Deficits in distal radius bone strength, density and microstructure are associated with forearm fractures in girls: an HR-pQCT study

Recommendations for High-resolution Peripheral Quantitative Computed Tomography Assessment of Bone Density, Microarchitecture, and Strength in Pediatric Populations

PURPOSE OF REVIEW

The purpose of this review is to summarize current approaches and provide recommendations for imaging bone in pediatric populations using high-resolution peripheral quantitative computed tomography (HR-pQCT).

RECENT FINDINGS

Imaging the growing skeleton is challenging and HR-pQCT protocols are not standardized across centers. Adopting a single-imaging protocol for all studies is unrealistic; thus, we present three established protocols for HR-pQCT imaging in children and adolescents and share advantages and disadvantages of each. Limiting protocol variation will enhance the uniformity of results and increase our ability to compare study results between different research groups. We outline special cases along with tips and tricks for acquiring and processing scans to minimize motion artifacts and account for growing bone. The recommendations in this review are intended to help researchers perform HR-pQCT imaging in pediatric populations and extend our collective knowledge of bone structure, architecture, and strength during the growing years.

Vitamin D and Forearm Fractures in Children Preliminary Findings: Risk Factors and Correlation between Low-Energy and High-Energy Fractures

Background: The forearm is the most common fracture site in childhood, accounting for every fourth pediatric fracture. It is well described that vitamin D is involved in the regulation of bone mineralization and skeletal homeostasis by the regulation of calcium absorption. The aim of our study was to determine the influence of 25-hydroxyvitamin D levels on forearm fracture falls in a pediatric population, depending on level of energy impact. Additionally, we also aimed to evaluate the correlation between 25-hydroxyvitamin D levels and other tested risk factors for pediatric fractures. Methods: We evaluated 50 eligible children aged 3 to 12 years with a forearm fracture. According to energy impact, patients were grouped into low-energy fractures (LEF) and high-energy fractures (HEF) groups. The general characteristics of the patients included age, gender, sport participation, and fractured bone and its localization. We analyzed 25-hydroxyvitamin D, parathyroid hormone (PTH), calcium, magnesium, phosphate, C-reactive protein (CRP) levels, and body mass index (BMI). Results: There is a significant difference in the 25-hydroxyvitamin D levels distribution between LEF and HEF (p < 0.001) and PTH levels (p = 0.002). For magnesium levels, calcium levels, phosphate levels, and CRP levels, there were no significant differences in their frequency distribution. For the group of patients with LEF, there is a significantly positive correlation between 25-hydroxyvitamin D and calcium levels (p = 0.019) and a borderline significantly positive correlation between 25-hydroxyvitamin D and magnesium levels (p = 0.050). For the group of patients with HEF, there was only a significantly positive correlation between 25-hydroxyvitamin D and PTH levels (p < 0.001). Conclusions: Children with LEF were more frequently insufficient in 25-hydroxyvitamin D levels but had normal calcium levels, compared to the ones with HEF. These findings suggest that LEF and HEF in children might to a certain degree have different pathophysiological mechanisms.

Preschool Obesity Is Associated With an Increased Risk of Childhood Fracture: A Longitudinal Cohort Study of 466,997 Children and Up to 11 Years of Follow-up in Catalonia, Spain

This study aimed to determine if having an overweight or obese range body mass index (BMI) at time of beginning school is associated with increased fracture incidence in childhood. A dynamic cohort was created from children presenting for routine preschool primary care screening, collected in the Information System for Research in Primary Care (SIDIAP) platform in Catalonia, Spain. Data were collected from 296 primary care centers representing 74% of the regional pediatric population. A total of 466,997 children (48.6% female) with a validated weight and height measurement within routine health care screening at age 4 years (±6 months) between 2006 and 2013 were included, and followed up to the age of 15, migration out of region, death, or until December 31, 2016. BMI was calculated at age 4 years and classified using WHO growth tables, and fractures were identified using previously validated ICD10 codes in electronic primary care records, divided by anatomical location. Actuarial lifetables were used to calculate cumulative incidence. Cox regression was used to investigate the association of BMI category and fracture risk with adjustment for socioeconomic status, age, sex, and nationality. Median follow-up was 4.90 years (interquartile range [IQR] 2.50 to 7.61). Cumulative incidence of any fracture during childhood was 9.20% (95% confidence interval [CI] 3.79% to 14.61%) for underweight, 10.06% (9.82% to 10.29%) for normal weight, 11.28% (10.22% to 12.35%) for overweight children, and 13.05% (10.69% to 15.41%) for children with obesity. Compared with children of normal range weight, having an overweight and obese range BMI was associated with an excess risk of lower limb fracture (adjusted hazard ratio [HR] = 1.42 [1.26 to 1.59]; 1.74 [1.46 to 2.06], respectively) and upper limb fracture (adjusted HR = 1.10 [1.03 to 1.17]; 1.19 [1.07 to 1.31]). Overall, preschool children with an overweight or obese range BMI had increased incidence of upper and lower limb fractures in childhood compared with contemporaries of normal weight. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

