3D foot joints angle description using projected lines on anatomical planes

Introduction An increasing trend for 3D kinematic analysis of multisegment foot has emerged both in clinical and biomechanical studies [1,2]. Nevertheless, existence of several joints among tiny bones of foot causes difficulties both for joint angle definition and their measurement. Unlike with the larger lower limbs bone, it is hardly possible to put three reflective markers over each foot bone. Subsequently, it is not practical to define local coordinate systems (LCS) for all foot segments bounding foot joints. This work proposed a simple method for foot joints angle description which is easy to interpret.