Sensitivity of musculoskeletal model parameters during gait simulations

Abstract-Text (inkl. Referenzen und Bildunterschriften)

Introduction

Personalized gait simulations enable the creation of individualized interventions [1]. This includes personalization of the musculoskeletal model, which is challenging as even a simple two-dimensional model contains more than 250 empirical parameters that could be personalized [2]. Furthermore, also simulation parameters such as movement objectives could be personalized. Our goal was to explore which parameters affect simulated gait most and thus should be personalized.

Methods

We assessed the sensitivity of musculoskeletal parameters via a Morris sensitivity analysis [3]. In Morris" method, a single parameter is changed per function evaluation while keeping others constant. Each function evaluation corresponds to one predictive 2D optimal control gait simulation. For every simulation parameter, we ran 80 simulations to obtain the mean absolute (μ*) and standard deviation (σ) of gait variations. We then evaluated to which extent simulation and musculoskeletal parameters affect simulated gait parameters, for example walking speed and knee range of motion.

Results & Conclusion

Figs. 1 & 2 show the average effect of a parameter deviation and its standard deviation. We found that muscle parameters had the largest influence on the gait speed (Fig. 1). When looking at muscle parameters separately, we found that contractile element and tendon lengths affected the knee range of motion most (Fig. 2). The results for variations in cadence are similar to both. In conclusion, we showed that muscle-related elements, particularly contractile element and tendon lengths, have the highest effect on simulated gait parameters.

References

[1] De Groote et al., Proc Royal Soc B (2021)

[2] Delp et al., IEEE Trans Biomed Eng (2007)

[3] Morris, Technometrics (1991)

Fig. 1: Parameter screening screening results regarding walking speed.

Fig. 2: Parameter screening screening results regarding muscle parameters" influence on knee range of motion.