QUANTIFICATION OF SUBJECT SPECIFIC MUSCLE MOMENT ARM AND MUSCLE LENGTH: AN ISSUE FOR MODELING

An accurate representation of the lower limb musculoskeletal system is required for the prediction of the muscle-tendon forces during human movement when using musculoskeletal models. The most recent models are very sensitive to musculoskeletal geometry. Usually muscletendon lengths and moment arms are estimated from joint angles using published data obtained from cadaver specimens of different heights (Gerrisent, 1998; Umberger, 2006). The determination of the length and of the line of action of the muscles personalized to subject morphology is one of the major steps in the development of reliable musculoskeletal models. In 2007, a non invasive method for determining the line of action of lower limb muscles with means of manual pointing on the subject has been proposed (Bonnefoy, 2007). The aim of this study is to compare the accuracy of these estimations using also ultrasound images for identifying muscle insertions, origins and via points of a specific subject, and comparing these estimations to subject specific anatomy reconstructed from MRI scans of the lower limbs.