The foot and ankle structures reveal emergent properties analogous to passive springs during human walking

Hedrick, Erica A.; Stanhope, Steven J.; Takahashi, Kota

doi:10.1371/journal.pone.0218047

Cited by 10 publications

(3 citation statements)

References 83 publications

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“…Moreover, the mechanical work applied to foot increases during push-off when walking speed being increased. Meanwhile, Hedrick et al (2019) characterized that the foot and ankle synthesize the force, displacement, and work distal to the shank. Thus, when walking speed being increased, ankle and foot cooperate to push shank faster.…”

Section: Ankle Contributes the Most During Push-off To Push Shank Faster During Walkingmentioning

confidence: 99%

Speed-Related Energy Flow and Joint Function Change During Human Walking

Ren

et al. 2021

Front. Bioeng. Biotechnol.

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During human walking, mechanical energy transfers between segments via joints. Joint mechanics of the human body are coordinated with each other to adapt to speed change. The aim of this study is to analyze the functional behaviors of major joints during walking, and how joints and segments alter walking speed during different periods (collision, rebound, preload, and push-off) of stance phase. In this study, gait experiment was performed with three different self-selected speeds. Mechanical works of joints and segments were determined with collected data. Joint function indices were calculated based on net joint work. The results show that the primary functional behaviors of joints would not change with altering walking speed, but the function indices might be changed slightly (e.g., strut functions decrease with increasing walking speed). Waist acts as strut during stance phase and contributes to keep stability during collision when walking faster. Knee of stance leg does not contribute to altering walking speed. Hip and ankle absorb more mechanical energy to buffer the strike during collision with increasing walking speed. What is more, hip and ankle generate more energy during push-off with greater motion to push distal segments forward with increasing walking speed. Ankle also produces more mechanical energy during push-off to compensate the increased heel-strike collision of contralateral leg during faster walking. Thus, human may utilize the cooperation of hip and ankle during collision and push-off to alter walking speed. These findings indicate that speed change in walking leads to fundamental changes to joint mechanics.

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Section: Ankle Contributes the Most During Push-off To Push Shank Faster During Walkingmentioning

confidence: 99%

Speed-Related Energy Flow and Joint Function Change During Human Walking

Ren

et al. 2021

Front. Bioeng. Biotechnol.

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“…There was no statistically significant differences between all three foot conditions, and at a subject level, the variations in walking speeds were all within m/s which according to Takahashi et al 63 would lead to variations in energy return within J/kg, almost one order of magnitude below the observed differences in energy return between foot conditions. In addition, positive foot work has been shown to increase with increased walking speed 63 – 65 . Here, on the contrary, the LLTE feet demonstrated increased energy return compared to daily-use feet while users walked at slower walking speeds, suggesting that the mechanical properties of the prosthetic feet affected the energy return rather than differences in walking speed.…”

Section: Discussionmentioning

confidence: 99%

Biomechanical evaluation over level ground walking of user-specific prosthetic feet designed using the lower leg trajectory error framework

Prost

Johnson

Kent

et al. 2022

Sci Rep

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The walking pattern and comfort of a person with lower limb amputation are determined by the prosthetic foot’s diverse set of mechanical characteristics. However, most design methodologies are iterative and focus on individual parameters, preventing a holistic design of prosthetic feet for a user’s body size and walking preferences. Here we refined and evaluated the lower leg trajectory error (LLTE) framework, a novel quantitative and predictive design methodology that optimizes the mechanical function of a user’s prosthesis to encourage gait dynamics that match their body size and desired walking pattern. Five people with unilateral below-knee amputation walked over-ground at self-selected speeds using an LLTE-optimized foot made of Nylon 6/6, their daily-use foot, and a standardized commercial energy storage and return (ESR) foot. Using the LLTE feet, target able-bodied kinematics and kinetics were replicated to within 5.2% and 13.9%, respectively, 13.5% closer than with the commercial ESR foot. Additionally, energy return and center of mass propulsion work were 46% and 34% greater compared to the other two prostheses, which could lead to reduced walking effort. Similarly, peak limb loading and flexion moment on the intact leg were reduced by an average of 13.1%, lowering risk of long-term injuries. LLTE-feet were preferred over the commercial ESR foot across all users and preferred over the daily-use feet by two participants. These results suggest that the LLTE framework could be used to design customized, high performance ESR prostheses using low-cost Nylon 6/6 material. More studies with large sample size are warranted for further verification.

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“…To further partition the contributions from the prosthesis components, we quantified the work done by the pylon compression. Power from pylon compression was calculated as the product between the force along the longitudinal axis (i.e., ground reaction force transformed from the laboratory to shank’s coordinate system [ 42 ]) and the compression velocity. The compression velocity of the pylon was computed as the derivative of the pylon’s displacement, or the length of the pylon during the entire stance phase.…”

Section: Methodsmentioning

confidence: 99%

Reducing stiffness of shock-absorbing pylon amplifies prosthesis energy loss and redistributes joint mechanical work during walking

Maun

Gard

Major

et al. 2021

J NeuroEngineering Rehabil

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Background A shock-absorbing pylon (SAP) is a modular prosthetic component designed to attenuate impact forces, which unlike traditional pylons that are rigid, can compress to absorb, return, or dissipate energy. Previous studies found that walking with a SAP improved lower-limb prosthesis users’ comfort and residual limb pain. While longitudinal stiffness of a SAP has been shown to affect gait kinematics, kinetics, and work done by the entire lower limb, the energetic contributions from the prosthesis and the intact joints have not been examined. The purpose of this study was to determine the effects of SAP stiffness and walking speed on the mechanical work contributions of the prosthesis (i.e., all components distal to socket), knee, and hip in individuals with a transtibial amputation. Methods Twelve participants with unilateral transtibial amputation walked overground at their customary (1.22 ± 0.18 ms−1) and fast speeds (1.53 ± 0.29 ms−1) under four different levels of SAP stiffness. Power and mechanical work profiles of the leg joints and components distal to the socket were quantified. The effects of SAP stiffness and walking speed on positive and negative work were analyzed using two-factor (stiffness and speed) repeated-measure ANOVAs (α = 0.05). Results Faster walking significantly increased mechanical work from the SAP-integrated prosthesis (p < 0.001). Reducing SAP stiffness increased the magnitude of prosthesis negative work (energy absorption) during early stance (p = 0.045) by as much as 0.027 Jkg−1, without affecting the positive work (energy return) during late stance (p = 0.159), suggesting a damping effect. This energy loss was partially offset by an increase in residual hip positive work (as much as 0.012 Jkg−1) during late stance (p = 0.045). Reducing SAP stiffness also reduced the magnitude of negative work on the contralateral sound limb during early stance by 11–17% (p = 0.001). Conclusions Reducing SAP stiffness and faster walking amplified the prostheses damping effect, which redistributed the mechanical work, both in magnitude and timing, within the residual joints and sound limb. With its capacity to absorb and dissipate energy, future studies are warranted to determine whether SAPs can provide additional user benefit for locomotor tasks that require greater attenuation of impact forces (e.g., load carriage) or energy dissipation (e.g., downhill walking).

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The foot and ankle structures reveal emergent properties analogous to passive springs during human walking

Cited by 10 publications

References 83 publications

Speed-Related Energy Flow and Joint Function Change During Human Walking

Speed-Related Energy Flow and Joint Function Change During Human Walking

Biomechanical evaluation over level ground walking of user-specific prosthetic feet designed using the lower leg trajectory error framework

Reducing stiffness of shock-absorbing pylon amplifies prosthesis energy loss and redistributes joint mechanical work during walking

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