Relationships of muscle strength and bone mineral density in ambulatory children with cerebral palsy

Five-year risk of fracture and subsequent fractures among adults with cerebral palsy

Background

Epidemiologic evidence documenting the incidence of fracture and subsequent fractures among adults with cerebral palsy (CP) is lacking, which could inform fracture prevention efforts. The objective was to characterize the 5-year rate of initial and subsequent fragility fractures among adults with CP.

Methods

This retrospective cohort study used Medicare claims from 01/01/2008–12/31/2019 from adults ≥18 years old with CP (n = 44,239) and elderly ≥65 years old without CP (n = 2,176,463) as a comparison. The incidence rate (IR), IR ratio (IRR), and site distribution were estimated for the initial and subsequent fragility fractures over 5-years by sex and age.

Results

The IR of fragility fracture at any site over the 5-year follow-up was similar for 18–30-year-old men with CP (IR = 5.2; 95%CI = 4.4–5.9) and 30–34-year-old women with CP (IR = 6.3; 95%CI = 5.3–7.2) compared to the same sex youngest-old (65–74 years old) without CP (IRR = 1.09 and 0.94, respectively, both P > 0.05), and increased with older age for those with CP. The number of fragility fractures and IR of subsequent fragility fractures was similar for young men and middle-aged women with CP compared to elderly without CP, and increased with older age for those with CP. The proportion of fragility fracture at the tibia/fibula decreased while the vertebral column and multiple simultaneous sites (most involved hip/lower extremities) increased with older age.

Conclusion

Young and middle-aged adults with CP had similar-to-worse initial and subsequent fragility fracture profiles compared to the general elderly population- a well characterized group for bone fragility. Findings emphasize the need for fracture prevention efforts at younger ages for CP, possibly by ~5 decades younger.

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Fracture prevention efforts are focused on the elderly and postmenopausal women.

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Fragility fracture risk is elevated for those with CP across the adult lifespan.

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For men, the risk for 18–29 year olds (CP) was on par with 65–74 year olds (no CP).

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For women, risk for 30–34 year olds (CP) was on par with 65–74 year olds (no CP).

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CP had a higher risk of subsequent fragility fractures that was also premature.

Measurement of Bone Mineral Density in Children with Cerebral Palsy from an Ethical Issue to a Diagnostic Necessity

Introduction

Due to concerns about cumulative radiation exposure in the pediatric population, it is not standard practice to perform dual-energy X-ray absorptiometry (DXA) analysis in the diagnostic process of musculoskeletal disorders, such as cerebral palsy (CP). This study aimed to evaluate the bone mineral density (BMD) in children with CP and the ethical justification of applying DXA analysis in these children. Material and Methods. In this monocentric retrospective analysis, data were collected from children and adolescents with CP who were treated for a primary illness for three years. A clinical examination, which included a DXA analysis, recommended by the multidisciplinary team, was performed. After applying inclusion and exclusion criteria, 60 scans remained for statistical analysis. BMD and Z-scores for the lumbar spine (LS), and hip right and left femoral neck (RFN and LFN, respectively), and total hip (TH) were recorded.

Results

The average age of children with CP when DXA analysis was first performed was about 7 years. The BMD (mean ± SD) at LS (LS-BMD) of all patients was 0.612 ± 0.12, at RFN 0.555 ± 0.11, at LFN 0.572 ± 0.1, and at TH (TH-BMD) 0.581 ± 0.13. The values of the Z-score (mean ± SD) at LS of all patients were −2.5 ± 0.22, at RFN −2.2 ± 0.21, at LFN -2.25 (SD = 0.2), and at TH -2.3 (SD = 0.23). There was no statistical significance between age and gender; however, BMI, walking ability, fracture history, and pattern of CP had a significant impact on BMD and Z-score values of these children.

Conclusion

The results of our study clearly indicate that children with CP have a higher risk of low BMD, osteoporosis, and bone fractures, which makes it ethically justifiable to perform the DXA analysis in these children.

