Lisa M. Abrams

Epidemiological study of failures of the Jaipur Foot

Abstract Objective: The purpose of this study was to examine effects of usage and demographics on damage to the Jaipur Foot prosthesis as well as the epidemiology and etiology of amputations performed at Santokba Durlabjhi Memorial Hospital (SDMH) in Jaipur, India. Design: Total time spent standing, total time spent wearing and total distance walked were compared against severity and location of damage to the prosthesis. Time between initial fitting and follow-up visit for damaged prosthetic was also considered in this analysis. A novel damage severity scale based on prosthesis functionality is presented along with a damage location legend. Results: Patients from 10 different states and two territories throughout India were included in the study. No main effects were found to be statistically significant in predicting severity or location of damage. Only the interaction between a patient’s total time spent standing and their total time spent wearing the prosthesis as well as the interaction between a patient’s total time spent standing and total distance walked was significant in predicting location of damage to the Jaipur Foot (p = .0327, p = .0278, respectively). Conclusions: The lack of significant usage factor effect on damage severity or location could support previous findings that lack standardization in materials and manufacturing processes, which is the major drawback of the Jaipur Foot. Implications for Rehabilitation The Jaipur Foot is a safe, reliable and stable product as no abrupt breakage or sudden falls causing injury to the patient were noted. Hence, it is a safe rehabilitation device for lost limbs. The population can squat and sit cross-legged while wearing the prosthetic foot and it does not affect damage severity or location of damage, allowing for these activities to be performed while rehabilitating. The manufacturing of the foot needs to be standardized to improve life of foot. Total time spent standing, total time spent wearing and total distance walked were not predictive of severity or location of damage to the prosthesis, hence providing patient guidelines for activity during rehabilitation.

Developing an Effective Platform for Introducing Mechanical Engineering in a Large Public University

In conjunction with a shift from an academic calendar based on ten–week quarters to one based on semesters, the Department of Mechanical and Aerospace Engineering at The Ohio State University has completely re–designed the mechanical engineering curriculum. As a part of this re–design, the MAE department has added a new course for sophomores entering the department that will emphasize hands–on skills in machining and electronics while simultaneously giving students a broad introduction to the kinds of problems that mechanical engineers typically confront in industrial practice.This paper describes the evolution of our thinking as we created the teaching platform that is the heart of the course, a multi–cylinder compressed air motor. Lectures are structured to provide ‘just in time’ information to the students as they build and test this platform in the laboratory. It was crucial to create a device that would be complex enough to challenge the students and provide an opportunity to explore the widest possible range of mechanical engineering concepts. After a review of similar courses in other programs, we decided to employ a multi–cylinder compressed air motor, controlled by a commercially available microprocessor, as the teaching platform.Because the course will be required of all students entering the major, an overriding constraint on the design is that the device is simple enough for three hundred students a year, working in teams, to construct and test it. At the same time, the air motors must also be complex enough to support the learning objectives of this course and subsequent courses in the curriculum. Our final design is a direct–injection six–cylinder radial compressed air motor that is controlled by an Arduino© microprocessor. Students will spend five weeks machining and assembling the motors in the machine shop, another four weeks learning to program the Arduino© to control the motor, and the remainder of the term testing and analyzing the performance of the motors.The air motors allow us to introduce students to machine design, engine design, thermodynamics, fluid flow, vibrations, electronics, and controls. We have pilot tested this course twice, and find that the students quickly take ownership of the motors, and are quite interested in optimizing the design to improve performance.Copyright

Assessment of the compressive and tensile mechanical properties of materials used in the Jaipur Foot prosthesis

Background: Designed by Dr. Sethi, the Jaipur Foot prosthesis is ideally suited for amputees in developing countries as it utilizes locally sourced, biodegradable, inexpensive materials and is focused on affordability and functionality. To date, however, no data have been reported on the material properties of the foot components. Objectives: The goal of this work was to evaluate mechanical properties of the Jaipur Foot components to guide foot design and manufacturing and reduce weight. Study Design: Experimental. Methods: Mechanical testing was conducted on two types of woods (ardu and cheed), microcellular rubber, tire cord, cushion compound, tread compound, and skin-colored rubber. Each material was subjected to testing in either tension or compression based on its location and function in the foot. Samples were tested before and after vulcanization. Two-sample t-tests were used to assess statistical differences. Results: Cheed compressed perpendicular to the grain had a significantly higher modulus of elasticity than ardu (p < 0.05); however, cheed had a higher density. Vulcanization significantly increased the modulus of skin-colored rubber, cushion compound, and tread compound (p < 0.05) and decreased the moduli of both microcellular rubber and tire cord (p < 0.05). Conclusion: The material property results from this study provide information for computer modeling to assess material construction on overall foot mechanics for design optimization. Ardu wood was ideal based on the desire to reduce weight, and the tire cord properties serve well to hold the foot together. Clinical relevance With new knowledge on the material properties of the components of the Jaipur Foot, future design modifications and standardized fabrication can be realized, making the Jaipur Foot more available on a global scale.