Children with cerebral palsy (CP) typically encounter a host of gait- and balance-related issues associated with spasticity, dyskinesia, and weakness. How severe these are depends on CP type and the individual case. As a result, experts have long debated how early to intervene with bracing strategies that include ankle-foot orthoses (AFOs), and how long to maintain those interventions.
By Cary Groner, Lower Extremity Review August 2019
Increasingly, a consensus seems to be emerging that earlier intervention is a better strategy, as is long-term commitment to wearing an AFO. Even so, each child’s situation is unique, and demands complex decision-making on the part of clinicians, orthotists, physical therapists, parents—and when they’re old enough, the kids themselves.
“Many pediatric therapists might consider early intervention only up to age 5 years, but we should be talking about anywhere from 6 months on,” said Elaine Owen MSc MCSP, a clinical professor and physiotherapist at the London Orthotics Consultancy in the UK.
“Ideally, you’ll have a list of goals,” Owen continued. “Where do you want to be with this 1-year-old in 3 weeks, in 6 months? What do you want to achieve by age 2, 6, 10, 16? And how will those choices affect their life when they’re 26, 46, or 76? Because whatever we do will affect their whole life, and how much pain they’re in.”
Pain, Owen noted, is one of the most significant indicators of quality of life, and because disabilities such as CP are often associated with lifelong pain, the choices made by care team members carry significant consequences, both physical and psychological.
“You have to set goals for the bones, the muscles, the brain, and for activity and participation,” Owen explained. “And these goals also have to include just letting them be a child, because however they end up physically, they have to be psychologically balanced. We’re still figuring out how to make the best orthotic decisions for each child, because it’s different for a preschooler than for a 7-year-old. Most of us are trying to get a child to skeletal maturity at 16 with the least contracture deformity and the least number of surgical interventions.” (See Goals of Therapy)
For Beverly (Billi) Cusick PT COF, it’s important that evaluation of a pediatric patient’s gait includes a careful look at how they load their feet, medially or laterally. Cusick, who practices primarily in Telluride, CO, and has lectured at a number of healthcare educational institutions internationally, told LER that she focuses less on a patient’s diagnosis than on what’s going on biomechanically.
“There’s a presumption that we know what AFO to order based on diagnosis, and it’s just nonsense,” she said, adding that it’s crucial to understand normal development in order to deal with children with CP and other disorders that affect gait.
“K.A. Ericsson said that achieving virtuosity in any skill takes 10,000 hours of practice,” Cusick continued. She considers walking a virtuoso-level skill and points out that even normal kids take years to get it down.
“Infants build stability skills; they need to engage their limbs in learning and moving in all postures,” she said. “Once they get to standing, they practice weight-shifting about 3,000 times an hour while they’re just cruising with furniture. Then, as walking develops, they deal with body-weight distribution, which normally means more weight on the lateral than the medial column because this protects fragile ligaments from pronatory strains. That’s when they gain strength and integrity.”
To that end, Cusick recommends orthotic intervention for any CP child who loads the medial column more than the lateral, regardless of age.
“If a child looks good in solid cast boots, if his kinematics are good, and he’s got control of posture and body weight in gait, then I say stay with them, or stay with the solid AFO that behaves most like a cast boot,” she said. “You can introduce degrees of freedom later—6 months, a year, whenever you think it’s necessary—to let them have a little plantar flexion but still keep control of dorsiflexion.”
One of Cusick’s mentors, the late pediatric physical therapist Mary Weck, included strengthening exercises for her patients’ feet and lower legs, Cusick explained. Weck continued the children in solid AFOs until the foot didn’t pronate through push-off, then weaned them from the orthotics and used night splints until their skeletal growth was complete.
“They maintained control of equinus and full function up to 14 years after the casting course,” Cusick said. (According to the unpublished data, the average was 5.6 years). “It’s not about how long it takes, it’s about how you get there.”
Scott Hinshon CO, who is CEO of both Orthotic Care Services and LaunchPad O&P (a manufacturer of AFO optimization components) in Minneapolis, agreed that biomechanics take precedence over diagnosis, at least to a point.
