|The Case For Early Intervention.|
Down Syndrome is associated with a long list of compensatory gait symptoms due to hypotonia, triplanar foot and ankle misalignments, sagittal and coronal compensation at the knee, proximal weakness, and equinus contractures, all of which need to be treated. How early depends on the individual child.
By Cary Groner, Lower Extremity Review September 2019
Several neurological conditions negatively affect children’s motor learning and development. They also contribute to gait abnormalities that clinicians treat with orthotic strategies based partly on the patient’s presentation rather than the underlying neurological disease.
Part 1 of this series looked at cerebral palsy (CP), which is associated with spasticity, dyskinesia, and muscle weakness. Part 2 examines diseases such as Down syndrome (DS) distinct from CP in that it manifests with hypotonia (low muscle tone and a reduced resistance to passive range of motion in the joints. Abnormalities such as toe walking, common to both CP and other neurological conditions—though relatively uncommon in DS—will be considered primarily in Part 2 as well.
Experts have long debated how to manage orthotic intervention in children with DS and other diseases associated with hypotonia.
“We determine the best approach from clinical experience and clinician preference,” said Kathy Martin PT DHS, a professor in the physical therapy doctorate program at the University of Indianapolis. “Not much has been published that guides specific decisions.”
DS, for example, includes not only hypotonia and joint instability but also musculoskeletal deformities, postural control deficits, and cardiopulmonary anomalies. These problems, in turn, affect gait stabilization and propulsion, delaying walking development. Studies have found that children with DS and other forms of hypotonia benefit from orthotic interventions, though the details can be contentious.[3,4]
“For me, it has to do with the degree of hypotonia and the quality of motor control, even though those things are hard to measure,” Martin said. “When I’m evaluating a child’s gait, I want to know whether the greater problem is stance-phase stability or swing-phase mobility. If they have a rigid foot, I want to address flexibility. If force transmission is a problem, then I want to stabilize the foot and give them a better push-off lever. But you have to have both.”
“So then I wonder how to provide that learning opportunity in a child that needs an orthosis? First of all, it’s giving them the most flexible orthosis possible—one that protects them from being stuck in pronation but doesn’t rigidly control the joint.” Kathy Martin PT DHS
Scott Hinshon CO, who is CEO of both Orthotic Care Services and LaunchPad O&P (a manufacturer of AFO optimization components) in Minneapolis, said that DS is associated with a long list of compensatory gait symptoms due to hypotonia, triplanar foot and ankle misalignments, sagittal and coronal compensation at the knee, proximal weakness, and equinus contractures.
“The gait symptoms themselves include toe striking, externally rotated feet, an anterior center of mass, high steppage, and other problems,” Hinshon added. “It all needs to be treated.”
Martin believes in starting orthotic therapy early in DS patients, often before they’ve begun to walk.
“We need a compensatory strategy to stabilize the joint, and that means an orthosis,” Martin said. “But our goal is to stabilize without immobilizing.”
Martin’s research and publishing colleague, Julia Looper PT PhD, is an associate professor in the PT program at the University of Puget Sound in Tacoma, WA. Looper has argued that intervening with orthoses before children start walking may interfere with their motor-learning skills.[4,5,6] Martin acknowledged that risk, but pointed out that it was important to consider the larger context of cognitive and emotional development. The two maintain a cordial professional disagreement about the matter, though in a past LER article, Looper conceded that she’d come closer to Martin’s way of thinking. Martin, for her part, acknowledged that Looper’s concerns have affected her own approach.
“I’ve listened to her a lot and it’s made me consider how a typically developing toddler learns to walk,” Martin said. “Tons of repetition, trial and error, and I see the value of letting kids go through that. So then I wonder how to provide that learning opportunity in a child that needs an orthosis? First of all, it’s giving them the most flexible orthosis possible—one that protects them from being stuck in pronation but doesn’t rigidly control the joint.”
|Development and dosage|
Looper takes what she calls a developmental approach to DS patients and other children with hypotonia.
“I think the most important thing for children is to explore their environment,” she said. “So if we’re intervening, we need to ask if it will help with that, and with their cognitive development.”
