Multiscale modelling methods in biomechanics

More and more frequently, computational biomechanics deals with problems where the portion of physical reality to be modelled spans over such a large range of spatial and temporal dimensions, that it is impossible to represent it as a single space-time continuum. We are forced to consider multiple space-time continua, each representing the phenomenon of interest at a characteristic space-time scale. Multiscale models describe a complex process across multiple scales, and account for how quantities transform as we move from one scale to another. This review offers a set of definitions for this emerging field, and provides a brief summary of the most recent developments on multiscale modelling in biomechanics. Of all possible perspectives, we chose that of the modelling intent, which vastly affect the nature and the structure of each research activity. To the purpose we organised all papers reviewed in three categories: さcausal confirmationざ, where multiscale models are used as materialisations of the causation theories; さpredictive accuracyざ, where multiscale modelling is aimed to improve the predictive accuracy; and さdetermination of effectざ, where multiscale modelling is used to model how a change at one scale manifest in an effect at another, radically different space-time scale. Consistently with the how the volume of computational biomechanics research is distributed across application targets, we extensively reviewed papers targeting the musculoskeletal and the cardiovascular system, and covered only a few exemplary papers targeting other organ systems. The review shows a research sub-domain still in its infancy, where causal confirmation papers remain the most common