Most orthoses made for children are motion-controlling or motion-altering, often referred to as functional foot orthoses. The presenting pathology in the child’s lower extremity often requires a device to reduce excessive motion in a foot with, for example, high ligamentous laxity and genu valgum or you may need the device to direct motion in a limb with a rotational disorder such as a femoral antetorsion and compensatory hyperpronation.
Accommodative devices are less frequently required in this age group. It is much more common in adults than in children to require accommodation of reduced joint motions, prominences and pressure points. If some accommodation is needed in a child, you can usually add it to a motion-controlling device as a soft-tissue supplement, creating a “hybrid” device.
The relatively light weight of a child means materials that are more forgiving — with increased flex in a heavier individual such as an adult — will resist collapse more readily in a child. This allows you to choose from a wide range of material properties, shell thicknesses and filler options while still achieving the desired goal of motion control.
Key Posting Considerations
Varus deformities of the rearfoot and leg should be identified at an early age. Dynamic compensations for these imbalances require posting, which effectively angles the surface the patient walks on a corresponding number of degrees to the measured deformity. This reduces or eliminates compensations in the foot and reduces the symptoms and gait changes associated with them.
The amount of control a post provides is determined by numerous factors including the number of degrees the post is angled. Other factors include the stiffness or resistance to compression of the posting material, anterior-posterior length of the post and the width of the post. A longer, wider post made of a stiffer material will offer the most control to the rearfoot and leg.
There is a reduced need for forefoot posting in children under the age of 6. The ideal orthosis for a child will limit excessive or undesired motions while still allowing normal motions that are so important for ideal development.
Be Aware Of Predisposing Risk Factors In The Pediatric Pronated Foot
A child may exhibit a weak foot structure leading to pronation, but may also have additional predisposing risk factors that may affect the foot in its overall development and function. These risk factors may modify the natural history of the pediatric pronated foot and often dictate the requirements for orthosis selection and design. These risk factors include, but are not limited to, ligamentous laxity, obesity, rotational and angular disorders and ankle equinus.
Shells made of more rigid materials and/or of increased thickness are the best choices for treating children who have generalized ligamentous laxity. Other modifications such as a deep heel seat, increased calcaneal pitch to lock the oblique midtarsal joint axis and medial and lateral flanges to reduce transverse plane compensations of the midfoot will aid in control of the foot with notable laxity.
Due to the significant medial and lateral instability of children with ligamentous laxity, employing an orthotic device capable of supramalleolar control in the frontal and transverse plane is often necessary to exert adequate control over the closed-chain foot and leg complex. An ideal device with the necessary medial and lateral support is the supramalleolar orthosis (SMO), which extends above the malleoli allowing for control of the tibio-fibular segment. The relatively low height of this device often makes it more cosmetically and functionally appealing than the higher ankle-foot orthosis.
In cases in which you find the SMO is not sufficient to manage superstructural compensations of the ankle and leg, an ankle foot orthosis is the device of choice. One example is the Dynamic Control Orthosis, which consists of a custom functional foot orthosis, a hinged ankle joint and custom molded medial and lateral leg uprights to control superstructural movements. This orthosis also includes a posterior bridge connecting the medial and lateral uprights, which enhancing the proximal control of the leg. This modification is an improvement over other hinged ankle braces that are currently available.
Using thicker shells and more rigid materials are also necessary in managing the pronated foot in the obese child. Longitudinal arch fillers will help reduce the increased compression of the arch area of the shell you’ll typically see in overweight patients. Soft tissue supplementation at the foot/orthosis interface may help reduce the hard feel of such devices and increase shock absorption necessary for sports.
How To Handle Rotational And Angular Disorders
Rotational and angular disorders that produce both in-toeing and out-toeing, bowing and knock-knees may contribute to a compensatory pes valgus. The presence of femoral anteversion, internal tibial torsion, genu varum or valgum will place an abnormal force on the developing foot and will either precipitate abnormal pronation or aggravate any existing abnormal pronation. An internal femoral torsion or position and internal or low tibial torsion will generally lead to an adduction or medial deviation of the talus in the closed kinetic chain. This precipitates the onset of pronation of the subtalar joint or aggravates an already pronated or everted attitude.
Similarly, an external femoral torsion/position or an external tibial torsion also contributes to excessive pronation in the child. A medial displacement of the center of gravity results from the externally positioned leg, facilitating compensation of the subtalar joint.
