Muscle-tendon unit length measurement using 3D ultrasound in passive condition: OpenSim validation and development of personalized models

3D ultrasound of the hamstring muscles (semimembranosus, semitendinosus, biceps femoris), rectus femoris, and gastrocnemius (gastrocnemius medialis, gastrocnemius lateralis) for 14 participants (8 men and 6 women), together with their associated musculoskeletal modeling in OpenSim software.

These data can be used to perform length measurements of muscle structures in static positions covering a wide range of joint angles. This type of data was accessible using conventional imaging techniques such as MRI for resting positions, notably lying down and with neutral or near-neutral joint angle configurations (i.e., little shortening or lengthening of muscle structures during measurements, and little variety in the angles measured). Unlike MRI, 3D ultrasound is more accessible, less costly, and allows us to overcome the constraints associated with experimental space (e.g. MRI tube, long position-holding time). It was thus possible to carry out repeated measurements in a variety of joint configurations, thereby improving our understanding of the behavior of bi-articular muscles (i.e., during lengthening, shortening or a combination of the two, in relation to a neutral reference position).

Combining this knowledge with musculoskeletal modeling enables integration of this new data into human movement simulation software such as OpenSim, to improve our understanding of human movement.