Effects of AFOs on distance, speed vary
By Larry Hand
A recent study demonstrates the importance of personalizing prescriptions for ankle foot orthoses (AFOs) in children with cerebral palsy, rather than applying group data to individuals.
AFOs weren’t consistently associated with the study’s primary outcome, enhanced walking activity and intensity in a community-based setting compared with footwear alone. However, some individual children demonstrated significant improvements with AFOs.
“Orthotics are prescribed as individualized interventions,” said Kristie F. Bjornson, PT, PhD, associate professor of pediatrics and developmental medicine at Seattle Children’s Hospital in Washington. “While classical scientific inquiry uses group-based analysis, we know that, with children with cerebral palsy, none of them look exactly alike. We need to keep the individual level of analysis because that is what we do in clinical practice: prescribe on an individual level.”
Bjornson and colleagues conducted a randomized crossover study involving 11 children with CP (mean age 4.3 years, range 3-6 years) who typically wore bilateral AFOs. They randomized the children to either AFOs plus footwear for two weeks or footwear only for two weeks. Then each group crossed over to the other condition for another two weeks.
At the group level, the two conditions had similar results for average total strides per day (4660 strides, AFO-on; 4897 strides, AFO-off). Secondary outcomes, the percent of daytime hours walking, average number of strides faster than 30 strides/minute, and peak activity index, were similarly close.
Individually, however, the results varied, with no clear pattern for a child’s age or AFO type.
- Two children (one aged 3.6 years with a solid AFO and a jump gait pattern, the other aged 4.3 years with a hinged AFO and a crouch gait pattern) took more steps per day with AFOs off than on. Another two children (one aged 3 years with a solid AFO and a true equinus gait pattern, and the other aged 3.6 years with a solid AFO and jump gait) took more steps with the AFOs on.
- The two children whose steps per day improved with the AFOs on also spent more time walking with the AFOs on than off. Two more children (one aged 3.2 years with a solid AFO and a true equinus gait pattern, the other aged 5 years with a nonarticulated AFO and a true equinus gait pattern) demonstrated similar improvement. One of the children who improved in steps per day with the AFOs off (the older of the two) also spent more time walking with the AFOs off than on.
- The same two children who improved in those two areas with AFOs on also had more strides per day at faster than 30 strides/minute and a higher peak activity index with AFOs on than off.
The pilot study results, published in the summer issue of Pediatric Physical Therapy, suggest most children weren’t wearing orthoses or footwear that helped them improve their daily walking activity in amount or intensity, Bjornson and colleagues wrote. They pointed out that the two children whose shank-to-vertical angle was optimized were also those who demonstrated the greatest positive effects of AFOs and footwear on daily walking activity and intensity.
“When they walked, they walked at higher rates,” Bjornson said. “Kids with CP walk slower and can’t keep up with their peers. So, hopefully, interventions would help them walk more, and, when they do walk, walk faster. Hopefully they can keep up with their peers walking to the bus, or they can run to first base when they want to when they play baseball.”
Elaine Owen, MSc, MCSP, a pediatric physical therapist at the Child Development Center in Bangor, North Wales, UK, told LER: Pediatrics the benefits for children with CP of walking outside with other children cover all areas of the International Classification of Functioning, Disability and Health, from body structure and functions to activities and participation.
“If they are walking with a good gait pattern they would be strengthening muscles, stretching muscles and joints, and [stimulating] motor learning, all things that will maintain or improve their physical condition,” Owen said. “Potentially, then, they may start to use less energy when walking and need fewer interventions. It may mean they have less pain in the teen and adult years.”
Bjornson is looking forward to more community-based research.
“Most orthotic research has been based on outcomes collected in a clinical or investigational gait lab. What a child does in front of somebody watching them is not necessarily what children do in their daily lives,” she said. “To my knowledge, nobody has ever looked at gait lab data compared to walking activity data. It’s a different kind of outcome.”
Larry Hand is a freelance writer in Massachusetts.
Bjornson K, Zhou C, Fatone S, et al. The effect of ankle-foot orthoses on community-based walking in cerebral palsy: a clinical pilot study. Pediatr Phys Ther 2016;28(2):179-186.