Jump Performance and its Relationship with Lower Body Joint Kinetics and Kinematics in Children with Cerebral Palsy.

PURPOSE: The aim was to quantify jump performance in children with cerebral palsy (CP) and determine if the expected deficit is related to their lower-body-joint kinetics and kinematics. METHODS: Twenty-four ambulatory (n = 17 level I and 7 level II in the Gross Motor Function Classification System) children with spastic CP (n = 13 unilateral and 11 bilateral) and 24 age-, sex-, and race-matched typically developing controls were studied. Jump height and peak power and range of motion at the hip, knee, and ankle of the more affected limb in children with CP and the nondominant limb in controls were assessed during a countermovement jump using three-dimensional motion capture and a force platform. RESULTS: Compared to controls, children with CP had lower jump height (33%, Cohen's d (d) = 1.217), peak power at the knee (39%, d = 1.013) and ankle (46%, d = 1.687), and range of motion at the hip (32%, d = 1.180), knee (39%, d = 2.067), and ankle (46%, d = 3.195; all p < 0.001). Jump height was positively related to hip, knee, and ankle power and range of motion in children with CP (rs range = 0.474-0.613, p < 0.05), and hip and ankle power and knee and ankle range of motion in controls (rs range = 0.458-0.630, p < 0.05). The group difference in jump height was no longer detected when ankle joint power, ankle range of motion, or knee range of motion was statistically controlled (p > 0.15). CONCLUSIONS: Jump performance is compromised in children with CP and is associated with low power generation and range of motion in the lower limb, especially at the ankle.

Prefrontal cortex hemodynamic activity during a test of lower extremity functional muscle strength in children with cerebral palsy: A functional near-infrared spectroscopy study.

Children with cerebral palsy (CP) exhibit impaired motor control and significant muscle weakness due to a brain lesion. However, studies that assess the relationship between brain activity and performance on dynamic functional muscle strength assessments in CP are needed. The aim of this study was to determine the effect of a progressive lateral step-up test on prefrontal cortex (PFC) hemodynamic activity in children with CP. Fourteen ambulatory children with spastic CP (Gross Motor Function Classification System level I; 5-11 y) and 14 age- and sex-matched typically developing control children completed a progressive lateral step-up test at incremental step heights (0, 10, 15 and 20 cm) using their non-dominant lower limb. Hemodynamic activity in the PFC was assessed using non-invasive, portable functional neuroimaging (functional near-infrared spectroscopy). Children with CP completed fewer repetitions at each step height and exhibited lower PFC hemodynamic activity across step heights compared to controls. Lower PFC activation in CP was maintained after statistically controlling for the number of repetitions completed at each step height. PFC hemodynamic activity was not associated with LSUT task performance in children with CP, but a positive relationship was observed in controls at the most challenging 20 cm step height. The results suggest there is an altered PFC recruitment pattern in children with CP during a highly dynamic test of functional strength. Further studies are needed to explore the mechanisms underlying the suppressed PFC activation observed in children with CP compared to typically developing children.

Mental health, physical activity, and sports among children with cerebral palsy.

BACKGROUND: People with cerebral palsy (CP) may be at an increased risk for mental health disorders due to co-occurring physical and communication limitations associated with the condition. Participation in physical activity (PA) and sports may provide opportunities to increase socialization and improve physical function. The purpose of this study was to examine associations between participation in daily PA and sports and mental health among children with CP. METHOD: Participants included children with CP (n = 458) and typically developing children (TDC) (n = 40 091) 6-17 years whose parents participated in the 2016-2020 National Survey of Children's Health. Mental health disorders included anxiety, depression, behavioural disorders and attention-deficit/hyperactivity disorder (ADHD). RESULTS: Compared with TDC, children with CP had a higher prevalence of mental health disorders (75.5% vs. 54.2%) and were more likely to receive mental health care (21.5% vs. 14.6%). Controlling for sociodemographic variables, children with CP were more likely to experience anxiety [odds ratio (OR) 2.6; 95% confidence interval (CI) = 2.1-3.3), depression (OR 1.8; 95% CI 1.3-2.4), behavioural disorders (OR 4.8; 95% CI 3.8-6.0) and ADHD (OR 2.1; 95% CI 1.6-2.6). The likelihood of these conditions decreased when children participated in sports for anxiety (OR 2.2; 95% CI 1.8-2.8), depression (OR = 1.4; 95% CI 1.0-2.0), behavioural disorders (OR 4.1; 95% CI 3.2-5.1) and ADHD (OR 1.9; 95% CI 1.5-2.5). The likelihood for anxiety (OR 2.3; 95% CI 1.8-2.8), depression (OR 1.4; 95% CI 1.0-1.9), behavioural disorders (OR 4.4; 95% CI 3.5-5.5) and ADHD (OR 1.9; 95% CI 1.5-2.4) also decreased with participation in daily PA. CONCLUSIONS: There is an overwhelming disparity in the number of children with CP who have a mental health disorder and those who receive mental health care. Increasing access to participation in sports and PA may be beneficial.

