[Significance of shape differences between medial and lateral knee joint menisci for functional change of position]

The attachments of the anterior and posterior horn of the menisci to the tibial plateau are of a most important functional value. At the medial meniscus the circumference is more widely configurated, because of the greater distance between anterior and posterior horns. The areas of sagittal cuts through the menisci slightly differ regarding medial and lateral side. A higher area momentum of inertia of the medial meniscus, related to a vertical axis within the examinated sagittal plane, is found. It derives from a geometrical distribution of partial areas more distant from the axis. The medial meniscus therefore has a higher stiffness against sagittal bending stress. Experiments and theoretical stress simulation prove these results. According to them, the medial meniscus is less mobile in comparison to the lateral. These findings are discussed as a basic geometrical cause for the higher incidence of injuries of the medial meniscus.