People with lower-limb amputations must regulate their stepping movements to prevent or recover from a loss of balance. A research team set out to identify how well persons with transtibial amputations regulate lateral stepping while walking with and without lateral perturbations.
Eight people with unilateral transtibial amputations and thirteen able-bodied controls walked in a virtual environment under three conditions: no perturbations, a laterally oscillating visual field, and a laterally oscillating treadmill platform. The researchers analyzed step-to-step time series of step widths and absolute lateral body positions. They computed means, standard deviations, and Detrended Fluctuation Analysis scaling exponents for each time series and how much the participants directly corrected step width and position deviations at each step. The researchers then compared the results to computational predictions to identify the underlying causes of the experimental findings.
All the participants exhibited significantly increased variability, decreased scaling exponents, and tighter direct control when perturbed. Simulations from the stepping regulation models revealed that people responded to the increased variability produced by the imposed perturbations by tightening their control of both step width and lateral position. The participants with amputations exhibited only a few minor differences from the able-bodied participants in lateral stepping regulation, even when subjected to substantially destabilizing lateral perturbations.
The research team concluded that because control of stepping is intrinsically multi-objective, developing effective interventions to reduce fall risk in people with amputation will likely require strategies that adopt multi-objective approaches.
The study “How persons with transtibial amputation regulate lateral stepping while walking in laterally destabilizing environments,” was published in Gait & Posture.