Cardiometabolic Risk and Its Relationship With Visceral Adiposity in Children With Cerebral Palsy.

Context: Adults with cerebral palsy (CP) display a higher prevalence of cardiometabolic disease compared with the general population. Studies examining cardiometabolic disease risk in children with CP are limited. Objective: The purpose of this study was to determine if children with CP exhibit higher cardiometabolic risk than typically developing children, and to examine its relationship with visceral adiposity and physical activity. Methods: Thirty ambulatory children with CP and 30 age-, sex-, and race-matched typically developing control children were tested for blood lipids, glucose, and the homeostatic model assessment of insulin resistance (HOMA-IR). Visceral fat was assessed using dual-energy x-ray absorptiometry. Physical activity was assessed using accelerometer-based monitors. Results: Children with CP had higher total cholesterol, low-density lipoprotein cholesterol, and non-high-density lipoprotein cholesterol (non-HDL-C), glucose, prevalence of dyslipidemia, prevalence of prediabetes, and visceral fat mass index (VFMI) and lower physical activity than controls (all P < .05). In the groups combined, non-HDL-C and glucose were positively related to VFMI (r = 0.337 and 0.313, respectively, P < .05), and non-HDL-C and HOMA-IR were negatively related to physical activity (r = -0.411 and -0.368, respectively, P < .05). HOMA-IR was positively related to VFMI in children with CP (r = 0.698, P < .05), but not in controls. Glucose was not related to physical activity in children with CP, but it was negatively related in controls (r = -0.454, P < .05). Conclusion: Children with CP demonstrate early signs of cardiometabolic disease, which are more closely related to increased visceral adiposity than decreased physical activity.

Measuring tibial hemodynamics and metabolism at rest and after exercise using near-infrared spectroscopy.

The bone vascular system is important, yet evaluation of bone hemodynamics is difficult and expensive. This study evaluated the utility and reliability of near-infrared spectroscopy (NIRS), a portable and relatively inexpensive device, in measuring tibial hemodynamics and metabolic rate. Eleven participants were tested twice using post-occlusive reactive hyperemia technique with the NIRS probes placed on the tibia and the medial gastrocnemius (MG) muscle. Measurements were made at rest and after 2 levels of plantarflexion exercise. The difference between oxygenated and deoxygenated hemoglobin signal could be reliably measured with small coefficients of variation (CV; range 5.7-9.8%) and high intraclass correlation coefficients (ICC; range 0.73-0.91). Deoxygenated hemoglobin rate of change, a potential marker for bone metabolism, also showed good reliability (CV range 7.5-9.8%, ICC range 0.90-0.93). The tibia was characterized with a much slower metabolic rate compared with MG (p < 0.001). While exercise significantly increased MG metabolic rate in a dose-dependent manner (all p < 0.05), no changes were observed for the tibia after exercise compared with rest (all p > 0.05). NIRS is a suitable tool for monitoring hemodynamics and metabolism in the tibia. However, the local muscle exercise protocol utilized in the current study did not influence bone hemodynamics or metabolic rate. Novelty: NIRS can be used to monitor tibial hemodynamics and metabolism with good reliability. Short-duration local muscle exercise increased metabolic rate in muscle but not in bone. High level of loading and exercise volume may be needed to elicit measurable metabolic changes in bone.

