Walk this Way

Until the mid-1980s, orthopedic surgeons had to rely on basic tools to diagnose children's problems with walking and to decide on corrective procedures. They used static physical examinations and observation of walking patterns, which provided limited information, and x-rays, which revealed only problems with bone structure. Because of their limited information, surgeons sometimes performed unnecessary invasive surgery or did not do necessary surgery because problems were not fully identified.

Now, leading technology gives surgeons detailed information for analyzing and correcting a patient's abnormal gait. Health teams in about 20 pediatric gait laboratories in the United States use data collection programs and 3-D modeling software to capture children in motion and to recreate their walking patterns.

According to Dr. Freeman Miller, a pediatric orthopedic surgeon who specializes in treating children with cerebral palsy, the impact of gait assessment technology on diagnosis and treatment has been significant. "It's allowed us to be much more specific about surgery, and the surgery we're doing has more predictable results," he says. "It's also decreased surgery on children who don't benefit from it." The technology collects data on children as they are actually walking, which allows doctors to compare their gait patterns against those of "normal" children. It also collects a range of information not visible to the naked eye or in x-rays.

Staff in one of America's leading pediatric gait labs, the Gait Analysis Laboratory at the Alfred I. duPont Hospital for Children, in Wilmington, Delaware, assess as many as 20 children a week.

One Step at a Time

Recently, a four-year-old boy with cerebral palsy went through a battery of evaluation tests. Physical therapist Lauren Kerstetter started by videotaping him as he walked up and down the room. Small, grinning, and dressed only in a pair of underpants, at first he refused to walk or participate in the exam. Giving up on the videotape, Kerstetter coaxed him into a thorough physical exam during which she measured the range of motion in various joints, as well as his muscle tone, motor control, and functional balance. Since it involves not only the use of careful observation but a number of devices to measure joint angles, this exam is much more thorough than the average physical therapy assessment.

Next Kerstetter and Jill Schuyler, a biomechanist, prepared to analyze his walking pattern. Working in the room where she did the assessment, Kerstetter attached small gray balls (called markers) covered with reflective tape to key joints on the child's body, from his feet to his shoulders. Meanwhile, Schuyler sat at a bank of computers and monitors in the large, open examining room checking the equipment. Six cameras are mounted near the ceiling of the large room: three on the left and three on the right, which emit strobe lights that are reflected by the markers.

Kerstetter brought the child into the room and asked him to walk up and down a red path marked on the floor. This time, captivated by a mural of the Emerald City of the Wizard of Oz on one wall, he moved and chattered to Kerstetter as she walked him up and down. As he moved, the cameras recorded the data from the markers and sent it to a computer that documented exactly where the markers appeared and how they moved as he walked.

The boy then walked across force plates that measured how his feet push and twist; this determines how hard the muscles work at different points during the gait cycle. Using the information, the data modeling software accurately recreated the boy's gait in the form of a 3-D stick figure. It moved across the computer screen exactly as the child walked across the floor of the room.

Two more tests were completed. First, electrodes were attached to the boy's legs to measure muscle activity during walking. Then, as the boy walked on a yellow brick road painted on the floor, sensors in the floor measured the pressure of his foot, and the information was sent to the computer for further evaluation.

Finally, Schuyler processed the data using a gait model, which produced graphs for the physician and the physical therapist to review and evaluate.

Not all children who are seen at the lab complete all these tests. Sometimes a physician will send a child to the lab, requesting only a videotape. The little boy Kerstetter and Schuyler worked with had most tests but did not need a metabolic analysis. For this test, children wear breathing masks as they walk, while measurements of their oxygen consumption, CO₂ production, heart rate, and volume of air are taken.

The Team and the Technology

Engineer Roland Starr, who manages the duPont Gait Lab, says it is one of the top five gait labs in the United States. The Wilmington facility, which is 30 miles south of Philadelphia, is unique in several ways. Few labs of this sort have a focus that is primarily aimed at diagnosis and treatment. Most carry out research and do not have the close relationship with physicians that this lab does.

