Pediatric orthotic management: Children are different

They are not just small adults; some things are very different, though some are just smaller. I often tell our physical medicine and rehabilitation residents in training that there are only two differences between adult and pediatric rehabilitation: 1) growth and 2) development… and maybe a few conditions or diseases of childhood onset they will need to learn about.

Surestep

Vikki Stefans MD MS, Healio O&P News April 1, 2001

I then tell them that there are three kinds of people in the world, those who can count and those who can’t; and that they only have to read about two things: everything they see on the wards or in clinic, and everything they don’t. But today I will try to be more helpful. This article will focus mostly on functional lower extremity orthotic use and how the pediatric practitioner must think a little differently.

What Is Really Different: Growth

Children outgrow orthoses. They really do grow in spurts; if there was a Murphy’s Law of pediatric orthotics, it would be that all growth spurts occur immediately after receiving a new orthosis, if one did not occur between the casting and the fitting. And yet, accurate fit is at least as crucial as it is in adults for comfort and function.

Frequent adjustments and replacements are to be expected. Many children “sprout up,” outgrowing the orthosis in length and height but actually having it become sloppy and loose in fit distally. If you use twister cables, particularly an articulated design, the joint must be kept close to the actual axis of rotation of the knee to avoid the mismatch gradually pulling the child down into a crouched position, with the waist belt falling down around his hips.

One of the few places we see less rapid change in size is for AFOs in the spina bifida clinic; the lower motor neuron deficit produces limited growth of the distal lower extremities. As a rule of thumb, limb length deficit, lower or upper, related to lower motor neuron conditions acquired early in life is dramatic, while upper motor neuron lesions are associated with mild but measurable difference.

Many orthopedic surgeons feel there is no need to correct for any discrepancy, but when we see gait deviations that may benefit, we proceed-almost never with a heel lift, but a full sole lift. A child who is neurologically sensitive for postural adjustments proximally will level his pelvis, either by showing aggravated equinus on the short side, or excess knee flexion on the long side, both of which may be undesirable. Walking with pelvic obliquity may or may not be related to any discomfort, but may tend to put one limb into undesirable valgus or varus deviation.

Growth theoretically has a plus side-malleability. For example, the very young child with Blount disease (pathologic tibia vara) or metatarsus adductus may be significantly corrected by bracing. But overall, we must recognize that bracing in the walking or walking-age child rarely corrects actual fixed deformity or influences bone growth directly. We do not expect to reverse fixed tibial torsion with twister cables, though in a case of dynamic excess internal versus external hip rotation, we may help point the toes more straight ahead and improve things long afterwards.

We can influence tone and improve gait, and possibly prevent some progressive deformities, particularly subtalar valgus. Malleability has a down side; a child’s valgus foot can progress very dramatically if left uncontrolled, when it is not simple, mild, painless, flexible flatfoot unassociated with neurologic disorder.

It will be worth seeing if children who receive valgus correcting orthotic management through their growing years are less likely to come to subtalar arthrodesis as young adults. A child who habitually walks in subtalar valgus will also have compensatory forefoot supination that leaves the first ray off the floor if the valgus alone is corrected.

The full-wrap orthotic designs often used as “inhibitive” or “dynamic” orthoses offer a very good chance to control both the valgus and the compensatory forefoot problems. People with adult onset disability will more likely show more normal and/or more fixed foot and subtalar structure, for better or for worse: off the shelf designs, with less subtalar stabilization, are more likely suitable, though they rarely, if ever, work for children.

What Is the “Inhibitive” or “Dynamic” Approach?

It is, first and foremost, not exclusively a pediatric technique, nor a universally applicable technique for all pediatric orthotics. That said, these orthoses have been extraordinarily useful, even in some cases beyond the classic indications-that of hypertonia with good passive range of motion, or hypotonia with underlying compensatory hypertonic patterns.

The underlying approach is to create a reflex-inhibiting posture of the foot and ankle, and to influence tone and gait without immobilization. Important techniques for these “new” types of orthoses are to carefully mold in all three arches of the foot, to be certain to achieve subtalar neutral, to create more of a full wraparound and yet to restrict joint movement only when necessary and usually only partially. Slight elevation of the lateral toes and sometimes abduction of the great toe often help to relax abnormal tone as well. This typically calls for a much more flexible plastic and careful attention to trimlines that will flex and not pinch with movement.