Cicloergômetro na melhora da função motora grossa de crianças comparalisia cerebral: uma revisão sistemática com meta-anális

RESUMO A paralisia cerebral é um grupo de desordens neurológicas causadora de inúmeros déficits, principalmente relacionados à função motora, comprometendo os movimentos e o seu controle seletivo. Dentre as diversas terapias disponíveis para tentar amenizar esse processo, o cicloergômetro aparece como um aparato estacionário que tem por finalidade facilitar a movimentação dos membros inferiores. Portanto, o objetivo deste estudo foi analisar os efeitos do cicloergômetro na função motora grossa de crianças com paralisia cerebral através da escala Gross Motor Function Measure (GMFM-66). Trata-se de uma revisão sistemática, com inclusão de ensaios clínicos randomizados publicados até julho de 2017. A busca foi realizada nas bases de dados: MEDLINE (PubMed), Physiotherapy Evidence Database (PEDro), SciELO e Embase. Para a avaliação da qualidade metodológica das investigações foi utilizada a escala da Cochrane Handbook. Foram selecionados artigos que aplicaram o cicloergômetro em crianças com paralisia cerebral, comparadas a crianças com paralisia cerebral no grupo-controle ou em outra intervenção, e que avaliaram a função motora grossa com a GMFM. A revisão incluiu três artigos e um total de 127 pacientes. Os resultados mostraram um aumento nos valores da GMFM-66, porém não significativo estatisticamente nem relevantes para uma melhora clínica. Por meio desta revisão sistemática, verificou-se uma grande heterogeneidade nos estudos que abordam esta área e que, apesar do incremento de valores no grupo que realizou o cicloergômetro, não houve diferença estatística quando comparado ao grupo-controle, demonstrando não beneficiar a função motora grossa dessa população quando avaliada pela GMFM66.

Low bone mineral density in ambulatory persons with cerebral palsy? A systematic review

Purpose: Non-ambulatory persons with cerebral palsy are prone to low bone mineral density. In ambulatory persons with cerebral palsy, bone mineral density deficits are expected to be small or absent, but a consensus conclusion is lacking. In this systematic review bone mineral density in ambulatory persons with cerebral palsy (Gross Motor Function Classification Scales I-III) was studied. Materials and methods: Medline, Embase, and Web of Science were searched. According to international guidelines, low bone mineral density was defined as Z-score ≤ -2.0. In addition, we focused on Z-score ≤ -1.0 because this may indicate a tendency towards low bone mineral density. Results: We included 16 studies, comprising 465 patients aged 1-65 years. Moderate and conflicting evidence for low bone mineral density (Z-score ≤ -2.0) was found for several body parts (total proximal femur, total body, distal femur, lumbar spine) in children with Gross Motor Function Classification Scales II and III. We found no evidence for low bone mineral density in children with Gross Motor Function Classification Scale I or adults, although there was a tendency towards low bone mineral density (Z-score ≤ -1.0) for several body parts. Conclusions: Although more high-quality research is needed, results indicate that deficits in bone mineral density are not restricted to non-ambulatory people with cerebral palsy. Implications for Rehabilitation Although more high-quality research is needed, including adults and fracture risk assessment, the current study indicates that deficits in bone mineral density are not restricted to non-ambulatory people with CP. Health care professionals should be aware that optimal nutrition, supplements on indication, and an active lifestyle, preferably with weight-bearing activities, are important in ambulatory people with CP, also from a bone quality point-of-view. If indicated, medication and fall prevention training should be prescribed.

Diversity of activity participation determines bone mineral content in the lower limbs of pre-pubertal children with developmental coordination disorder

This study examined the relationships between activity participation and bone mineralization in children with developmental coordination disorder. Limited participation in physical, recreational, social, and skill-based and self-improvement activities contributed to lower bone mineral content. For improved bone health, these children should participate in a variety of activities, not only physical activities.