Additionally, the lab team's close relationship with the orthopedics staff means that the physical therapists play a key role in working with physicians to assess patients. Here, the physical therapists spend at least 20 minutes working with a physician to evaluate the results of every patient's tests.

The lab maintains a database of between 2,100 and 2,200 children, which is available for research. This database includes gait information of about 100 "normal" children in ages ranging from three to 18, which the software uses as a basis for comparing the gait patterns of the children seen in the lab.

The database also helps staff assess the progress of children who are seen multiple times. Because each patient's foot length and width, physical therapy evaluation, gait analysis information, and gross motor functional measurement are all saved, results can be compared from visit to visit, and pre- and post-surgery or pre- and post-treatment.

The duPont Gait Lab played a key role in developing the technology it uses. Lab staff, with the help of Jim Richards, a University of Delaware software engineer, developed the data modeling software that is now commercially available.

The lab started out in the late 1980s at the University of Delaware with a focus on using computer technology to measure movement in sports. Miller, who was working on the project, wondered how the technology could be used to assess and treat abnormal gait patterns.

He and others defined the elements they wanted to measure for clinical purposes. Richards then wrote the software program to get the desired results.

"We went through lots of iterations," says Miller. "Jim would make the system and then we'd look at it and say 'well maybe we need to change it a little.'" Miller praises Richards' unusual ability to understand both the science of movement and the engineering behind the software. Richards continues to work on the software, and he has an ongoing relationship with the duPont Gait Lab.

"Jim has excellent matches in skill; it has allowed us to make a lot of progress," comments Miller.

What is in the future for the Gait Lab? A move to digital technology for both the cameras and the EMG equipment? Perhaps electronic storage of the reports for the doctors so that they can be more easily shared?

Miller would also like the technology to produce end results that are more easily shared with children's families so they better understand treatment options. But one thing that will stay the same is the close teamwork, which has produced some of the best assessment tools that technology has to offer children.

This is Engineering? Although mechanical engineering may not seem like an obvious path into a medical profession, it turned out to be a natural progression for both Roland Starr and Jill Schuyler. They both work at Gait Analysis Laboratory at the Alfred I. duPont Hospital for Children. Starr studied math and physics and was working on a PhD in math when he "watched his friends get jobs they didn't like as math professors." So he switched to mechanical engineering. A course of study in robotics led him to the Gillette Children's Hospital in Saint Paul, Minnesota, where he helped them build a gait lab. Schuyler, by her own description, an athletic person who is interested in movement, graduated into a depressed economy in the early 1990s with a degree in mechanical engineering. When she could not find a job, she pursued her interests with a degree in biomechanics and movement science at the University of Delaware. Both Starr and Schuyler love the clinical applications of their work and working with people, especially children. "I like what the body does. I love kids," Schuyler says. "It just kind of all fit together."

A Different Role for a PT In spite of the work's demands, Lauren Kerstetter and Nancy Lennon value their opportunity to focus on the evaluative side of therapy. The two physical therapists work in the gait lab at the Alfred I. duPont Hospital for Children in Wilmington, Delaware. Evaluating patients can be exhausting. A full analysis may take more than three hours, and Kerstetter and Lennon play an additional role somewhere between coach, nursery school teacher, and play buddy (especially for the younger children). But both enjoy the challenge of figuring out exactly what the children need and working with a variety of patients. "You see 10 new patients a week, and you don't keep treating them," Lennon said. "I learn a lot because there's always a new patient. You learn what capabilities a child has versus another, and you can make a better recommendation. It takes a lot longer to do that in a traditional PT setting."

Discuss This Article

Have something you'd like to say? Tell us what you think! Read and post comments for this article.

Find a Job

Choose your career:

MedHunters is the world's biggest healthcare job board. Our job directory has 17,514 jobs with 2,480 hospitals and other direct employers.

We want you to find your next job on MedHunters. Need Help? Call us at 1-888-884-8242, email us at info@medhunters.com or sign up now.