Bone densities and bone size at the distal radius in healthy children and adolescents: a study using peripheral quantitative computed tomography

Cortical impairment and reduced muscle mass in children and young adults with nephropathic cystinosis

Nephropathic cystinosis is an orphan autosomal recessive lysosomal storage disease characterized by a deficiency of cystinosin, a cystine transporter protein, leading to tissue damage, primarily in the kidney and cornea. With the introduction of cystine-depleting therapy with cysteamine and the possibility to survive to adulthood, new challenges of skeletal complications are a concern, with sparse data available regarding bone development. The aim of the current study was to gain more information on bone density and geometry in these patients. Fifty-one patients (29 males, 22 females) with genetically proven nephropathic cystinosis were clinically evaluated with a medical history, physical examination, grip strength measurements, and biochemical and imaging studies. Bone mineral density, bone geometry, and muscle cross sectional area were measured, and muscle was evaluated. Results were compared with age- and gender-specific reference data. Z-scores for height (mean [M] = -1.75, standard deviation [SD] = 1.43), weight (M = -1.67, SD = 1.29), and BMI (M = -0.98, SD = 1.29) were lower than reference data. Medullary cross-sectional area (CSA) and cortical density z-scores were not compromised (M = 0.12, SD = 1.56 and M = -0.25, SD = 1.63, respectively), but cortical CSA z-scores and Strength-Strain Index (SSI) were reduced (M = -2.16, SD = 1.08, M = -2.07, SD = 1.08). Muscular deficits were reflected by reduced z-scores for muscle CSA (M = -2.43, SD = 1.27) and grip strength (M = -3.01, SD = 1.10), along with jump force (34% lower than reference value). Multiple regression analyses indicated an association of muscle mass with medullary CSA and SSI, but not with cortical CSA. While bone density parameters were normal, bone geometry was altered, resulting in a thinner cortex with possible impact on bone strength. Muscle weakness be partially responsible for altered bone geometry and could provide a potential treatment target.

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.

Bone mass and biomarkers in young women with anorexia nervosa: a prospective 3-year follow-up study

INTRODUCTION

Anorexia nervosa (AN) increases the risk of impaired bone health, low areal bone mineral density (aBMD), and subsequent fractures. This prospective study investigated the long-term effects of bone and mineral metabolism on bone and biomarkers in 22 women with AN.

MATERIALS AND METHODS

Body composition and aBMD were measured by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography. Total and free 25-hydroxyvitamin D (25OHD), C-terminal collagen cross-links (CTX), osteocalcin, bone-specific alkaline phosphatase (BALP), leptin, sclerostin, and oxidized/non-oxidized parathyroid hormone (PTH) were analyzed before and after 12 weeks of intensive nutrition therapy and again 3 years later. An age-matched comparison group of 17 healthy women was recruited for the 3-year follow-up.

RESULTS

Body mass index (BMI) and fat mass increased from baseline to 3 years in women with AN. Sclerostin decreased during nutrition therapy and further over 3 years, indicating reduced bone loss. CTX was elevated at baseline and after 12 weeks but decreased over 3 years. BALP increased during nutrition therapy and stabilized over 3 years. Free 25OHD was stable during treatment but decreased over 3 years. Non-oxidized PTH was stable during treatment but increased over 3 years. Trabecular volumetric BMD in AN patients decreased during the first 12 weeks and over 3 years despite stable BMI and bone biomarkers implying increased BMD.

CONCLUSION

Our findings highlight the importance of early detection and organized long-term follow-up of bone health in young women with a history of AN.

The relationship between circulating hormone levels, bone turnover markers and skeletal development in healthy boys differs according to maturation stage

INTRODUCTION

This study investigates peri-pubertal changes in bone turnover markers, Wnt-signalling markers, insulin-like growth factor-1 (IGF-1) and sex steroid levels, and how they reflect skeletal development in peri-pubertal boys.

MATERIALS AND METHODS

Population-based study in 118 peri-pubertal boys from the NINIOS cohort (age range at baseline 5.1-17.3 years) with repeated measurements at baseline and after two years. Serum levels of the classical bone turnover markers (BTM) procollagen type 1 N-terminal propeptide and carboxy-terminal collagen crosslinks, as well as sex-hormone binding globulin, IGF-1, osteoprotegerin, sclerostin and dickkopf-1 were measured using immunoassays. Sex steroids (estradiol, testosterone, and androstenedione) were measured using mass spectrometry and free fractions calculated. Dual energy x-ray absorptiometry was used for bone measurements at the lumbar spine and whole body. Volumetric bone parameters and bone geometry at the proximal and distal radius were assessed by peripheral QCT. Pubertal development was categorized based on Tanner staging.

RESULTS

During puberty, sex steroid and IGF-1-levels along with most parameters of bone mass and bone size increased every next Tanner stage. In contrast, classical bone turnover markers and sclerostin peaked around mid-puberty, with subsequent declines towards adult values in late puberty. Especially classical BTM and sex steroid levels showed consistent associations with areal and volumetric bone parameters and bone geometry. However, observed associations differed markedly according to pubertal stage and skeletal site.

