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Frameworks for the Design of Passive Prosthetic Knee Components Using User-centered Methods and Biomechanics of Level-ground Walking

2019
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Release : 2019
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Book Synopsis Frameworks for the Design of Passive Prosthetic Knee Components Using User-centered Methods and Biomechanics of Level-ground Walking by : Venkata Narayana Murthy Arelekatti

Download or read book Frameworks for the Design of Passive Prosthetic Knee Components Using User-centered Methods and Biomechanics of Level-ground Walking written by Venkata Narayana Murthy Arelekatti. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt: Passive knee prostheses in developing countries use low-cost components driven primarily by the need to prevent falls, resulting in undesirable gait deviations during walking. There is a severe lack of reliable data on the specific needs of low-income amputees, which poses a significant challenge towards developing globally appropriate prosthetic technology. This thesis presents the analysis of user-centered needs and relevant lower leg dynamics as frameworks for the design of passive prosthetic knee components that can enable transfemoral (above-knee) amputees to ambulate with minimal gait deviations leading to higher user satisfaction. The goal of developing these frameworks is ultimately to design a low cost, fully passive prosthetic knee device for persons with transfemoral amputations living in the developing world. To identify user needs, structured oral interviews of 19 transfemoral amputees in India were conducted regarding 22 different Activities of Daily Living (ADLs). A scale of relative importance for different needs was compiled, which can help designers, doctors, and administrators provide better clinical solutions to amputees. Cross-legged sitting was identified as the most critical user need with the potential for highest improvement in the quality of life of amputees. Two identical rotator prototypes were designed and validated for cross-legged sitting on 9 amputees in India. To compute and replicate the target knee moment profile for a prosthetic knee device, the dynamics of level-ground walking were analyzed using a conceptual link-segment model of the prosthetic leg with the knee joint modeled as a combination of passive linear springs and dampers. The effects of changes in inertial properties (mass, radius of gyration, and center of mass location) of the prosthetic leg on the lower leg kinetics were also quantified in the model. The knee moment required for achieving normative joint kinematics at the hip, knee and ankle by the optimal engagement of spring and dampers was replicated computationally with a maximum R2=0.90 in an idealized clutching scheme. Multiple prototypes of modular knee mechanisms were built to replicate the model, including (i) an automatic locking module for stability during early stance, (ii) a linear spring module for facilitating knee flexion-extension during early stance, and (iii) a rotary damping module for control during terminal stance and swing. Qualitative feedback from two unilateral transfemoral amputees in India showed the automatic locking module provided the predicted performance for timely stance to swing transition. Fluid-based viscous damping was found to provide more optimal control compared to friction-based damping. A comprehensive biomechanical framework was developed that predicted the range of optimal damping coefficients for transfemoral amputees. The framework used the results from the link-segment model and empirical data of transfemoral gait characteristics such as slower walking speeds and asymmetries in the stance-swing duration. An experimental prosthetic knee with five different damping conditions was built and tested on three subjects with unilateral transfemoral amputation in a motion capture lab. Increased damping led to reduced peak knee flexion during terminal stance and swing, as predicted by the framework. The framework predicted the optimal damping value for achieving normative peak knee flexion to within one standard deviation of the able-bodied value during the swing phase.

Identification of Design Requirements for a High-performance, Low-cost, Passive Prosthetic Knee Through User Analysis and Dynamic Simulation

2013
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Release : 2013
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Book Synopsis Identification of Design Requirements for a High-performance, Low-cost, Passive Prosthetic Knee Through User Analysis and Dynamic Simulation by : Yashraj Shyam Narang

Download or read book Identification of Design Requirements for a High-performance, Low-cost, Passive Prosthetic Knee Through User Analysis and Dynamic Simulation written by Yashraj Shyam Narang. This book was released on 2013. Available in PDF, EPUB and Kindle. Book excerpt: In January 2012, a partnership was initiated between the Massachusetts Institute of Technology and Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS, a.k.a., Jaipur Foot) to design a high-performance, low-cost, passive prosthetic knee for transfemoral amputees in India. The knee was primarily intended to improve the walking gait of amputees relative to existing low-cost devices. This thesis aimed to identify detailed design requirements for the prosthetic knee through user analysis and dynamic simulation. User analysis identified the needs and constraints of numerous stakeholders in the prosthesis development process. Members of the Indian biomechanics, prosthetics, and rehabilitation communities were interviewed to identify general requirements for the design, manufacturing, evaluation, and fitting of a prosthetic knee, and a structured survey of Indian amputees was conducted to quantify the demographics, functional capabilities, and functional needs of future end users. Dynamic simulation identified methods to enable transfemoral amputees to walk with reduced energy expenditure and normative gait kinematics. 2-dimensional inverse dynamics simulations were used to calculate the effects of inertial alterations of a prosthetic leg on the energy expenditure required to walk with normative kinematics. In addition, simulations were performed to compute the effects of inertial alterations on the knee moment required to walk with normative kinematics. Mechanical power analysis, sensitivity analysis, and optimization were used to formulate a passive mechanical model that could accurately reproduce the specified knee moment. The effects of walking cadence on critical results were also examined. Through the identification of user-centered and biomechanical requirements, the thesis provides a blueprint for the mechanism design comprising the next phase of the project.