HR-pQCT Measures of Bone Microarchitecture Predict Fracture: Systematic Review and Meta-Analysis

High-resolution peripheral quantitative computed tomography (HR-pQCT) is a noninvasive imaging modality for assessing volumetric bone mineral density (vBMD) and microarchitecture of cancellous and cortical bone. The objective was to (1) assess fracture-associated differences in HR-pQCT bone parameters; and (2) to determine if HR-pQCT is sufficiently precise to reliably detect these differences in individuals. We systematically identified 40 studies that used HR-pQCT (39/40 used XtremeCT scanners) to assess 1291 to 3253 and 3389 to 10,687 individuals with and without fractures, respectively, ranging in age from 10.9 to 84.7 years with no comorbid conditions. Parameters describing radial and tibial bone density, microarchitecture, and strength were extracted and percentage differences between fracture and control subjects were estimated using a random effects meta-analysis. An additional meta-analysis of short-term in vivo reproducibility of bone parameters assessed by XtremeCT was conducted to determine whether fracture-associated differences exceeded the least significant change (LSC) required to discern measured differences from precision error. Radial and tibial HR-pQCT parameters, including failure load, were significantly altered in fracture subjects, with differences ranging from -2.6% (95% confidence interval [CI] -3.4 to -1.9) in radial cortical vBMD to -12.6% (95% CI -15.0 to -10.3) in radial trabecular vBMD. Fracture-associated differences reported by prospective studies were consistent with those from retrospective studies, indicating that HR-pQCT can predict incident fracture. Assessment of study quality, heterogeneity, and publication biases verified the validity of these findings. Finally, we demonstrated that fracture-associated deficits in total and trabecular vBMD and certain tibial cortical parameters can be reliably discerned from HR-pQCT-related precision error and can be used to detect fracture-associated differences in individual patients. Although differences in other HR-pQCT measures, including failure load, were significantly associated with fracture, improved reproducibility is needed to ensure reliable individual cross-sectional screening and longitudinal monitoring. In conclusion, our study supports the use of HR-pQCT in clinical fracture prediction. © 2019 American Society for Bone and Mineral Research.

Reliability of Annual Changes and Monitoring Time Intervals for Bone Strength, Size, Density, and Microarchitectural Development at the Distal Radius and Tibia in Children: A 1-Year HR-pQCT Follow-Up

High-resolution peripheral quantitative computed tomography (HR-pQCT) imaging, together with computational finite element analysis (FEA), offers an attractive, noninvasive tool to quantify bone strength development in pediatric studies. Evidence of annual changes and errors in repeated HR-pQCT measures is limited, and time intervals required to reliably capture changes in children's bone strength or microarchitecture have not yet been defined. Our objectives were: (1) to quantify annual changes in bone strength and microarchitectural properties; (2) to define precision errors for pediatric bone strength outcomes; (3) to characterize annual changes in contrast to pediatric precision errors; and (4) to estimate monitoring time intervals (MTIs) required to reliably characterize bone development at the distal radius and tibia. We obtained distal radius (7% of ulnar length) and tibia (8%) bone properties using HR-pQCT and FEA from 38 follow-up study participants (21 girls) at baseline (mean age 10.6 years, SD 1.7 years) and after 1 year; and from 32 precision study participants (16 girls) at baseline (mean age 11.3 years, SD 1.6 years) and after 1 week. We characterized mean annual changes (paired t tests) contrasted to pediatric precision errors (CV%_RMS ) and estimated MTIs. Annual increases in bone strength, total area, cortical thickness, and density ranged between 3.0% and 25.3% and 2.4% and 15.6% at the distal radius and tibia, respectively. Precision errors for all bone strength outcomes were ≤6.8% and ≤5.1% at the distal radius and tibia, respectively, and appeared lower than annual gains in bone strength at both sites. Cortical porosity decreased 19.6% at the distal radius and 6.6% at the distal tibia; these changes exceeded respective precision errors, indicating cortical bone consolidation. MTIs ranged between 0.5 years and infinity at the distal radius and 0.5 and 5.9 years at the distal tibia. Estimated MTIs suggest that pediatric bone strength, cortical bone density, and porosity development can be reliably monitored with annual measurements. © 2019 American Society for Bone and Mineral Research.

