Computational representation of the aponeuroses as NURBS surfaces in 3D musculoskeletal models

Computational musculoskeletal (MSK) models – 3D graphics-based models that accurately simulate the anatomical architecture and/or the biomechanical behaviour of organ systems consisting of skeletal muscles, tendons, ligaments, cartilage and bones – are valued biomedical tools, with applications ranging from pathological diagnosis to surgical planning. However, current MSK models are often limited by their oversimplifications in anatomical geometries, sometimes lacking discrete representations of connective tissue components entirely, which ultimately affect their accuracy in biomechanical simulation. In particular, the aponeuroses – the flattened fibrous connective sheets connecting muscle fibres to tendons – have never been geometrically modeled. The initiative was thus to extend Anatomy3D – a previously developed software bundle for reconstructing muscle fibre architecture – to incorporate aponeurosis-modeling capacity. Two different algorithms for aponeurosis reconstruction were written in the MEL scripting language of the animation software Maya 6.0, using its NURBS (non-uniform rational B-splines) modeling functionality for aponeurosis surface representation. Both algorithms were validated qualitatively against anatomical and functional criteria.