“It’s helpful if I understand their diagnosis, but their clinical presentation is going to drive the orthosis design, and that in turn is based on goals,” he said.
“For a spastic patient, if you can’t influence where the knee is in space as it’s traveling through stance phase, you can’t normalize gait,” Hinshon said.
For Hinshon, the point is to evaluate the patient globally, from the foot to the head. Many of his patients have weaknesses in the core, in the quadriceps, and in gluteals that affect downstream biomechanics.
“Proximal compensations create distal symptoms,” he said. “Some people try to adjust alignment of the foot and ankle with an SMO (supramalleolar orthosis) instead of treating the sagittal plane compensations at the ankle, the knee, and the hip. As a result, they’re not optimizing the patient’s mobility or potential for rehabilitation.”
CP patients, he acknowledged, are among the most difficult to manage.
“They’re internally rotated, they’re trying to advance, their mass is in front of their feet, they’re leading with their head, and their arms are out because they’re ready to fall,” he said. “Often they have compensations related to mobility, alignment, and limited range of motion in the joints. They have to learn how to move over this device, and they’ll take longer to normalize their gait than those who have low tone.”
It’s important to recognize that change takes time and you need patience and persistence with the process, Hinshon said.
“Our care protocol is evaluation, then fit a week or 2 later, follow-up 2 weeks after that, then more follow-ups at 1 month, 2 months, and so forth. I think about orthotics as a process of care rather than a device, because if you do your job well, those kids will change really quickly.” Hinshon noted that even though his company produces a range of adjustable orthoses, he and his staff are strong proponents of solid-ankle AFOs if they offer a given patient the best prognosis.
“The brace doesn’t restore range of motion in the ankle,” he said. “It’s improved gait that restores both ROM and strength.”
Nicole Brown DPT, who works in developmental and rehabilitation services at Children’s Hospitals and Clinics of Minnesota, frequently collaborates with Hinshon on patient care. She agreed that CP patients present special challenges.
“They have the tonal [spastic] influence, but typically with an underlying muscle weakness,” she said. “Our goal is to get them to use more muscle strength. In patients with a crouch gait, the muscles with the most tone are the adductors, hamstrings, and plantar flexors; so as those muscle fibers are lengthening, they’ll kind of catch. If you don’t have the strength to keep that leg moving, you’re going to stop, and that tone will hold your muscle fibers in place. That’s why they step down with knee flexion and femoral internal rotation. So we do significant strengthening programs with them in a solid AFO.”
Kathy Martin PT DHSc, a professor in the Krannert School of Physical Therapy at the University of Indianapolis, agreed.
“We know that a spastic muscle is a weak muscle,” she said. “The question is how to address that weakness. If the child has voluntary control, then we have a shot at getting them stronger, but if they don’t, we’re going to have to compensate with some kind of rigid support.”
Cusick concurred. “Solid AFOs have a tremendous place in management,” she said. “They are far more effective at teaching children how to load their foot and move over it than articulating devices.”
She added that in this context, tibial inclination—sometimes called shank-to-vertical angle (SVA) [1,2] is critical to patients’ achieving more normalized gait.
“For me, the decision to use solids over others has everything to do with that,” she said.
|Relevancy of shank-to-vertical angle|
Professional disagreements about the best way to measure SVA have led to confusion among practitioners. Briefly, Owen supports measuring from the anterior tibial border, whereas Hinshon usually aims for the mid-sagittal line, from the fibula head to the lateral malleolus. Cusick also prefers using the fibula and noted that because this approach yields slightly different numbers, it’s important that clinicians not mistake these as equivalent to Owen’s figures.
Hinshon noted that optimal angles vary between patients, in any case.
“For one child it might be 8 degrees; for another 10 or 11 degrees. You have to evaluate the function and quality of the gait, and the measurement simply validates your success or failure. It’s really only important if you’re not achieving your functional goals.” (See Post-Fitting Optimization Tips)
“It doesn’t really matter where you measure it from,” added Owen. “It’s just that when people report their results, they need to state which measurement they used so accurate comparisons can be made. Tuning is about getting the most normal walking for the best prognosis.”
