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A Comparison of Gait Parameters Using Varying Orthotic Designs in a Child With Spastic Diplegic Cerebral Palsy After Selective Dorsal Rhizotomy Surgery

A Case Report

Barkocy, Marybeth, PT, DPT; Zhang, Zhenxiong, PT, DPT; Dexter, James, PT, MA; Doty, Deane, CPO

JPO: Journal of Prosthetics and Orthotics: April 2019 - Volume 31 - Issue 2 - p 152–158
doi: 10.1097/JPO.0000000000000189
CASE REPORTS
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Introduction Cerebral palsy (CP) is the most common developmental disorder in children. Selective dorsal rhizotomy (SDR) is an effective neurosurgical treatment to reduce lower-limb spasticity in children with spastic diplegic CP. An intensive period of rehabilitation, including gait training, is required for most children after this surgery. Orthoses have been widely used in children with CP. However, there is a lack of research showing which orthosis type is the most appropriate for children with spastic diplegic CP after SDR.

Materials and Methods In this retrospective case report, we compared spatial and temporal gait parameters using three commonly used orthoses: foot orthosis (FO), supramalleolar orthosis (SMO), and ankle-foot orthosis/footwear combination (AFO/FC), before and after 3-month accommodation of combination use in a 5-year-old male patient with spastic diplegic CP after SDR.

Results The results showed that although all orthoses improved gait function, the AFO/FCs appeared to initially provide the most stable support; however, after acclimatization, spatial and temporal gait parameters generally demonstrated greater improvement in FO and SMO conditions compared with AFO/FC.

Discussion This report suggests stance phase stability may be enhanced with AFO/FCs, but swing phase may improve with FO and SMO conditions in children with weakness after SDR. Further studies analyzing gait, balance, and motor function using varying orthoses in children with CP after SDR are warranted.

MARYBETH BARKOCY, PT, DPT; ZHENXIONG ZHANG, SPT, DPT; and JAMES DEXTER, PT, MA, are affiliated with the Division of Physical Therapy, Department of Orthopaedics, University of New Mexico, Albuquerque, New Mexico.

DEANE DOTY, CPO, is affiliated with Clinical Specialist, Active Life, Inc, Albuquerque, New Mexico.

Disclosure: The authors declare no conflict of interest.

Correspondence to: Marybeth Barkocy, PT, DPT, Division of Physical Therapy, Department of Orthopaedics, University of New Mexico, 8813 Robin Ave NE, Albuquerque, NM 87112; email: MBarkocy@salud.unm.edu

Cerebral palsy (CP), a motor disorder from a nonprogressive disturbance in the fetal or infant brain, causes muscle tone differences, musculoskeletal problems, and activity limitations.1 The pooled overall estimated prevalence of CP from 19 studies from 1996 to 2010 was 2.11 per 1000 live births.2 As one of the most common disabilities affecting children, CP can be classified either according to the disordered movement type (spastic, athetoid, ataxic, and hypotonic), or a combination of these types, or according to which body area is affected (hemiplegia, diplegia, and tetraplegia).3–5 Spastic diplegic CP, with predominant lower-limb involvement, is the most common subtype of CP with spasticity as the primary motor disorder.6 Spasticity causes muscle stiffness, pain, discomfort, and secondary complications, which interfere with function, including ambulation.6,7

Selective dorsal rhizotomy (SDR) is a well-established and effective neurosurgical treatment to reduce lower-limb spasticity and improve mobility in children with spastic diplegic CP.6 The rationale of SDR is based on neurophysiological evidence that spasticity is the result of decreased inhibition of alpha motor neurons from upper motor neuron descending tracts, creating an imbalance of overabundant excitatory input from muscle spindles.8 By selectively dividing and sectioning some portions of the dorsal lumbosacral roots of the spinal cord, SDR interrupts the spinal reflex arc through decreasing the excitatory sensory input from muscle spindles, thereby reducing the amount of excitation experienced by the alpha motor neurons. This results in diminished spasticity without causing motor paralysis.9 However, after SDR, most children experience significant lower-limb muscle weakness when the spasticity they previously used to move is diminished, and they may initially have largely compromised motor ability, so an intensive period of rehabilitation is required after the surgery.10,11

