Ankle moment measurement in biomechanics

Biomechanical movement analysis is based on a set of kinematic measurements, generally obtained through video recordings, and kinetic measurements usually through a force platform. In order to obtain more detailed information for example as regards internal joint forces and moments, a biomechanical model is required. Model inputs are kinematic and kinetic measurement data, while internal forces and moments are its outputs. Particularly interesting when dealing with lower limbs models for describing for example walking, jumping or lifting on tiptoes, is the ankle moment. Usually ankle is the first joint in the model and external forces act on it producing moments that foot and ankle have to withstand with muscles acting on it. The measurement of such moment is critical due to several factors primarily the unknown position of centre of rotation for the foot. Several methods are available to indirectly measure ankle moment, we propose here a comparison of different measurement approaches considering their results for different gestures, commenting pros and cons and giving some practical indications.