“Tuning is about getting the most normal walking for the best prognosis.” Elaine Owen MSc MCSP
LER has covered AFO tuning in past issues. According to Owen, tuning an AFO involves an optimization of static alignment to influence shank and thigh kinematics, so that during stride the shank passes through vertical and reaches an incline of roughly 10–12 degrees at midstance. Ideally, this enhances stability; improves sagittal plane kinematics; helps align ground reaction forces (GRFs) relative to the knee and hip; and may contribute to energy conservation. A well-tuned AFO also improves rocker function.
Shoes are an important part of the tuning equation, as well—so much so that clinicians often use the term AFO-FC, for “AFO-footwear combination.”  Studies support the efficacy of this approach in treating gait deformities in pediatric CP patients.[5,6]
“If I’m going to optimize the gait of a CP patient, I have to anticipate what’s going to happen to the knee extension moment at heel strike, at initial contact, and at terminal stance,” explained Hinshon. “We use plantar flexion stops and heel lifts to get our shank angles where they need to be.”
Most clinicians would agree that pediatric patients present with stance-phase related issues. The majority of Hinshon’s patients have the greatest need at midstance to late stance. He discovered that tibial resistance was the best way to manage pronatory foot postures and to generate power in late stance that enhances step length, improves single-limb stance stability and increases cadence.
“To manage knee compensations, we use dorsiflexion stop motion for crouch presentations and dorsiflexion resistance for recurvatum. The resistance prevents fall-off at the knee and promotes tibial progression.” Hinshon continued, “Contrary to common belief, recurvatum is best treated with dorsiflexion resistance, not plantar flexion stop motion. This is why I invented X-tension bands, there just wasn’t any product on the market that would provide the resistance I needed.”
“We know that a spastic muscle is a weak muscle. The question is how to address that weakness.” Kathy Martin PT DHSc
Owen has developed a comprehensive approach to evaluation and treatment. A chart summarizing her method contains 4 columns for tracking issues with:
- bones, joints, and ligaments;
- musculotendinous units (MTUs) and skin;
- neurological control and developmental mobility; and
Under the first column head, readers will find a detailed breakdown of strategies to manage deformities. The second column describes ways to address abnormal neuromuscular function, including compensation for weak MTUs and controlling the effects of MTU hyperactivity. The third deals with standing and walking kinematics as well as the quality and development of gait patterns. The fourth primarily addresses posture, balance, and social interaction.
Owen told LER that she always tries to involve the parents—and to the extent possible, the child—in the consultation and treatment process.
“I ask the family to talk to me about their worries, what they want to get better,” she said. “I write everything down in those 4 columns on a board, we’ll add in things the clinical team may be concerned about, then we’ll see if an orthosis is the best option. Based on all that, we set goals.”
Starting when the children are young can prevent extensive surgeries later, and when the parents realize this, they usually become enthusiastic about bracing options.
“You just walk them through it,” Owen continued. “Let’s start with the column with the bones. If you want your child’s feet to look like normal adult feet, you’ve got 7 or 8 years to get there, and that means considering orthoses, often a fixed-ankle AFO. Once the parents have the information, and they become an equal partner in the process, they come to the same conclusion.”
“Once they get to standing, they practice weight-shifting about 3,000 times an hour while they’re just cruising with furniture.” Beverly (Billi) Cusick PT COF
Hinshon acknowledged that it can take work to help parents understand that the more quality in-brace steps patients can take, the more likely they are to achieve their goals. “There is a direct correlation between compliance and outcome. You can’t expect ‘full time’ results with a ‘part time’ wear schedule.”
Owen believes in balancing physical and psychological goals but noted that they’re usually compatible.
“You get kids through life addressing both their physical condition and their emotional state,” she continued. “I think the most important thing is for them to end up psychologically well, but that doesn’t mean ignoring their physical disability. You might decide that they need to wear the orthoses only 60% of the time—so then, what 60% will that be? You negotiate. If the child wants to dance and the AFOs hinder them, take them off. If they can’t dance without them, leave them on. Once you have your overall goals, you just have to decide on the right orthosis for the right amount of time. Over the years, the negotiations become much easier because the child learns to trust you.”
|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