Characterization of a bipartite medial cuneiform: micro-CT and anatomical study

Abstract

A bipartite medial cuneiform is an anatomical variant consisting in a horizontal division of the bone. Previous descriptions of the joint type, obtained from archaeological material or clinical reports, are unclear. This study was conducted in a fresh-frozen left foot, which allowed studying the morphology of the ligaments after anatomical dissection. In addition a Micro-CT analysis was performed to elucidate the osseous structure supporting the articular surfaces. A complex ligamentous system was found between the two halves of the bipartite medial cuneiform. Two articular surfaces were observed between the two components. Hyaline cartilage was observed at the posterior surface, while fibrous tissue was found at the anterior surface. Micro-CT analysis revealed different osseous structures for each articular surface, thus proving the existence of two joint types. The finding of a bipartite medial cuneiform in a fresh-frozen specimen allowed us to perform an analysis of the soft-tissues and articular surfaces that shows the presence of hyaline cartilage and articular ligaments in the diarthrodial joint as well as the fibrous component of the synfibrosis. Micro-CT analysis further reinforces our morphological findings. Our results prove that two different joint types exist, which could help explaining the disparity of descriptions in the literature.