The Cost and Utility of Postreduction Radiographs After Closed Reduction of Pediatric Wrist and Forearm Fractures

BACKGROUND

Formal radiographs are frequently obtained after reduction of closed pediatric wrist and forearm fracture performed under mini C-arm fluoroscopy. However, their utility has not been clearly demonstrated to justify the increased time, cost, and radiation exposure. We hypothesized that formal postreduction radiographs do not affect the rereduction rate of pediatric wrist and forearm fractures. We further sought to determine the time, monetary, and opportunity costs associated with obtaining these radiographs.

METHODS

A total of 119 patients presented to our urban, level I pediatric trauma center from April 2015 to September 2015 with isolated, closed wrist and forearm fractures who underwent sedation and reduction using mini C-arm fluoroscopy. Demographic and injury variables were collected, along with incidence of rereduction and need for future surgery. Time intervals for sedation, awaiting x-ray, and total encounter periods were noted, and total direct and variable indirect costs for each encounter were obtained from our institution's cost accounting and billing databases. Marginal time and monetary costs were noted and further calculated as a percentage of the total encounter. Opportunity costs were calculated for the time spent obtaining the postreduction radiographs.

RESULTS

Of 119 patients with isolated, closed wrist or forearm fractures, none required rereduction after initial reduction using sedation and mini C-arm fluoroscopy. Postreduction radiographs required an average of 26.2 minutes beyond the end of sedation, or 7.3% of the encounter time and cost. The direct cost of the x-ray was 2.6% of the encounter cost. With our institution's annual volume, this time could have been used to see an additional 656 patients per year.

CONCLUSIONS

Postreduction formal radiographs did not result in changes in management. There are significant direct and opportunity costs for each patient who undergoes additional formal radiographs. Pediatric patients with isolated, closed wrist or forearm fractures do not routinely need formal radiographs after reduction under mini C-arm fluoroscopy.

LEVEL OF EVIDENCE

Level IV-Therapeutic.

Bone Strength in Girls and Boys After a Distal Radius Fracture: A 2-Year HR-pQCT Double Cohort Study

We recently reported impaired bone strength in girls with low- to moderate-energy distal radius fractures (Fx) compared with girls with no history of forearm fractures (Non-Fx). We aimed to determine whether bone strength deficits observed at baseline were still present after 2 years. We assessed bone strength, microarchitecture, and bone mineral density (BMD) of the non-fractured (Fx) and non-dominant (Non-Fx) distal radius (7% site) at baseline, 12, and 24 months using high-resolution pQCT (Scanco Medical, Brüttisellen, Switzerland) in 104 girls (aged 11.0 ± 1.7 years; 47 Fx, 57 Non-Fx) and 157 boys (aged 12.7 ± 1.7 years; 86 Fx, 71 Non-Fx). Bone outcomes included total area (Tt.Ar) and bone mineral density (Tt.BMD), trabecular bone volume ratio (BV/TV), thickness (Tb.Th), separation (Tb.Sp), and number (Tb.N), and cortical BMD (Ct.BMD), thickness (Ct.Th), and porosity (Ct.Po). We used finite element analysis to estimate bone strength (failure load [F.Load]; ultimate stress [U.Stress]; load-to-strength ratio). We used sex-specific mixed-effects models to compare bone outcomes between Fx and Non-Fx over 2 years. In girls, those with fractures had 18% to 24% lower U.Stress and 5% to 9% lower Tt.BMD than Non-Fx at all time points (p < 0.017). In secondary analysis by fracture degree, girls with low-energy (LE) fractures had 19% to 21% lower F.Load, 25% to 47% lower U.Stress, 11% to 14% lower Tt.BMD, and 11% to 15% lower BV/TV than Non-Fx at all time points (p < 0.017). In contrast, boys' bone outcomes were similar between Fx and Non-Fx at all time points. In secondary analysis by fracture degree, boys with LE fractures had 10% lower Tt.BMD and 10% lower Ct.Th compared with Non-Fx at 12 months only. Deficits in distal radius bone strength and trabecular bone microarchitecture appear to track across 2 years after a forearm fracture in girls but not in boys. Longer follow-up is needed to determine whether deficits persist into adulthood in women and how they may influence future risk of fragility fracture. © 2017 American Society for Bone and Mineral Research.