Genu valgum or varum outside of physiologic ranges is detrimental to the pronated foot. Abnormal frontal plane forces placed on the rearfoot lead to compensatory pronation of the subtalar joint. For example, in the case of genu valgum, the center of gravity passing through the leg is displaced medially over the foot relative to the axis of the subtalar joint. This maintains the foot in the pronated position.
Orthoses for rotational disorders benefit from flanges and extensions such as gait plates. Orthoses for angular disorders benefit from high posting and out-flared or wide posts to stabilize the post plate in the frontal plane.
Treatment Tips For Ankle Equinus
The fully compensated equinus foot, often characterized by pronation of the subtalar joint with consequent unlocking of the oblique midtarsal joint axis to allow for dorsiflexion and abduction to occur at the midfoot, is a major cause of pediatric pronation. It may be a primary cause or an aggravating factor that produces significant adverse effects on the foot.
Childhood ankle equinus may be developmental or pathologic. Developmental equinus typically accompanies a rapid bone growth spurt, resulting in relative shortening of the muscles. If you re-evaluate the foot and it has not shown improvement after four to six months, a pathologic equinus is likely. Pathologic equinus may be congenital or result from other etiologic causes. Developmental and pathologic equinus both exert detrimental forces on the foot, either initiating abnormal pronation or aggravating pronation already present in the child.
In addition to stretching the tight musculature, orthotic control of the abnormal midfoot is usually necessary. Adding heel raises to an orthotic device to plantarflex the foot and increasing the amount of available dorsiflexion of the ankle for midstance are effective at helping to reduce compensation in this foot type. In addition, the presence of equinus may limit the degree of control that can be tolerated by the child. If this is the case, selecting a more flexible, forgiving shell may be a better choice for the equinus patient.
Why The UCBL Is Good For Moderate To Severe Pronation
Podiatrists should also be well versed on pediatric speciality devices that can have an impact in treatment.
One such device is the UCBL, a polypropylene foot orthosis with high medial and lateral flanges and a deep heel cup. The flanges extend just proximal to the first and fifth metatarsophalangeal joints.
First developed in 1967 by Henderson and Campbell at the University of California Biomechanics Laboratory, the UCBL is the device of choice for the pediatric patient with a moderate to severely pronated foot as it enables you to apply corrective forces to the rearfoot, midfoot and forefoot. The extended flanges resist forefoot abduction and talar adduction often associated with moderate to severe pes valgus.
The UCBL is also an excellent choice for treating pediatric patients with a pes valgus complicated by conditions such as Down’s Syndrome and equinovalgus foot associated with cerebral palsy.
Reviewing The Benefits Of The Gait Plate Orthosis
A gait plate orthosis is a rigid device to alter function of the leg in a child with an in-toe or out-toe gait. Schuster originally described the device as a flat, rigid plate cut to the outline of the shoe. The distal edge was angulated to alter the break in the shoe. Under normal conditions, a shoe breaks at a right angle to the line of progression of the foot. The rigid extension, crossing the MPJs, alters this break, forcing a change in the walking direction.
A gait plate to induce out-toe starts proximal to the first MPJ and extends distally past the fifth MPJ. The rigid lateral extension prevents dorsiflexion of the lesser MPJs in the (in-toed) line of progression. The leg is then forced to rotate externally to allow lesser MPJ dorsiflexion and forward progression over the distal edge of the device.
Using a gait plate is effective during the propulsive phase of gait so you should only use it for patients after the age of 3 to 3 and a half when the mature heel-to-toe gait pattern has developed. You should also ensure that a minimum of 25 degrees of lateral or external hip rotation is available in order to enable the device to exert the desired effect.
The device is most effective in a sneaker or shoe with flexibility to the ball of the foot. A shoe that is stiff in the ball will not bend during propulsion and prevent the device from exerting an external rotation torque on the internally positioned limb.
Although the original gait plate was a flat plate made directly to the shoe, a gait plate extension is frequently added as a modification on a foot orthosis. This enables you to control excessive pronation of the rearfoot and midfoot in contact and midstance while inducing an out-toe during propulsion with the forefoot extension.
You should keep in mind that with control of pronation, there is an increase in the amount of adduction of the foot. This increase in adduction will exacerbate the appearance of in-toe in the child with an underlying rotational disorder.
A gait plate to induce in-toe is rarely used. The biomechanical concept is the same with the distal angulation in the reverse direction. It is most appropriate for a child with an external femoral or tibial torsion without pronation of the foot. However, using an orthosis to control motion of the foot in a child with compensatory pronation will sufficiently reduce abduction and out-toe in most cases.