The construct and concurrent validity of brief standing sway assessments in children with and without cerebral palsy.

BACKGROUND: Standing postural sway is often quantified from center of pressure trajectories. During assessments of longer durations, children may fidget, thus limiting the feasibility and validity of sway recordings. RESEARCH QUESTION: Do postural sway sample durations less than 30 s maintain construct and concurrent validity? METHODS: In this case-control, observational study, we measured postural sway in 41 children (age 5-12 years, 23 typically developing (TD); 18 with spastic cerebral palsy (CP), 13 diplegic and 5 hemiplegic, 11 GMFCS level I and 7 level II) for 30-second eyes-opened and eyes-closed conditions. From a single recording, 5-second incremental durations of 5-30 s were considered in this analysis. We quantified anteroposterior, mediolateral, and transverse-plane sway using seven time-domain variables: root-mean-square error, total excursion, mean frequency, mean distance, sway area, and 95 % confidence circle and ellipse areas. Variables were calculated in eyes-opened and eyes-closed conditions, as well as the ratio of the two. Construct validity was evaluated by the persistence of large effect sizes (Glass's Δ ≥ 0.80) between CP and TD participants at shorter durations than 30 s. Concurrent validity was evaluated by the correlations of shorter duration measures to the 30 s measure. RESULTS: Seven sway measures had large between-group effects (Glass's Δ ≥ 1.02) for the 30 s measure that persisted (Glass's Δ ≥ 0.81) at shorter durations (5-25 s) and also maintained concurrent validity (r ≥ 0.83). Six of these seven measures were taken in the eyes-closed condition, and all seven measures were in the mediolateral direction or transverse plane. SIGNIFICANCE: Our analysis suggests that sway durations less than 30 s can uphold construct and concurrent validity. These measures were primarily in the eyes-closed conditions and mediolateral direction. These results are a promising indicator that shorter-duration sway measures may be of utility when fidgeting prevents longer recordings.

Test-Retest Reliability and Correlates of Vertebral Bone Marrow Lipid Composition by Lipidomics Among Children With Varying Degrees of Bone Fragility.

The reliability of lipidomics, an approach to identify the presence and interactions of lipids, to analyze the bone marrow lipid composition among pediatric populations with bone fragility is unknown. The objective of this study was to assess the test-retest reliability, standard error of measurement (SEM), and the minimal detectable change (MDC) of vertebral bone marrow lipid composition determined by targeted lipidomics among children with varying degrees of bone fragility undergoing routine orthopedic surgery. Children aged 10 to 19 years, with a confirmed diagnosis of adolescent idiopathic scoliosis (n = 13) or neuromuscular scoliosis and cerebral palsy (n = 3), undergoing posterior spinal fusion surgery at our institution were included in this study. Transpedicular vertebral body bone marrow samples were taken from thoracic vertebrae (T11, 12) or lumbar vertebrae (L1 to L4). Lipid composition was assessed via targeted lipidomics and all samples were analyzed in the same batch. Lipid composition measures were examined as the saturated, monounsaturated, and polyunsaturated index and as individual fatty acids. Relative and absolute test-retest reliability was assessed using the intraclass correlation coefficient (ICC), SEM, and MDC. Associations between demographics and index measures were explored. The ICC, SEM, and MDC were 0.81 (95% CI, 0.55-0.93), 1.6%, and 4.3%, respectively, for the saturated index, 0.66 (95% CI, 0.25-0.87), 3.5%, and 9.7%, respectively, for the monounsaturated index, and 0.60 (95% CI, 0.17-0.84), 3.6%, and 9.9%, respectively, for the polyunsaturated index. For the individual fatty acids, the ICC showed a considerable range from 0.04 (22:2n-6) to 0.97 (18:3n-3). Age was positively correlated with the saturated index (r 2 = 0.36; p = 0.014) and negatively correlated with the polyunsaturated index (r 2 = 0.26; p = 0.043); there was no difference in index measures by sex (p > 0.58). The test-retest reliability was moderate-to-good for index measures and poor to excellent for individual fatty acids; this information can be used to power research studies and identify measures for clinical or research monitoring. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Quantifying bone marrow fat using standard T1-weighted magnetic resonance images in children with typical development and in children with cerebral palsy.

