Achieving High Performance and Low Cost: Development of a High-Performing Passive Prosthetic Knee for Emerging Markets
Abstract: There is significant need for low-cost, high-performance prosthetic knees in low- and middle-income countries (LMICs) due to a large number of amputees and particularly challenging socioeconomic and environmental conditions. Prostheses are important for maintaining one’s participation in society, culture, and the economy, but many are either prohibitively expensive or do not provide near-able-bodied kinematics. Poor performing prosthetic knees cause discomfort and draw unwanted attention to transfemoral amputees. In this study, we refine the design of a high-performing, single-axis, passive prosthetic knee developed with a focus on the Indian market in order to reduce cost, weight, and part count; enhance manufacturability; and improve aesthetics. The load paths and functional componentry were critically analyzed to identify opportunities to streamline the design while maintaining strength and the near-able-bodied kinematics offered by the original design. The part count was reduced almost four-fold, and the mass of the prosthesis was reduced three-fold. An enclosure was also designed to encase the functional componentry in an aesthetically acceptable package. The changes made to the design are believed to significantly advance the usability and commercial viability of the prosthetic knee. This study may serve as an example of how products developed for emerging markets may achieve affordability without sacrificing performance.
https://doi.org/10.1115/DETC2023-116478
https://doi.org/10.1115/DETC2023-116478
Development of a Novel Diabetic Foot Risk Assessment for L0w-resource Healthcare Settings: A Case Study of Lean Design
Abstract: Interest in applying a “lean” philosophy to design has been slowly growing in recent years, but there are still few broadly applicable methodologies and illustrative cases published in the literature to guide lean design processes. Lean approaches promise cost reduction and increased product value, which could be particularly beneficial in product development for low- and middle-income country markets, where value demands are high. We use the clinical need of efficient diabetic foot risk assessment in low-resource healthcare settings to present an example of lean early-stage design of a medical device. The background of existing medical literature and commercial products is intentionally leveraged throughout the design process to streamline development and minimize the need for independent validation of product strategies and design features. Our approach resulted in an efficient design process that generated a novel, purely mechanical plantar pressure evaluation device that can indicate high risk of diabetic foot ulcer in resource-constrained settings. This case provides a practical example of how design processes can be adapted to be leaner where there are large gains from minimizing design cycle time and cost.
https://doi.org/10.1017/pds.2023.147
https://doi.org/10.1017/pds.2023.147
UmbreLAA: Design of a Variable-sized Left Atrial Appendage Occlusion Device for Stroke Prevention
Abstract: Blood clots originating in the left atrial appendage (LAA) are the leading cause of ischemic stroke in patients with nonvalvular atrial fibrillation (AF). Complications from and contraindications to oral anticoagulants (OACs), in addition to the recent successes of endocardial LAA closure devices, have driven increased interest in mechanical LAA occlusion. However, current devices are limited in their abilities to accommodate diverse LAA anatomies, motivating the development of a novel endocardial LAA occluder that supports more anatomical variability. We present the design of an in-situ expandable plug as well as an accompanying pacifier module for LAA occlusion. The final design accommodates LAA diameter ranges of 14 millimeters for each device size (10-24mm and 24-38mm), double that of any approved device. This adaptability can help to overcome imperfect pre-procedural imaging and suboptimal device fit. Benchtop tug and leak tests demonstrate the stability and sealing capacities of the design.
https://doi.org/10.1115/DMD2023-1984
https://doi.org/10.1115/DMD2023-1984
A Scoping Review of Footwear Worn by People With Diabetes in Low- and Middle-Income Countries: Implications for Ulcer Prevention Programs
Abstract: International guidelines advise people with diabetes to wear close-toed, thick-soled footwear to protect against foot ulceration. However, this type of footwear is incompatible with some of the cultures, climates, and socioeconomic conditions in many low- and middle-income countries (LMICs). This scoping review aims to summarize what is known about footwear used by people with diabetes in LMICs and consider whether international diabetic foot guidelines are practical and actionable in these contexts, given current practices. PubMed, CINAHL, Scopus, Embase, Web of Science, Latin American and Caribbean Health Sciences Literature, and African Journals Online were searched for articles that documented the footwear used by people with diabetes in LMICs. Twenty-five studies from 13 countries were eligible for inclusion and indicated that a large proportion of people with diabetes wear footwear that is considered inappropriate by current guidance, with sandals and flip-flops being popular choices in a majority of the studies. Reasons given for these choices include poverty, lack of awareness of and provider communication about the importance of footwear selection, comfort, and cultural norms. We recommend that LMIC health care systems relying on international guidelines critically consider whether their recommendations are sensible in their settings. Diabetic foot experts and LMIC-based health care stakeholders should collaborate to design alternative guidelines, strategies, and interventions specifically for LMIC contexts to increase preventative practice feasibility and uptake.
