Past Research Projects
Muscle Activity in forefoot and heelstrike running techniques
This project will use up to ten trained runners on a treadmill running while striking with their forefoot or heel first while we record muscle activity on eight major muscles in the lower limb. We are particularly interested in muscles controlling the ankle joint and how their activity may be changed based on the particular running technique. This work should help understand why some people get shin-splints and some do not. Two DPT students, Lindsey Landreneau and Kayla Watts.
Accuracy and Precision of the Dartfish Express iPad application for gait analysis
There are a variety of new and exciting ways to measure human movement. The iPad application Dartfish Express allows someone to record a video with an iPad and then draw on angles to quantify how someone is moving. This is particularly exciting because the application only costs $4.99 and may allow rehabilitation clinician (Prosthetist, Orthotist, Physical Therapist, etc.) to quantify a patient's progress. However, it is not known if this application can actually measure what they say they can measure. We are comparing joint angles measured with Dartfish Express to the same angles calculated with our Vicon motion capture system. This project involves a MSOT student, Alan Deal, and a collaboration with Dr. Scott Conger at Boise State University.
Measurement of motion between the residual limb and the prosthetic socket during gait
When a person walks with the prosthetic leg, their residual limb is actually moving inside the prosthetic socket. This movement has a positive side, in that it may be necessary for the person to control the prosthesis but also has a negative because this movement is linked to skin breakdown. However, because the prosthetic socket covers the residual limb, trying to quantify this movement is incredibly difficult. We are developing a technique using special marker arrays, prosthetic socket modifications, and advanced mathematical techniques to quantify this movement. This work should provide an entirely new way of analyzing gait in prosthetic users while defining what types of prosthetic suspension systems may work best. This project involves a MSPO student from the Georgia Institute of Technology, Steven Siebert, and a collaboration with a mechanical engineer from Pheonix Nuclear Labs, Jin Lee.
Development of an uneven walkway to measure gait over uneven terrain
Most biomechanics laboratories (ours included) have nice level and even walkways to study human gait, yet the "real world" outside is anything but level. We feel it is important to start understanding human locomotion on uneven terrain, especially in users of prosthetic and orthotic devices. Yet, how "uneven" is "uneven"? How can the walkway design be standardized so other people can make it? This project is designing and testing just such an uneven walkway. The "unevenness" is hidden by a rubber mat so the person cannot see (and prepare) for what will happen until their foot hits the ground. We will be testing this walkway in people without a gait pathology walking with and without an ankle foot orthosis (AFO) while we measure movement of their center of mass (CoM). The eventual goal of this research is to use people with amputation to understand if/or how prosthetic feet designed to handle uneven terrain reduce energetic cost of walking. This project involves two MSPO students, Brett Parrish and Lauren Cartwright, and will be continued with two DPT students, Jon Wilson and Chad Elliot.
Optimization of a cycling specific prosthesis
The mechanics of cycling are different than walking, therefore, the design of a prosthetic specific for cycling should be optimize for cycling mechanics. We will be using one experienced cycling with a uni-lateral transtibial amputation and optimizing the socket design, cleat location, and overall design to cycling time trials. We will be using a set of special set of pedals that can measure the forces applied by each limb. This work will help develop a protocol for the fitting of prosthetic cyclists. This project involves two MSPO students, Pete Williams and Dexter Constant. The socket design we will be testing is currently being fitted to our veterans of OIF and OEF by Peter Harsch in San Diego.
Motor Control of Olympic Lifting in a person with uni-lateral transtibial amputation
Olympic lifting requires enormous coordination to contend with the mechanics of the environment and perform the task of rapidly lifting a weight off the floor and overhead. A person with a transtibial amputation has lost control of one important joint (the ankle joint) and now must contend with not only the mechanics of the lift but with a prosthetic foot not designed for this task. This challenging task has potential to improve adaptation of exercise gyms and provide an interesting model to study motor control. This project involves Dr. TJ Esco from the dept. of Health, Physical Education and Recreation at ASU and a collaboration with Dr Mike Esco at Auburn University Montgomery.
Motor adaptation to prosthetic cycling in people with transtibial amputation
Cycling is a rhythmic task (like walking) yet it is more concerned with propulsion than balance and the environment can be better controlled by the researcher. We used cycling was used a model to study motor adaptation. This project examined how someone with a transtibial amputation used their remaining physiological systems to control the bicycle pedal through the interface of a prosthetic socket. What we discovered was the neuromuscular system used the prosthesis as you would a screwdriver. In other words, the prosthesis is just a tool, and the differences in control and coordination were related to the amputated side control the prosthetic socket, similar to how you have to control the handle of the screwdriver before you control the tip. This work is a collaboration with Drs. Robert Gregor and Boris Prilutsky at Georgia Tech.
The work was a portion of Dr Childers's dissertation, presented at the 2012 meeting of the American Academy of Orthotists and Prosthetists, and is currently in review for publication.
Does a Parathlete with transtibial amputation have an advantage in the 4km individual pursuit?
The individual pursuit is a cycling time trial performed on a velodrome during the Paralymics as well as the US national and World track championships. A transtibial amputation removes the foot and ankle joint and this contributes to a disadvantage for these individuals for generate power in cycling. However, the artificial limb has less frontal area (therefore less aerodynamic drag) than the original limb. Aerodynamic drag constitutes ~96% of the power requirements for the individual pursuit. Therefore it is possible the aerodynamic gains associated with the prosthetic leg could outweigh the power losses associated with the amputation, i.e. these Parathletes may have an advantage for this cycling discipline. This project examined the interplay between aerodynamic gains and power output losses with computer simulations and found people with a uni-lateral transtibial amputation do not have a net advantage in the Pursuit. This work is a collaboration with Tim Gallagher, an aerodynamicist at Georgia Tech, Dr. Chad Duncan, and Dr. Douglas Taylor, director of the Southeast Community Research Center.
The work was the basis for Dr. Childers residency research project for his certification in prosthetics, presented at the 2013 meeting of the American Academy of Orthotists and Prosthetists, and is currently in review for publication.