Excess bone marrow adiposity may have a negative effect on bone growth and development. The aim of this study was to determine whether a procedure using standard T1-weighted magnetic resonance images provides an accurate estimate of bone marrow fat in children with typical development and in children with mild spastic cerebral palsy (CP; n = 15/group; 4-11 y). Magnetic resonance imaging was used to acquire T1-weighted images. It was also used to acquire fat and water images using an iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) technique. Bone marrow fat volume and fat fraction in the middle-third of the tibia were determined using the standard T1-weighted images (BMFVT1 and BMFFT1, respectively) and the fat and water images (BMFVIDEAL and BMFFIDEAL, respectively). In both groups, BMFVT1 was highly correlated with (both r > 0.99, p < 0.001) and not different from (both p > 0.05) BMFVIDEAL. In both groups, BMFFT1 was moderately correlated with (both r = 0.71, p < 0.01) and not different from (both p > 0.05) BMFFIDEAL. There was no group difference in BMFVT1 or BMFVIDEAL (both p > 0.05). BMFFIDEAL was higher in children with CP (p < 0.05), but there was no group difference in BMFFT1 (p > 0.05). We conclude that a procedure using standard T1-weighted magnetic resonance images can produce estimates of bone marrow fat volume similar to estimates from the IDEAL technique in children. However, it is less sensitive to variation in the bone marrow fat fraction.

Anteroposterior balance reactions in children with spastic cerebral palsy.

AIM: To compare anterior and posterior standing balance reactions, as measured by single-stepping thresholds, in children with and without spastic cerebral palsy (CP). METHOD: Seventeen ambulatory children with spastic CP (eight males, nine females) and 28 typically developing children (13 males, 15 females; age range 5-12y, mean [SD] 9y 2mo [2y 3mo]), were included in this cross-sectional, observational study. Balance reaction skill was quantified as anterior and posterior single-stepping thresholds, or the treadmill-induced perturbations that consistently elicited a step in that direction. In order to understand the underlying mechanisms of between-group differences in stepping thresholds, dynamic stability was quantified using the minimum margin of stability. Ankle muscle activation latency, magnitude, and co-contraction were assessed with surface electromyography. RESULTS: We observed an age and group interaction for anterior thresholds (p=0.001, partial η2 =0.24). At older (≈11y; p<0.001, partial η2 =0.48), but not younger (≈7y; p=0.33, partial η2 =0.02) ages, typically developing children had larger anterior thresholds than those with CP. In response to near-threshold anterior perturbations, older typically developing children recovered from more instability than their peers with CP (p=0.004, partial η2 =0.18). Older children had no between-group differences in ankle muscle activity. No between-group differences were observed in posterior thresholds. INTERPRETATION: The effects of CP on balance reactions are age- and direction-specific. Older typically developing children are more able or willing to withhold a step when unstable. WHAT THIS PAPER ADDS: Children with spastic cerebral palsy have age- and direction-specific balance-reaction impairments. Lower anterior stepping thresholds were observed in older, but not younger children. Older typically developing children withheld a forward step at higher levels of instability. No between-group differences were seen in posterior stepping thresholds.

The effect of zoledronic acid on attenuation of bone loss at the hip and knee following acute traumatic spinal cord injury: a randomized-controlled study.

