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Left to right: Professor Rick Neptune, recent graduate Dr. Nick Fey, and current graduate students Nicole Guckert and Courtney Shell display various customized prosthetics they are designing under a contract with the U.S. Military for use by wounded soldiers.

Left to right: Professor Rick Neptune, recent graduate Dr. Nick Fey, and current graduate students Nicole Guckert and Courtney Shell display various customized prosthetics they are designing under a contract with the U.S. Military for use by wounded soldiers.

This story originally appeared on the Cockrell School of Engineering website.

Professor Rick Nepture holds a prosthetic foot made by his team using the selective laser sintering process.

Professor Rick Nepture holds a prosthetic foot made by his team using the selective laser sintering process.

In this photo, Mechanical Engineering Professor Rick Neptune holds a smooth and lightweight prosthetic foot. The prosthetic is rounded at the toes, raised at the heel and, at first glance, may not appear that revolutionary.

Take a closer look. It's the details you can't see with a cursory glance that make this prosthetic so remarkable. Consider the soldier who suffers an amputation and, after months of therapy, learns to walk, play basketball again, or even return to active duty by wearing a tailored-made prosthetic like the one Professor Rick Neptune is holding. In a way, Neptune is holding more than a prosthetic. He's holding a second chance.

"It's so encouraging to see all these individuals who are working hard to return to active duty, and some of the injuries they've had are just devastating," Neptune said. "It's inspiring for the work that we're doing, and if we can help in any small way to give them a piece of their lives back – well, there isn't anything more satisfying than that."

Neptune has been working the past few years to do just that through research collaborations with the Department of Veteran Affairs Center of Excellence for Limb Loss Prevention and Prosthetic Engineering in Seattle and the San Antonio Military Medical Center's Center for the Intrepid, a rehabilitation facility treating veterans and active military with amputations, traumatic extremity injuries and severe burns.

Neptune and a team of graduate students are designing prosthetics and parts for ankle-foot orthotic devices, or braces, that not only improve functional mobility, they increase patient comfort, are customized to each patient's needs, and could reduce costs. The prosthetics and orthotics are built to account for variations in each patient's physical build, such as height and weight, walking characteristics, and the severity of injuries.

"We're having them walk over uneven ground, going up and down stairs, running and a whole battery of other tests, to be able to understand how they adapt to the different stiffness levels of these orthotic and prosthetic devices," Neptune said. "One of the challenges is that everybody has a different injury."

Providing the best treatment

Because protective gear and equipment have improved drastically for soldiers in the last few decades, more are surviving traumatic injuries, meaning doctors must respond quickly to treating and rehabilitating injuries that would have previously proved fatal.

Among those at the forefront of prosthetic and orthotic research is the Center for the Intrepid. Through funding from the U.S. Department of Defense, Dr. Jason Wilken, director of the center's Military Performance Laboratory, is working collaboratively with Neptune and others around the world to restore functional mobility to the roughly 130 patients being treated at the center each day.

"It's rewarding to be able to give back to the people who have done so much for our country," said U.S. Army Colonel Rachel Evans, research director for the Center for the Intrepid, who recently returned from a six-month deployment in Afghanistan. "When you watch a patient who's been injured walk or run again for the first time, and you see the look on their face, it's very moving."

"The goal of the center is beyond restoring functional mobility," Evans said. She and others aim to restore soldiers to the highly active lives they had prior to their injuries, and which were a part of their jobs in the military.

Struts provide added mobility to patients

One of the ankle-foot braces developed by Dr. Neptune and his graduate students.

One of the ankle-foot braces developed by Dr. Neptune and his graduate students.

Using a brace designed by Center for the Intrepid prosthetist "Ryan Blanck, Neptune and his students are creating struts—the part of an ankle-foot orthotic device that acts like a muscle.

Struts and prosthetic devices built by Blanck, Neptune and his students store and release elastic energy. These customized struts enable patients to run and jump, and they're customized to meet the specific needs of a patient, unlike many struts and prosthetic devices commonly used. For instance, a patient's height and length of stride may mean he needs an orthotic device that's longer or more elastic than an standard commercial product.

