UNLV computer system analyzes prosthetics

Jennifer Knight

Monday, July 14, 2003 | 11:03 a.m.

A specialized video-capture system that was once used to make video games is now being put to use at UNLV in an effort to find a way to make prosthetics more comfortable to wear.

The University of Nevada, Las Vegas was recently given a 12-camera system by Westwood Studios after the studio's Las Vegas office closed down.

The $170,000 system, which had been used to capture the nuances of human movement to create realistic video game characters, is now being used to analyze the gaits of people with lower extremity prosthetic devices.

"The system will facilitate the research that will point the way to answers and perhaps guidelines for designing more effective prosthetics," Ed Neumann, a professor of civil and environmental engineering at UNLV, said.

The high-tech biomechanics camera equipment offers a whole array of research applications, but the system will mainly be put to use analyzing the gaits of athletic amputees with prosthetics -- a field that until now has seen very little research.

"No one has really taken a good look at the requirements of more active users, particularly athletic activities," Neumann said. "We think we can make progress there."

Neumann said the proper fit of a prosthetic can be affected by a weight change, age, activity level or even the type of material used to make the device. A bad fit can result in vascular problems and even ulcers.

By looking at a large sample group of patients with prosthetics, Neumann and his collaborator, kinesiology professor John Mercer, will use the system to map the movement of the prosthetic patient and collect information on design stability, the amount of pressure placed on the leg sockets and the level of activity of the individual.

"This takes what is basically an art form and allows us to pose scientific questions with it," Mercer said.

The cameras work by capturing white markers placed on a black body suit. When the body moves, so do the markers. The cameras that surround the room capture different angles of that movement and can be compiled into a single three-dimensional image.

Practitioners may eventually be able to rely on UNLV's 12-camera system to pick up characteristics not seen with the naked eye.

"What I've been doing for 18 years is I use my eyes to look at how the patient walks with the prosthetic," said Gwen Johnson of the Prosthetic Center of Excellence in Las Vegas. "I can see any unevenness with my eye."

So-called gait labs such as the one at the VA Hospital in Long Beach, Calif., are using a six-camera system to pick up subtleties not easily noticed by the human eye.

"Every once in a while there are some things that the eye can pick up better, but there are things that we can look at more easily with the system like what compensatory things a person has to do to avoid socket pressure," said Dana Craig, a biomedical engineer at the Long Beach lab.

The socket, which is the device inserted into the amputated leg or arm, often determines whether a prosthetic is comfortable. An analysis of all of the parts is often necessary for makers of prosthetics.

"It's a very valuable resource for manufacturers to have because it helps establish the proper gait and whether or not the device is doing what it is designed to do," Carlos Sambrano, owner of Life Like Prosthetics in Torrance, Calif., said.

The Vicon camera system has other applications as well. Mercer said graduate students will likely use the system, as will students interested in animation. It can also be used by various athletes to analyze performance or test shoe designs.

"This is something that potentially has a lot of applications," Mercer said. "I don't know of any other university that has a 12-camera system like this."