In the process of SDR postoperation rehabilitation, gait training is an important component of physical therapy to increase mobility and function.11 During gait training, lower-limb orthoses have been widely used in children with CP and can improve the gait function by normalizing joint kinematics, providing proprioceptive sensory cues, and automatic postural responses in the lower limbs, maintaining correct ankle-foot alignment, improving energy use, improving stability in stance, and preventing joint contractures by slowly stretching spastic muscles.8,12–15 Although the effect of different types of orthoses on the gait pattern of children with CP has been studied,16 there is a lack of research showing which orthosis type is the most appropriate for children with spastic diplegic CP after SDR and if a combination of various orthoses is an appropriate choice for these children. The purpose of this case report was 2-fold: 1) to provide practitioners some objective clinical reference for the appropriate choice of orthoses after SDR in children with spastic diplegic CP, GMFCS level III; and 2) to provide a pilot case report for future studies analyzing gait, balance, and motor function using different orthoses in children with spastic CP after SDR.

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MATERIALS AND METHODS

Written consent was obtained from the child's mother for his participation in this case report.

In this retrospective case report, 3-dimensional gait analysis was used as a clinical decision-making tool to determine which orthoses would provide optimal gait outcomes in a child with spastic diplegic CP, Gross Motor Function Classification System (GMFCS) level III1,17 after SDR. We compared spatial and temporal gait parameters using three commonly used orthoses: foot orthosis (FO),18,19 supramalleolar orthosis (SMO),16,20 and ankle-foot orthosis footwear combination (AFO/FC),14,16 before and after a period of accommodation of combination use.

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CASE DESCRIPTION

The child in this retrospective case report was a 5-year-old Hispanic male patient diagnosed with spastic diplegic CP of periventricular leukomalacia (PVL) origin, GMFCS level III and Gross Motor Function Measure (GMFM) total score of 73%. An MRI showed normal brain and spine development, other than PVL. At the age of 3 years, he underwent SDR surgery at the lumbar levels 1 to 3. After SDR, the physical therapy evaluation revealed no spasticity on the Modified Ashworth Scale, but increased weakness in his lower limbs.

His GMFCS level changed from a IV to a III with surgery and rehabilitation. Before surgery, he demonstrated a crouched, scissor gait pattern with hip adduction, excessive hip and knee flexion, in-toeing up to 90°, pronation, and plantarflexion during the stance phase of gait. He ambulated short household distances with a posterior walker, close supervision, and assistance for safety due to frequently tripping over his left foot and subsequent loss of balance. After the surgery, the child received intensive physical therapy 2 to 4 times per week including joint mobilization, stretching, strengthening, positioning, parent education, functional skill training, balance training, Kinesio-Taping, aquatic therapy, and gait training. Orthoses use, as recommended by his SDR team, included SMOs for the past 1.5 years throughout the day to provide medial/lateral ankle stability and then bilateral FOs substituted during therapy starting 6 months postsurgery. Eventually, he used only the FOs, but continued to present with persistent plantarflexion during both stance and swing phases of gait. He gradually progressed from use of the walker or quad canes for ambulation to single-point canes instead. His scissor gait pattern and in-toeing were eliminated. Instead of hamstring and adductor spasticity causing a scissor gait, he began developing a crouch gait pattern. His stance phase posture was characterized by excessive hip and knee flexion due to weakness in his gluteal, quadriceps, and gastrocnemius muscles; excessive plantarflexion was evident in swing phase due to weakness and lack of motor control in his anterior tibialis muscles according to the physical therapy clinical examination from the hospital where his surgery was performed.

