A novel pivot ankle/foot prosthesis reduces sound side loading and risk for osteoarthritis: a pragmatic randomized controlled trial.
Phoebe Runciman, John Cockcroft, Wayne Derman
PMID 35019886WHAT IT FOUND
Walking with a pivot-ankle foot reduced loading on the sound-side knee compared to standard feet.
It also increased push-off power from the prosthetic side. This biomechanical shift may lower osteoarthritis risk, but the study did not track patients over time to prove clinical benefit.
Key findings
01The novel pivot-ankle foot (N-ESAR) produced lower peak external knee adduction moment (EAM) on the sound side compared to both the standard energy storage foot (ESAR) and the solid-ankle cushioned-heel (SACH) foot.
02The N-ESAR foot generated significantly more distal shank power (DSP) on the prosthetic side during late stance than the ESAR and SACH feet.
03Participants using the SACH foot experienced markedly higher loading rates and peak vertical ground reaction forces on the sound side compared to the other two feet.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was not longitudinal; it measured biomechanical surrogates for osteoarthritis risk (like knee moments) but did not follow patients over time to see if they actually developed osteoarthritis or pain. All participants were habitual users of ESAR feet, which may have biased results against the SACH foot, as they were less experienced using it. The acclimatization period was only two weeks, which is short for adapting to a novel prosthetic design. The sample size was small (n=20) and participants were recruited from private care in South Africa, limiting generalizability to public sector users or those with different activity levels.
Declared interests
The paper does not explicitly state funding sources or conflicts of interest in the provided text.
The easy way to misread this
Do not interpret the reduced knee loading as proof that the N-ESAR foot prevents osteoarthritis. The study measured biomechanical markers over a short period in a small group, not clinical outcomes like pain or radiographic changes over years.