Children with cerebral palsy present special considerations when fitted for bracing.

Cerebral palsy (CP), a neurological condition caused by a lesion in the brain, can result in a multitude of impairments affecting the lower extremities. Impairments may include, but are not limited to, spasticity and other movement disorders, decreased strength, limited range of motion (ROM), and musculoskeletal malalignment. These impairments can impact the child’s activity and participation levels, including gait and gross motor activities. Orthotic intervention in ambulatory children with spastic CP is intended to prevent deformity, achieve a stable base, improve dynamic efficiency of gait, and help build motor skills.1 This article will describe the different types of orthotics available and identify the process of orthotic selection for ambulatory children with CP.

The most common reason to use an orthotic device in children with CP is to prevent contractures and deformity. Limitation of full ankle dorsiflexion mobility, diagnosed as equines, is the most common problem of foot and ankle alignment and function in children with hypertonic neuromotor disorders.² Other goals include: correction of deformity; provision of optimal joint alignment; selective, minimal restriction of motion; protection of weak antigravity muscles; control of tone and tonus-related deviations; and enhancement of experience.3 When selecting an orthotic device, therapists need to look at the child’s overall functioning. During the evaluation, assess the daily activities in which the child will be involved. Are they standing or walking? Do they play on the floor or climb stairs? Are they involved in sports? Also, assess the standing posture. Where is their center of mass? What is their body mass? Do they exhibit age-appropriate musculoskeletal alignment?

The family should take part in the decision-making process to ensure carryover of goals and wearing schedules. It is important to remember that there is no hierarchy of orthotic devices. One style is not better than another, but one style may be a more appropriate choice at certain times in the child’s life. For example, therapists need to help families understand that changing from a hinged ankle-foot orthosis (HAFO) to a solid ankle foot orthosis (SAFO) or posterior leaf spring (PLS) is not a step backward but a lateral step to best support the child for their current level of function and ROM. The therapist needs to communicate to the family that as a child grows, developmental needs and alignments will change, and they will influence the style of orthotic devices used during the child’s growing years.

The following section will highlight frequently used styles of orthotic devices, indications for their use, and the clinical decision-making process used by the physical therapist.

Supramalleolar Orthotic

A supramalleolar orthotic (SMO) gives the medial and lateral support needed for calcaneal valgus, pronation, and supination with high or low tone. It does not control sagittal motion, so the child must have foot clearance through active dorsiflexion to ambulate safely. For children who play on the floor and are in-between floor, standing, and walking activities, a SMO is a good choice because it limits the torque placed on the knee when the ankle is locked in a position with an ankle-foot orthosis (AFO).

Solid Ankle Foot Orthotic

This is the most restrictive orthotic, and it is most commonly used to provide stability. A SAFO limits ankle motion at a preset degree, usually 90°. If knee hyperextension is present in stance, the SAFO can be set in 2–5° of dorsiflexion to facilitate knee flexion. Other impairments that would lead the therapist to choose a SAFO are: spasticity of the triceps surae, toe drag caused by anterior tibialis weakness, the need to control eccentric motion of the tibia at the stance phase of gait, equinovalgus deformity, or the time following surgical intervention at the ankle and/or after serial casting.

Limitations of ankle motion imposed by the SAFO compete with its advantages for the child who is active and ambulatory, in that it prohibits normal excursion of the tibia forward over the plantigrade foot during postural transitions, such as squatting and rising from a sit to stand position. In gait, the normal 10–15° of motion of the tibia over the plantigrade foot after midstance is also prohibited using the SAFO. The ankle joint normally plantarflexes 20° at heel-off and immediately following heel strike. This plantarflexion is blocked from occurring in the SAFO, resulting in an early heel rise.3,4 

Posterior Leaf Spring

The PLS has a smaller posterior trim line, which promotes resisted ankle plantarflexion and dorsiflexion but allows push-off and may limit knee hyperextension if the shaft height is sufficient. Advantages of using the PLS are its smaller trim line and the increased movements compared to the SAFO. However, dorsiflexion motion remains limited compared to a HAFO. The disadvantage of a PLS is the decreased rocker functions of the ankle, which are prohibited in any orthotic device that is higher than the ankle.