STUDY DESIGN: Randomized double blind, placebo-controlled trial. OBJECTIVES: To examine the effect of early intravenous zoledronic acid (ZA) on bone markers and areal bone mineral density (aBMD) in persons with acute ASIA Impairment Scale (AIS) A traumatic spinal cord injury (SCI). SETTING: Two inpatient rehabilitation units. METHODS: Thirteen men, 2 women, aged 19-65, C4-T10 AIS A SCI, received 5 mg intravenous ZA vs. placebo 12-21 days post injury. Markers of bone formation (procollagen N-1 terminal propeptide [P1NP]), bone resorption (serum C-telopeptide [CTX]), and aBMD by dual-energy X-ray absorptiometry (DXA) for hip (femur-proximal, intertrochanteric, neck), and knee (distal femur, proximal tibia) were obtained at baseline, 2 weeks post infusion (P1NP, CTX only), 4 and 12 months post injury. RESULTS: P1NP remained unchanged, while CTX decreased in ZA but increased in controls at 2 weeks (mean difference = -97%, p < 0.01), 4 months (mean difference = -54%, p < 0.05), but not 12 months (mean difference = 3%, p = 0.23). Changes in aBMD at the hip favored ZA at 4 months (mean difference 10.3-14.1%, p < 0.01) and 12 months (mean difference 10.8-13.1%, p < 0.02). At 4 months, changes in aBMD favored ZA at the distal femur (mean difference 6.0%, 95% CI: 0.7-11.2, p < 0.03) but not proximal tibia (mean difference 8.3%, 95% CI: -6.9 to 23.6, p < 0.23). Both groups declined in aBMD at 12 months, with no between group differences. CONCLUSION: ZA administered ≤21 days of complete traumatic SCI maintains aBMD at the hip and distal femur at 4 months post injury. This effect is partially maintained at 12 months.

Complicated Muscle-Bone Interactions in Children with Cerebral Palsy.

PURPOSE OF REVIEW: The goal of this review is to highlight the deficits in muscle and bone in children with cerebral palsy (CP), discuss the muscle-bone relationship in the CP population, and identify muscle-based intervention strategies that may stimulate an improvement in their bone development. RECENT FINDINGS: The latest research suggests that muscle and bone are both severely underdeveloped and weak in children with CP, even in ambulatory children with mild forms of the disorder. The small and low-performing muscles and limited participation in physical activity are likely the major contributors to the poor bone development in children with CP. However, the muscle-bone relationship may be complicated by other factors, such as a high degree of fat and collagen infiltration of muscle, atypical muscle activation, and muscle spasticity. Muscle-based interventions, such as resistance training, vibration, and nutritional supplementation, have the potential to improve bone development in children with CP, especially if they are initiated before puberty. Studies are needed to identify the muscle-related factors with the greatest influence on bone development in children with CP. Identifying treatment strategies that capitalize on the relationship between muscle and bone, while also improving balance, coordination, and physical activity participation, is an important step toward increasing bone strength and minimizing fractures in children with CP.

Preferential deficit of fat-free soft tissue in the appendicular region of children with cerebral palsy and proposed statistical models to capture the deficit.

BACKGROUND: Cerebral palsy (CP) is a neurological disorder characterized by a profound skeletal muscle deficit. However, whether there is a regional-specific skeletal muscle deficit in children with CP is unknown. The purpose of this study was to determine whether fat-free soft tissue mass (FFST), a commonly used surrogate for skeletal muscle mass, is more compromised in the limbs than in the trunk in children with CP. A second purpose was to determine whether physical characteristics can be used to accurately estimate appendicular FFST (AFFST) in children with CP. METHODS: Forty-two children with CP (4-13 y) and 42 typically developing children matched to children with CP for sex, age and race were studied. Whole body FFST (FFSTwhole), FFST in the upper limbs (FFSTupper), FFST in the lower limbs (FFSTlower), the ratio of AFFST to height (AFFST/ht), the ratio of AFFST to height2 (AFFST/ht2) and non-appendicular FFST were estimated from dual-energy X-ray absorptiometry. Statistical models were developed to estimate AFFST, AFFST/ht and AFFST/ht2 in both groups of children, and the leave-one-out method was used to validate the models. RESULTS: Children with CP had 21% lower FFSTwhole, 30% lower AFFST, 34% lower FFSTlower, 14% lower non-appendicular FFST, 23% lower AFFST/ht, 19% lower AFFST/ht2 and 9% lower AFFST/FFSTwhole (all p < 0.05). Statistical models developed using data from typically developing children overestimated AFFST, AFFST/ht and AFFST/ht2 by 35%, 30% and 21% (all p < 0.05), respectively, in children with CP. Separate models developed using data from children with CP yielded better accuracy, with the estimated results highly correlated (r2 = 0.78, 0.66 and 0.50, respectively; all p < 0.001) and not different from calculated AFFST, AFFST/ht and AFFST/ht2 (all p > 0.99). However, when the difference in estimated values and measured values of AFFST, AFFST/ht and AFFST/ht2 were plotted against measured values, there was an inverse relationship (r = -0.38, -0.47 and -0.61, respectively, all p < 0.05). CONCLUSION: Children with CP have a remarkable deficit in FFST that is more pronounced in the appendicular than in the non-appendicular region and more pronounced in the lower than in the upper limbs. Preliminary models developed using data from children with CP can provide reasonable estimates of AFFST and indexes of AFFST relative to height, but further development of the models may be needed.