Neptune and his students can account for these specific needs through cutting-edge design technology developed at The University of Texas at Austin called selective laser sintering (SLS). The process allows them to design a prosthetic limb or orthotic device on a computer, and then produce a finished three-dimensional product using the additive manufacturing technology laser technology that melts, or "sinters" a special nylon powder. The powder is transformed layer by layer as the product is made into a hard, but elastic prosthetic device that is specific to each individual's physical and walking characteristics.

While the research is currently focused on prosthetics and orthotics for military personnel, its applications are far-reaching and come at a crucial time. The number of people living with major lower limb amputations in the U.S. is projected to dramatically increase over the next 40 years due to complications associated with diabetes.

Because of these startling projections, more researchers are focusing on improved prosthetics and orthotics, and The University of Texas at Austin stands to be a leader in the field.

"When I think about the things and new skills I have learned in this program in the last year, it's phenomenal," said Nicole Guckert (pictured above), a second-year mechanical engineering graduate student who is designing ankle-foot orthoses for troops. The end goal is to improve the lives of patients and give doctors better guidance on treating them.

"In the end, we want to be able to understand the relationship between these design characteristics and the gait performance of the individual, so that clinicians are better informed when prescribing an appropriate orthotic device or prosthetic device for each patient," Neptune said.

Dr. Nick Fey, recent graduate student of Dr. Neptune, with three prosthetic feet designs. The stiffness of each is different to accommodate different body weights, the level of activity and needs of the user.

Dr. Nick Fey, recent graduate student of Dr. Neptune, with three prosthetic feet designs. The stiffness of each is different to accommodate different body weights, the level of activity and needs of the user.

By Alex Lou

One of Neptune's recent graduate students, Dr. Nicholas Fey, was recently awarded the Popular Choice Research Award at the 2011 Annual Meeting of the American Society of Biomechanics (ASB). The conference, held last August in Long Beach, California, is one of the biggest and most recognized biomechanics conferences in the country covering a broad range of biomechanics research.

The Popular Choice Research Award

As part of the conference, research abstracts submitted prior to the event are reviewed by a committee that ranks them. Roughly 30 of the top ranked abstracts are selected and their respective researchers are invited to present their work to the conference. Last year, Fey was one of these researchers chosen for his abstract titled "Response of below-knee amputee muscle activity to changes in energy storage and return foot stiffness using additive manufacturing." Over the course of the conference, attendees are asked to vote for their favorite poster in terms of research quality and presentation. Fey's poster received the most votes, making him winner of the 2011 Popular Choice Research Award.

This is an image from Dr. Fey's dissertation. Prosthetic feet fabricated using SLS (selective laser sintering) additive manufacturing technology that encompassed a wide range of stiffness levels. The linear stiffness of these feet closely matched the nominal stiffness of a widely prescribed carbon fiber foot (Nominal), and were 50% more stiff (Stiff) and 50% more compliant (Compliant).

This is an image from Dr. Fey's dissertation. Prosthetic feet fabricated using SLS (selective laser sintering) additive manufacturing technology that encompassed a wide range of stiffness levels. The linear stiffness of these feet closely matched the nominal stiffness of a widely prescribed carbon fiber foot (Nominal), and were 50% more stiff (Stiff) and 50% more compliant (Compliant).

Fey's abstract was part of his Ph.D. dissertation research which involved manufacturing custom prosthetic feet of varying stiffness using selective laser sintering. By altering the stiffness of prosthetic feet, Fey is able to influence the muscle activity and walking mechanics of below-knee amputees who used them, providing rationale for a more effective foot prescription. Experimental data for this work, collected at the Department of Veteran Affairs Center of Excellence for Limb Loss Prevention and Prosthetic Engineering in Seattle, was presented in his abstract.

This article by Melissa Mixon originally appeared on the Cockrell School of Engineering site in November 2011. Recent modifications have been made by Alex Lou, Carol Grosvenor and Nick Fey. Please contact Professor Rick Neptune for further information regarding this research.


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