Dataset Information

Mechanical and dynamic characterization of prosthetic feet for high activity users during weighted and unweighted walking.

ABSTRACT: 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.

SUBMITTER: Koehler-McNicholas SR

PROVIDER: S-EPMC6135372 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Mechanical and dynamic characterization of prosthetic feet for high activity users during weighted and unweighted walking.

Koehler-McNicholas Sara R SR Nickel Eric A EA Barrons Kyle K Blaharski Kathryn E KE Dellamano Clifford A CA Ray Samuel F SF Schnall Barri L BL Hendershot Brad D BD Hansen Andrew H AH

PloS one 20180912 9

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 inves ...[more]

PMID: 30208040

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Project description:BackgroundPostpartum women are at increased risk for lower limb musculoskeletal disorders. Foot arch collapse following pregnancy has been reported as a mechanism for this increased risk. However, dynamic changes during gait in postpartum women have not been reported. Therefore, we assessed the association between parity and dynamic foot pronation during gait.ObjectiveTo determine (1) if there is an association between parity and dynamic foot pronation (center of pressure excursion index, CPEI) during gait; and (2) the extent to which there is a dose-effect of parity on foot pronation.DesignThe Multicenter Osteoarthritis Study (MOST) Study is a longitudinal cohort study of adults with or at risk for knee osteoarthritis (OA).SettingTwo communities in the United States, Birmingham, Alabama and Iowa City, Iowa.InterventionsNot applicable PARTICIPANTS: A population-based sample of 1177 MOST participants who were female, had complete CPEI and parity data and completed the baseline, 30- and 60-month visits.Main outcome measuresOdds of a one quintile decrease in CPEI by parity group and mean CPEI by parity group.ResultsIn 1177 women, mean age was 67.7 years and mean body mass index (BMI) was 30.6 kg/m2 . As parity increased, there was significantly greater foot pronation, lower mean CPEI: 19.1 (18.2-20.1), 18.9 (18.4-19.4), 18 (17.5-18.6) to 17.5 (16.4-18.6) in the 0 to 4 and >5 children groups, respectively; (P = .002), which remained significant after adjusting for race and clinic site (P = .005). There was a positive linear trend (β = 1.08, 1.03-1.14) in odds ratios of a one quintile decrease in CPEI (greater pronation) with increasing parity level (P = .004), which remained significant after adjusting for race and clinic site (P = .01). After adjusting for age and BMI, these two associations were no longer statistically significant.ConclusionsThis study indicates a positive correlation between parity and greater dynamic pronation of the feet.

Project description:Characterizing the dynamic mechanical properties of spinal cord tissue is deemed important for developing a comprehensive knowledge of the mechanisms underlying spinal cord injury. However, complex viscoelastic properties are vastly underexplored due to the spinal cord shows heterogeneous properties. To investigate regional differences in the biomechanical properties of spinal cord, we provide a mechanical characterization method (i.e., dynamic mechanical analysis) that facilitates robust measurement of spinal cord ex vivo, at small deformations, in the dynamic regimes. Load-unload cycles were applied to the tissue surface at sinusoidal frequencies of 0.05, 0.10, 0.50 and 1.00 Hz ex vivo within 2 h post mortem. We report the main response features (e.g., nonlinearities, rate dependencies, hysteresis and conditioning) of spinal cord tissue dependent on anatomical origin, and quantify the viscoelastic properties through the measurement of peak force, moduli, and hysteresis and energy loss. For all three anatomical areas (cervical, thoracic, and lumbar spinal cord tissues), the compound, storage, and loss moduli responded similarly to increasing strain rates. Notably, the complex modulus values of ex vivo spinal cord tissue rose nonlinearly with rising test frequency. Additionally, at every strain rate, it was shown that the tissue in the thoracic spinal cord was significantly more rigid than the tissue in the cervical or lumbar spinal cord, with compound modulus values roughly 1.5-times that of the lumbar region. At strain rates between 0.05 and 0.50 Hz, tan δ values for thoracic (that is, 0.26, 0.25, 0.06, respectively) and lumbar (that is, 0.27, 0.25, 0.07, respectively) spinal cord regions were similar, respectively, which were higher than cervical (that is, 0.21, 0.21, 0.04, respectively) region. The conditioning effects tend to be greater at relative higher deformation rates. Interestingly, no marked difference of conditioning ratios is observed among all three anatomical regions, regardless of loading rate. These findings lay a foundation for further comparison between healthy and diseased spinal cord to the future development of spinal cord scaffold and helps to advance our knowledge of neuroscience.

Dataset Information

Mechanical and dynamic characterization of prosthetic feet for high activity users during weighted and unweighted walking.

Publications

Mechanical and dynamic characterization of prosthetic feet for high activity users during weighted and unweighted walking.

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