Prediction of hip contact forces and muscle activations during walking at different speeds

The validation of musculoskeletal models is a challenging task necessary to obtain confidence in the numerical predictions they can provide. In this paper, a musculoskeletal model of the lower limb is used to predict the hip contact forces and muscle activations resulting from walking at different speeds for three total hip replacement patients implanted with instrumented prostheses (Bergmann et al., J. Biomech. 34:859-871, 2001). The developed model is shown to estimate the magnitude of hip contact forces with encouraging accuracy in terms of relative peak error (on average within 22% of the experimental value) and global prediction error measurements. Hip contact force predictions were found to be generally more accurate for a slow walking speed. The static optimization technique adopted to estimate muscle activation profiles reproduced for the majority of muscles the modulation and variation in activation patterns documented in the literature for different walking speeds.