was a free osteochondral fragment surrounded by normal osteochondral tissue. The free fragment included articular cartilage, subchondral plate, and subchondral cancellous bone. The result of this study may explain why the prevalence of the lateral traumatic osteochondritis dissecans is higher, and its lesion crater shallower, than that of the medial aspect of the talar dome.