CONCLUSION

Serum levels of sex steroids, IGF-1 and bone metabolism markers reflect skeletal development in peri-pubertal boys. However, skeletal development during puberty is nonlinear, and the relations between skeletal indices and hormonal parameters are nonlinear as well, and dependent on the respective maturation stage and skeletal site.

A systematic review and meta-analysis of pediatric normative peripheral quantitative computed tomography data

BACKGROUND

Peripheral-quantitative computed tomography (pQCT) provides an intriguing diagnostic alternative to dual-energy X-ray absorptiometry (DXA) since it can measure 3D bone geometry and differentiate between the cortical and trabecular bone compartments.

OBJECTIVE

To investigate and summarize the methods of pQCT image acquisition of in children, adolescents and/or young adults (up to age 20) and to aggregate the published normative pQCT data.

EVIDENCE ACQUISITION

A literature search was conducted in MEDLINE and EMBASE from 1947 to December 2020. Quality of the included articles was assessed using Standards for Reporting of Diagnostic Accuracy (STARD) scoring system and United States Preventative Services Task Force (USPSTF) Study Design Categorization. Seven articles, encompassing a total of 2134 participants, were aggregated in the meta-analysis. Due to dissimilar age groups and scan sites, only seven pQCT parameters of the 4% radius, 4% tibia and 38% tibia were analyzed in this meta-analysis.

EVIDENCE SYNTHESIS

The overall fixed-effect estimates of trabecular vBMD of the 4% radius were: 207.16 (201.46, 212.86), mg/cm3 in 8 to 9 year-old girls, 210.42 (201.91, 218.93)in 10 to 12 year-old girls, 226.99 (222.45, 231.54) in 12 to 13 year-old girls, 259.97 (254.85, 265.10) in 12 to 13 year-old boys and 171.55 (163.41,179.69) in 16 to 18 year-old girls. 21 of 54 (38.9%) primary papers received a 'good' STARD quality of reporting score (<90 and 70 ≥ %) (mean STARD score of all articles = 69.4%). The primary articles of this review had a 'good' level USPSTF study design categorization. However, most of the normative data in these articles were non-comparable and non-aggregable due to a lack of standardization of reference lines, acquisition parameters and/or age at acquisition.

CONCLUSION

There is not sufficient evidence to suggest that pQCT is appropriately suited for use in the pediatric clinical setting. Normative pediatric data must be systematically derived for pQCT should it ever be a modality that is used outside of research.

CLINICAL IMPACT

We demonstrate the need for normative pQCT reference data and for clinical guidelines that standardize pediatric acquisition parameters and delineate its use in pediatric settings.

Bone health in long-term survivors of pediatric acute lymphoblastic leukemia. An assessment by peripheral quantitative computed tomography

BACKGROUND

Loss of bone mineral is a common concomitant of the treatment of acute lymphoblastic leukemia (ALL) due mainly to chemotherapy, especially with corticosteroids. Osteopenia/osteoporosis may be encountered long into survivorship. Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry is limited to two-dimensionality and cannot distinguish trabecular from cortical bone.

METHODS

A sample of 74 subjects, ages 13.5-38.3 years more than 10 years from diagnosis, underwent peripheral quantitative computed tomography (pQCT) at metaphyseal (trabecular bone) and diaphyseal (cortical bone) sites in the radius and tibia. pQCT provides three-dimensional assessment of bone geometry, density, and architecture.

RESULTS

Average values in multiple metrics were similar to those in healthy individuals, but deficits in both trabecular and cortical bones were revealed by lower Z scores using an ethnically comparable sample of healthy individuals. Connectivity, a measure of bone architecture and a surrogate measure of bone strength, was lower in females than males. Survivors of standard-risk ALL had greater connectivity in and more compact trabecular bone than high-risk survivors who had received more intensive osteotoxic chemotherapy. There were no statistically significant differences in any of the metrics at any of the sites between subjects who had or had not a history of fracture, cranial irradiation, or use of a bisphosphonate.

CONCLUSIONS

These long-term survivors of ALL have somewhat compromised bone health, but data in comparable healthy populations are limited. Longitudinal studies in larger and more ethnically diverse cohorts will provide greater insight into bone health in this vulnerable population.

The Significance of the FTO Gene for Weight and Body Composition in Swedish Women With Severe Anorexia Nervosa During Intensive Nutrition Therapy

OBJECTIVE

The aim of this prospective study was to investigate the potential influence of the fat mass and obesity-associated gene (FTO), SNP rs9939609, on body mass index (BMI) and body composition in women with anorexia nervosa (AN) undergoing intensive nutrition therapy.

METHOD

Twenty-five female patients with AN (20.1 ± 2.3 years; BMI, 15.5 ± 0.9 kg/m²) were included for 12 weeks of treatment with a high-energy diet. FTO was genotyped and body composition parameters were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography at baseline and after 12 weeks.