Development and Validation of a Passive Prosthetic Foot Design Framework Based on Lower Leg Dynamics

2021
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Release : 2021
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Book Synopsis Development and Validation of a Passive Prosthetic Foot Design Framework Based on Lower Leg Dynamics by : Victor Prost

Download or read book Development and Validation of a Passive Prosthetic Foot Design Framework Based on Lower Leg Dynamics written by Victor Prost. This book was released on 2021. Available in PDF, EPUB and Kindle. Book excerpt: People with lower limb amputations face considerable challenges to everyday mobility that affect their quality of life. This is especially the case in low and middle income countries (LMIC) where the lack of affordable high-performance prosthetic devices forces people to use inadequate limbs that require more effort and exhibit unnatural walking motions. This thesis develops methods for designing customized, high-performance, low-cost, and durable passive prosthetic feet that enable users to replicate able-bodied walking patterns. The current development process of prosthetic feet relies on extensive user testing and iterative design rather than a predictive and quantitative design methodology that would facilitate the development of improved prosthetic devices. Here, we further developed the lower leg trajectory error (LLTE) framework, a novel design methodology that connects the mechanical characteristics of a prosthetic foot to the user's walking pattern. We extended the methodology to describe the entire prosthetic step for multiple walking activities and foot architectures, including durability requirements, and efficient constitutive modelling of prosthetic foot designs. These developments resulted in more than a two-fold improvement in the walking performance of LLTE-designed prosthetic feet that fulfilled the international standards durability requirements, and a ten-times reduction in computational time compared to the original LLTE methodology. The LLTE design framework and foot architectures described in this work should provide designers, engineers, and clinicians with a practical, predictive, and quantitative tool for designing and evaluating prosthetic feet. Using the LLTE framework, low-cost, customized passive prosthetic feet prototypes were designed and clinically evaluated for level ground walking against conventional carbon fiber prostheses. The LLTE feet performed as predicted with no iteration for a wide variety of patients. In addition, these prosthetic feet demonstrated 14% closer replication of able-bodied walking motion, 46% higher propulsion, 13% lower peak leg loading, and higher user preference compared to a standard commercial carbon fiber foot for less than a tenth of its cost. These results suggest that the LLTE framework can be used to design customized, low-cost prostheses that enable able-bodied walking pattern, with reduced effort and risk of long-term injuries. A systematic sensitivity investigation of five foot prototypes designed using the LLTE framework showed that users' most closely replicated the target able-bodied walking pattern with the predicted LLTE-optimal foot, experimentally demonstrating that the predicted optimum was a true optimum. In addition, the predicted LLTE performance of the prototype feet was correlated to the user's ability to replicate the target walking pattern, user's preference, and conventional clinical outcomes. This sensitivity study illustrated the utility of the LLTE framework as an systematic and robust evaluation methodology for prosthetic feet, potentially improving the development and prescription of prosthetic devices. A rugged prosthetic foot with a cosmetic overmold was also designed using the LLTE framework to accommodate the economic, environmental, and cultural requirements for users in India. The foot was distributed to 16 prosthetic users in India to be used for several months. Users walked 16% faster with the foot compared to their daily-use prosthesis, the Jaipur foot, and commented on the reduced effort of walking. The rugged foot endured one million cycles of fatigue testing, and the wear and tear of daily living without alterations in its mechanical performance. This mass-manufacturable, high-performance rugged foot could replace conventional feet used in low-resource settings and significantly improve the mobility and quality of life of LMIC prosthesis users.

Biomechanical Evaluation and Comparison of Microprocessor and Mechanical Prosthetic Knee Mechanisms

2014
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Release : 2014
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Book Synopsis Biomechanical Evaluation and Comparison of Microprocessor and Mechanical Prosthetic Knee Mechanisms by : Anthony Crimin

