Gerald Harris, Ph.D., PE, explains how motion analysis is improving care for cerebral palsy, and bone disorders.
Melanie Cole (Host): During the early years, there can be some obvious gait abnormalities in children. While many of these disturbances are quite common and correct themselves on their own; some require medical assistance as is the case with conditions such as cerebral palsy. My guest today is Dr. Gerald Harris. He is the technical director of the Motion Analysis Center at Shriners Hospital for Children – Chicago. Welcome to the show Dr. Harris. So, let’s just start with gait analysis and what does gait analysis entail?
Dr. Gerald Harris, PhD, PE (Guest): Well, that’s a great question. Gait analysis has evolved today to a technical system that is able to quantify the three-dimensional motion of the joints of the lower extremities. So, we are looking at the hip, the knee and the ankle joint and we are also able to actually quantify the forces inside those joints and in addition to that, the activity of the muscles of the lower extremities.
Melanie: What is a gait analysis like for a child?
Dr. Harris: For a child at Shriners, it is a very pleasant experience. We have a laboratory that is set up. It’s very colorful. It’s very friendly. The child comes into the laboratory, is introduced to the staff. They spend a brief time in a separate room where we put little markers on their lower extremities, on anatomic landmarks. They look like little ping pong balls and we do a physical examination. We look at strength and range of motion. Then they come out of the exam room and into the laboratory and they are simply asked to walk back and forth along a runway. Our laboratory is about 40 feet long and about 20 feet wide and as they walk back and forth, the system silently runs in the background and collects data.
Melanie: That’s fascinating. So, tell us about some of the latest research in children and specifically some of the work that you are doing as it relates to cerebral palsy.
Dr. Harris: Oh, I would be happy to. I guess the most important thing to remember at Shriners Hospital here in Chicago, all of our research in the gait lab is clinical research, so we identify our research hypothesis on the basis of clinical problems that our surgeons and clinicians are seeing from day to day. And one of our biggest populations is the population of children with cerebral palsy. And within that population, our biggest concern is for mobility. And of course, you think gait, walking and that is in fact, is one of our major areas of focus. So, I will give you a couple of examples.
In one large project, we are right now looking at kids with cerebral palsy that have severe flat foot, that is called pes planovalgus. And the questions that we have are I guess number one what are the best indicators to select the most appropriate surgery for the various foot types that these children present with. And there are probably 15-20 different surgeries that are done to help restore mobility in these children and if you look at this from the context of motion analysis you start with gait of the lower extremities and you look at the femur, the tibia and the foot, but if you really want to get more detailed; you actually can look at the segments of the foot individually. And that’s what we are doing now. So, when children present with severe flat foot, pes planovalgus; we have a motion analysis system that we apply that looks at the big joints, but also focuses on the tiny segments of the foot and ankle during walking. When that’s completed; we do a statistical analysis and on the basis of large population studies; try to put together an algorithm that helps the surgeon determine for each particular child, the individual needs, what are the best surgical fits. So, that’s one example.
Another example is equinovarus foot deformity. These are children with cerebral palsy and they have sort of the opposite deformity. They walk on their toes. And they also present with a complex condition and again we use a multi-segmented foot model in addition to the whole-body gait model to do an analysis of those children and again, decide among the spectrum of surgeries available, what is the best choice for this individual.
Melanie: Tell us about some of the other onsite support services for families with children with CP.
Dr. Harris: Well the onsite support services here are quite thorough. In the motion analysis lab for instance, we have a group of physical therapists that are part of the staff. The therapists help us obtain the quantitative information that we use to as an adjunct to surgical and treatment planning and then again for follow-up after that is applied. We also have kinesiologists in the gait lab which are specialists in motion assessment. Our staff includes three PhDs that assist in various phases of assessment and help as well in the surgical decision-making process and the treatment decision making process. From the motion lab, the children also participate in all the activities and services available through the entire hospital which is quite extensive.
Melanie: So, how do you see this research improving future care for kids with cerebral palsy? Where do you see it going from here?