Precision of bone density and micro-architectural properties at the distal radius and tibia in children: an HR-pQCT study

Precision errors need to be known when monitoring bone micro-architecture in children with HR-pQCT. Precision errors for trabecular bone micro-architecture ranged from 1 to 8% when using the standard evaluation at the radius and tibia. Precision errors for cortical bone micro-architecture ranged from 1 to 11% when using the advanced cortical evaluation.

INTRODUCTION

Our objective was to define HR-pQCT precision errors (CV%_RMS) and least significant changes (LSCs) at the distal radius and tibia in children using the standard evaluation and the advanced cortical evaluation.

METHODS

We scanned the distal radius (7% of ulnar length) and tibia (8% of tibia length) of 32 children (age range 8-13; mean age 11.3; SD 1.6 years) twice (1 week apart) using HR-pQCT (XtremeCT1). We calculated root-mean-squared coefficients of variation (CV%_RMS) to define precision errors and LSC to identify differences required to detect change.

RESULTS

Precision errors ranged between 1-8 and 1-5% for trabecular bone outcomes (obtained with standard evaluation) and between 1.5-11 and 0.5-6% for cortical bone outcomes (obtained with advanced cortical evaluation) at the distal radius and tibia, respectively. Related LSCs ranged between 3-21 and 3-14% for trabecular bone outcomes and between 4-30 and 2-16% for cortical bone outcomes at the distal radius and tibia, respectively.

CONCLUSIONS

HR-pQCT precision errors were between 1 and 8% (LSC 3-21%) for trabecular bone outcomes and 1 and 11% (LSC 2-30%) for cortical bone outcomes at the radius and tibia in children. Cortical bone outcomes obtained using the advanced cortical evaluation appeared to have lower precision errors than cortical outcomes derived using the standard evaluation. These findings, combined with better-defined cortical bone contours with advanced cortical evaluation, indicate that metrics from advanced cortical evaluation should be utilized when monitoring cortical bone properties in children.

Bone Strength Estimated by Micro-Finite Element Analysis (µFEA) Is Heritable and Shares Genetic Predisposition With Areal BMD: The Framingham Study

Genetic factors contribute to the risk of bone fractures, partly because of effects on bone strength. High-resolution peripheral quantitative computed tomography (HR-pQCT) estimates bone strength using micro-finite element analysis (µFEA). The goal of this study was to investigate if the bone failure load estimated by HR-pQCT-based µFEA is heritable and to what extent it shares genetic regulation with areal bone mineral density (aBMD). Bone microarchitecture was measured by HR-pQCT at the ultradistal tibia and ultradistal radius in adults from the Framingham Heart Study (n = 1087, mean age 72 years; 57% women). Radial and tibial failure load in compression were estimated by µFEA. Femoral neck (FN) and ultradistal forearm (UD) aBMD were measured by dual-energy X-ray absorptiometry (DXA). Heritability (h2 ) of failure load and aBMD and genetic correlations between them was estimated adjusting for covariates (age and sex). Failure load values at the non-weight-bearing ultradistal radius and at the weight-bearing ultradistal tibia were highly correlated (r = 0.906; p < 0.001). Estimates of h2 adjusted for covariates were 0.522 for the radius and 0.497 for the tibia. Additional adjustment for height did not impact on the h2 results, but adjustment for aBMD at the UD and FN somewhat decreased h2 point estimates: 0.222 and 0.380 for radius and tibia, respectively. In bivariate analysis, there was a high phenotypic and genetic correlation between covariate-adjusted failure load at the radius and UD aBMD (ρP  = 0.826, ρG  = 0.954, respectively), whereas environmental correlations were lower (ρE  = 0.696), all highly significant (p < 0.001). Similar correlations were observed between tibial failure load and femoral neck aBMD (ρP  = 0.577, ρG  = 0.703, both p < 0.001; ρE  = 0.432, p < 0.05). These data from adult members of families from a population-based cohort suggest that bone strength of distal extremities estimated by micro-finite element analysis is heritable and shares some genetic composition with areal BMD, regardless of the skeletal site. © 2017 American Society for Bone and Mineral Research.

