The way you walk or run can help health care professionals learn more about how to help people with arthritis, cerebral palsy and other mobility conditions as well as gather data to find ways to better prevent and treat injury.
At the Motion Analysis Laboratory at Shriners Hospitals for Children-Chicago, orthopedic surgeon Peter Smith frequently uses gait analysis to help figure out suitable treatment for children with cerebral palsy.
Jaryn Smith, 19, one of Smith’s patients but no relation to him, has cerebral palsy that affects both of her legs. She’s been coming to Shriners since 2000 and has undergone many gait analyses, including before and after her surgeries there. She says she thinks gait analysis has helped people at the hospital to know what requires improvement.
“They’re helping me walk better,” she says.
At the Motion Analysis Laboratory, children wearing reflective markers (small Styrofoam balls covered in tape) walk back and forth on a walkway. The cameras emit near-infrared light, which bounces off the markers and back into the lenses of the camera, recording the person’s motion. Force plates measure how much force the person’s body exerts on the ground as he or she walks, and that lets computer software calculate rotational forces exerted on the joints.
Credit: Joseph Krzak
Children also wear wireless electrodes on their skin on distinct muscles, which picks up on when those particular muscles fire.
Software can figure out attributes of the child’s movement, such as joint angles and positions, how quickly the joints move, length of the space between his or her steps, and forces that act on the joints while he or she moves.
Doctors and physical therapists and others at Shriners can compile all the data gathered to prescribe treatment and also see how a patient changes over time. They look at whether the child is using certain muscles improperly (via the electrode data), whether abnormal forces are acting on the joints (via the force plate data) and pressure distribution on the bottom of the foot (via pressure mat data).
Data collection for research also takes place at the Shriners.
Joseph Krzak, senior motion analysis laboratory physical therapist, conducted research for his Ph.D. in kinesiology, nutrition and rehabilitation at UIC, studying children with hemiplegic cerebral palsy (which directly impacts just one side of the body) with equinovarus foot and ankle deformity.
Equinovarus foot and ankle deformity results from cerebral palsy. When children are affected by the deformity, they point one of their feet inward and walk on the toes of that foot. This can result in pain and greater risk of trips and falls, Krzak says. Children must also use extra energy to get from place to place; what’s more, it can cause skin issues and it might be hard for kids to locate shoes that fit them.
Depending on the child, equinovarus deformity can affect different foot segments in different ways. Krzak wanted to describe how various groupings of foot bones are affected in order to distinguish distinct foot types that children with this particular deformity have. That insight could help doctors, physical therapists and orthotists (who make braces and splints) better decide what kinds of treatments would best help individual patients.
Gait analysis systems add up to the search for better treatment, diagnosis and prevention for problems that impact the legs and feet of millions of people.
At Rush University Medical Center’s Human Motion Analysis Laboratory orthopedic surgeon Shane Nho of Midwest Orthopedics at Rush is using gait analysis as part of a study to demonstrate the effectiveness of a surgical procedure called hip arthroscopy in correcting femoral acetabular impingement, or FAI, by proving that people move better after the surgery. The condition typically results from deformities (bumps) on the femur and hip socket, Nho says. It can cause pain and inhibits normal hip movement, and doctors believe it can lead to hip arthritis. Hip arthroscopy smooths out the bone, eliminating the deformities.
Dr. Najia Shakoor, a rheumatologist at Rush University Medical Center, has used gait analysis to study people with knee osteoarthritis for the last several years. She examines the knee adduction moment, or the amount of force that people apply to the knee’s inner side when they walk. Calculating the knee adduction moment is a way to measure how much load (force) the person is exerting on the knee and it measures whether the person is putting too much force on the inner knee.
Other gait analysis research has demonstrated that osteoarthritis severity, likelihood of pain, and faster progression is linked to more extreme knee adduction moment, she says. Based on findings that barefoot walking and walking in minimalistic shoes were both associated with a decreased knee adduction moment, Shakoor and co-investigators have tested out a “mobility shoe” – a minimalistic, flexible, lightweight shoe – that imitates what it’s like to walk in bare feet. They’ve found that these shoes decrease loading at the inner side of the knee.
Shakoor’s current study investigates how the mobility shoes might be causing changes in foot motion that in turn might be lessening knee load at the inner side of the knee. If her team can determine whether there’s a link between changes in foot motion and decreased loading over time, Shakoor says, that knowledge can help doctors better treat people dealing with knee osteoarthritis so those people can decrease loading.
Researchers can use gait analysis to look for connections between gait and injury. Karrie Hamstra-Wright, a clinical associate professor of kinesiology and nutrition at the University of Illinois at Chicago, uses three-dimensional gait analysis system in an ongoing study with members of UIC’s cross-country team. She’s looking to help those runners get more information about gait patterns that might be leading to overuse injury. and how injury might affect their gait. Participants get a pre-season gait analysis, and later Hamstra-Wright takes the group of team members who were injured and compares it against the non-injured runner group, searching for contrasts in gait between the groups.
She pointed out that she hasn’t yet noticed any specific gait pattern being a risk factor for overuse injury among these runners, with the caveat that the sample size is still not quite big enough.