Looper and Martin recently completed a study, now in press at the Journal of Prosthetics & Orthotics, that compared aspects of the Gross Motor Function Measure (walking, running, jumping, single-leg balance, stairs, etc.) in older children with DS when wearing a flexible supramalleolar orthosis (SMO) versus no SMO. The subjects ranged from age 3 to 10 and had been walking independently for at least 1 year. Participants were asked to identify 2 personal goals (eg, walking endurance, or the ability to stay outside and play in the yard), and researchers measured progress toward those goals.
The authors chose to sidestep the topic on which they disagree—how early to start orthotic treatment—and focus instead on when children should quit.
“Usually, when a child with Down is walking well, and they outgrow their orthoses at 8 or 9 years old, they don’t get another pair,” said Martin. “But we put some of those kids back into a Surestep SMO for a month and found that they still got benefit, that there was more progress to be made even though their gait pattern was stable. They were quitting too soon.”
“Wearing orthoses improved their function in a social context, so that was pretty cool. If they’re going to be out, active, and participating in sports, I think it’s important to wear the device for peak performance.” Julia Looper PT PhD
According to Looper, this was the first time anyone had been able to directly link orthosis use to participation goals.
“Wearing orthoses improved their function in a social context, so that was pretty cool,” she said. “If they’re going to be out, active, and participating in sports, I think it’s important to wear the device for peak performance.”
Both researchers believe it’s critical to consider time in the orthosis within the context of daily use, too; but that turns out to be a different story.
“The standard has always been to wear orthoses 8 to 10 hours a day,” Martin said. “But we have zero data to support that. Could they get the same results wearing them 4 hours a day? Should they wear them outside playing but be allowed to go barefoot in the house?”The heart of the matter is whether there’s a compromise that still provides therapeutic benefit but doesn’t impair the child’s progress. Martin’s clinical experience suggests there is.
“I’ve had families admit to me, ‘Hey, it’s summertime, she hasn’t had her braces on, she wore sandals all week while we were on vacation,’” she explained. “And I look at this kid and she’s no worse. So that makes me wonder how many weeks out does she get worse? We don’t know yet.”
Even so, Looper noted that all children, and particularly those with DS and other cognitive impairments, need a lot of practice to get better at gait-related tasks.
“I think the orthotics help kids with their confidence,” she said. “They get stability so they can move. The downside is that if you’re locking up a joint, they’re not really practicing at that joint, so it’s kind of a double-edged sword. But the practice is really important.”
Elaine Owen MSc MCSP, a clinical professor and physiotherapist at the London Orthotics Consultancy in the U.K., told LER that in cases of DS or other hypotonic conditions, not surprisingly, clinicians should base their approach on the needs and capabilities of the patient. Sometimes this might mean a flexible SMO, as advocated by Martin and Looper, but sometimes it might not.
“Does the orthosis control pronation?” she asked. “If it doesn’t, and a hinged AFO doesn’t, you’ve got to go to a fixed-ankle AFO, otherwise you’re deforming the foot. Young children adapt very quickly to fixed-ankle AFOs, but if they get to be 9 or 10, it’s very hard to suddenly do that.”
Owen agreed, however, that the amount of time children spend in their devices each day should be negotiable.
“You just need to work on when they’re on and when they’re off,” she said. “You have to look at the whole child, and where that orthosis fits in. Is it good for running and playing football? Great, but then is it going to do harm somewhere else? What are the goals of the family and the child? What do they want out of their life?”
Nicole Brown DPT, specializes in complex gait disorders at Children’s Hospitals and Clinics of Minnesota. Her patients include children with DS, other neurological conditions, and toe walking—which itself may arise due to diseases of the central or peripheral nervous system, paralytic muscle disease, behavioral disorders including autism, and musculoskeletal conditions.
Brown told LER that she and her colleagues consider patients’ clinical diagnoses less crucial to treatment decisions than the biomechanical issues they present with.
“We really want to see what the biomechanics are showing us, so we can improve skeletal alignment throughout development,” she said. “We’ve found that if we can normalize gait pattern, we can start to normalize biomechanics globally, which affects all their functional skills.”
This approach typically means serial casting for kids with equinus contracture, as well as mostly solid AFOs to better control knee alignment in space. Brown said that her care team uses Elaine Owen’s tuning guidelines regarding shank-to-vertical angle (see Part 1).
