The Effect of Quadriceps Contractures on Gait and its Adaptation Strategy

Muscle functions may adopt abnormal activation patterns to achieve ambulation in response to the contracture in the lower extremity muscles. This study implements a forward simulation based on dynamic optimization method to investigate gait compensation strategy adopted by a person with quadriceps contracture. A simulated controller optimization environment (SCONE) was used to solve the problem using the single shooting method. The results are in good agreement with experimental data and other studies. Some significant deviations were found, which were primarily attributed to the simplification of the musculoskeletal model used. The model exhibited reduced knee and hip flexion up to 90.63% and 77.72% at the impaired limb, which were potentially related to overactivity of rectus femoris and vasti, that generated excessive knee extension moment. The unimpaired limb exerted a greater vertical ground reaction force as a mean to maintain weight-bearing stability, in which gluteus maximus contributed a significant effort to support the contralateral limb, thus leading to an increase in knee flexion by 64.25%. The findings presented in this study provides another step forward in validating a physics-based simulation independent of the experimental data. The forward dynamic optimization is expected to be a valuable clinical and engineering tool in the future.