Cerebral palsy (CP) describes a group of permanent motor disorders attributed to disturbances that occur in the developing brain.1 Although the brain lesion is not progressive, it results in secondary muscle pathology.2
Children with spastic CP often have increased muscle tone, weakness, decreased flexibility, and muscle imbalance.3 During growth, increasing muscle fiber length is essential for muscle to keep pace with skeletal elongation. The ability of muscle to adapt in length is beneficial unless the working range of motion (ROM) is truncated by excessive shortening, as occurs in multiple conditions that primarily affect muscles of the extremities, including spastic CP. In these conditions, the muscle fibers that contract at a shortened length are thought to adapt to the abbreviated working range by decreasing the number of in-series sarcomeres.4–6 The decrease in ROM involves the soft tissues, including tendons, ligaments, and joints. The contractures and the changes in the soft tissues arise from the muscle being maintained in a shortened position.6,7 Therapeutic and medical interventions include stretching programs, serial casting, orthotics, tenotomies, intrathecal baclofen, botulinum toxin, and muscle electrical stimulation.7,8
The motor ability of children with CP can be classified into 5 levels using the Gross Motor Functional Classification System (GMFCS). Children at levels I and II walk without support, children in GMFCS III are expected to learn to walk with a mobility device, whereas children in GMFCS IV to V do not usually sit or walk without support.9 Nordmark et al10 reported that mean ROM of hip abduction decreases from 43° to 34°, mainly in early childhood in those with bilateral spastic CP. The relationship of hip ROM and GMFCS levels shows a more pronounced decrease in hip abduction, popliteal angle, and knee extension in children at lower functional levels of the GMFCS. A decrease in mean ROM with age may result in decreased mobility.10 Decreased locomotion has been shown to limit activities of the child and restrict participation in the community.11–13
Stretching is widely used for the treatment and prevention of contractures. The use of muscle stretching is based on the assumptions that stretching will increase muscle extensibility, preserve joint ROM for functional movement, and prevent or delay the need for orthopedic surgical interventions.14 However, limited and weak evidence indicates that manual stretching can increase ROM, reduce spasticity, or improve walking efficiency in children with spasticity.15,16 Evidence suggests that the exclusive application of passive stretches is not enough to prevent muscles from shortening.5 However, stretches combined with isometric contractions have resulted in significant increases in joint ROM and extensibility.5 According to Fowless contraction is required in combination with a stretch to preserve the number of sarcomeres, and maintain proper muscle fiber length.17
In studies of children with spasticity, some evidence indicates that sustained stretching is preferable to improve ROM and reduce spasticity in joints and muscles, respectively, when compared with manual stretching.15,18 Sustained muscle stretch is defined as “holding the targeted joint in the available end range of movement through biomechanical means such as standing tables or position equipment”15p. 860 for an extended period. Equipment such as orthoses, splinting, and serial casting can be used as alternatives to sustained stretching.6,15,19,20 Other techniques, such as positioning, provide a way of administering stretch for extended periods.21
Children with spastic diplegic CP commonly have muscle shortening and decreased ROM of the lower limb muscles. Soft tissue abnormalities include muscular imbalance between the stronger flexors, adductors and internal rotators of the hip, and the weaker hip extensors, external rotators, and abductors.22 These, combined with decreased voluntary muscle strength, balance deficits, and impaired motor control, lead to considerable deterioration of functional skills such as walking, standing, sitting, and transfers.10 During standing and walking, the adductor muscles and hip flexors tend to adopt a preferential pattern of hip flexion, adduction, and internal rotation, whereas the abductors, extensors, and external rotators are globally weak, poorly controlled, and finally elongated as the opposing musculature becomes contracted.23 This lower limb walking pattern increases energy expenditure leading to less efficient walking.24 With growth, the dynamic muscle imbalance often results in myostatic contractures in the hip adductors. These contractures can also be related to progressive changes in the femur and the acetabulum.10,23,25–27
Hip adduction contractures in children with spastic diplegia GMFCS level III decreases the base of support in standing, and the children require assistance to stand and walk, and demonstrate a scissoring pattern causing problems with foot clearance.4
Therapists who used standers in their supported standing programs reported benefits on weight-bearing, pressure relief, ROM, muscle strength, psychological well-being, and other positive effects. The strongest evidence after a standing program was found on hamstring ROM improvements.28 Researchers concluded that standing at least 45 to 60 minutes daily is necessary and 60 minutes is optimal to increase hip, knee, and ankle ROM.18,28–32
Most models of standing devices on the market do not allow more than 40° of combined hip abduction when the child is standing. For children with adductor spasticity, this degree of abduction is felt to be insufficient to maintain the extensibility of the hip adductor muscles.33 A standing frame that could be adapted to the individual characteristics of each child and allowing more abduction for each leg is desired to promote flexibility of the hip adductor musculature and acetabular development.31
In 1995, our Public Early Intervention Department initiated a program to manage hip ROM in children with spastic CP. This involved children who had not attained independent walking by 12 to 14 months of age, who demonstrated decreased weight-bearing because of their delayed walking skill development, and who showed muscle imbalance at the hip with a tendency toward increased hip adduction in standing or supported walking. This program recruited and followed children with spastic diplegia that evolved to GMFCS level III. This allowed study of the effects of the standing program to prevent decreasing ROM and promote muscle flexibility in the children. We choose these children because of the documented hip flexibility complications for children with spastic diplegic CP hoping they could benefit from this program. The purpose of this study was to assess whether standing programs with hip abduction would affect hip abduction ROM in children with spastic diplegic CP with GMFCS level III.