A Few Thoughts About The Dynamic Stabilizing Innersole System
Finding a device to limit abnormal motion but still allow normal motion and encourage ideal development of the foot is a challenge facing those who treat the pediatric flatfoot.
The Dynamic Stabilizing Innersole System (DSIS), first described by Jay, Schoenhaus, et. al., in 1992, is a device designed to limit abnormal motion, allow normal motion and encourage the developmental unwinding of fetal positions retained in the foot such as forefoot varus.
This orthosis is characterized by a deep, 5-degree varus offset heel seat (an intrinsic rearfoot post sometimes referred to as a Kirby skive). It has extended medial and lateral flanges similar to the UCBL. It incorporates a longitudinal split in the plantar aspect of the shell. This is designed to allow independent function of the medial and lateral columns of the foot. Theoretically, it allows for independent plantarflexion of the medial column while the lateral column is stabilized against the ground.
The authors hypothesized this would decrease the likelihood that the forefoot would maintain a varus position while the rearfoot is controlled, as might be expected from a rigid device such as a UCBL. If the device maintains the varus position of the forefoot, there is a reduced likelihood that normal developmental unwinding of the forefoot deformity will occur. The independent medial arm of the DSIS will allow plantarflexion of the medial column while the lateral column is controlled, allowing the forefoot varus to reduce with development.
Jay and Schoenhaus, et. al., in their own study of 50 children with and without the DSIS, found a statistically significant correction of hyperpronation with the use of the device. This device is ideal for the young child with a mild to moderate pes planovalgus deformity. It works well in the toddler and pre-school population in which developmental flatfoot is a frequent diagnosis and unwinding of the foot and leg is still occurring.
Other Helpful Treatment Insights
Patients with a talocalcaneal coalition have reduced subtalar joint motion and frequent peroneal spasm. Employing a rigid orthosis from a pronated cast with a deep heel seat and a 0-degree rearfoot post is often successful at reducing painful motion. When you treat children with a calcanonavicular coalition, keep in mind that reduced subtalar joint motion and peroneal spasm are less common. Therefore, using a more controlling device with high posting made from a neutral cast has a higher success rate.
Calcaneal apophysitis (Sever’s disease) is an inflammation (sometimes considered an osteochondrosis) of the secondary growth center of the calcaneus. It is frequently accompanied by a tight heel cord and may be aggravated by high loads through the heel.
When treating this condition, you should consider using a device with a more flexible shell, such as a Flexible All Sport, a deep heel seat to maintain the calcaneal fat pad beneath the apophysis and a heel raise to reduce the strain from the tendo-Achilles.
When treating children, it’s important to be aware of useful specialty devices as well as contributing risk factors which may complicate the natural history of the pediatric pronated foot.
Dr. Volpe is Professor and Chairman of the Department of Pediatrics at the New York College of Podiatric Medicine/Foot Clinics of New York. He is a Medical Consultant to Langer, Inc. and is in private practice in Farmingdale, N.Y.
1. Valmassay R: Biomechanical evaluation of the child. In: Valmassay R. ed. Clinical biomechanics of the lower extremity. St Louis: Mosby; 1996: 244-247.
2. Altman MI: Sagittal angles of the talus and calcaneus in the developing foot. J Am Podiatr Assoc 1968; 58(11): 463-470.
3. Beighton P, Grahame R, Bird H: Hypermobility of joints. Berlin: Springer-Verlag; 1983.
4. Valmassay R, Stanton B: Tibial torsion, normal values in children. J Am Podiatr Med Assoc 1989; 79(9): 432-435.
5. Valmassay R: Torsional and frontal plane conditions of the lower extremity. In: Thomson P, Volpe RG, eds. Introduction to Podopediatrics, 2nd edition. Edinburgh, Churchill-Livingstone: 2001:231-255.
6. Resseque B: Orthotic management. In: Thomson P, Volpe RG, eds. Introduction to Podopediatrics, 2nd edition. Edinburgh, Churchill-Livingstone: 2001:317-334.
7. Krivickas L: Anatomival factors associated with overuse sports injuries. Sports Med 24(2): 1997:132-146.
8. Napolitano C, Walsh S, Mahoney L, McCrea J: Risk factors that may adversely modify the natural history of the pediatric pronated foot. Clinics in Pod Med and Surg 2000: 17(3):397-417.
9. Schuster RO: A device to influence the angle of gait. J Am Podiatr Assoc 1967; 57(6):269-270.
10. Jay R, Schoenhaus H, Seymour C, et. al: The dynamic stabilizing innersole system (DSIS) for the management of hyperpronation in children. J Foot Ankle Surg 1995: 34(2):124-131.