Understanding patient preference in prosthetic ankle stiffness.
Tyler R Clites, Max K Shepherd, Kimberly A Ingraham and 2 others
PMID 34433472WHAT IT FOUND
Seven people with below-knee amputation preferred less stiff prosthetic ankle settings at their comfortable speed.
Metabolic cost did not change with stiffness. Ankle movement symmetry was highest near preference, and overground walking speed was faster at stiffness at or above preference.
Key findings
01Six of the seven participants preferred their lowest ankle stiffness at their self-selected treadmill speed.
02Metabolic rate was not measurably affected by stiffness changes within the range tested.
03A measure of ankle movement symmetry had its turning point near the preferred stiffness, and overground walking speed was faster at stiffness at or above the preferred stiffness.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only seven community ambulators with unilateral below-knee amputation, and the group was mostly men, so results may not apply to lower-activity users or women. All testing used one research VSPA foot with a specific torque-angle shape, so findings may not transfer to ordinary passive feet or powered ankles. Acclimation was short, and the authors state preferences and gait mechanics may continue to change over longer adaptation periods. The analysis was exploratory and did not include electromyography, upper-body kinematics, or comprehensive patient-reported comfort and stability surveys. The sample was not representative of all people with below-knee amputation because participation required substantial walking ability.
Declared interests
Funding was provided by the Congressionally Directed Medical Research Programs.
The easy way to misread this
Do not read the faster overground walking speed at stiffness at or above preference as proof that stiffer settings are better for everyone. The participants often preferred lower stiffness at their comfortable speed, metabolic cost did not change with stiffness, and the study used one research device in seven community ambulators.