Dataset Information

Prosthetic energy return during walking increases after 3 weeks of adaptation to a new device.

ABSTRACT: BACKGROUND:There are many studies that have investigated biomechanical differences among prosthetic feet, but not changes due to adaptation over time. There is a need for objective measures to quantify the process of adaptation for individuals with a transtibial amputation. Mechanical power and work profiles are a primary focus for modern energy-storage-and-return type prostheses, which strive to increase energy return from the prosthesis. The amount of energy a prosthesis stores and returns (i.e., negative and positive work) during stance is directly influenced by the user's loading strategy, which may be sensitive to alterations during the course of an adaptation period. The purpose of this study was to examine changes in lower limb mechanical work profiles during walking following a three-week adaptation to a new prosthesis. METHODS:A retrospective analysis was performed on 22 individuals with a unilateral transtibial amputation. Individuals were given a new prosthesis at their current mobility level (K3 or above) and wore it for three weeks. Kinematic and kinetic measures were recorded from overground walking at 0, 1.5, and 3 weeks into the adaptation period at a self-selected pace. Positive and negative work done by the prosthesis and sound ankle-foot were calculated using a unified deformable segment model and a six-degrees-of-freedom model for the knee and hip. RESULTS:Positive work from the prosthesis ankle-foot increased by 6.1% and sound ankle-foot by 5.7% after 3 weeks (p?=?0.041, 0.036). No significant changes were seen in negative work from prosthesis or sound ankle-foot (p?=?0.115, 0.192). There was also a 4.1% increase in self-selected walking speed after 3 weeks (p?=?0.038). Our data exhibited large inter-subject variations, in which some individuals followed group trends in work profiles while others had opposite trends in outcome variables. CONCLUSIONS:After a 3-week adaptation, 14 out of 22 individuals with a transtibial amputation increased energy return from the prosthesis. Such findings could indicate that individuals may better utilize the spring-like function of the prosthesis after an adaptation period.

SUBMITTER: Ray SF

PROVIDER: S-EPMC5787280 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Prosthetic energy return during walking increases after 3 weeks of adaptation to a new device.

Ray Samuel F SF Wurdeman Shane R SR Takahashi Kota Z KZ

Journal of neuroengineering and rehabilitation 20180127 1

<h4>Background</h4>There are many studies that have investigated biomechanical differences among prosthetic feet, but not changes due to adaptation over time. There is a need for objective measures to quantify the process of adaptation for individuals with a transtibial amputation. Mechanical power and work profiles are a primary focus for modern energy-storage-and-return type prostheses, which strive to increase energy return from the prosthesis. The amount of energy a prosthesis stores and ret ...[more]

PMID: 29374491

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Project description:BACKGROUND:Promising studies have shown that the gait symmetry of individuals with hemiparesis due to brain lesions, such as stroke, can improve through motor adaptation protocols forcing patients to use their affected limb more. However, little is known about how to facilitate this process. Here we asked if increasing propulsion demands during split-belt walking (i.e., legs moving at different speeds) leads to more motor adaptation and more symmetric gait in survivors of a stroke, as we previously observed in subjects without neurological disorders. METHODS:We investigated the effect of propulsion forces on locomotor adaptation during and after split-belt walking in the asymmetric motor system post-stroke. To test this, 12 subjects in the chronic phase post-stroke experienced a split-belt protocol in a flat and incline session so as to contrast the effects of two different propulsion demands. Step length asymmetry and propulsion forces were used to compare the motor behavior between the two sessions because these are clinically relevant measures that are altered by split-belt walking. RESULTS:The incline session resulted in more symmetric step lengths during late split-belt walking and larger after-effects following split-belt walking. In both testing sessions, subjects who have had a stroke adapted to regain speed and slope-specific leg orientations similarly to young, intact adults. Importantly, leg orientations, which were set by kinetic demands, during baseline walking were predictive of those achieved during split-belt walking, which in turn predicted each individual's post-adaptation behavior. These results are relevant because they provide evidence that survivors of a stroke can generate the leg-specific forces to walk more symmetrically, but also because we provide insight into factors underlying the therapeutic effect of split-belt walking. CONCLUSIONS:Individuals post-stroke at a chronic stage can adapt more during split-belt walking and have greater after-effects when propulsion demands are augmented by inclining the treadmill surface. Our results are promising since they suggest that increasing propulsion demands during paradigms that force patients to use their paretic side more could correct gait asymmetries post-stroke more effectively.

Project description:Many Service members and Veterans with lower-limb amputations have the potential for high function and the desire to resume physically demanding occupations that require them to carry heavy loads (e.g., military service, firefighters, farmers, ranchers, construction workers). However, it is currently unclear which prosthetic feet best accommodate heavy load carriage while also providing good overall function and mobility during unweighted activities. The main objective of this study was to investigate the ability of currently available prosthetic ankle-foot systems to accommodate weighted walking by examining the mechanical characteristics (i.e., forefoot stiffness) and dynamic function (i.e., rocker radius, effective foot length ratio, and late-stance energy return) of prosthetic feet designed for high activity users. Load versus deflection curves were obtained for nine prosthetic ankle-foot systems using a servohydraulic test frame and load cell. Effective roll-over shape characteristics and late-stance energy return measures were then obtained using quantitative gait analysis for three users with unilateral, transtibial amputation. Results from mechanical and dynamic testing showed that although forefoot stiffness varied across the nine feet investigated in this study, changes measured in roll-over shape radius and effective foot length ratio were relatively small in response to weighted walking. At the same time, prosthetic feet with more compliant forefoot keel structures appeared to provide more late-stance energy return compared to feet with stiffer forefoot keel structures. These results suggest that prosthetic ankle-foot systems with compliant forefoot keel structures may better accommodate weighted walking by reducing the metabolic cost of physically demanding activities. However, to more fully understand the biomechanical and functional implications of these results, other factors, such as the residual-limb strength of the user and the overall stiffness profile of the prosthetic foot, should also be considered.

Dataset Information

Prosthetic energy return during walking increases after 3 weeks of adaptation to a new device.

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Prosthetic energy return during walking increases after 3 weeks of adaptation to a new device.

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