A well-made inhibitive orthosis allows for activity and development of all muscle groups and a more free range of motion much more likely to be accepted by an active child. An early idea that the inhibitive cast, a predecessor to this technique, worked only via creating disuse atrophy and weakening the spastic muscle was incorrect. The studies on these orthoses in general show there is an increase in stride length at the same level of muscular activity-which physiologically corresponds with an increased threshold of the stretch reflex, i.e., an actual reduction in functional spasticity. If the cadence changes little, the gait is faster and more efficient.

The “Forrest Gump” Syndrome

Despite this, what I call the “Forrest Gump” syndrome is commonplace. Families do not think about orthoses the same way we do. They expect a cure. They may think of orthotic devices as temporary and terrible, to be endured briefly, and are surprised to have us expect better rather than worse function with them. They may regard as gospel what the first person says who states the child does not “need” the brace, which may be orthopedically true but functionally devastating.

The effect of inhibitive orthotics often persists for a while after removing them, as did the inhibitive casts of yesteryear. After this phenomenon fooled an orthopedist into thinking they were no longer needed for one young lady with cerebral palsy post-rhizotomy, her absolutely horrified therapist made multiple photos and videotapes over the subsequent months demonstrating her severe progression without them. This fortunately convinced the doctor to reverse his opinion, who in turn revised his advice to her mother, who in turn started letting her wear her orthoses to therapy again, if nothing else. However, she did come to subtalar arthrodesis and heel cord release not long afterwards.

Families may also expect that if the orthosis is outgrown before a cure occurs, it was no good. They are not just being forgetful or negligent when they return to clinic without the allegedly outgrown or non-working device and with the child having been out of bracing for some time. They do not come to us complaining that their child shows excessive subtalar valgus and a shortened stride length.

If we correct valgus and provide a smoother gait for a child with spina bifida and internal tibial torsion, they see that the feet turn in more, and they may not like it. When a local “doctor” sells them a pair of pristine white high-top orthopedic shoes and from the outside it looks like their child is standing with 90 degrees dorsiflexion, it may be hard to explain that this is not what is really happening inside. They may expect that a brace worn an hour or two a day will have an effect like a medication given once or twice a day, rather than seeing it as an aid to full-time better walking.

Many families reduce the amount of time any orthosis is worn rather than have it adjusted to fit better, which probably accounts for a great many failures of management of scoliosis via TLSO. They may assume their child is being stubborn or non-compliant when a brace is pinching or outgrown and deem the situation unmanageable. In one case, a young lady’s family stated that she walked very poorly and sometimes not at all in her braces, which in clinic appeared to work and fit well. (We must have done something right-they were actually brought in so we could see what was wrong!) The root of the problem was a grandmother who believed that the brace had to be applied as tightly as possible for it to take effect. A great deal of education and shaping of expectations must take place.

Surprisingly, families who think even today’s lightweight plastic low AFO or SMO is heavy and cumbersome and families who request high top orthopedic shoes with full metal HKAFOs for children with mild problems may meet us in the same clinic, both being very unaware of the history and principles behind current practice.

Things That Are the Same

The orthosis must fit well. Acceptance of cosmesis and the level of concern about “being different” varies tremendously from one individual to the next. Interesting colors and patterns are not necessarily just for kids-camouflage makes a lot of plastic AFOs more palatable, and using regular tennis shoes or boots with a metal and leather design rather than a traditional orthopedic shoe may make all the difference in the world. Plastic orthoses are not for everyone; my residents must learn about double action joints and varus or valgus correction straps because of their utility for patients with deformity only partially correctable to subtalar neutral, poor thermal tolerance, or inability to effectively monitor skin condition or to come in for the more intimate readjustments these will require.

The skin must be watched for pressure and adjustments must be made when needed. Serial casting may elongate connective tissues to allow for a true neutral casting and final orthotic position, which is highly desirable for both children and adults, particularly for those with increased tone. Our old textbooks recommend a slightly plantarflexed ground reaction design post CVA “to support weak knee extension.” However, in most children and even in many adults for whom this is a classic recommendation, this aggravates spasticity and proximal deviation and may even produce progressive recurvatum. The selection and design must be individual, not reflexively based on a either a diagnosis or a theory, even though diagnosis may be terribly important to understanding the observed biomechanics of gait.

Reevaluation is essential, on both an individual and an overall practice level. At one time, when plastic was new, we gave everyone solid ankle, sturdy ones because those were best. We even said things like “no plastic for spastics” and certainly would not consider hinged or flexible ones for those with high tone, but now experience has shown that flexibility is key to optimal function in many, if not most, cases. People need to climb steps and go up ramps, and if they have the proximal strength and/or plantarflexor strength plus the range to use them, the more mobile design is strongly preferred.

