MIT Team Works to Simplify Jaipur Fittings

In the United States, a typical prosthetics specialist who fits artificial legs for amputees might handle 15 or 20 such patients a year, fitting them with custom-built legs that can cost upward of $6,000 apiece. Each patient then gets a series of follow-up visits to make sure the new limb was properly fitted.

But in India, the Jaipur Foot Organization handles that many patients every day in each of its local centers. The charity is the world's largest provider of prosthetics and has worked with about a million patients since being founded in 1975.

The JFO, also known as Bhagwan Mahavir Viklang Sahyata Samiti, is based in Jaipur, a city of more than three million people that is the capital of Rajhastan in northern India. The artificial legs they provide, based on a locally developed design, cost about $40, and the company has little time or funding for follow-up consultations, or for developing new methods.

A team of students from the Massachusetts Institute of Technology (MIT), Cambridge, has been working on a new device that could greatly simplify the process of fitting these legs, producing a better fit while eliminating some steps in the process and reducing waste materials. The hand-powered system, which requires no external power, would also greatly simplify the fitting of legs in rural areas, where the present electrically powered fitting system requires bringing along a bulky generator.

The first step in fitting a leg is to make a mold of the person's residual limb to provide a precise fit. This is done by placing the stump into a container filled with tiny glass beads and covered with soft silicone rubber, and then creating a vacuum so that the beads seal tightly around the limb. This negative mold is filled with more glass beads, or sand, to form a positive mold--an exact replica of the residual limb--and the socket of the prosthesis is made to fit that replica. Alternatively, the two steps can be done with plaster of Paris instead of the sand--a process that doesn't require electricity but does use heavy, non-reusable plaster.

The MIT system was designed under the auspices of the D-Lab in the Department of Mechanical Engineering. Mechanical engineering students Philip Garcia, Maria Luckyanova, and Tess Veuthey, physics student Jessica Schirmer, and D-Lab instructor Goutam Reddy have been working on the project--some of them for more than a year.

The new fitting system they devised uses a hand-crank to produce the vacuum, eliminating the need for electric power. And the same device can be used to produce both the initial negative mold and the positive mold that replicates the shape of the stump.

Garcia, Luckyanova, Reddy, and Schirmer spent two weeks at the Jaipur facility January 2008, thanks in part to a grant from MIT's Public Service Center and a $7,500 award from last year's IDEAS competition. They did one test run of a fitting for JFO personnel. "They were really pleased with the results," Luckyanova said.

They liked the fact that the new system produced less waste, required no electricity, and seemed to produce a better fit that might lead to a longer-lasting prosthetic, the team said.

The Jaipur technicians also had some useful suggestions for simplifying and streamlining the device. "Basically, they wanted a black box," Garcia said, a system in which the working parts are hidden from view and would be simple to set up and use in the field. Luckyanova said some field testing will be done in Jaipur this summer.

This article was written by David Chandler, MIT News Office.