A retrospective cohort of 13 children, 9 boys and 4 girls, with spastic diplegic CP, at GMFCS level III participated in the study. For the calculation of the sample size, we used a main outcome minimal difference of 4° on the basis of on our pilot work. Thirteen children participated in the study to obtain statistical power of 80% and an alpha level of 5%.
Exclusion criteria included previous surgery in the lower limbs, epilepsy, intellectual disability that would not allow the child to fully cooperate with the standing program, and perceived difficulty with parental compliance to carry out the standing program with their child. During the study, none of the children received botulinum toxin or surgery in lower extremities.
The intervention consisted of fabricating a standing frame with hip abduction to be used in their regular physical therapy program. The children started with the standing program at 12 to 14 months of age and continued until they were 5 years of age when the early intervention period was finished.
The ethics and research committee at the Universitat Internacional, Barcelona, Spain, approved this study. All parents and/or caregivers gave their written informed consent before their children entered the study.
Before fabrication of the plaster stander, hip abduction ROM was assessed goniometrically using a standardized protocol.10,34,35 Goniometric measurement was selected as it is the most commonly used method to assess hip flexibility in children with CP. The protocol included measuring the child in the supine position. Each leg was abducted separately to the limit of the child's passive ROM. In this position, the goniometer was placed with 1 arm parallel to a line connecting the anterior superior iliac spines and the other arm parallel to the longitudinal axis of the femur. With the pelvis stable, the number of degrees of hip abduction was recorded. A slow stretch of 30 to 45 seconds was used to promote relaxation and to promote measurement of the full available ROM. The measurement was taken 3 times by an experienced physical therapist and the average was recorded.
The first measurements for abduction ROM were taken at 12 to 14 months of age. Other measures were taken when it was necessary to fabricate new standing equipment or to adjust the standing frame to the ROM of hip abduction for the child.
At 5 years of age, the children ended the early intervention program and the goniometric measures were repeated and recorded by the same physical therapist following the same protocol.
Fabrication of Standers
The stander for each child was fabricated by the physical therapist in the early intervention department. It was fabricated with plaster using the child's body as a mold, and included any orthotic used by the child while in the stander. The child's hip abduction position determined the shape of the stander. The stander controlled the child's legs and pelvic position, and placed the pelvis in an appropriate position avoiding any asymmetry in the frontal plane or excessive lordosis in the sagittal plane. The amount of hip abduction in the stander was fabricated 10° less than maximum extensibility of the combined hip adductor muscle flexibility to ensure tolerance of the stretch. Most standers were made with approximately 30° of abduction of each leg.
To fabricate the stander, the child was positioned in the prone position and the feet extended off the table. The skin and shoes were covered with plastic wrap (Figure 1). The legs were placed in symmetrical hip abduction during fabrication. A goniometer was fixed at the degree of abduction required to avoid any asymmetry during the fabrication process. Plaster strips were prepared using 8 to 10 layers for each leg, pelvis, and waist. The plaster covered the legs from the waist to just above the heel of the shoes. Having applied all the bands of plaster, the foot position was adjusted so that the soles of the shoes were horizontal and not oblique to the ground.
After drying for 24 hours, the stander was painted with plastic paint. The child's parents usually participated in the painting of the stander according to the preferences of the child.