Some Different Diagnoses

Cerebral palsy is what you will see the most of, and refers to a group of conditions rather than a specific disease, varying tremendously in severity and functional implications. The definition we use has four parts: 1) motor disorder, 2) due to cerebral pathology, 3) of a non-progressive nature, and 4) with early developmental onset.

Prematurity is the most common known risk factor or cause, being related to the development of intraventricular hemorrhage in the newborn with later periventricular leukomalacia, which usually correlates with the spastic diplegic type of cerebral palsy. This means that the arms are less involved than the legs. Intrauterine stroke or brain malformation may produce true hemiplegia or quadriplegia. Severe quadriplegia with microcephaly may be related to lack of oxygen around birth of a moderate to severe and prolonged degree; these cases account for only about 10 percent of all cerebral palsy.

A different picture, with better cognitive function but varying degree of movement disorder may be seen with either brief though severe hypoxic etiology, or some metabolic disorders. Movement disorder may evolve over the first several years of life, and initially hypotonic children may develop spasticity as part of the natural development of their condition. Dramatic worsening of function without an orthopedic explanation or increasing severe ataxia can be a sign that the diagnosis is not cerebral palsy but rather a neurodegenerative disease such as leukodystrophy.

Orthopedic complications such as developmental hip dysplasia and subluxation can progress even though the underlying brain injury is static, due to the influence of abnormal tone and patterns of movement on bone and joint development and alignment. Associated sensory or cognitive problems are common but by no means universal and also not always correlated to the degree of motor involvement; at least 50 percent of people with cerebral palsy have normal intelligence and another 25 percent have borderline scores rather than any degree of mental retardation.

Duchenne’s muscular dystrophy, though not the most common pediatric diagnosis, is very specifically different and cannot be managed like cerebral palsy. Cerebral palsy is at least ten times more prevalent, and some cases of Duchenne’s can be mistaken for it early on, as the characteristic weakness is mild and compensable, and there is heel cord tightness and motor delay in both conditions.

AFOs are rarely if ever indicated, because it is physiologic to rise slightly on the toes. This maneuver allows for the weight line to fall behind the hip yet in front of the knee and becomes critical as those muscles lose antigravity strength. Resting AFOs and enough stretching to allow for range to neutral are helpful measures, but trying to have a child walk in AFOs will increase falls.

Ankle supports and elastic knee supports which slightly resist flexion may be of help instead once falls are occurring often. Knee-extension assist orthoses are in an experimental stage for this and the milder but related condition, Becker’s muscular dystrophy. After heel cord surgery, if it is needed, KAFOs are mandatory and must be ready the day after surgery to resume weight bearing; even the slight loss of strength due to deconditioning over a few days can make resuming walking or even standing difficult or impossible. Keeping hamstrings and hip flexors free of contracture is essential; we worry more about a five to ten degree hip flexion contracture or a tight ilio-tibial band than a plantarflexion contracture of a similar or even a little greater degree.

Angelman syndrome is often incorrectly diagnosed as cerebral palsy, but characteristically there is no history of either prematurity or birth trauma or asphyxia; the head is small, the facial appearance may be unusual, and patients have a tremorous tone and ataxic-like movement. They do not learn to speak though they may learn by imitating or may use communication devices. Valgus feet are nearly universal and often very difficult to manage. Diagnosing this one is helpful to families who can find a great deal of support and information through the national organizations for this condition.

Spina bifida operta (myelomeningocele) of various levels: We define the level by the key muscle group being antigravity and the next proximal being good grade or better. At a thoracic level, walking is not always practical, especially in the older and taller child. For selected individuals who are very interested in walking despite the effort and energy cost, there are two basic options.

The conventional reciprocating HKAFO and variations such as the isocentric design are more widely used. It works well for those with flaccid paraplegia with good upper body strength, and is suitable for sitting as well; intermittent urinary catheterization, especially for girls, is very difficult while wearing it, however. The ORLAU Parawalker is tolerant of spasticity but less tolerant of contracture and requires superb upper body strength. It is easier to don and doff, but not designed for sitting. Either device is better in efficiency than swing-through gait, which young children may do wonderfully well but eventually must give up as they grow.

