Orthoses have long been used for children with cerebral palsy (CP) to prevent deformity1 and assist function2 and it is assumed that postural alignment, balance, and gait will improve. However, literature reviews provide little evidence that orthoses are always beneficial,3,4 and no research verifies these fundamental assumptions or the conclusion that orthoses are better than shoes.5 It has also been demonstrated that wearing ankle-foot orthoses (AFOs) of various designs altered the biomechanics of gait in individuals without neurologic impairments.6 In their study, Evans and colleagues7 showed insufficient evidence for beneficial effects for children with CP who were not yet walking. O'Reilly and colleagues8 compared hinged and leaf spring AFOs and found neither to benefit function. Brehm and colleagues9 found orthoses to be helpful for those with quadriplegic CP but not those with hemiplegia or diplegia when compared with barefoot walking but made no comparison to walking with shoes alone. These authors did not discuss orthotic fit and alignment or mobility of the ankle joint.
The focus of this report is to illustrate the importance of subtalar joint (STJ) alignment when casting children for an orthotic device. Visual observations of the child during gait activities and study of videotape to assess the child's function with or without orthoses were used. Four individual cases were examined covering a range of impairment severity and orthoses quality.
Observational gait analysis has been found to be reliable, particularly when the physical therapist has extensive clinical experience.10 Dickens and Smith11 compared visual gait assessment with 3-dimensional gait analysis of children with hemiplegic CP. Inter- and intrarater reliability showed moderate to almost perfect agreement for foot contact characteristics and ankle position in stance. Thus, it is suggested here that to evaluate whether an orthosis is functioning as desired, visual observation aided with a videotape is adequate to provide important objective information.
It is hypothesized here that, in some instances, the orthotic devices themselves may actually contribute to lack of progress. Blocked dorsiflexion, for example, has been shown to be detrimental to development and may lead to unnecessary surgical recommendations.12
Outcome measures such as range of motion (ROM), ankle pronation, muscle strength, and gait velocity are important to show changes over time to evaluate progress but do not give immediate information as to whether the orthoses are functioning as expected and are better than shoes alone. Non–weight-bearing measures have not been found to be beneficial13 and clinical signs have little to do with function.14 Outcome measures of function identified as appropriate for children with CP include the Gross Motor Function Measure (GMFM-88 and GMFM-66) and the Pediatric Evaluation of Disability Inventory.15 If a child changes Gross Motor Function Classification System (GMFCS) levels,16 progress is considered clinically significant.17 Videotaping the child's gait and using the walking and standing dimensions of the GMFM-66 test18 are helpful to compare the child's function when using orthoses or shoes. A timed walking test may also be helpful for those who can walk independently. However, one also needs to observe the gait pattern to see whether the orthotic device is associated with unwanted movement compensations. Children who do not walk independently can use a walker or canes or even hold the parent's hand during gait analysis. If they are classified as GMFCS level IV, they can be supported as needed for the videotaping.
THE SUBTALAR NEUTRAL POSITION
The natural arch occurs when the subtalar joint (STJ) is in neutral and the arch height varies considerably in a large population. There is controversy about the function of the STJ as it is difficult to measure neutrality.19 The STJ is very important as it influences the rotational forces of the tibia and the superstructures.20 The term STJ neutral means if the STJ is in mid-position, not pronated or supinated, the joint is neutral, and the knee will track over the second toe. If the STJ is pronated, the anatomy of the tibia and the talus will cause the tibia to rotate internally, moving the knee medial to the foot, and hip and knee joints will flex.21,22 This flexion is similar to a beginning crouch position. The reader can experience these compensations by standing and moving the foot from pronation to supination while bearing weight. As the talus moves medially, the tibia moves with it. The legs further compensate by flexing at the hips and knees as the tibia rotates inward and the foot pronates. The opposite happens during supination. The talus moves laterally and the tibia externally rotates as the hips and knees extend. If the reader then holds the supinated or pronated position and walks, compensations for the lack of mobility will be experienced. Because the STJ is so influential for the superstructure23 it is important that the foot and ankle be aligned as well as possible even in the child's first orthoses, to allow more typical growth and development. One of the children in this report was given an orthosis with the foot in moderate pronation. The physician's medical notes said that since the child's heel was on the ground the moderate pronation was not a problem. Therefore, the child learned to walk with the lower extremity in some degree of medial tibial rotation and flexion of the ankle, knee, and hip.1,21
To allow needed supination and pronation without excessive tibial rotation, the STJ should function close to the neutral position.1,6,24 It is critical that the patient's STJ be held in a neutral position while the child is being cast for an orthotic mold. The size and shape of the medial and lateral sides of the foot change as the STJ is moved from pronation to neutral and it is very difficult to adjust a mold to duplicate the neutral contours if the foot is cast in pronation. The controversy over orthotic fabrication appears to have returned to the classic belief that STJ neutrality is best.19 An orthotist cannot adequately change the mold after it has been fabricated to preserve the foot's true neutral contours needed for appropriate fit and comfort.
