The Jaipur Foot and the "Jaipur Prosthesis"

Walking speeds are lower for short distance and turning locomotion: Experiments and modeling in low-cost prosthesis users

Preferred walking speed is a widely-used performance measure for people with mobility issues, but is usually measured in straight line walking for fixed distances or durations, and without explicitly accounting for turning. However, daily walking involves walking for bouts of different distances and walking with turning, with prior studies showing that short bouts with at most 10 steps could be 40% of all bouts and turning steps could be 8-50% of all steps. Here, we studied walking in a straight line for short distances (4 m to 23 m) and walking in circles (1 m to 3 m turning radii) in people with transtibial amputation or transfemoral amputation using a passive ankle-foot prosthesis (Jaipur Foot). We found that the study participants' preferred walking speeds are lower for shorter straight-line walking distances and lower for circles of smaller radii, which is analogous to earlier results in subjects without amputation. Using inverse optimization, we estimated the cost of changing speeds and turning such that the observed preferred walking speeds in our experiments minimizes the total cost of walking. The inferred costs of changing speeds and turning were larger for subjects with amputation compared to subjects without amputation in a previous study, specifically, being 4x to 8x larger for the turning cost and being highest for subjects with transfemoral amputation. Such high costs inferred by inverse optimization could potentially include non-energetic costs such as due to joint or interfacial stress or stability concerns, as inverse optimization cannot distinguish such terms from true metabolic cost. These experimental findings and models capturing the experimental trends could inform prosthesis design and rehabilitation therapy to better assist changing speeds and turning tasks. Further, measuring the preferred speed for a range of distances and radii could be a more comprehensive subject-specific measure of walking performance than commonly used straight line walking metrics.

Experimental and numerical analyses of alternate materials for performance enhancement of Jaipur foot

BACKGROUND

The Jaipur foot is the gold standard in low-cost prosthetics, and the amputee population in low-income and middle-income countries has benefited immensely from this innovation. The ability of the Jaipur foot to mimic the behavior of a regular foot, albeit to a limited extent, has made it a popular choice among clinicians and patients. However, the immense popularity has also hindered further research because minimal efforts have been made to investigate the scope of improvement of the Jaipur foot, particularly with new materials.

OBJECTIVE

This article focuses on numerical and experimental analyses of various materials for the performance enhancements of the Jaipur foot.

METHODS

Contemporary materials are used in finite element analysis to filter the most suitable alternate material for microcellular rubber. The performance of the Jaipur foot fabricated with alternate material is compared with the conventional Jaipur foot through compression testing simulating gait cycle conditions.

RESULTS

The EVA foot showed 1-3 mm higher deformation than the MCR foot during the dorsiflexion or heel strike phases, which indicates an appropriate shock absorption and energy storage capacity in heel striking conditions. In forefoot strike phase or plantarflexion, the EVA foot and MCR foot showed identical behavior in deformations. Replacing the MCR with EVA also resulted in reduced weight of the Jaipur foot by 23%.

CONCLUSIONS

The weight reduction can help the amputee to expend less energy, thereby improving patient comfort and walking patterns and hence a more natural performance similar to a regular human foot.

Low-cost prosthetic feet for underserved populations: A comparison of gait analysis and mechanical stiffness

BACKGROUND

Lower-limb loss is an ongoing cause of disability throughout the world. Despite advancements in prosthetic technologies, there are numerous underserved populations in need of effective low-cost prosthetic foot options.

OBJECTIVE

To evaluate the biomechanical performance of several low-cost prosthetic feet, using a combination of instrumented gait analysis and mechanical stiffness testing.

STUDY DESIGN

Randomized crossover with additional case study.

METHODS

We compared the solid-ankle-cushioned-heel (SACH), Jaipur, and Niagara feet with carbon fiber feet. Mechanical stiffness was evaluated using a cantilever-style bending test at 2 angles that was designed to mimic late stance gait loading. Eight below-knee amputees participated in the gait analysis, which focused on foot and ankle motion and energetics.

RESULTS

Metric analysis showed significant differences among feet in ankle motion and power as well as distal-to-shank power, with SACH showing reduced ankle motion and positive work compared with the other feet. Waveform analysis additionally revealed a compensatory knee flexion moment in SACH and a knee extension moment in Niagara and Jaipur during midstance. In mechanical stiffness testing, SACH had the highest stiffness, with Niagara and carbon fiber roughly similar, and Jaipur the most compliant with the greatest hysteresis.

CONCLUSIONS

There may be an optimal stiffness range for future prosthesis designs that maximizes propulsive energy. This may be achieved by combining some characteristics of Jaipur and Niagara feet in new designs. Ultimately, optimizing stiffness and energetics for gait biomimicry while maintaining cost, availability, and versatility across cultures will alleviate the effects of limb loss among underserved populations.

Delivering High-Quality, Equitable Care in India: An Ethically-Resilient Framework for Healthcare Innovation After COVID-19

Developing countries struggle to provide high-quality, equitable care to all. Challenges of resource allocation frequently lead to ethical concerns of healthcare inequity. To tackle this, such developing nations continually need to implement healthcare innovation, coupled with capacity building to ensure new strategies continue to be developed and executed. The COVID-19 pandemic has made significant demands of healthcare systems across the world-to provide equitable healthcare to all, to ensure public health principles are followed, to find novel solutions for previously unencountered healthcare challenges, and to rapidly develop new therapeutics and vaccines for COVID-19. Countries worldwide have struggled to accomplish these demands, especially the latter two, considering that few nations had long-standing systems in place to ensure processes for innovation were on-going before the pandemic struck. The crisis represents a critical juncture to plan for a future. This future needs to incorporate a vision for the implementation of healthcare innovation, coupled with capacity building to ensure new strategies continue to be developed and executed. In this paper, the case of the massive Indian healthcare system is utilized to describe how it could implement this vision. An inclusive, ethically-resilient framework has been broadly laid out for healthcare innovation in the future, thereby ensuring success in both the short- and the long-term.