Browsing by Subject "Prosthetic feet"
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Item Experimental analysis and computational simulation of unilateral transtibial amputee walking to evaluate prosthetic device design characteristics and amputee gait mechanics(2010-05) Ventura, Jessica Dawn; Neptune, Richard R.; Barr, Ronald E.; Crawford, Richard H.; Fernandez, Benito R.; Abraham, Lawrence D.Over one million amputees are living in the United States with major lower limb loss (Ziegler-Graham et al. 2008). Lower limb amputation leads to the functional loss of the ankle plantar flexor muscles, which are important contributors to body support, forward propulsion, and leg swing initiation during walking (Neptune et al. 2001; Liu et al. 2006). Effective prosthetic component design is essential for successful rehabilitation of amputees to return to an active lifestyle by partially replacing the functional role of the ankle muscles. The series of experimental and computer simulation studies presented in this research showed that design characteristics of energy storage and return prosthetic ankles, specifically the elastic stiffness, significantly influence residual and intact leg ground reaction forces, knee joint moments, and muscle activity, thus affecting muscle output. These findings highlight the importance of proper prosthetic foot stiffness prescription for amputees to assure effective rehabilitation outcomes. The research also showed that the ankle muscles serve to stabilize the body during turning the center of mass. When amputees turn while supported by their prosthetic components, they rely more on gravity to redirect the center of mass than active muscle generation. This mechanism increases the risks of falling and identifies a need for prosthetic components and rehabilitation focused on increasing amputee stability during turning. A proper understanding of the effects of prosthetic components on amputee walking mechanics is critical to decreasing complications and risks that are prevalent among lower-limb amputees. The presented research is an important step towards reaching this goal.Item The influence of load carriage and foot stiffness on knee joint loading and metabolic cost during amputee walking(2019-05-09) Templin, Tylan Nixon; Neptune, Richard R.Individuals experience sudden load changes during activities of daily living. This added weight places an increased demand on the muscles providing body support, forward propulsion and balance control. For non-amputees, the mechanical output from the ankle muscles are seamlessly modulated to meet the altered demands of load carriage. However, for individuals with a lower-limb amputation, the stiffness properties of standard-of-care prosthetic feet are constant and do not change with varying load conditions. Thus, lower limb amputees often develop gait asymmetries to compensate for the loss of ankle muscles, which may be exacerbated by load carriage. These asymmetries may increase the risk for developing overuse injuries and osteoarthritis in the intact knee as well as elevate the metabolic cost of walking relative to non-amputees. Unfortunately, it is not well understood how prosthetic foot stiffness and load carriage technique influences joint loading asymmetries during amputee gait. The purpose of this study was to use a forward dynamics simulation framework to assess the influence of load carriage technique and prosthetic foot stiffness on knee joint loading and metabolic cost during amputee gait. Forward dynamics simulations were generated to track experimental amputee walking data for each loading condition (unloaded, with a backpack, and with a frontpack) and prosthetic foot condition (four commercially available elastic energy storage and return (ESAR) feet). The results of these simulations showed that amputees rely on their intact limb as a compensatory strategy to meet the increased demands of carrying a load. Carrying the load in a backpack was found to reduce metabolic cost but increase intact knee joint loading. When varying prosthetic foot stiffness, there was no consistent effect on metabolic cost or knee joint loading in any of the three loading conditions. Future work should focus on designing prosthetic components that help reduce the joint loading asymmetry and elevated metabolic cost during load carriage for lower limb amputees. In addition, the tradeoff between metabolic cost and joint loading should be considered when determining the appropriate load carriage technique.