Bone Mineralization and Fracture Risk Assessment in the Pediatric Population

Identifying children most susceptible to clinically significant fragility fractures (low trauma fractures or vertebral compression fractures) or recurrent fractures is an important issue facing general pediatricians and subspecialists alike. Over the last decade, several imaging technologies, including dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, have become useful to identify abnormal bone mineralization in children and in adolescents. This review aimed to summarize the latest literature on the utility of these modalities as they pertain to use in pediatrics. In addition, we review several disease states associated with poor bone health and increased fracture risk in children, and discuss the implications of low bone mineral density in these patients. Finally, we will highlight the gaps in knowledge with regard to pediatric bone health and make recommendations for future areas of research.

Muscle power in children, youth and young adults who acquired HIV perinatally

OBJECTIVES

To compare muscle power between youth who acquired HIV perinatally and HIV unexposed uninfected (HUU) youth.

METHODS

We assessed muscle power (relative to body mass, P_max/mass), muscle force normalized to body weight (F_max/BW), force efficiency, jump height (H_max) and velocity (V_max) during a single two-legged jump with hands on waist on a force platform (Leonardo) in HIV+ youth (n=35, 9-21 y). Thirty-three and 22 participants returned at 12- and 24-months, respectively. We compared age- and sex-specific z-scores in the HIV+ youth to those in HUU controls (n=716, 9-21 y) adjusting for height and muscle cross-sectional area (MCSA, by pQCT).

RESULTS

At baseline, z-scores for Pmax/mass, F_max/BW and V_max were less than 1 standard deviation lower than HUU after adjusting for height and MCSA (p⟨0.05). P_max/mass z-score was negatively associated with level of immunosuppression (p=0.013), but this relationship was not significant after adjusting for height and MCSA (p=0.07). Z-scores for all mechanography outcomes remained stable over time in HIV+ youth.

CONCLUSION

Small deficits in muscle power were apparent in children and youth who acquired HIV perinatally, and the trajectory of muscle power did not change over two years. Further study is needed to identify effective strategies to improve dynamic muscle function in this population.

A Pediatric Patient with a CYP24A1 Mutation: Four Years of Clinical, Biochemical, and Imaging Follow-Up

BACKGROUND

A female infant was admitted to hospital due to failure to thrive. She presented hypercalcemia (4.09 mmol/L, normal range: 2.2-2.65 mmol/L), high 25-hydroxyvitamin D (283 nmol/L, normal range: 75-250 nmol/L), 1,25-dihydroxyvitamin D in the upper normal range, and low parathyroid hormone. Vitamin D intoxication was suspected. The patient had received routine rickets prophylaxis.

METHODS

Williams-Beuren syndrome was genetically excluded. Sequencing of CYP24A1 showed 2 mutations: c.443T>C and c.1186C>T.

RESULTS

The patient's clinical status improved after intravenous rehydration, cessation of supplementation, and on a low-calcium diet. 25-Hydroxyvitamin D concentrations normalized within days, while 1,25-dihydroxyvitamin D remained in the upper normal range. We also investigated our patient's bone health.

CONCLUSION

The patient was hospitalized initially on suspicion of vitamin D intoxication but proved to be a case of compound heterozygosity. Data on the long-term clinical and biochemical evolution of patients with idiopathic infantile hypercalcemia are sparse. Our follow-up showed seasonal variations of vitamin D and calcium parameters, with no influence on kidney function or bone health for the investigated period.