At the L2 (hip flexor) level, KAFOs may be an option. These are usually standard solid ankle design, not the Craig-Scott design sometimes tried for paraplegic ambulation after spinal cord injury. At an L3 (knee extension) level, we sometimes still use KAFOs if there are significant proximal rotational or coronal plane (usually valgus) deviations at the knee, but with antigravity quadriceps function available, they should be used unlocked.

More commonly, at the L3 level, ground reaction AFOs are prescribed. There is a school of thought that anyone without hip extensor function should use HKAFOs, but they can also use upper extremities to compensate via forearm crutches and/or shift their center of gravity back behind the hip joint just as others with proximal weakness do. Most with an L3 level really need crutches to safely compensate their Trendelenberg, though they may wish (and try) to do without in order to have their hands free.

In spina bifida, the multi-level muscles are active at about one level higher lesion than would be expected in a traumatic injury. At the L4 (ankle dorsiflexion) level, for example, this means the hip abductors may be partially active, and crutches are more likely optional. The L4 level may require efforts to decrease calcaneal gait and unweight the hindfoot; pressure sores on the heel may occur, and a cast boot with cutaway heel may be an invaluable adjunct to healing while continuing to walk. At this and even at the L5 (great toe dorsiflexion) level, though solid AFOs are traditionally advocated, a moderate resistance to dorsiflexion may be a better objective. This may be achievable with an anterior wrap SMO.

Ideally, orthotic management will allow for an increase in stride length as the patient can slightly dorsiflex, “leaning” on this resistance instead of having to keep the weight line behind the ankle due to weak plantarflexion. Isolated plantarflexion weakness is not commonly seen elsewhere, and most people think of the role of plantar flexors in “push-off” (late stance) instead of their critical role in preventing excess dorsiflexion by eccentric contraction instead. You may observe an almost “peg-leg” type of gait where the person is walking as if they do not have a forefoot.

Alternatively, there may be an appearance of “hanging” on the Achilles complex, similar to the way the Y ligaments are used in hands-free standing with weak hip extensors. This may create a crouched gait even without hip or knee flexion contractures or hamstring tightness. Firmer dorsiflexion resistance, such as the Cascade ground reaction design, may be more helpful when this pattern is observed. At the S1 (plantarflexion) level or lower, no orthotic or perhaps just an insert for any varus, valgus, or adductus tendency is usually all that is indicated.

Osteogenesis Imperfecta is a condition also known as brittle bone disease, and there are several types with variation in severity and frequency of fractures. Currently, medical treatment with IV pamidronate shows great promise in reducing fractures and increasing bone density and should be offered to all. Some children may benefit from “clam-shell” style fully articulated HKAFOs to decrease fracture risk while walking. Be aware of this condition and note that not all types have blue sclera; it can be confused with child abuse since fractures occur with minimal or no trauma.

Arthrogryposis Multiplex Congenita is a syndrome of congenital contractures. There is a common or classic pattern with elbow extension and wrist flexion, hip pathology, extended or flexed knees, and clubfoot. Most commonly, it is believed to be due to lack of development or loss of groups of anterior horn cells early enough in gestation that the muscle they would have innervated does not develop either. However, it is a static, non-progressive loss, and life expectancy is absolutely normal. The clubfoot requires surgery in most cases, but other contractures may respond very well to a progressive splinting program. These children are commonly very bright, having intact central nervous systems, and their compensatory ways of getting things done should not be disregarded in making surgical or orthotic plans.

This concludes an overview of the pediatric orthotic scene from the point of view of one pediatric physiatrist. There is much more information available on any facet of what I have presented, both in our journals and on the Internet. I especially recommend the caascadedafo.org site, as well as oandp.com and the web site amcsupport.org, a US national support group for arthrogryposis multiplex congenita. There is always more to learn, both from our collective past professional experience, and from observing and listening to our patients and families.

Vikki Stefans MD MS is an associate professor at the University of Arkansas for Medical Sciences, Pediatrics and Physical Medicine & Rehabilitation Departments (PM&R), and medical director for the Arkansas Children’s Hospital Progressive Rehabilitation Unit, Habilitation, and Muscular Dystrophy Association clinics. Her research interests are dysphagia, functional outcomes, orthotics, prosthetics, seating and other adaptive technology, osteopenia in children with disability, and pulmonary function in muscular dystrophy. For more information, contact Dr. Stefans at the Arkansas Children’s Hospital, 800 Marshall Street, Little Rock, Arkansas 72202 USA

Source Healio O&P News