The interaction between muscle pathophysiology, body mass, walking speed and ankle foot orthosis stiffness on walking energy cost: a predictive simulation study.
N F J Waterval, M M van der Krogt, K Veerkamp and 4 others
PMID 37679784WHAT IT FOUND
Simulations suggest optimal AFO stiffness for reducing energy cost is higher than previously thought.
Stiffer orthoses are needed for severe weakness and faster walking, while standard low-stiffness devices may be insufficient for many patients.
Key findings
01Optimal AFO stiffness for minimizing walking energy cost increased with severity of plantarflexor weakness and walking speed.
02The stiffness required to minimize energy cost was consistently higher than the stiffness needed to normalize joint angles and moments.
03Simulations predicted that commonly provided off-the-shelf AFOs with stiffness up to 3 Nm/degree are often too low to optimize energy cost or normalize gait.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study is a simulation, not a clinical trial, so findings require experimental verification. The model overestimated the effect of weakness on gait when no AFO was worn, casting doubt on the exact energy cost reductions. The simulation ignored mediolateral balance and footplate stiffness, which affect real-world gait. Validation was based on only 11 participants with specific diagnoses.
Declared interests
The work was funded by ZonMw. No other conflicts of interest were declared in the provided text.
The easy way to misread this
Do not assume these simulation results prove that stiffer AFOs work better in patients. The model had accuracy issues when simulating walking without an AFO, and the authors state that clinical implementation requires improved predictions and further research.