Greater Visceral Fat but No Difference in Measures of Total Body Fat in Ambulatory Children With Spastic Cerebral Palsy Compared to Typically Developing Children.

BACKGROUND: Individuals with cerebral palsy (CP) are at increased risk for obesity and obesity-related complications. Studies of total body fat in those with CP are inconsistent and studies of abdominal fat are lacking in children with CP. The objective of this study was to determine if ambulatory children with spastic CP have greater central adiposity compared to typically developing children. METHODOLOGY: Eighteen ambulatory children with spastic CP (n = 5 girls; 8.6 ± 2.9 yr) and 18 age-, sex-, and race-matched typically developing children (controls; 8.9 ± 2.1 yr) participated in this cross-sectional study. Children with CP were classified as I or II using the Gross Motor Function Classification System. Dual-energy X-ray absorptiometry assessed body composition, including total body, trunk and abdominal fat mass, fat-free mass, fat mass index (FMI), and fat-free mass index (FFMI). RESULTS: There were no group differences in fat mass, fat-free mass, FMI, and FFMI in the total body, fat mass, fat-free mass, and FFMI in the trunk, or fat mass, visceral fat mass, and subcutaneous fat mass in the abdomen (p > 0.05). Compared to controls, children with CP had higher trunk FMI, abdominal FMI, and visceral FMI (p < 0.05). Although marginally insignificant (p = 0.088), children with CP had higher subcutaneous FMI. CONCLUSIONS: Ambulatory children with spastic CP have elevated central adiposity, especially in the visceral region, despite no differences in measures of total body fat. How this relates to cardiometabolic disease progression in those with CP requires further investigation.

The cross-sectional relationships between age, standing static balance, and standing dynamic balance reactions in typically developing children.

BACKGROUND: Static balance performance is a common metric for evaluating the development of postural control in children. Less is known about the potentially independent development of dynamic balance performance. RESEARCH QUESTION: How does age relate to static (i.e. postural sway) and dynamic (i.e. stepping thresholds) standing balance performance, and what is the relationship between postural sway and stepping thresholds? METHODS: Twenty-six typically developing children (12 males, 14 females; 5-12 years of age) were recruited for this cross-sectional study. Static balance performance was quantified as the total path length during a postural sway assessment using a force platform with conditions of eyes open and eyes closed. Dynamic balance performance was quantified using a single-stepping threshold assessment, whereby participants attempted to prevent a step in response to treadmill-induced perturbations in the anterior and posterior directions. Relationships between age and body-size scaled measures of static and dynamic balance performance were assessed using Spearman rank correlations. RESULTS: There was a weak correlation between age and postural sway (|rs| < 0.10, p >  0.68), but a moderate-to-strong correlation between age and single-stepping thresholds (rs > 0.68, p < 0.001). A weak correlation was found between postural sway and single-stepping thresholds (|rs| < 0.20, p >  0.39). SIGNIFICANCE: Dynamic, but not static standing balance performance, may improve with typical development between the ages of 5 and 12 years. Static and dynamic balance should be considered as unique constructs when assessed in children.