Sex Differences and Growth-Related Adaptations in Bone Microarchitecture, Geometry, Density, and Strength From Childhood to Early Adulthood: A Mixed Longitudinal HR-pQCT Study

Sex differences in bone strength and fracture risk are well documented. However, we know little about bone strength accrual during growth and adaptations in bone microstructure, density, and geometry that accompany gains in bone strength. Thus, our objectives were to (1) describe growth related adaptations in bone microarchitecture, geometry, density, and strength at the distal tibia and radius in boys and girls; and (2) compare differences in adaptations in bone microarchitecture, geometry, density, and strength between boys and girls. We used HR-pQCT at the distal tibia (8% site) and radius (7% site) in 184 boys and 209 girls (9 to 20 years old at baseline). We aligned boys and girls on a common maturational landmark (age at peak height velocity [APHV]) and fit a mixed effects model to these longitudinal data. Importantly, boys showed 28% to 63% greater estimated bone strength across 12 years of longitudinal growth. Boys showed 28% to 80% more porous cortices compared with girls at both sites across all biological ages, except at the radius at 9 years post-APHV. However, cortical density was similar between boys and girls at all ages at both sites, except at 9 years post-APHV at the tibia when girls' values were 2% greater than boys'. Boys showed 13% to 48% greater cortical and total bone area across growth. Load-to-strength ratio was 26% to 27% lower in boys at all ages, indicating lower risk of distal forearm fracture compared with girls. Contrary to previous HR-pQCT studies that did not align boys and girls at the same biological age, we did not observe sex differences in Ct.BMD. Boys' superior bone size and strength compared with girls may confer them a protective advantage. However, boys' consistently more porous cortices may contribute to their higher fracture incidence during adolescence. Large prospective studies using HR-pQCT that target boys and girls who have sustained a fracture are needed to verify this. © 2016 American Society for Bone and Mineral Research.

Prevalence of Fracture in Healthy Iranian Children Aged 9-18 Years and Associated Risk Factors; A Population Based Study

OBJECTIVE

To determine the prevalence of fractures and associated risk factors in healthy Iranian children and adolescents.

METHODS

In this cross sectional population based study, 478 healthy Iranian children and adolescents aged 9-18 years old participated. Baseline data and bone mineral content and density have been determined. One questionnaire was completed for all individuals including previous history of fracture, its location, and level of trauma. Albumin, calcium, phosphorus, alkaline phosphatase, and vitamin D levels were measured.

RESULTS

We found a prevalence of 12.9% for fracture. (34.5% for girls and 65.5% for boys); about 71% suffered long bone fracture with distal forearm as the most common site. Totally 58% of the boys and 54% of the girls had fracture with low-energy trauma. The fracture group had lower bone mineral apparent density in the lumbar spine (0.19±0.04 vs. 0.20±0.03, p=0.04), lower serum albumin (4.6±0.5 vs 4.8±0.4, p=0.02), and higher serum alkaline phosphatase level (446±174 vs. 361±188, p=0.02) compared with non-fracture subjects. By logistic regression analysis, we found a significant association for sex, and bone mineral content of the lumbar spine with fracture (p=0.003, p=0.039).

CONCLUSION

Compared to other studies, our subjects had lower rate of fracture. We found an association between low bone density and fracture in children and adolescents. This finding has important implications for public health. Further research may contribute to recognition of preventive measures.

Reference data for jumping mechanography in Canadian children, adolescents and young adults

OBJECTIVES

To provide age- and sex-specific reference data for mechanography-derived parameters of muscle function in Canadian children and youth using the single two-legged jump (S2LJ) with hands-on-waist.

METHODS

Our sample included 2017 observations from 715 participants (9-21 years; 338 girls). Participants performed three S2LJ with hands-on-waist on a force platform (Leonardo Mechanograph, Novotec). Outcomes were maximum peak power (P_max), P_max/mass, peak force/body weight (F_max/BW), force efficiency, maximum jump height (H_max), and velocity (V_max). We used the LMS method to construct age- and sex-specific percentile curves and mixed effects models to examine sex and ethnic differences.

RESULTS

With the exception of Efficiency, mechanography outcomes were greater in girls (4-40%, p<0.05) than boys at age 9. Boys' advantage in mechanography parameters emerged in adolescence (age 11-13 years; 3-65%, p<0.05) and persisted into young adulthood, except for F_max/BW which was not greater in boys until age 17 (4-10%, p<0.05). Mechanography outcomes were 3-9% (p<0.05) greater in Asian compared with white participants.