Knowing his surgical team encouraged strengthening of his ankle muscles through the use of FOs, his therapist was concerned about the developing compensatory crouch gait pattern in stance and persistent ankle plantarflexion in swing, affecting stance stability, foot clearance, and gait speed. The child's orthotist fabricated an AFO/FC because this design has been shown to reduce sagittal deformity of lower limbs and improve gait quality.21 The AFO/FC design falls conceptually within the work of Elaine Owen, physiotherapist, United Kingdom. This is theoretically not only appropriate for children developing crouch gait, but also for maximizing the alignment possibilities for people during the four rockers of gait cycle.21 Comparison of 3-dimensional gait analysis of spatial and temporal parameters of gait in three different types of orthoses (FOs, SMOs, and AFO/FCs) was used to retrospectively determine the effects of the AFO/FC addition on functional gait parameters.

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INTERVENTION

Three kinds of bilateral orthoses were used as shown in Figure 1: 1) foot orthosis (Cascade Chipmunk, prefabricated and custom-sized FO) with heel cup extending proximally to the inframalleolar area and distally to the toes; the Chipmunk shell is made of a semirigid thermoplastic shell with gait plate forefoot trimlines, foam arch fill, and a thin fabric top cover; 2) custom SMO made of one-sixteenth polypropylene with a rigid footplate to provide greater calcaneal control in the frontal plane and to stabilize the midfoot; and 3) AFO/FC (AFO: Allard KiddieROCKER, PreFab blue) to provide consistent heelstrike and rigid forefoot lever to encourage knee extension at terminal stance as well. A cork and rubber foot orthosis was used with the AFO/FCs to help stabilize the midfoot. The chosen design was used in combination with a 13° heel-toe incline and shoe modifications to induce anatomical alignment of the center of gravity and move the ground-reaction force vector anterior to the knee and just posterior to the hip joint axes. This provides an extensor moment in the knee and hip in midstance to reduce tendency for crouch during the most stable part of stance. The shoe sole modifications included a steel shank, 1 inch left under the heel and tapered to one-fourth inch bilaterally. The heel was negatively reduced slightly to reduce the heel rocker force at heelstrike. The midfoot sole was flat, and the forefoot rocker was designed to allow rollover.

Figure 1

Figure 1

The child wore FOs during physical therapy and SMOs throughout the day for the previous year, but the AFO/FCs were introduced at the initial gait analysis visit; therefore, he had not practiced in them before this fitting. As part of his therapy program, 3 months of alternate use of the three orthoses (accommodation period) was applied with the FOs worn during physical therapy sessions (60 minutes per session twice a week, per orders from the SDR hospital team), SMOs in community activity (where he primarily ambulated with a posterior walker for shorter community distances or used a manual wheelchair for longer community distances), and AFO/FCs in school (for convenience and compliance). Use of 3-dimensional gait analysis provided spatial and temporal parameter data before and after the accommodation period.

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SPATIAL AND TEMPORAL GAIT ANALYSIS

A 10-camera Vicon motion analysis system (Nexus v.1.8.4, Polygon v.3.5.2) was used to compare spatial and temporal parameters of gait under three separate orthotic conditions. The gait model used was Plug-in Gait, the data capture rate was 100 Hz, and the data filtering was done with a Woltring Filter, whose mean squared error was set at 10 at the marker level before Plug-in Gait calculations. Reflective markers were applied on anatomical landmarks on the skin proximal to the orthoses/shoes and on the orthoses/shoes over the distal landmarks to capture gait performance. The child was asked to walk along a 10-m straight walkway with the assistance of bilateral canes at self-selected speeds (Figure 2). Two trials were performed to check for reproducibility and were what this child could functionally achieve due to fatigue. A 5-minute rest was given between captures. In this report, temporal parameters were cadence (step/min), double-limb support time, ratios of single-limb support to double-limb support, and velocity/walking speed. The only spatial parameter was step length (m). Heelstrike and toe-off for each step were identified manually by the same trained individual on the digital gait capture with frame-by-frame observation in Nexus. The parameters of step length, cadence, stance and swing times, and single- and double-limb support times were computed by the Nexus system.22 The step length was determined by the linear distance between the heel marker of the forward foot and the heel marker of the trailing foot at each consecutive initial contact. Cadence measures steps/minute, and although it typically incorporates both right and left steps, it is the default option in Polygon to report them separately. Walking velocity was calculated by the Nexus system by tracking the speed of progression of the subject's center of mass as he was walking during each capture, and this is the default option in Polygon. Because the child was unable to walk more than three steps without falling in barefoot conditions, gait analysis was only performed in orthotic conditions. Data were collected in the SMO condition first (because that is what the subject was wearing when he came in), AFO/FC second, and FO last in both the initial and final captures.

