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Prof. Matt Ratto holds a conventional prosthetic socket (left) and one his lab printed.
Matt Ratto. Photo by ginger coons

A Foot in Two Worlds

3-D printing is creating new opportunities – and raising intriguing questions – as digital and physical realms meld

A U of T lab is partnering with an international NGO and a Ugandan hospital to use 3-D scanning and printing to speed the process of creating and fitting sockets for artificial limbs.

While three-dimensional printing has been around for some time, a new generation of fast, cheap 3-D printers offers up a world of new possibilities for highly customized products.

Prosthetic limbs are a natural application for the technology. Although they can be mass-produced, prostheses must be customized to suit a recipient’s individual physiology. Traditional assessing and fitting procedures take many days or weeks, and require specialized knowledge of an on-site prosthetic technician.

“The major issue with prosthetics in the developing world is not access to the materials of prosthetics; it is access to the expert knowledge required to form and create them,” says Matt Ratto, a professor in the Faculty of Information. “We’re lacking prosthetic technicians, not prosthetics themselves.”

Today, though, a 3-D scan of a Ugandan’s residual limb can be sent within seconds to another part of the world where a prosthetist can digitally design a replacement, sending that file back to Africa to be printed. Printers are increasingly sophisticated, capable of using a wide range of resins and polymers to create three-dimensional objects.

The implications of such a system are many, but one is the capacity to make a prosthesis in less than 24 hours. For many Ugandans, speed is more than a matter of convenience; it’s the difference between getting a prosthetic limb or not. “The underserved population is largely rural,” said ginger coons (who spells her name in lower-case), a PhD student in Ratto’s lab. “People have to come to the hospital. Not many can afford the long stay. We want to make their stay a lot shorter.”

Ratto and Coons hope that what they learn from the Uganda project will help them develop similar solutions in other parts of the world.

Their research also explores the increasing blurriness between physical and virtual realms. While the loss of a leg and its replacement with an artificial limb are fundamentally bodily experiences, the body scans and prosthetic designs are digital.

This raises questions that are central to Ratto’s research and the “Critical Making” lab he directs at U of T: Who owns the scan of the patient’s body and the digital model of the prosthesis? How can a patient control medical information about their person once it has been digitized? How much of an issue is it if the skilled parts of the job happen somewhere other than Uganda?

For Ratto, this project exemplifies exactly what “critical making” – understanding new technologies through first-person experiences of creating things with them – is best at. “As a society, we’ve developed practices that are different digitally and physically,” Ratto says. “But we are starting to lose the separation. Digital and physical modes are getting entangled. That’s something that needs to be thought about. The prosthetics project is an example of how to explore these ideas.”

Matt Ratto talks about 3D printing and prosthetics on CBC’s Metro Morninglisten to the podcast on their website (runs 6:10)

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