CONCLUSIONS

We provide the first reference data for the S2LJ using the hands-on-waist protocol in children, youth and young adults. These data support previous findings using freely moving arms and can be used when evaluating muscle function in pediatric studies.

No difference in the level of physical activity between children who have or have never sustained a fracture

This study investigates whether children with an acute fracture have a different level of physical activity compared to children who have never sustained a fracture, as measured by the Physical Activity Questionnaire for older children (PAQ-C). The PAQ-C scores of 683 children (295 girls) aged 6-12 years (mean age 9.4 years) who presented to our institution with an acute fracture were compared to the PAQ-C scores of 151 random children (81 girls) aged 6-12 years (mean 9.1 years) in the same area who had never sustained a fracture. Multivariate regression analysis was employed, controlling for age and gender. The mean PAQ-C score of the children who presented to the institution with an acute fracture was 2.85 (95% confidence interval [CI], 2.80-2.91). For the children who had never sustained a fracture, the mean PAQ-C score was 2.78 (95% CI, 2.69-2.87). If there is a true difference in the level of physical activity between children who have or have never sustained a fracture, the PAQ-C questionnaire is not sensitive enough to identify it.

Forearm bone mineralization in recently diagnosed female adolescents with a premenarchal onset of anorexia nervosa

OBJECTIVE

Data available on bone mineralization by peripheral quantitative computed tomography (pQCT) in adolescents with an early onset anorexia nervosa (AN) is limited. We investigated whether a disturbed bone mineralization can be observed at the distal radius in recently diagnosed female adolescents with AN and a premenarchal onset of this disease.

METHOD

Twenty-four premenarchal patients with AN and 22 healthy females which were age and height matched, were selected from our reference database; both groups underwent a pQCT bone assessment at the distal radius of the nondominant arm.

RESULTS

The patients age ranged between 13.3 and 18.4 years. Their percent weight loss ranged between 5 and 36% (median 23%) and occurred within the preceding 3 to 44 months. Trabecular volumetric bone mineral density of the patient group was significantly lower than the comparison group (185.6 ± 30.2 vs.209.3 ± 34.0 mm(2) ; p = 0.02). Bone cross-sectional area, bone mineral content, total volumetric bone mineral density and periosteal circumference were also lower, albeit not significantly. The bone parameters were unrelated to the under nutrition severity and duration.

DISCUSSION

In premenarchal patients with AN the trabecular bone mineralization of the forearm is significantly reduced, this might be an early indicator of altered bone mineral accrual. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2016; 49:809-812).

Differences in childhood adiposity influence upper limb fracture site

INTRODUCTION

Although it has been suggested that overweight and obese children have an increased risk of fracture, recent studies in post-menopausal women have shown that the relationship between obesity and fracture risk varies by fracture site. We therefore assessed whether adiposity and overweight/obesity prevalence differed by upper limb fracture site in children.

METHODS

Height, weight, BMI, triceps and subscapular skinfold thickness (SFT) were measured in children aged 3-18 years with an acute upper limb fracture. Data was compared across three fracture sites (hand, forearm and upper arm/shoulder [UA]), and to published reference data.

RESULTS

401 children (67.1% male, median age 11.71 years, range 3.54-17.27 years) participated. 34.2%, 50.6% and 15.2% had fractures of the hand, forearm and UA, respectively. Children with forearm fractures had higher weight, BMI, subscapular SFT and fat percentage z-scores than those with UA fractures (p<0.05 for all). SFT and fat percentage z-scores were also higher in children with forearm fractures compared to hand fractures, but children with hand and UA fractures did not differ. Overweight and obesity prevalence was higher in children with forearm fractures (37.6%) than those with UA fractures (19.0%, p=0.009). This prevalence was also higher than the published United Kingdom population prevalence (27.9%, p=0.003), whereas that of children with either UA (p=0.13) or hand fractures (29.1%, p=0.76) did not differ. These differences in anthropometry and overweight/obesity prevalence by fracture site were evident in boys, but not present in girls.

CONCLUSION

Measurements of adiposity and the prevalence of overweight/obesity differ by fracture site in children, and in particular boys, with upper limb fractures.