Hinged Ankle Foot Orthotic

This type of orthotic allows free dorsiflexion and limits plantarflexion at a predetermined degree. The HAFO benefits children who need increased motion at the ankle to accomplish higher-level balance and functional activities. Children should have some eccentric control of triceps surae, but they may require assistance to clear their foot and facilitate anterior tibialis contraction. If the patient is showing a crouched position due to weak triceps surae musculature or tightened hamstrings, the HAFO could increase the appearance of crouching and feed into the knee-flexion pattern.

Conversely, Buckon et al5 found this evident in only one out of 30 children who demonstrated a concomitant increase in knee flexion in stance compared to barefoot. In addition, a study by Radtka6 on diplegia reports that clinicians’ concerns regarding the possibility of more knee flexion for a crouched gait pattern as a result of the use of a hinged or solid AFO were not substantiated. Like the SAFO, the HAFO blocks the normal plantarflexion moments during the gait cycle using the plantarflexion stop.

Solid Versus Hinged

Regardless of which type of orthotic you choose, many things should improve from its use, such as stride length, energy consumption, improved gait to a more “normal” pattern, and power generation in the musculature surrounding the ankles. Several research studies comparing the SAFO, the HAFO, and the PLS are based on children with spastic hemiplegia or diplegia. The majority of these children are between 7–9 years of age and are independent ambulaters with at least 5° of dorsiflexion with knee extended.

When comparing all three orthotics on hemiplegic children, most children had the greatest benefit from the HAFO and the PLS. The HAFO allows the greatest degree of ankle dorsiflexion in stance, maximizes ankle-power generation, normalizes the stance-phase motion in children with knee hyperextension, and improves the energy efficiency of gait in the largest number of children. The PLS was the most effective in normalizing gait parameters and improving stance-phase knee motion in children with a tendency toward knee flexion in stance.5 Again, this outcome is for higher-functioning children with hemiplegia, and the authors warn about generalizing this data to children with spastic diplegia.

In a similar study involving children with spastic diplegia functioning at Level II on the Gross Motor Function Classification system, the researchers demonstrated a subtle but detrimental effect on function using an HAFO. This was demonstrated by an increase in the peak knee-extensor moment in early stance, excessive ankle dorsiflexion, decreased walking velocity, and greater energy cost. Therefore, constraining ankle motion using a PLS or a SAFO should be considered for most, but not all, children with spastic diplegia.7 

Night Bracing

According to Tardeui et al,8 the soleus muscle must be stretched 6 hours per day to prevent progressive contractures. In their study, they also showed the importance of night bracing with correct positioning. Tardeui describes the threshold angle measured clinically as the angle at which palpation reveals slight tautness of the tendo Achilles during slow, passive dorsiflexion of the ankle. The study also supports the need for correct angle measurements for night bracing to prevent the contractures. Two cases were reported: one wearing the night splint at the threshold angle, the other worn at past 15° of the threshold angle. In the case where the threshold angle and the night brace were equal, no contracture was measured. However, the brace that was set at 15° past the threshold was ineffective at preventing contractures. They concluded that the angle was too great for the given threshold angle, leading to an improperly fit brace.

Several factors result in the heel rising in the splint: excessive contraction of the soleus muscle, active or passive tension of the gastrocnemius muscles, or distension of the plantar ligaments. In addition, the smaller the passive muscle range, the more difficult it is to maintain the foot at an angle equal to or smaller than the threshold angle for a long time, as the margin between effectiveness and discomfort is very small.8 If the ROM is less than neutral, other means of achieving the desired ROM need to be considered before orthotic intervention for ambulation can be used, such as serial casting, botulinum toxin Type A injections, or a combination of the two. If the contracture is severe enough that conservative measures are not appropriate, surgical intervention may be required.