The procedure followed in this clinic is for one physical therapist to hold and maintain the STJ in neutral and correct the forefoot as much as possible to neutral while a second physical therapist wraps the foot in the casting material. If the forefoot lacks the ROM to attain the neutral position at the STJ and forefoot, the orthotist can post the orthotic device (apply wedges to heel and/or forefoot). None of the children discussed here needed forefoot posting.
Solid Ankle-foot Orthosis
The solid ankle-foot orthosis (SAFO) is a rigid AFO that blocks all dorsiflexion, plantar flexion, and digit extension. Inversion and eversion are usually also blocked to various degrees, depending on the tightness of fit. Solid ankle-foot orthoses are proposed to improve posture and gait patterns.25 Traditionally, they were used to correct equinus and reduce gastrocnemius activity,26 thus blocking or preventing spastic calf muscles from overworking and responding to a stretch reflex and causing an equinus gait.27 However, they decrease gastrocnemius muscle activation during standing and thus inhibit balance reactions and the learning of an ankle strategy while young.28 Children learn to balance by first using an ankle strategy and then a hip strategy. An ankle strategy (ankle flexion and extension) is used for balance and develops in children developing typically by 10 months of age, after much time in standing, often while holding the crib or other support, and flexing and extending the ankles, hips, and knees toward a squat position. The hip strategy (bringing the trunk back over the base of support) is also used for balance when standing on a narrow beam, rope, or other narrow surface and is not seen in children developing typically until 6 months after the onset of walking. The hip strategy is never seen without an ankle strategy.29 Solid ankle-foot orthoses prevent ankle motion and prevent children with CP from flexing and extending the ankle joint. Thus, they are unable to develop an ankle strategy although a hip strategy is possible. Clinical experience suggests that children using SAFOs may develop a hip strategy and not an ankle strategy, resulting in limited balance reactions. Three of the cases presented here arrived at our clinic with SAFOs, which were changed to a hinged ankle-foot orthosis (HAFO) in 2 cases.
The supramalleolar orthosis (SMO) is an orthotic device that extends to just above the malleoli to control inversion and eversion of the foot. It has been found to be beneficial for children with CP.30 However, it has also been demonstrated that if the top of the SMO comes over the foot it can block dorsiflexion and thus act like an SAFO as dorsiflexion is not permitted.31
This boy came to this clinic as a 12-year-old with spastic diplegia, GMFCS level III and posthamstring neurectomy. Figure 1A shows the child's pronated feet with a strongly everted heel when standing barefoot. However, he had full passive ROM of the STJ and metatarsal heads. Figure 1B shows the top of the pronated feet when sitting. In Figure 1C, the everted heels in the SAFOs are visible. A line bisects the right calf and calcaneus to show misalignment, which the SAFO does not correct but rather preserves his pronation. In Figure 1D, he is standing on his toes despite using SAFOs while holding on to a rail of a stationary treadmill. He is also wearing an overhead harness that partially supports his weight. The SAFOs were not supplying any of the benefits purported for SAFOs. He was recast in a neutral STJ position since adequate ROM was available and given an HAFO to allow dorsiflexion mobility. His STJ-neutral position is seen as he stands in Figure 1E. With the foot in correct alignment, he could stand with his feet flat on the support surface.
