Sever

Growing up in Sierra Leone during the country’s civil war (1991-2002), David Moinina Sengeh often encountered civilians whose arms or legs had been severed by rebel fighters. Yet many of the wounded didn’t wear the prosthetic limbs that aid programs had given them. Later, as a Ph.D. student at the Massachusetts Institute of Technology, Sengeh set out to understand why.

The National Geographic Explorer learned that prosthetics often fit poorly, causing blisters, pressure sores, and pain. So he began working with U.S. military veterans, survivors of the Boston Marathon bombing, and other amputees to develop a system that uses 3D printing to make a prosthetic socket modeled from MRI scans and other data of a patient’s residual limb. The process is quick and cheap—and it creates a more comfortable fit. “It’s so soft,” Sengeh recalls one veteran saying of his personalized socket, “it’s like walking on pillows.”