Solid Versus Adjustable Night Bracing

A SAFO set in the end range of motion is more comfortable for children to wear, per family report. Families also report that their children can sleep longer and more comfortably using a SAFO. The parents feel more confident that the brace is in the right position, as compared to the pulling of an adjustable night splint. But the adjustable night splint can be beneficial if the motion is available in the hindfoot. If the ROM to be gained is minimal, or progressive stretching is needed, adjustable splints may be appropriate. If the ROM is limited, you need to be careful that the motion you are getting is from the hindfoot, not the midtarsal joint, to avoid causing a rocker-bottom foot deformity. In another study, Tardieu9 points out that careless cast lengthening may result in muscle-fiber breakdown, because sarcomeres are much more lengthened than in a normal-developing muscle. If night splinting for lengthened times affects muscle fibers, careless pulling on adjustable night splints can also break down the muscle fiber.

An orthotic can help a child only if it is made from a well-formed mold of the child’s foot. Experienced, well-trained therapists and orthotists align the foot with the lower leg, achieve subtalar neutral position, firmly capture the heel, and maintain forefoot alignment. Orthotists can make a better-fitting brace from a mold with a solid heel cup. The orthotist depends on the therapist’s thorough evaluation of the child to achieve the best-fitting orthotic.

Clinicians should use their assessment of the child and the child’s evaluated impairments, and chose an appropriate orthotic based on their information. Many orthotics are available; the ones discussed here are the most common among high-functioning children with hemiplegia or diplegia. As the research continues and new materials become available, orthotic selection should become easier for clinician selection and, more importantly, easier for the child to wear and achieve a more normalized gait pattern.

Kelly Bossola, MS, PT, has been a therapist for 4 years. After graduating from Regis University in Denver, she started pediatric work in early intervention and schools in Virginia. In August 2003, she joined the staff at Children’s Hospital of Pittsburgh. She can be reached at kelly.bossola@chp.edu.

References

1. Condie DN, ed. International Society of Prosthetics and Orthotics Consensus Conference on Lower Limb Orthotic Management of Cerebral Palsy. Copenhagen, Denmark: 1995.

2. Bleck EE. Orthopaedic management in cerebral palsy. Clinics in Developmental Medicine No. 99/100. Philadelphia, PA: JB Lippincott; 1987.

3. Cusick BD, ed. Progressive Casting and Splinting for Lower Extremity Deformities in Children with Neuromotor Dysfunction. Tucson, AZ: Therapy Skill Builders; 1990.

4. Cusick, BD. Splints and casts; managing foot deformity in children with neuromotor disorders. Phys Ther. 1988;68: 1903–1912.

5. Buckon CE, Thomas SS, Huston SJ, Moor M, Sussman M, Aiona M. Comparison of three ankle-foot orthosis configurations for children with spastic hemiplegia. Dev Med Child Neurol. 2001;43: 371–378.

6. Radtka SA, Skinner SR, Johanson ME. A comparison of gait with solid and hinged ankle-foot orthoses in children with spastic diplegic cerebral palsy. Gait Posture 2005;21:303–310.

7. Buckon CE, Thomas SS, Huston SJ, Moor M, Sussman M, Aiona M. Comparison of three ankle-foot orthosis configurations for children with spastic diplegia. Dev Med Child Neurol. 2004;46: 590–598.

8. Tardieu C, Lespargot A, Tabary C, Bret MD. For how long must the soleus muscle be stretched each day to prevent contracture? Dev Med Child Neurol. 1988;30:3–10.

9. Tardieu G, Tardieu, C. Cerebral Palsy: Mechanical evaluation and conservative correction of limb joint contractures. Clin Orthop Rel Res. 1987;219:63–70.