INTRODUCTION

Limited activity participation in children with developmental coordination disorder (DCD) may have a negative impact on bone mineral accrual. The objectives of this study were to compare bone mineralization and activity participation patterns of pre-pubertal children with DCD and those with typical development, and to determine the association between activity participation patterns and bone mineralization in children with DCD.

METHODS

Fifty-two children with DCD (mean age = 7.51 years) and 61 children with typical development (mean age = 7.22 years) participated in the study. Appendicular and total body (less head) bone mineral content (BMC) and bone mineral density (BMD) were evaluated by a whole-body dual-energy X-ray absorptiometry scan. Activity participation patterns were assessed using the Children's Assessment of Participation and Enjoyment (CAPE) questionnaire.

RESULTS

Children with DCD had lower appendicular and total body BMCs and BMDs than children with typical development overall (p < 0.05). They also had lower CAPE total activity and physical activity diversity scores (p < 0.05). After accounting for the effects of age, sex, height, lean mass, and fat mass, the total activity diversity score remained independently associated with leg BMC in children with DCD, explaining 5.1% of the variance (p = 0.030). However, the physical activity diversity score was no longer associated with leg BMC (p = 0.090).

CONCLUSIONS

Diversity of activity participation and bone mineralization were lower in pre-pubertal children with DCD. Decreased total activity participation diversity was a contributing factor to lower BMC in the legs of children with DCD.

The functional muscle-bone unit in children with cerebral palsy

Our results suggest that the prevalence of bone health deficits in children with CP was overestimated, when using only age- and height-adjusted bone mineral content (BMC) and areal bone mineral density (aBMD). When applying the functional muscle-bone unit diagnostic algorithm (FMBU-A), the prevalence of positive results decreased significantly. We recommend applying the FMBU-A when assessing bone health in children with CP.

INTRODUCTION

The prevalence of bone health deficits in children with cerebral palsy (CP) might be overestimated because age- and height-adjusted reference percentiles for bone mineral content (BMC) and areal bone mineral density (aBMD) assessed by dual-energy X-ray absorptiometry (DXA) do not consider reduced muscle activity. The aim of this study was to compare the prevalence of positive DXA-based indicators for bone health deficits in children with CP to the prevalence of positive findings after applying a functional muscle-bone unit diagnostic algorithm (FMBU-A) considering reduced muscle activity.

METHODS

The present study was a monocentric retrospective analysis of 297 whole body DXA scans of children with CP. The prevalence of positive results of age- and height-adjusted BMC and aBMD defined as BMC and aBMD below the P3 percentile and of the FMBU-A was calculated.

RESULTS

In children with CP, the prevalence of positive results of age-adjusted BMC were 33.3% and of aBMD 50.8%. Height-adjusted results for BMC and aBMD were positive in 16.8 and 36.0% of cases. The prevalence of positive results applying the FMBU-A regarding BMC and aBMD were significantly (p < 0.001) lower than using age- and height-adjusted BMC and aBMD (8.8 and 14.8%).

CONCLUSIONS

Our results suggest that the prevalence of bone health deficits in children with CP was overestimated, when using age- and height-adjusted BMC and aBMD. When applying the FMBU-A, the prevalence decreased significantly. We recommend applying the FMBU-A when assessing bone health in children with CP.

Bone mineral density and vitamin D status in ambulatory and non-ambulatory children with cerebral palsy

This study assessed distal femur and lumbar spine bone mineral density (BMD) Z-scores in children with cerebral palsy. BMD z-score was lower in non-ambulatory than in ambulatory children. Somewhat surprisingly, among ambulatory children, those with better walking abilities had higher BMD z-score than those with more impaired walking ability.

INTRODUCTION

Children with cerebral palsy (CP) have increased risk for low bone mineral density (BMD). The aim was to explore the difference in BMD at the distal femur and lumbar spine between ambulatory and non-ambulatory children with CP and the relationship between vitamin D status and BMD.

METHODS

Fifty-one children (age range 8-18 years; 20 girls) with CP participated. Their BMD Z-scores were measured in the lumbar spine and the distal femur using dual X-ray absorptiometry, and 25-hydroxy-vitamin D (25-OHD) concentrations were measured in serum. Children with GMFCS level I-III were defined as 'walkers' while children with level IV-V were defined as 'non-walkers.