To apply the stander and to adjust it comfortably, strips of Velcro were used to stabilize the knees and the pelvis. The parents were informed about how to use the stander at home, and putting a table in front of the child while in the stander was recommended. Instruction included assurance that the feet were positioned correctly for symmetrical weight-bearing. The standers were refabricated every 8 to 10 months, depending on the child's growth.
Overall, children were positioned in their standers for 70 to 90 minutes a day, from Monday to Friday. Standing time was split into 2 sessions of 35- to 45-minutes duration each. The duration of standing was introduced gradually with a minimum of 70 minutes daily. Not to interfere with family routines, on weekends the prescribed standing time was 35 minutes per day. Children could play games appropriate to their age and preference while using the stander (Figure 2). Although all children started to walk with mobility aids between 30 to 36 months of age, they continued with the standing program until they were 5 years of age, to promote hip flexibility.
To ensure compliance, the physical therapist did home visits every 4 to 6 weeks to assess and instruct the parents and other caregivers on how to handle the child's position while using the standing device to ensure the child's comfort, safety, and appropriate height of the table with respect to the height of the child. If parents had problems following the standing program at home, the possibility was offered of using it in the nursery school, with assessment and instruction for the educators.
All children received physical therapy once a week in the early intervention service, and no other type of stretching program was implemented or carried out during this period. However, positioning for sitting was monitored.
Statistical data analysis was performed using the statistical package SPSS 18.00. The Mann-Whitney U test, a nonparametric statistic, was used to assess the differences in hip measures because of the small sample size and the fact that the distribution was not normally distributed. The alpha level was set at .05. The mean and median values, and 95% confidence interval of hip abduction ROM, were calculated at the beginning of the standing program, when children were on average 14 months of age, and at 5 years of age.
A significant difference between hip abduction ROM at baseline (14 month) and at the end of the standing program (5 years) was found (Table 1), using the nonparametric test.
All children increased or maintained hip abduction ROM during the standing program up to age 5 years. Table 1 shows the 95% confidence intervals at baseline and at 5 years. Although the variability in the ROM is slightly higher at 5 years, we have the same values at baseline (95% confidence interval = 41.0, 43.0) and at 5 years (confidence interval = 41.8, 43.8). Figure 3 shows the individual ROM values at baseline (14 months) and at 5 years.
The main results of this study show that hip abduction ROM can be maintained over a period of 4 years with a daily standing program.
The results of this research support the findings of Gibson et al,28 Martinsson and Himmelmann,31 Salem et al,18 and Paleg et al,32 which show that muscle flexibility can be maintained through the use of a sustained stretching program. According to a recent systematic review by Paleg et al32 on recommendations for pediatric standing programs, the use of standing devices seems to have positive effects on lower-extremity ROM, hip biomechanics, and spasticity.
The results of this study are in agreement with studies where the hip adductor muscles are placed in a lengthened position through standing in abduction.30,31 Other authors have provided support for the use of prolonged stretch through the use of a night-time hip abduction positioning system.36 According to the study by Martinsson and Himmelmann,31 weight-bearing with 60° of total hip abduction and 0° of hip extension for at least 1 hour per day reduced hip migration percentage and preserved ROM. However, we think that the use of the standing program twice a day for at least 45 minutes is better than once a day. For young children, combining activity with the standing program is more enjoyable and therefore the program is better tolerated.
Although all children in the study started to walk with mobility aids between 30 and 36 months of age, they continued with the standing program until they were 5 years of age, to promote hip flexibility. Because spastic muscles cannot grow in accordance with skeletal growth,20 finding ways to intervene in early childhood is crucial to maximize a physiological balance in growth between muscles and bones.
Daily periods of stretching through standing and during the child's daily routines can help in maintaining the ROM, as shown in the results of this study.
To ensure compliance with the program, visiting the families' homes every 4 to 6 weeks and the child's nursery school is necessary. During every weekly session, parents reported feedback if they had problems to ensure compliance rates, the child's tolerance, and the games they played during the regular routine while standing. Parents reported less scissoring of the legs following use of the stander, and this was very encouraging for them. Perhaps this leads to consistency for the parents and removes the need for use traditional stretching techniques that can be a burden because of the number of other interventions their child may require. With time the ability to take steps without the feet crossing the midline was another reason to encourage the parent's compliance.