Figure 2

Figure 2

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RESULTS

EFFECT OF VARIOUS ORTHOSES ON SPATIAL-TEMPORAL GAIT PARAMETERS BEFORE AND AFTER 3 MONTHS OF ACCOMMODATION PERIOD

Table 1 summarizes the comparative spatial-temporal parameters of this 5-year-old boy with spastic diplegic CP, GMFCS level III, while walking with the three orthoses before and after 3 months of accommodation period. Polygon, which draws data from Nexus, measures cadence for right and left sides, which are helpful data for assessing symmetry. As shown in Table 1 before the accommodation period, AFO/FCs resulted in the fastest cadence (steps/min) with 33% (L) and 19% (R) faster compared with FOs and 17% (L) and 21% (R) faster compared with SMOs. AFO/FCs also demonstrated the least double-limb support time in a gait cycle with 31% (L) and 23% (R) less compared with FOs and 15% (L) and 22% (R) less than SMOs. The ratio of single-limb support to double-limb support is greatest in AFO/FCs with left (1:7) and right (1:4) compared with that in SMOs and FOs. These values indicate asymmetry from one side to the next.

Table 1

Table 1

Little differences in walking velocity and step length were noted among the three orthotic conditions before the accommodation period. However, after 3 months of accommodation, FOs and SMOs showed obvious increase in cadence with 50% (L) and 39% (R) improvement for FOs and 63% (L) and 46% (R) improvement for SMOs. Conversely, AFO/FCs did not show any increase in cadence with even 21% decrease on the right. FOs and SMOs underwent obvious increases in velocity with 114% (L) and 78% (R) improvement for FOs and 122% (L) and 100% (R) improvement for SMOs. For double-limb support time, decreases of 45% (L) and 33% (R) were observed for FOs and 51% (L) and 45% (R) for SMOs. The ratio of single-limb support to double-limb support increased by 140% on the left leg with no change on the right leg for FOs and by 125% (L) and 100% (R) for SMOs. However, there was limited change in velocity, double-limb support time, and ratio of single-limb support to double-limb support for AFO/FCs. All three orthoses conditions resulted in obvious increase in step length of left foot, but not the right foot, after the 3-month accommodation period.

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FUNCTIONAL CHANGES

After the 3-month accommodation period, the subject began using single-point canes instead of his posterior walker for not only household distances but also for community ambulation.

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DISCUSSION

Children with spastic diplegic CP have impaired gait patterns and walking ability due to spasticity in lower-limb muscles, which can be effectively reduced by SDR.6 Biomechanically, efficient walking is an important goal for children with CP because functional mobility is associated with independence and participation of the child in society.14 Although various orthoses have been used in children with CP to improve their gait function,8 to our knowledge, this is the first case report that presents the comparison of spatial and temporal gait parameters of a child using three commonly prescribed lower-limb orthoses in children with spastic diplegic CP after SDR. All three orthoses improved variable portions of gait function for this child because he was able to walk with assistance of bilateral canes while wearing any of the three orthoses, but could not walk in bare feet. Our case report demonstrates that the FOs and SMOs had the greatest functional gait improvement during 3 months of accommodation period, although AFO/FCs initially provided the most stable support to the lower limbs in stance phase of gait cycle. However, data were collected from only two passes because the child's endurance and functional strength limited his ability to perform more. With the limited amount of data collected and inconsistency in his gait parameters, variability in the spatial and temporal data is expected and is a limitation of the study. The capture of his gait in FOs, then SMOs and then AFO/FCs, may have been affected by fatigue, because his weakness and endurance impact his gait function.

