Energy cost of ambulation in trans-tibial amputees using a dynamic-response foot with hydraulic versus rigid 'ankle': insights from body centre of mass dynamics.
Graham N Askew, Laura A McFarlane, Alberto E Minetti and 1 others
PMID 30871573WHAT IT FOUND
Switching from a rigid prosthetic foot attachment to one with a small hydraulic ankle reduced metabolic energy cost per meter by 11.8% on level ground and 20.2% on declines.
This allowed faster walking at the same perceived effort, particularly on 10-degree slopes.
Key findings
01Metabolic cost of locomotion was lower by 11.8% during level walking and 20.2% during gradient walking when using the hydraulic ankle attachment compared to the rigid attachment.
02For the same level of metabolic effort, participants could walk at faster speeds with the hydraulic ankle, reaching 1.18 m/s versus 1.09 m/s at a specific power output.
03The hydraulic attachment improved gait symmetry and locomotor efficiency, with the most striking differences in body center of mass trajectory observed on a 10-degree decline.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study included only nine male participants, which limits the generalisability of the findings to women or more diverse amputee populations. The sample size was small, which reduced the statistical power to detect significant differences in some secondary outcomes like gait symmetry. Participants had only 30 to 40 minutes to acclimate to the new hydraulic attachment, which may not reflect long-term adaptation. The study was conducted on a treadmill, which may not perfectly replicate overground walking conditions. The hydraulic attachment added approximately 400 g to the prosthesis mass, yet still reduced metabolic cost, suggesting the benefit outweighs the added weight.
Declared interests
The study was funded by the Engineering and Physical Sciences Research Council. The text notes that the prosthetic components were provided by Chas. A Blatchford & Sons Ltd., but does not explicitly state a conflict of interest regarding the funding source's involvement in the study design or analysis.
The easy way to misread this
Do not assume this device will improve walking for all amputees or all terrain types. The benefits were measured in nine physically active men on a treadmill, and the study did not test overground walking or patients with other comorbidities. The improvement in gait symmetry was a trend and not statistically significant for most measures.