Effects of bicycle geometry and riding position on the potential of residual limb muscles to pedaling with a transfemoral prosthesis: a computer simulation study

We performed musculoskeletal simulations to provide information on the effects of riding position and bicycle geometry on pedaling with a transfemoral prosthesis. Sixty-four models and their corresponding kinematics in one pedaling cycle were generated from the baseline one-leg cycling model by varying one of the six variables (seat height, seat-tube angle, crank length, pelvic tilt, anteroposterior seating position, and thigh length relative to the leg). Induced acceleration analysis was performed to compute the potentials of the residual hip muscles for crank rotation in each model. The simulation results quantified the effects of each variable on the hip and knee kinematics and muscle potential during a pedaling cycle; seat height, crank length, and pelvic tilt were the primary candidates for bicycle fitting considering their accessibility and simple effects on the joint kinematics and muscle potential. The seat-tube angle (similar to pelvic tilt) and the anteroposterior seating position (similar to seat height and seat-tube angle) seemed to have an effect similar to the other variables and thus can be reserved for fine-tuning after gross fitting of the bicycle. Although not considered for adjustment, considering the effects of the thigh length could help as it affects hip kinematics and muscle potentials.