Standing with the legs in the elongated position with the trunk in a symmetric and stable position, children played comfortably and were using the trunk and arm muscles, which may have also resulted in activating the leg muscles in the extended position and could have contributed to the results.
At 5 years of age, all children were again classified at GMFCS level III because they could not walk 100 meters without a mobility aid. However, 4 could walk short distances indoors without mobility aids and 6 could walk at home and over flat surfaces with 1 crutch. All of them walked with mobility aids outdoors (posterior walkers or crutches). None crossed their feet during walking, showing more flexibility in their mobility, and running games with their peers.
According Harris and colleagues37 good evidence shows that if the hip is centered before the age of 4 years, subsequent acetabular dysplasia and hip dislocation is less likely. Other authors reported that postural management of children with CP when using equipment could maintain muscle length and joint range of movement to promote acetabular growth and to prevent hip subluxation.21,28,36 We are evaluating the radiologic findings with the same study group that is the subject of this report, and preliminary results suggest that the migration percentage of these children remained within stable limits at 5 years of age.
Although an actual increase in ROM was not seen in the study, the lack of development and progression of contracture is the significant finding of this research. Although all children learned to walk with mobility aids before the age of 5 years, we decided to continue to use the standing program to help maintain hip adductor flexibility because the decrease in ROM is greatest early in life.10 Maintaining the flexibility of hip adductors in the first years of life can prevent a narrow base of support and increase walking speed during walking, important goals for children with CP who are at GMFCS level III and partially ambulatory.30
None of the children in this study required surgical intervention for any leg muscles as no progression in hip contracture was seen. Although the results of this study show a statistically significant difference in hip abduction ROM at 5 years, we cannot say that the increase the ROM was clinically significant because the magnitude was small. However, the adductor muscles did not lose ROM with age, which is common in children with spastic diplegic CP.10,38 The longitudinal data published by Nordmark et al10 show that for measurements such as hip abduction and the popliteal angle, there can be a considerable change during the early years, with the mean ROM of hip abduction decreasing from 43° to 34°, between age 2 and 14 years. McDowell et al38 found significant reductions in passive ROM for the hamstrings and hip adductor musculature in children with spastic CP. The mean of hip abduction in children of 4 to 10 years at GMFCS level III was 25.9° ± 9.5°.38 These children also had no history of lower limb surgery.
Another benefit of using a custom standing frame is that plaster is a cheaper material allowing for less cost with the changes in the cast that were needed while the child grows in comparison to the cost of changing commercially available standers.
Although standing devices seem to improve body functions and structure, they also promote participation in upright activities, allowing the child to be at eye level with peers.32
A limitation of this study is the lack of established reliability of the goniometric measures. This limitation was minimized by use of a standardized protocol and also having the same experienced tester performing all measurements without knowing the baseline measures. On average 3 standings frames were made for each child due to growth and the measures of abduction did not differ from the measurement made at 5 years. Although this does not remove bias, it does help to ensure consistency of the measurements. Despite the disadvantages of goniometric measurements such as low reliability, they are the most commonly used clinical measure and easily applied to assess muscle shortening, usually in children with spasticity.35,39 The fact that children did not cross their feet during walking at 5 years of age also justifies maintaining ROM and flexibility of the adductor muscles.
Other limitations of this study include a lack of a control group, and the small number of children. Further research is necessary with larger sample sizes to replicate these findings. However, the findings provide new insights into the management of children with spastic diplegic CP through the use of a sustained standing program. This is the first study that demonstrates that sustained stretch of the adductors muscles has maintained their ROM and promotes muscle flexibility using a daily standing frame in adduction across 4 years. Because of the lack of a control group, we cannot assume a causal relationship between use of the stander and maintenance in hip abduction ROM. At 4 years of age, children had preserved ROM of hip adductors; and at 5 years of age they were able to take steps with foot clearance, without having received botulinum toxin while still maintaining muscle flexibility of the hip adductors. It could be recommended that this study be replicated for children at GMFCS level IV.
Future studies might also address the combined effects of a standing program in abduction, which causes an isometric muscle contraction of hip adductors through passive static stretch, with exercises that generate active contractions of the same muscles.5
The results of this study indicate that children with spastic diplegic CP, GMFCS level III, who use a standing program with hips in abduction maintained the flexibility of their adductor muscles. Because the number of children in this study was small, these results have to be interpreted with caution and cannot be generalized to the larger population of children with spastic diplegia.
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