Simbios Talk by Clay Anderson, Stanford University, March 7, 2006

Title: Elucidating Muscle Function during Movement Using Forward Dynamic Simulation

Quantifying how muscles contribute to an observed movement is challenging, yet this information is important for treating movement disorders where muscles are often the targets of treatment. For example, in individuals with cerebral palsy, muscles are frequently transferred or lengthened to treat crouch or stiff-knee gaits. The challenge in quantifying muscle function is due in part to the fact that there is currently no non-invasive method for measuring muscle forces. It is also challenging because muscles accelerate joints they do not span and in directions that are sometimes non-intuitive. For example, the hamstrings muscle group, which generates a flexion moment at the knee, can accelerate the knee into extension. Forward dynamic simulation coupled with efficient control techniques offers a powerful methodology for elucidating muscle function. It provides an approach for not only estimating muscle forces but also quantifying how muscles accelerate joints. In this talk, I will describe how we model the musculoskeletal system, obtain simulations of movement using computed muscle control, and use perturbation analysis to quantify muscle function. I will end with a description of our software framework.