Lateral reactive stepping responses differ between individuals with and without transfemoral amputation

Effective reactive stepping is critical for preventing falls. Although falls are common in individuals with transfemoral amputation (TFA), mediolateral reactive stepping responses in this population remain poorly understood. This study investigated limb-specific mediolateral reactive stepping responses in individuals with and without TFA. Seventeen individuals with TFA and seventeen healthy controls experienced lateral perturbations applied at the waist using a custom system. Step thresholds, stepping strategies, step latency, and center of pressure (CoP) metrics were compared for perturbations that loaded the prosthetic limb, sound limb, or control's dominant limb. Two participants with TFA were unable to complete the protocol and were excluded. Step thresholds did not differ based on loaded limb (p = 0.062). However, participants with TFA showed longer step latency and selected different stepping strategies than controls (p ≤ 0.001). Within the group with TFA, responses depended on the loaded limb: perturbations that loaded the prosthetic limb elicited more crossover steps and greater CoP path length than perturbations that loaded the sound limb, despite similar CoP position at step onset. Individuals with TFA had altered timing and execution of mediolateral reactive stepping responses, particularly when perturbations load the prosthetic limb.