https://doi.org/10.9745/GHSP-D-22-00392
https://doi.org/10.9745/GHSP-D-22-00392
A Purely Mechanical Plantar Pressure Evaluation Device for Diabetic Foot Assessment in Low-Resource Healthcare Settings (pre-print)
Abstract: As global diabetes rates skyrocket, diabetic foot complications constitute a massive and rapidly growing global health problem, causing at least one million lower-extremity amputations every year. These amputations are typically preceded by largely preventable diabetic foot ulcers. However, 80% of the world’s more than half a billion diabetics now live in low- and middle-income countries (LMICs), where many healthcare settings lack the resources to implement recommended diabetic foot assessment and ulcer prevention practices. Evidence from LMICs suggests the need for a novel method of diabetic foot risk evaluation specifically for low-resource contexts. In this study, we present the design of a device that enables a new mode of measuring plantar pressure, a variable established in the medical literature as an accurate predictor of future diabetic foot ulceration. The purely mechanical pressure evaluation device consists of a grid of plastic bistable compliant mechanisms that a subject can step onto and off of with natural gait. Under a relevant pressure threshold, the compliant mechanisms move to a second stable position, an event that can be observed and interpreted by a healthcare provider as indicative of high risk for future ulceration. In settings where standard diabetic foot risk screening is infeasible or insufficient, healthcare providers may evaluate patient foot ulcer risk using the device in a matter of seconds with no need for electricity, computation, or a specialist. Using this simple screening method, strained health systems may be able to allocate scarce healthcare resources more efficiently to prevent costly diabetic foot ulcers and amputations.
https://doi.org/10.31224/2682
https://doi.org/10.31224/2682
Iterative Design and Prototyping of Computer Vision Mediated Remote Sighted Assistance
Abstract: Remote sighted assistance (RSA) is an emerging navigational aid for people with visual impairments (PVI). Using scenario-based design to illustrate our ideas, we developed a prototype showcasing potential applications for computer vision to support RSA interactions. We reviewed the prototype demonstrating real-world navigation scenarios with an RSA expert, and then iteratively refined the prototype based on feedback. We reviewed the refined prototype with 12 RSA professionals to evaluate the desirability and feasibility of the prototyped computer vision concepts. The RSA expert and professionals were engaged by, and reacted insightfully and constructively to the proposed design ideas. We discuss what we learned about key resources, goals, and challenges of the RSA prosthetic practice through our iterative prototype review, as well as implications for the design of RSA systems and the integration of computer vision technologies into RSA.
https://dl.acm.org/doi/full/10.1145/3501298
https://dl.acm.org/doi/full/10.1145/3501298
A Comparison of Approaches to Reweighting Anthropometric Data
Abstract: The objective of this work is to identify the most effective techniques for reweighting anthropometric data such that it accurately represents a target user population. Seven methods are compared, including uniform weighting, stratification, and permutations of nearest neighbour reweighting. The analysis illuminates the performance of existing and novel approaches to reweighting data specifically for approximating body size and shape (“anthropometry”). While uniform weighting and stratified sampling are often used in this field, the present analysis indicates that lower-order nearest neighbour approaches will produce more representative results. Although anthropometric data are crucial to the design of artifacts, tasks, and environments, finding appropriate representative data is challenging. Designers and ergonomists are unlikely to find data that are simultaneously accessible, up-to-date, detailed, and from the relevant population. The application of new statistical weights--reweighting—is one useful strategy for meeting this shortfall. This research indicates the best methods for reweighting and provides guidance for sampling strategies in future data collection efforts.
https://doi.org/10.1080/00140139.2022.2039409
https://doi.org/10.1080/00140139.2022.2039409
Designing for Independence for People with Visual Impairments
Abstract: The notion of "independence'' is frequently used to motivate technology design in the HCI sub-field of accessible and assistive technology for people with disabilities. Despite the term's pervasive use, the literature lacks a recent articulation of its meaning in the context of assistive technology. What does independence really mean? Scoping the study to people with visual impairments (PVI), we posed this question to 10 individuals from diverse backgrounds through in-depth, semi-structured interviews. Our findings reveal that PVI have internal experiences of independence and social experiences of independence, with surprising insights into the roles that people and technology play in supporting independence. We also discuss new ways to design for independence.
https://doi.org/10.1145/3449223
https://doi.org/10.1145/3449223
Human-Computer Synergies in Prothetic Interactions
Abstract: Remote sighted assistance provides prosthetic support to people with visual impairments (PVI) through internet-mediated conversational interactions. In these interactions, PVI broadcast live video to remotely-located, sighted people who engage in speech interactions with PVI to create prosthetic support. These interactions can be quite nuanced, creative, and effective. In this paper, we present a design investigation of remote sighted assistance (RSA) in which computer vision capabilities are integrated into the prosthetic interaction, supporting the human participants in various ways. Our study involved creating design scenarios to identify and concretize future possibilities in order to articulate and analyze design rationale for these scenarios, that is to say, strengths and challenges of RSA integrated with CV. We discuss implications for the design of the next generation of remote sighted assistance.
http://www.mifav.uniroma2.it/inevent/events/idea2010/doc/44_2.pdf
http://www.mifav.uniroma2.it/inevent/events/idea2010/doc/44_2.pdf
The Emerging Professional Practice of Remote Sighted Assistants for People with Visual Impairments
Abstract: People with visual impairments (PVI) must interact with a world they cannot see. Remote sighted assistance (RSA) has emerged as a conversational assistive technology. We interviewed RSA assistants ("agents") who provide assistance to PVI via a conversational prosthetic called Aira (https://aira.io/) to understand their professional practice. We identified four types of support provided: scene description, navigation, task performance, and social engagement. We discovered that RSA provides an opportunity for PVI to appropriate the system as a richer conversational/social support tool. We studied and identified patterns in how agents provide assistance and how they interact with PVI as well as the challenges and strategies associated with each context. We found that conversational interaction is highly context-dependent. We also discuss implications for design.
https://doi.org/10.1145/3313831.3376591
https://doi.org/10.1145/3313831.3376591
© 2023 Madison Reddie
Any opinion, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.
Any opinion, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.