# How Do Lower Limb Prosthetic Stiffness and Power Affect the Biomechanics, Metabolic Costs, and Satisfaction of Veterans with Transtibial Amputations DuringWalking?

> **NIH VA I01** · VA EASTERN COLORADO HEALTH CARE SYSTEM · 2021 · —

## Abstract

Previous studies suggest that use of the recommended prosthetic foot stiffness category and/or ankle
power output setting may not optimize the function of Veterans with transtibial amputations (TTAs). Due to the
functional impairments and lifetime of healthcare costs incurred by Veterans with TTAs, it is vital to determine
how different prosthetic foot and ankle properties/parameters such as passive-elastic prosthetic foot stiffness
and battery-powered prosthetic ankle power output affect the metabolic cost and biomechanics of Veterans
with TTAs. Further, determining the optimal prosthetic foot stiffness and/or power output could dramatically
improve the function of people with TTAs, which would promote increased physical activity, while reducing pain
and the risk of comorbidities. Veterans with TTAs typically use a passive-elastic prosthetic foot such as the
Össur Low Profile Vari-flex with Evo (LP) with a stiffness category based on manufacturer-recommendations,
user body mass, and anticipated activity level. Previous evidence demonstrates that Veterans with TTAs using
the recommended passive-elastic prosthetic foot stiffness category for walking have greater metabolic
demands, asymmetric biomechanics, leg and back pain, and discomfort compared to non-amputees. Further,
some Veterans use a battery-powered ankle-foot prosthesis such as the Ottobock BiOM. [The Össur Low
Profile Vari-flex with Evo (LP) is the only passive-elastic prosthetic foot that integrates with the BiOM. The LP is
utilized beneath (in-series with) the BiOM with a stiffness category based on manufacturer-recommendations,
user body mass and activity level. Then, the BiOM is tuned by adjusting nine different parameters within the
prosthesis using different software settings so that the combination of the user and prosthesis produce net
positive prosthetic ankle work equivalent to average non-amputee net positive ankle work within two standard
deviations (SD) of the mean. Use of BiOM has resulted in normative metabolic costs and biomechanics for
people with TTAs compared to non-amputees, but one study found that use of the BiOM with a recommended
LP prosthetic foot stiffness category and prosthetic power output setting did not elicit differences in metabolic
cost at preferred walking speeds compared to use of participants’ own passive-elastic prosthesis.]
 We will systematically assess how prosthetic foot stiffness and power output affect physical function in
Veterans with TTAs. First, we will quantify prosthetic and torsional stiffness (force/displacement or
torque/angle) values of LP prostheses. Determining stiffness values (in kN/m and kN·m/rad) for a given
passive-elastic prosthetic foot stiffness category is essential for deriving the dynamic biomechanical function of
prosthetic feet. Then, we will systematically measure and compare the metabolic cost, biomechanics, muscle
activity, and satisfaction resulting from using the LP passive-elastic prosthetic foot alone with four ...

## Key facts

- **NIH application ID:** 10201776
- **Project number:** 5I01RX002941-03
- **Recipient organization:** VA EASTERN COLORADO HEALTH CARE SYSTEM
- **Principal Investigator:** Alena Grabowski
- **Activity code:** I01 (R01, R21, SBIR, etc.)
- **Funding institute:** VA
- **Fiscal year:** 2021
- **Award amount:** —
- **Award type:** 5
- **Project period:** 2019-08-01 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10201776

## Citation

> US National Institutes of Health, RePORTER application 10201776, How Do Lower Limb Prosthetic Stiffness and Power Affect the Biomechanics, Metabolic Costs, and Satisfaction of Veterans with Transtibial Amputations DuringWalking? (5I01RX002941-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10201776. Licensed CC0.

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