German Research Foundation (DFG) - Project number: 554365017
Menisci are crucial for the complex mechanics of the knee joint. For example, they play an important role in joint lubrication, load distribution, and joint stability. The wedge-shaped menisci have a multi-layered structure and increase the congruence between the convex femoral condyles and the relatively flat tibial head. In this way, they protect the articular cartilage from excessive axial stress and abrasion.
Despite the great importance of the menisci for locomotion, no multiscale model exists to date that describes the mechanical behaviour of the meniscus at different levels (from the micro to the tissue to the organ level) and enables valid predictions to be made about the load-bearing capacity, deformation and mechanobiology of the menisci.
The aim of the research project is to develop and validate a biphasic hyperporo-viscoelastic multiscale model for predicting the material behaviour of porcine meniscal tissue. The research project explicitly focuses on the methodological development of experimental and numerical methods that can also be applied to menisci of other species in the future.
The realisation of this goal takes place in several steps, which are characterised by a close link between experiment and modelling. In a first experimental step, targeted experimental investigations are carried out on meniscus cubes on the µm scale (sample edge length approx. 200 µm), which allow a high layer resolution from a mechanical point of view.
Mechanical investigations on the mm-scale form the second working step and allow conclusions to be drawn about the interaction of the tissue components/layers. In order to record the material properties of the meniscus tissue, permeability investigations are carried out in combination with microstructural investigations.
In experiments on the intact total meniscus, the interaction of the subcomponents under defined loads is investigated. Indentation experiments provide data on the local material properties and on meniscus deformation. In experiments on the complete knee joint, the pressure distributions during guided roll-slide movements are recorded.
Based on these data, the meniscus model to be developed will be validated in several steps, whereby the degree of complexity will be increased step by step. The multiscale experiments to be conducted in the research project will enable rigorous validation of the model to be developed, in addition to an improved understanding of the load transfer mechanisms prevailing in the meniscus.
The multiscale model will allow more precise statements to be made about the mechanobiology, function, and load-bearing capacity of menisci and thus represents a future methodological approach for characterising and describing the meniscal behaviour of other species and conditions (e.g. influence of age, overload and injury).