This girl sustained a traumatic brain injury as an infant and began physical therapy (PT) in this clinic when she was 14 years old. She presented with spastic quadriplegia, GMFCS level IV; that is, she was not able to walk alone or independently with a walker. Figures 2A and 2B show one SAFO and both feet photographed on her first visit. In Figure 2A, the toe strap is unattached to show how pronation causes forefoot abduction. When the toe strap is attached, it pulls the first toe and forefoot back in line with the foot and over the footplate but does not correct the pronation of the STJ. The pronation causes medial pressure on the foot when in the SAFO (Figure 2B). She had worn these orthoses for 5 months and the redness and alignment had not improved. She was recast in STJ neutral. The plan was not to use a toe strap as it is usually not needed to correct a forefoot in STJ neutral (Figure 2C). Because her right foot lacked dorsiflexion when in the STJ neutral position, it was necessary to cast the foot in some plantar flexion and to put a wedge on the sole (Figure 2D) of the foot to maintain STJ neutral. She was given an HAFO, which allowed 10° of plantar flexion for ankle mobility to move from sit to stand and for assisted walking. The wedge on the sole allowed her to bear weight over the entire sole. Electrical stimulation provided during task performance was used in her PT program to improve sensory-motor function of the calf, hip, and trunk muscles.32–34 While using the corrected hinged orthoses, right ankle dorsiflexion ROM improved as she worked on standing, sit to stand, and assisted walking. The wedge was gradually lowered and completely removed after 3½ months. With assistance, she could stand and walk with a plantigrade foot in the HAFOs without pressure marks.
A girl came to our clinic, at the age of 4 years with spastic diplegia, GMFCS level III. She came because her gait function was not progressing. In fact, she had been regressing. Since her diagnosis at 10 months of age, she had attended a medical therapy clinic that included PT, OT, and MD services, and she continued there where a conventional spasticity management program35 was followed.
She walked in a crouch, taking minuscule steps as shown in Video 1 (see Supplemental Digital Content 1, available at http://links.lww.com/PPT/A31) on her initial visit while wearing SAFOs, which held the feet in 3° to 5° of dorsiflexion. Her mother said that was her usual gait pattern for the last 2 years but with fewer steps in the past 6 months. This is consistent with the finding that children classified at GMFCS level III begin regression in gait at 3½ years of age.36 She could not take steps independently without the orthoses. She could take 2 or 3 independent minuscule steps while in a crouched position and then fall forward to the floor with a controlled fall. Video 2 (see Supplemental Digital Content 2, available at http://links.lww.com/PPT/A32) shows Case 3 attempting to walk in SMOs, which were set in 3° to 5° of dorsiflexion, not molded in STJ neutral, and with plastic that blocks dorsiflexion. When given assistance, she could take more steps. At times the top strap on the SAFO was removed with the assumption she would then have some dorsiflexion but no change was noted, probably because the plastic at the top of the foot wrapped around the foot and prevented the tibia from moving forward.
Two months later, she received new orthoses at another clinic, which had been accepted by the physical therapist and worn for 2 weeks before bringing them to our clinic. These were SMOs with the back cut out to allow full plantar flexion and fixed at 3° to 5° of dorsiflexion. This position does not allow a vertical talus and appeared to promote a crouched stance and gait. Video 2 shows a lack of dorsiflexion apparently caused by plastic wrapping high over the ankle joint, which makes the SMO function as a SAFO. This wrapping can be seen at the end of the video more easily if the film is stopped to show a single frame. The SMOs were not in STJ neutral and toe straps were used to pull the foot back on the foot plate. She stands in a greater crouched position than in Video 1 as the pronation is greater and the SMOs block the tibia from a vertical position. Her inability to walk in the SMOs even after 2 weeks of use is seen in Video 2. She could walk a few steps if given support for both hands. The new SMOs were a problem not because SAFOs are better than SMOs but because cast alignment was not in an STJ-neutral position, which adversely affected the alignment of the knee, hip, and trunk.23 Although she could not walk in the SMOs, she was able to take steps in shoes alone (Figure 3B and Video 3, see Supplemental Digital Content 3, available at http://links.lww.com/PPT/A33).