As shown in Table 1, during the initial gait analysis (before accommodation period), although the step lengths of the three orthoses were similar, use of AFO/FCs resulted in the fastest cadence and walking speed among the three orthoses.

AFO/FCs also initially demonstrated the greatest ratio of single-limb support to double-limb support compared with those in SMOs and FOs. The combination of data from the initial gait capture suggests that AFO/FCs initially provided the most stable support to the lower limbs during walking for this child, especially the left AFO/FC.

When comparing data pre-accommodation and post-accommodation data period, spatial and temporal parameters improved across all three orthotic conditions, except AFO/FC velocity and step length on the right. Specifically, cadence and velocity increased across FO and SMO conditions, but this was diminished during the AFO/FC condition on the right. According to Morita et al.,23 enhanced gait efficiency is highly correlated with an increase in velocity, and children with CP would use increased cadence as their main strategy to increase velocity, especially if balance is impaired. The velocities reported are well below age norms and are not functional, which was one of the activity limitations being addressed in physical therapy. This child had more functional weakness on the left, so supporting himself on the left leg during stance was diminished compared with the right. In addition, when comparing orthotic conditions, this child's gait velocity and step length were reduced in the AFO/FCs on the right, but demonstrated an increase in FO and SMO conditions. Ratios of single-limb support to double-limb support improved across all conditions with both legs, but remain far from the normal value (4:1)24 due to impaired single-leg stance. With the exception of the right side when using the AFO/FCs, the subject demonstrated diminished double-limb support percentage in the gait cycle on both sides under all orthotic conditions, which may indicate increased overall gait stability after the accommodation period.

Because one of the concerns for this child was his increasing crouched gait pattern and persistent weakness in lower-limb postural muscles after SDR, the AFO/FCs were introduced to provide improved gait function for the following reasons: First, the off-the-shelf ground-reaction AFO was chosen because this design is thought to be effective in limiting ankle dorsiflexion and reducing knee flexion in stance. This occurs by preventing excessive forward movement of the tibia over the foot during the second rocker, resulting in a decrease in elevated knee extensor activation associated with crouch gait.25 As a result, less effort is required of the knee extensors to stabilize the knee, leading to a more efficient and sustainable gait pattern.25 Foot orthoses (FOs) and SMOs are appropriate for controlling closed chain, coronal plane movement of foot/ankle with limited control in the sagittal plane.26,27 Second, a ground reaction-force AFO can compensate for lower-limb muscle weakness commonly seen after SDR.28 These compensations improve gait quality, postural control, and postural stability,29 as well as sagittal plan kinematics.27,30 A custom-molded AFO may have been more appropriate than the Allard Blue prefabricated orthosis for this case, but this type was the easiest, fastest, and least expensive option for a trial orthosis. Third, due to the ability to provide the optimal shank to vertical angle (SVA) and the specific sole profile, the AFO/FCs can help improve abnormal rocker movements during the gait cycle by the use of simulated rockers (appropriate heel toe incline and sole profile), created by the design of the footwear that is combined with the ankle-foot orthosis.21 The sole profile fabricated was an extended toe plate with beveled toe rocker to keep the heel in contact with the ground as long as possible and then facilitate toe-off at terminal stance.

Although the AFO/FCs provided a fairly stable support in single- and double-limb stance, the weight of AFO/FCs might have had a negative impact on his limb swing. This patient reported that it was difficult to move the “heavy shoes.” It is a reasonable possibility to use AFO/FCs for strengthening and gait training after SDR in some children with spastic diplegic CP only if these children have enough strength to swing the heavier AFO/FCs. If the weight of the AFO/FCs could be reduced, this child may have tolerated this orthosis design better. In addition, a longer training period in the AFO/FCs may be warranted for strengthening and motor learning for carryover to gait.