RESULTS

Non-walkers had lower mean BMD Z-scores (range -1.7 to -5.4) than walkers at all sites (range -0.8 to -1.5). Among walkers, BMD Z-scores at the distal femur were lower in those with GMFCS level II than with level I (p values < 0.004). A similar difference was found between the affected and unaffected limb in children with hemiplegia. Mean 25-OHD concentration was 45 nmol/L (SD = 18); lower in walkers (mean = 41 nmol/L; SD = 18) than in non-walkers (mean = 53 nmol/L; SD = 19; p = 0.041). There were no correlations between 25-OHD and BMD z-scores.

CONCLUSIONS

The main predictor of low BMD Z-scores in the distal femur was the inability to walk, but the results suggest that the degree of the neuromotor impairment may also be a significant predictor. Vitamin D status did not correlate with BMD z-scores.

Rotational osteotomy with submuscular plating in skeletally immature patients with cerebral palsy

BACKGROUND

In cerebral palsy, intoeing gait with increased femoral anteversion is not uncommon and often requires surgical intervention. Although several conventional methods have been used, complications are common. We applied a new technique of rotational osteotomy with submuscular plating in skeletally immature patients with cerebral palsy.

METHODS

Eighteen patients (26 femora, 8 bilateral) with a mean age of 8.7 years (range, 6-16) were prospectively treated with this technique. The anatomic distribution of patients was hemiplegia (n = 7), diplegia (n = 8), and asymmetric diplegia (n = 3). Percutaneous osteotomy was performed at the middle of the femoral shaft. After rotational correction, submuscular plating was done using a locking compression plate. Femoral anteversion was evaluated by a trochanteric prominence angle test (TPAT) and computed tomography.

RESULTS

In all cases, each osteotomy healed in an average of 12 weeks (range, 10-14). The mean femoral anteversion by TPAT improved to 12° (range, 5°-30°) after surgery from 44° (range, 30°-65°) (p < 0.001). There were no complications of deep infection, implant failure, or limb length discrepancy over 1 cm.

CONCLUSIONS

In skeletally immature patients with cerebral palsy, femoral anteversion can be safely corrected using submuscular plating with a locking compression plate.

Efficacy of home-based virtual cycling training on bone mineral density in ambulatory children with cerebral palsy

The 12-week home-based virtual cycling training (hVCT) improved lower limb muscle strength and areal bone mineral density (aBMD) than the control program in children with cerebral palsy (CP). A muscle strengthening program, rather than general physical activity, is more specific in enhancing aBMD for these children. A novel hVCT is an effective and efficient strategy that enhances lower limb bone density in these children.

INTRODUCTION

This is the first study to assess the efficacy of a novel hVCT program on bone density for children with spastic CP using a well-designed randomized controlled trial.

METHODS

Twenty-seven ambulatory children with spastic CP, aged 6-12 years, were randomly assigned to the hVCT group (n=13) or control group (n=14). Outcome measures-motor function [Gross Motor Function Measure-66 (GMFM-66)], muscle strength (curl up scores and isokinetic torque of knee extensor and flexor muscle) and aBMD of the lumbar and distal femur-were administered before and immediately after the 12-week intervention.

RESULTS

Analysis of covariance results show that the hVCT group had greater distal femur aBMD and isokinetic torques of knee extensor and flexor muscles than the control group at posttreatment (p<0.05). However, curl up scores, GMFM-66, and lumbar aBMD at posttreatment did not differ between the two groups.

CONCLUSIONS

Analytical findings suggest that the muscle strengthening program is more specific in enhancing bone density for children with CP than general physical activity. Thus, the proposed 12-week hVCT protocol is an effective and efficient strategy for improving lower limb aBMD in these children.