Video 3 continues with a few steps to show her ability to step when using shoes. With shoes only, she walked as many as 7 steps before reaching for support. Videos 2 and 3 support the hypothesis that orthoses may not be more beneficial than shoes alone.
This child with CP demonstrating ataxia and hypotonia was treated at the age of 3½ years initially in this clinic. He continued with his original physical and occupational therapy at another private facility. His main problems were inadequate balance, STJ pronation (Figure 4A), genu recurvatum, and a wide-based gait. He was initially classified at GMFCS level III as he needed a hand or available support to walk independently more than 50 steps before falling. He was seen for intervention once weekly for a trial of adding task-specific electrical stimulation intervention to assist his gait skills.
He progressed well as demonstrated by scores on the GMFM-66 (Figure 5). The clear triangle represents his initial test score when at GMFCS level III. At the age of 4½ years, he was able to walk outside without his hand-held and without falling often and was newly classified at GMFCS level II. The clear circles represent these 4 data points: from age 4 to 6½ years. Over the time period until he was aged 5½ years, he had used various foot orthoses, which did not correct his foot pronation but did not seem to be blocking movement. When he started kindergarten, PT at this clinic was changed to consultation only and he was not seen for 4 months. When he returned, he wore new SMOs, which he had been wearing for 4 months (Figures 4B, 4C, and 4D). The forefoot of the SMO was very stiff and prevented metatarsal extension and thus heel rise. The SMOs were not in STJ neutral and held the foot in pronation, which resulted in forefoot abduction with the foot tending to slip off the footplate (Figure 4B). The forefeet of the SMOs were posted (Figures 4C and 4D), perhaps to support the excessively inverted forefoot. These SMOs may have contributed to a decrease in his balance abilities. Previous ankle and foot ROM allowed passive positioning at 90° with STJ neutral position and a neutral forefoot. He needed a medial post at the calcaneus as the heel was inverted approximately 3°. He was no longer able to squat or walk between parallel lines, step over a bar at ankle height, or stand on 1 foot for more than 3 seconds. His GMFM-66 test was taken when barefoot as usual and demonstrated a clinically important difference; he lost 2.5 points over only 8 months (Figure 5, open circles last data point). Case 4 shows open-circle scores, which rise faster than expected for his age but then drop after wearing non-STJ-neutral SMOs. His faulty SMOs were used 4 months before the last test. The significant drop in total test score was due to score reductions in standing, walking, running, and jumping. It may be that the SMOs were not beneficial because cast alignment was not in an STJ-neutral position and may have adversely affected alignment of the knee, hip, and trunk.
Before he used the SMOs, he had been able to walk and balance noticeably better with shoes alone without the SMOs and he could walk with a narrow gait, no genu recurvatum, with a heel strike, and between parallel lines 8 inches apart (Figure 6). With the SMOs, he could not walk between the parallel lines.
Both Russell and colleagues37 and Rosenbaum and colleagues16 found that children do not change GMFM scores significantly after the age of 5 years. It can be assumed that children who do not improve in GMFM will not change GMFCS levels.16 It is very disappointing that 73% of all children with CP do not change GMFCS levels. One wonders whether GMFM test scores over time might be different from those currently found if children in the underlying research studies wore orthoses that did not block movement, thus forcing unwanted compensations that become part of the child's movement patterns even when completing a barefoot test.
These 4 cases demonstrate how orthotic device alignment in the STJ neutral position contributes to beneficial outcomes. If orthoses are not molded in a neutral position, the ankle, hip, and knee alignment may be adversely affected and place the child at risk for gait deviation (all cases) pressure sores (Case 2) or inability to walk (Case 3). Research is needed to determine how wearing ill-fitting versus correctly molded orthotic devices contributes to the lack of progress or progress in gross motor development and function. Case 3 demonstrates that visual evaluation of orthoses and gait can assist the physical therapist in determining whether the orthotic device should be used or remade to promote an STJ neutral position. Research studies of children with CP rarely describe the orthoses used so it is unknown how specific orthotic devices may affect study outcomes. It is critical for research and evidence-based practice that all orthoses be evaluated and considered in relation to outcome studies in children with CP.
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adolescent; cerebral palsy; child; neurologic gait disorder; orthoses; physical therapy; subtalar joint/physiology