“We really want to see what the biomechanics are showing us, so we can improve skeletal alignment throughout development. We’ve found that if we can normalize gait pattern, we can start to normalize biomechanics globally, which affects all their functional skills.” Nicole Brown DPT
“To have a more normal gait pattern you need about 10 degrees of dorsiflexion as you move through your stance phase,” she said. “But in a rigid brace you can be locked anywhere at neutral, so we add lift in the heel of the shoe to reach that angle, which you see at the knee instead of the ankle joint.”
In terms of patients with DS, this means that Brown’s team may take a different approach to that advocated by Martin and Looper.“In Down syndrome, your first thought for bracing is usually an SMO,” she said. “But those kids have low tone, which means their strength is impaired and they move quickly with an anterior weight shift—a forward-leaning trunk, those kinds of things. If we put them in an SMO, that will help their ankle instability medial-laterally, but it doesn’t do anything up the chain.”
Brown and her team want their patients to activate their core muscles, gluteals, hamstrings, and quadriceps, which means getting them into a position to do so with every step instead of using gravity and momentum to move forward.
“To do that, we need a longer lever to get the hip and pelvis in the right alignment to activate those muscles,” she explained.
Some philosophical tension exists between SMO advocates and those in favor of the fixed-ankle AFO approach Brown describes. LER has covered this in the past, noting that in patients with Duchenne’s muscular dystrophy, spina bifida, and polio, an orthosis that takes away compensatory motions may create instability due to the underlying muscle weakness. However, for Brown and those in her camp, strengthening the patient is a preferable way to address the problem.
“For patients with Duchenne’s, their conditions are constantly changing, but in general, it’s hard to stand without a brace,” she pointed out. “It’s also hard to be social if you’re not upright at least some of the time. We do significant strengthening programs with our patients in a solid AFO, then we take the orthoses off so they learn to balance. They have to have the strength to do that, and all of our kids have gone from poor balance to above-average balance, so I don’t think we’re impairing them. True, you can’t use an ankle strategy for balance while your brace is on, but you can circumvent that.”
Hinshon often works closely with Brown on treatment plans and orthotic strategies for these patients, and he shares her take on the importance of core strength.
“All of my toe walkers have weak cores, glutes, and quads,” he said. “If you walk on your toes, there’s no demand for those muscles to work, so they shut off. If we put them in solid-ankle AFOs, it forces them to strengthen proximally.”
Hinshon said that one common misunderstanding about orthotics, and particularly solid-ankle bracing, is that the child is going to atrophy and become weaker due to dependence on the device.
“There’s no truth to that,” he said.
All the professionals LER spoke with emphasized that the process doesn’t end with the prescription of an SMO or an AFO but responds to the child’s growth and progress.
“We tune them repeatedly in terms of shank angle until we get optimal function,” Hinshon said. “I’m watching the foot, the ankle, the hip, everything, but 80% of my focus is on the knee. I want full extension at initial contact, then terminal extension at third rocker with the foot plantargrade. If I have that, along with straight foot projection, I know I’ve optimized their gait.”
Many children with DS could benefit from earlier orthotic treatment, Hinshon added, but the problem is complicated because of extreme variability in the patient population.
“I’ve seen Down patients that didn’t show any interest in standing until age 4,” he said. “They should have been treated 2 years earlier to give them some stability and an opportunity to be mobile. The earlier the better, even before they start walking. If the foot starts deviating to varus or valgus, it’s like cables on a bridge; that elongating ligament structure starts to degrade, and now you’ve got a really unstable base.”
Ultimately, the best orthotic intervention for children with hypotonia—whether due to Down syndrome or other conditions—is achieved when the care team works closely with the parents and the children themselves. This allows the team to establish goals and design the best strategy for realizing them, whether that be a flexible SMO, a rigid AFO, or varying approaches at different times. In the best cases, children can grow stronger, achieve better control, and enjoy the benefits of exercise and social life that come with those gains.
|Cary Groner, a freelance writer in the San Francisco Bay area, has been writing about biomechanics for LER for 10 years.|
|Editor’s Note: This article is sponsored by an educational grant from LaunchPad O&P and Orthotic Care Services, Minneapolis, Minnesota.|
Source Lower Extremity Review
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