Because FOs and SMOs had been used in the child for at least 1 year before the gait analysis started and the child was assumed to have already been used to them, it was not expected that there would be big differences in gait parameters using these orthotic systems before and after the accommodation period. However, after combined with use of AFO/FCs, the spatial-temporal parameters of the gait of FOs and SMOs improved considerably while those of AFO/FCs did not after accommodation period in our report. One reasonable explanation is that use of AFO/FCs may have improved the subject's spatial and temporal gait parameters when using the lighter and less restrictive FOs and SMOs. A 3-month accommodation period of alternating use of the three orthoses was used for this child with FOs used in physical therapy, AFO/FCs used intermittently at school, and SMOs used at all other times. Despite the introduction of AFO/FCs at school, the spatial-temporal parameters of gait in FO and SMO conditions improved, while those of AFO/FCs showed little or no improvement in the varying gait parameters: cadence, walking speed, step length, and single-limb support percentage in gait cycle were increased in FOs and SMOs, but not in AFO/FCs. Although the child had experience over the last year wearing FOs and SMOs throughout the day, it is possible that adding the AFO/FCs for gait training improved this child's muscle activation pattern and timing in a more upright alignment, which required a period of motor learning.28 Another possibility for the improvement in spatial and temporal gait parameters in FO and SMO conditions during the accommodation period is strengthening that occurred due to ongoing physical therapy intervention and/or use of the heavier AFO/FCs. These could explain the improvement in FO and SMO conditions, but does not explain why there is little difference in AFO/FC conditions. It appears the most stable support provided by the AFO/FCs was achieved right after its application, but not following the accommodation period, which is supported by another study31 where the spatiotemporal parameters and joint kinematics and kinetics did not significantly change after 4 weeks of accommodation period using a ground-reaction AFO in children with spastic CP. The heaviness of the AFO/FCs along with this child's persistent leg weakness could have limited the spatial and temporal gait parameter progress in the AFO/FCs in this case. Controlled studies are needed to determine outcomes of the combination of AFO/FCs use with FOs or SMOs use for children with spastic diplegic CP after SDR.

Although there are benefits to AFO/FC use, prolonged wear of AFOs may influence the gastrocnemius and tibialis anterior muscle activity32 and cause peroneal neuropathy,33 affecting further functional improvement. These problems can be avoided by using FOs because FOs have free dorsiflexion and plantarflexion needed for children's daily activities such as crawling, pulling to stand, and squatting, in addition to their ability to correct functional foot deformity27 and improve gait performance (velocity and cadence) in children with cerebral palsy.19 Therefore, it appears that the combination of AFO/FCs and FOs may improve gait outcomes, which was shown in the study by Christovao et al.,17 where the alternate use of AFOs and FOs led to a greater improvement in static balance among children with CP. This resulted in the reduction in body sway when walking and a better performance on the Timed Up-and-Go Test compared with using an AFO alone.

This is a preliminary retrospective report of clinically relevant spatial and temporal gait parameters, which did not include kinematic or kinetic analyses of the gait cycle nor an objective functional evaluation. Future formally designed research studies are needed to compare gait, balance, and motor function using different orthoses in children with CP after SDR. Although this case report may provide some clinical reference regarding appropriate choice of orthoses in children with spastic diplegic cerebral palsy, GMFCS level III, after SDR, this population has a widely varying range of functional ability and limb deformity, so orthoses that might be appropriate for one child might not be generalizable. Thoroughly understanding the pathophysiology and pathomechanics of gait disruption in each individual and the biomechanical characteristics of various orthoses are needed to make optimal clinical decisions.24,34,35

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Keywords:

orthoses; cerebral palsy; selective dorsal rhizotomy; gait analysis

© 2019 by the American Academy of Orthotists and Prosthetists.