Download or read book Biomechanical Evaluation and Comparison of Microprocessor and Mechanical Prosthetic Knee Mechanisms written by Anthony Crimin. This book was released on 2014. Available in PDF, EPUB and Kindle. Book excerpt: For the lower limb amputee, one of the principal aims of rehabilitation is to allow them to maximise their functional ability with the prosthesis, the first step of which is the selection of an appropriate foot, knee and socket. As the histories of all individuals who have suffered a lower limb amputation differ, knee and foot components are now designed and manufactured by a number of leading manufacturers, such as Otto-Bock, Össur and Blatchfords. Of all the lower limb prosthetic components now produced by such leading manufacturers, it is claimed that those that incorporate an embedded system will help facilitate a more natural gait.It was Blatchfords who first revolutionised lower limb technology with the commercial release, in 1991, of the intelligent prostheses (IP), which incorporated a microprocessor that controlled the swing phase of gait. There has since been further development of microprocessor controlled prosthetic knees (MCPKs), and they now assist the user during swing and stance as well. Considering the high relative cost, there has been debate about the efficacy of MCPKs compared to non-microprocessor controlled knees (non-MCPKs). Despite the well-documented, positive feedback from MCPK user trials, there is little scientific evidence quantifying why the prosthetic user generally prefers the MCPK compared to the non-MCPK.Therefore, the objective of this investigation was to quantify the benefits of MCPKs and, in doing so, to establish the user group that may benefit most from this class of knee. In pursuance of this aim, six trans-femoral prosthetic users were recruited, all of whom were capable of outdoor community ambulation, though their abilities did vary; they could be described as either K2 (restricted outdoor) or K3 (unrestricted outdoor) ambulators according to Medicare Functional Classification Level (MFCL). The participants were asked to ambulate in two crossover groups in an indoor laboratory environment while wearing, an MCPK (Blatchfords Orion) and a non-MCPK (Otto Bock 3R80), which were incorporated into their prosthesis during level, ramp, and stair ambulation activities. The kinetics of motion were captured using force plates, and kinematics using infrared cameras.The results of this investigation suggest that for ambulation beyond level walking, the restricted, rather than the unrestricted, outdoor community ambulator would benefit most from the MCPK. The outcomes indicated an improved involuntary response by the MCPK, and that the MCPK offered improved voluntary control. Despite the improved involuntary response and voluntary control during the level and ramp activities, the stair activities did not highlight that the MCPK offered such advantages. Furthermore, the outcomes of this study have shown that it is possible to use simple tests in the clinical environment to determine whether the voluntary or involuntary control can be considered as having improved through the use of the MCPK, and these include indoor ramp ascent and descent activities, and recording the ground reaction force during level walking.

Design and Evaluation of a Biomimetic Agonist-antagonist Active Knee Prosthesis

2012
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Release : 2012
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Book Synopsis Design and Evaluation of a Biomimetic Agonist-antagonist Active Knee Prosthesis by : Ernesto Carlos Martinez Villalpando

Download or read book Design and Evaluation of a Biomimetic Agonist-antagonist Active Knee Prosthesis written by Ernesto Carlos Martinez Villalpando. This book was released on 2012. Available in PDF, EPUB and Kindle. Book excerpt: The loss of a limb is extremely debilitating. Unfortunately, today's assistive technologies are still far from providing fully functional artificial limb replacements. Although lower extremity prostheses are currently better able to give assistance than their upper-extremity counterparts, important locomotion problems still remain for leg amputees. Instability, gait asymmetry, decreased walking speeds and high metabolic energy costs are some of the main challenges requiring the development of a new kind of prosthetic device. These challenges point to the need for highly versatile, fully integrated lower-extremity powered prostheses that can replicate the biological behavior of the intact human leg. This thesis presents the design and evaluation of a novel biomimetic active knee prosthesis capable of emulating intact knee biomechanics during level-ground walking. The knee design is motivated by a mono-articular prosthetic knee model comprised of a variable damper and two series elastic clutch units spanning the knee joint. The powered knee system is comprised of two series-elastic actuators positioned in parallel in an agonist-antagonist configuration. This investigation hypothesizes that the biomimetic active-knee prosthesis, with a variable impedance control, can improve unilateral transfemoral amputee locomotion in level-ground walking, reducing the metabolic cost of walking at selfselected speeds. To evaluate this hypothesis, a preliminary study investigated the clinical impact of the active knee prosthesis on the metabolic cost of walking of four unilateral above-knee amputees. This preliminary study compared the antagonistic active knee prosthesis with subjects' prescribed knee prostheses. The subjects' prescribed prostheses encompass four of the leading prosthetic knee technologies commercially available, including passive and electronically controlled variable-damping prosthetic systems. Use of the novel biomimetic active knee prosthesis resulted in a metabolic cost reduction for all four subjects by an average of 5.8%. Kinematic and kinetic analyses indicate that the active knee can increase self-selected walking speed in addition to reducing upper body vertical displacement during walking by an average of 16%. The results of this investigation report for the first time a metabolic cost reduction when walking with a prosthetic system comprised of an electrically powered active knee and passive foot-ankle prostheses, as compared to walking with a conventional transfemoral prosthesis. With this work I aim to advance the field of biomechatronics, contributing to the development of integral assistive technologies that adapt to the needs of the physically challenged.

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