Dynamic stability during walking in children with and without cerebral palsy.

BACKGROUND: Cerebral palsy (CP) is associated with a high risk of falling during walking. Many gait abnormalities associated with CP likely alter foot placement and center of mass (CoM) movement in a way that affects anterior or lateral dynamic stability, in turn influencing fall risk. RESEARCH QUESTION: Do children with CP demonstrate altered anterior or lateral dynamic stability compared to typically-developing (TD) children? METHODS: In this case-control, observational study, we measured gait kinematics of two groups of children (15 CP, 11 GMFCS level I, 4 GMFCS level II; 14 TD; age 5-12) in walking conditions of a preferred speed, a fast speed, and a preferred speed while completing a cognitive task. For dominant and non-dominant limbs, the margin of stability (MoS), a spatial measure of dynamic stability, was calculated as the distance between the edge of the base of support and the CoM position after accounting for scaled velocity. Statistical comparisons of were made using mixed factorial ANOVAs. Post hoc comparisons were Sidak adjusted. RESULTS: The anterior MoS before foot strike and at mid-swing differed between each condition but not between groups. Based on the minimum lateral MoS, children with CP had more stability when bearing weight on their non-dominant limb compared to TD children. These differences were not apparent when on the dominant limb. SIGNIFICANCE: This high-functioning group of children with CP exhibited a more conservative lateral stability strategy during walking when bearing weight with the non-dominant limb. This strategy may be protective against lateral falls. We observed no between-group differences in anterior stability. Because CP has been previously associated with impaired anterior balance reactions, and there was no observed compensation in anterior gait stability, this lack of group differences could contribute to a higher risk of falling in that direction.

Statistical Models to Assess Leg Muscle Mass in Ambulatory Children With Spastic Cerebral Palsy Using Dual-Energy X-Ray Absorptiometry.

Cerebral palsy (CP) is a movement disorder associated with small and weak muscles. Methods that accurately assess muscle mass in children with CP are scarce. The purpose of this study was to determine whether dual-energy X-ray absorptiometry (DXA) accurately estimates midleg muscle mass in ambulatory children with spastic CP. Ambulatory children with spastic CP and typically developing children 5-11 y were studied (n = 15/group). Fat-free soft tissue mass (FFST) and fat mass at the middle third of the tibia (i.e., midleg) were estimated using DXA. Muscle mass (muscleMRI) and muscle mass corrected for intramuscular fat (muscleMRIfc) in the midleg were estimated using magnetic resonance imaging (MRI). Statistical models were created to predict muscleMRI and muscleMRIfc using DXA. Children with CP compared to typically developing children had lower FFST (38%), muscleMRI (40%) and muscleMRIfc (47%) (all p < 0.05) and a lower ratio of muscleMRIfc to FFST (17%, p < 0.05). DXA-based models developed using data from typically developing children overestimated muscleMRI (13%) and muscleMRIfc (22%) (both p < 0.05) in children with CP. DXA-based models developed using data from children with CP explained 91% of the variance in muscleMRI and 90% of the variance in muscleMRIfc in children with CP (both p < 0.05). Moreover, the estimates were not different from muscleMRI and muscleMRIfc (both p > 0.99). We conclude that DXA-based statistical models accurately estimate midleg muscle mass in children with CP when the models are composed using data from children with CP rather than typically developing children.

BMI does not capture the high fat mass index and low fat-free mass index in children with cerebral palsy and proposed statistical models that improve this accuracy.

