At the end of a recent study comparing three categories of prosthetic feet, participants were asked a straightforward question: Which one would you choose?
Only 21 percent picked the powered foot.
The other 79 percent preferred one of the two nonpowered options they had tested.
Those choices became particularly interesting when researchers compared them with the rest of the study results. Detailed gait analysis showed clear biomechanical differences among the devices. Standard clinical mobility tests, meanwhile, detected almost none.
In other words, depending on how researchers measured performance, they got a different picture of which prosthetic foot performed best.
So what does “better” actually mean?
For the 2026 study, published in PLOS ONE, researchers recruited 91 people with unilateral transtibial limb loss for a randomized crossover trial conducted at four VA and military medical centers. Each participant tested three categories of ankle-foot devices: energy-storing-and-returning (ESR), articulating ESR, and powered. Participants had a week to acclimate to each device before researchers assessed them using clinical mobility tests, questionnaires, and, for a subset of 29 participants, detailed gait analysis.
The different measures didn’t tell the same story.
Biomechanical analysis proved particularly sensitive to differences among the feet. Researchers identified 19 gait parameters that varied by device type, most involving ankle mechanics. The powered foot produced significantly different results on several measures, including ankle power generation and range of motion.
Participants’ assessments pointed elsewhere.
They rated conventional ESR feet higher than powered feet for satisfaction, frustration, utility, and perceived response. When the trial ended, 41 percent chose an ESR foot as their preferred device, 38 percent chose an articulating foot, and 21 percent chose the powered option.
Some familiar clinical measures revealed surprisingly little about those differences.
Participants completed the six-minute walk, Timed Up and Go, Four Square Step Test, Amputee Mobility Predictor, and assessments involving stairs and hills. With the exception of a small difference in Timed Up and Go performance that did not reach the threshold for a detectable clinical change, the tests did not significantly distinguish among the three device categories.
That’s important because clinicians have a lot of feet to choose from.
The researchers note that more than 300 prosthetic ankle-foot devices are commercially available, yet there is no “gold standard” assessment for determining which device is best suited to an individual user. Prescription instead draws on factors including clinical judgment, a person’s goals and abilities, previous prosthesis use, and available research evidence.
The study doesn’t identify a winning foot. Instead, it exposes a challenge in determining what should count as a meaningful difference between them.
Biomechanical testing detected changes that clinical mobility assessments largely missed. Clinical tests suggested relatively similar performance among devices that participants experienced differently. And the most technologically complex option was the least frequently chosen.
The researchers hope identifying measures that are sensitive to differences among prosthetic feet will ultimately support more objective, individualized prescriptions.
Their findings also leave behind a question that can’t necessarily be settled in a gait lab: When the biomechanics, clinical tests, and the person wearing the prosthesis tell different stories, which should matter most?