Knee muscle strength at varying angular velocities and associations with gross motor function in ambulatory children with cerebral palsy

The aim of this study was to evaluate the relationships of muscle strength at different angular velocities and gross motor functions in ambulatory children with cerebral palsy (CP). This study included 33 ambulatory children with spastic CP aged 6-15 years and 15 children with normal development. Children with CP were categorized into level I (n=17) or level II (n=16) according to Gross Motor Function Classification System (GMFCS) levels. All children underwent curl-up test and isokinetic tests of the knee extensor and flexor muscle. Children with CP underwent the gross motor function assessments, including the Gross Motor Function Measure (GMFM-66) and the gross motor subtests of Bruininks-Oseretsky Test of Motor Proficiency (BOTMP). The hamstring-quadriceps ratio (HQ ratio) was calculated as 100%×(isokinetic peak torque of hamstring (knee flexor)/isokinetic peak torque of quadriceps (knee extensor)). Children with GMFCS level II had lower BOTMP and GMFM-66 scores, curl-up scores, HQ ratio, and knee muscle strength, especially knee flexor, compared to those with GMFCS level I. The regression analysis showed that knee flexor torques at 60 and 90°/s are mainly related to balance (r(2)=0.167, p=0.011) and strength (r(2)=0.243, p=0.002) while knee flexor torques at 120°/s mainly contribute to running speed and agility (r(2)=0.372, p<0.001). These findings suggest that children with CP had knee strength deficits, especially knee flexor. Postural muscle (knee flexor) strength dominated gross motor function than antigravity muscle strength (knee extensor). The knee flexor strength at different angular velocities was associated with various gross motor tasks. The HQ ratio may be used as a potential biomarker to probe the therapeutic effectiveness for muscle strengthening in these children. These data may allow clinician for formulating effective muscle strengthening strategies for these children.

Muscle strength enhancement following home-based virtual cycling training in ambulatory children with cerebral palsy

This study is the first well-designed randomized controlled trial to assess the effects of a novel home-based virtual cycling training (hVCT) program for improving muscle strength in children with spastic cerebral palsy (CP). Twenty-eight ambulatory children with spastic CP aged 6-12 years were randomly assigned to an hVCT group (n=13) or a control group (n=15). Outcome measures, including gross motor function of the Bruininks-Oseretsky Test of Motor Proficiency (BOTMP) and muscle strength (isokinetic torque of knee extensor and flexor muscle), were administered before and immediately after the 12-week intervention. Analysis of covariance (ANCOVA) at post-treatment showed that, compared to the control group, the hVCT group had significantly higher isokinetic torque in the knee extensor and flexor muscles at 60°/s and 120°/s angular velocities (p<0.05). At post-treatment, the hVCT group also showed greater isokinetic strength improvement in the knee flexor than in the knee extensor at 60°/s (knee flexor: 41%; knee extensor: 19%) and at 120°/s (knee flexor: 36%; knee extensor: 30%). However, the BOTMP scores at post-treatment did not differ between the two groups. Although the proposed 12-week hVCT protocol does not improve gross motor function, it enhances knee muscle strength in children with CP. The protocol obtains larger gains in the knee flexor than in the knee extensor at different angular velocities. The study findings will help clinicians to provide more effective and efficient strategies for muscle strength training in children with CP.

Aging and bone health in individuals with developmental disabilities

Low bone mass density (BMD), a classical age-related health issue and a known health concern for fair skinned, thin, postmenopausal Caucasian women, is found to be common among individuals with developmental/intellectual disabilities (D/IDs). It is the consensus that BMD is decreased in both men and women with D/ID. Maintaining good bone health is important for this population as fractures could potentially go undetected in nonverbal individuals, leading to increased morbidity and a further loss of independence. This paper provides a comprehensive overview of bone health of adults with D/ID, their risk of fractures, and how this compares to the general aging population. We will specifically focus on the bone health of two common developmental disabilities, Down syndrome (DS) and cerebral palsy (CP), and will discuss BMD and fracture rates in these complex populations. Gaining a greater understanding of how bone health is affected in individuals with D/ID could lead to better customized treatments for these specific populations.