BACKGROUND/OBJECTIVES: Children with cerebral palsy (CP) are at risk for having a misclassified overweight/obesity status based on BMI thresholds due to their lower fat-free mass and similar fat mass compared with typically developing children. The primary objective was to determine if BMI could predict fat mass index (FMI) and fat-free mass index (FFMI) in children with CP. SUBJECTS/METHODS: Forty-two children with CP and 42 typically developing children matched to children with CP for age and sex participated in the study. Dual-energy X-ray absorptiometry was used to assess body composition. Children with CP who could ambulate without assistance were considered ambulatory (ACP) and the rest were considered nonambulatory (NACP). RESULTS: Children with CP had higher percent body fat (%Fat) and FMI and lower fat-free mass and FFMI than controls (p < 0.05) but no difference in fat mass (p = 0.10). When BMI was statistically controlled, NACP had higher %Fat, fat mass and FMI and lower FFMI than ACP and controls (p < 0.05). NACP also had lower fat-free mass than controls (p < 0.05). ACP had higher %Fat and FMI and lower fat-free mass and FFMI than controls (p < 0.05). BMI was a strong predictor of FMI (r2 = 0.83) and a moderately strong predictor of FFMI (r2 = 0.49) in children with CP (both p < 0.01). Prediction of FMI (R2 = 0.86) and FFMI (R2 = 0.66) from BMI increased (p < 0.05) when age, sex and ambulatory status were included. CONCLUSION: Compared with typically developing children, children with CP have a higher FMI and lower FFMI for a given BMI, which is more pronounced in NACP than ACP. The finding suggests that the prevalence of overweight/obesity status may be underestimated in children with CP.

Bone Marrow Fat Physiology in Relation to Skeletal Metabolism and Cardiometabolic Disease Risk in Children With Cerebral Palsy.

Individuals with cerebral palsy exhibit neuromuscular complications and low physical activity levels. Adults with cerebral palsy exhibit a high prevalence of chronic diseases, which is associated with musculoskeletal deficits. Children with cerebral palsy have poor musculoskeletal accretion accompanied by excess bone marrow fat, which may lead to weaker bones. Mechanistic studies to determine the role of bone marrow fat on skeletal growth and maintenance and how it relates to systemic energy metabolism among individuals with cerebral palsy are lacking. In this review, we highlight the skeletal status in children with cerebral palsy and analyze the existing literature on the interactions among bone marrow fat, skeletal health, and cardiometabolic disease risk in the general population. Clinically vital questions are proposed, including the following: (1) Is the bone marrow fat in children with cerebral palsy metabolically distinct from typically developing children in terms of its lipid and inflammatory composition? (2) Does the bone marrow fat suppress skeletal acquisition? (3) Or, does it accelerate chronic disease development in children with cerebral palsy? (4) If so, what are the mechanisms? In conclusion, although inadequate mechanical loading may initiate poor skeletal development, subsequent expansion of bone marrow fat may further impede skeletal acquisition and increase cardiometabolic disease risk in those with cerebral palsy.

Obese Versus Normal-Weight Late-Adolescent Females have Inferior Trabecular Bone Microarchitecture: A Pilot Case-Control Study.

Though still a topic of debate, the position that skeletal health is compromised with obesity has received support in the pediatric and adult literature. The limited data relating specifically to trabecular bone microarchitecture, however, have been relatively inconsistent. The aim of this pilot cross-sectional case-control study was to compare trabecular bone microarchitecture between obese (OB) and normal-weight (NW) late-adolescent females. A secondary aim was to compare diaphyseal cortical bone outcomes between these two groups. Twenty-four non-Hispanic white females, ages 18-19 years, were recruited into OB (n = 12) or NW (n = 12) groups based on pre-specified criteria for percent body fat (≥32 vs. <30, respectively), body mass index (>90th vs. 20th-79th, respectively), and waist circumference (≥90th vs. 25th-75th, respectively). Participants were also individually matched on age, height, and oral contraceptive use. Using magnetic resonance imaging, trabecular bone microarchitecture was assessed at the distal radius and proximal tibia metaphysis, and cortical bone architecture was assessed at the mid-radius and mid-tibia diaphysis. OB versus NW had lower apparent trabecular thickness (radius and tibia), higher apparent trabecular separation (radius), and lower apparent bone volume to total volume (radius; all P < 0.050). Some differences in radius and tibia trabecular bone microarchitecture were retained after adjusting for insulin resistance or age at menarche. Mid-radius and mid-tibia cortical bone volume and estimated strength were lower in the OB compared to NW after adjusting for fat-free soft tissue mass (all P < 0.050). These trabecular and cortical bone deficits might contribute to the increased fracture risk in obese youth.