Dr. Harris: So, from here, the natural extension of what we are doing is the only limitation that we really have with a number of our projects is that we are restricted to the children that come to this individual hospital in Chicago. So, one of the large breakthroughs that we have been able to accomplish in the last two or three years is to link the motional analysis labs together in the Shriners Hospital system, of which there are 13 right now. So, we have another large research project whereby we have developed a database system that links all 13 of these hospitals together so that now the benefit of doing a research project in a one or two-year period is you will no longer be looking at 30 or 40 children and making a decision, but you will be looking at 2500 or 3000.
Melanie: Wow. How cool is that. So, how is this gait analysis as you are discussing the future just for children with CP, but how is it also being used for other issues with children such as osteogenesis imperfecta, brittle bone disorders? Tell us about some of the research in gait studies and how that relates.
Dr. Harris: That’s great, great question. So, the lab does motion analysis and we have just talked a good bit about walking, gait. But the same techniques, the same principles have been applied in our laboratory to look at all sorts of other types of motion. So, for instance, we have done a lot of work in children that have spine and spinal cord injury challenges that use manual wheelchairs. So, we have developed a motion analysis system that analyzes the upper extremities during wheelchair mobility. So, we can help these children through the studies that we have done; use a safer propulsion pattern that reduces shoulder strain but maintains mobility in the wheelchair. That’s one example.
Another example, you mentioned OI, osteogenesis imperfecta or brittle bone disease. Let me give you a couple examples. I think one of the best is a combined project. So, OI is a genetic condition and these children are fragile and they present with a special challenge in which you have to be very aware of the forces they experience in various activities. So, we recently developed a two-part system. Part one is to quantify the material and the mechanical characteristics of the bone in these children and we do that because many of these children when they experience fractures they undergo surgical repair. In the past, small little chips of bone that were removed to provide a – to straighten a leg for instance, were discarded. We developed a process where we can take those tiny little chips and we can actually determine material properties from them. So, that’s phase one. Phase two was then to have those – assess those children in the motion lab as they are walking or using their wheelchairs and take the data from that which give us forces applied to the limbs, put that together with the bone material properties and predict fracture. So, basically come up with sophisticated musculoskeletal models of the upper and lower extremities that allow us to predict the strain and the stress in the various bones of the body that are individualized to the child that we have assessed.
Melanie: Isn’t that incredible? So, wrap it up for us Dr. Harris, with what you would like parents and families to know about the motion analysis center at Shriners Hospital for Children – Chicago and also cerebral palsy. Kind of wrap it up for us and give your best advice.
Dr. Harris: Well sure. I think that the truly exciting novelty here is that we are everyday coming up with new solutions for problems, many of which have not been addressed in the past. And the future holds a number of very exciting possibilities. I just gave you an example of being able to predict fracture in osteogenesis imperfecta, which means you could prevent it. You could come up with better methods for therapy and you could advise families in what is really safe and what is not safe. We have also come up with methods for children with club foot, better methods of correcting club foot. We have done the same in spine and cerebral palsy and a spectrum of different challenges. So, my news is good news and that is that by looking at clinical needs of the clinicians and the surgeons and combining that with engineering and technology and new discoveries in medicine and biomechanics; we are able to put that all together and actually determine in the short-term better solutions for current problems.
Melanie: Thank you so much for such great information and for being with us today. This is Pediatric Specialty Care Spotlight with Shriners Hospital for Children – Chicago. For more information, please visit www.shrinerschicago.org , that’s www.shrinerschicago.org . I’m Melanie Cole. Thanks so much for listening.
About The Speaker
Gerald Harris, Ph.D, PE
Gerald Harris, PhD, PE, is technical director of the Motion Analysis Center at Shriners Children's Chicago. Dr. Harris is an established researcher, advisor and educator. He is also a professor of biomedical engineering at Marquette University, and a professor and director of research at the Medical College of Wisconsin Department of Orthopaedic Surgery.
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