RESULTS

The distribution of the different FTO genotypes were as follows: AA, 24%; TA, 48%; and TT, 28%. Patients gained a median of 9.8 kg (range, 5.5-17.0 kg) and BMI increased to 19.0 ± 0.9 kg/m². The increase in BMI, fat mass, and the quotient fat/muscle area was significant for the TT and TA genotype groups. Total lean mass was stable in all genotype groups. We could not demonstrate any difference among the 3 FTO genotypes related to the increases in BMI during nutrition therapy when the additive, dominant, and recessive models of inheritance were applied.

CONCLUSIONS

Irrespective of the FTO genotype, there was no difference in weight response during nutrition therapy. Hence, in this small study there was limited support for individualized nutrition therapy for AN based on FTO genotype.

Bone microarchitectural alterations in boys with Duchenne muscular dystrophy on long-term glucocorticoid treatment

INTRODUCTION

Osteoporosis is a major health issue in boys with Duchenne muscular dystrophy (DMD). Data on the specific bone deficits and microarchitectural alterations in children with DMD were limited. This study aimed to assess the bone microarchitectural alterations in boys with DMD on long-term glucocorticoid using high-resolution peripheral quantitative computed tomography (HR-pQCT).

MATERIALS AND METHODS

This was a cross-sectional, case-control study. Boys with DMD older than 5 years with no prior history of symptomatic fracture and had been on long-term glucocorticoid treatment were recruited from a single tertiary centre. For each participant, three gender- and age-matched controls were selected randomly from an existing HR-pQCT database of healthy individuals.

RESULTS

Nine boys with DMD at a median age of 9.3 years were included. Three were found to have asymptomatic vertebral compression fracture. The HR-pQCT findings of these nine boys were compared with 27 healthy controls. Trabecular microstructure indices at the distal radius were significantly lower but the cortical vBMD was significantly higher in the DMD boys when compared with healthy controls.

CONCLUSION

Lower microarchitectural measurement of trabecular bones, but higher cortical vBMD, was observed in DMD boys on long-term oral glucocorticoid. The results from this study provide preliminary, yet important insights into the bone microarchitecture of this group of patients.

A prospective case-control pilot study to evaluate bone microarchitecture in children and teenagers on long-term parenteral nutrition using HR-pQCT

Long-term parenteral nutrition (PN) may induce bone complications. Tridimensional bone imaging techniques such as high-resolution peripheral quantitative computed tomography (HR-pQCT) allow the assessment of both compartmental volumetric densities and microarchitecture. Our aim was to evaluate these parameters in children and teenagers receiving long-term PN. This cross-sectional, case–control study included children older than 9 years undergoing PN for at least 2 years. They were age-, gender- and puberty-matched with healthy controls (1:2). Evaluation included biological assessment of bone metabolism (serum calcium, phosphate, and albumin; urinary calcium and creatinine; 25-OH vitamin D, osteocalcin and PTH), dual X-ray absorptiometry (DXA) and HR-pQCT at the ultradistal tibia and radius. Results are presented as median [range]. Eleven patients (3 girls) with a median age of 16 [9–19] years were included. Bone parameters assessed by HR-pQCT at the ultradistal radius and tibia were similar in patients and controls. Parathyroid hormone (PTH) levels were higher (14 [7–115] vs 16 [12–27]) and osteocalcin levels were lower (44 [15–65] vs 65 [38–142]) in patients than in controls, although within the normal range. Conclusions: there were no differences for compartmental bone densities and microarchitecture in patients undergoing chronic PN. Further longitudinal studies are required to confirm these quite reassuring preliminary results.

Trabecular Bone Score has Poor Association With pQCT Derived Trabecular Bone Density in Indian Children With Type 1 Diabetes and Healthy Controls

BACKGROUND

In children with type 1 diabetes mellitus (T1DM), low trabecular volumetric bone mineral density (Trab vBMD) has been reported. However, studies using the trabecular bone score (TBS) are scarce. The objective of our study was to assess areal bone mineral density at the lumbar spine (LS aBMD), the TBS and Trab vBMD in children with type 1 diabetes in comparison with healthy controls and to assess the relationship of Trab vBMD with TBS.

METHODS

A total of 205 children were assessed for their LS bone mineral content (BMC) and LS aBMD by dual energy x-ray absorptiometry (DXA) and Trab vBMD at distal radius by peripheral quantitative computed tomography (pQCT). Machine generated Z-scores for both LS aBMD and Trab vBMD were used. The retrospective DXA LS scans in children with T1DM (n=137, age 13.1 ± 3.2 years) and controls (n = 68, age 13.0 ± 2.7 years) were analysed with a research trial version of TBS iNsight software (Medimaps Group). The established TBS cut-offs were used to categorize TBS.

RESULTS

The mean LS BMC, LS aBMD, TBS and Trab vBMDs were lower in children with T1DM. TBS was positively correlated with LS aBMD but not with Trab vBMD in both groups. Distribution of T1DM and control children was similar in the TBS categories. Over a fourth of the T1DM children with low Trab vBMD (below -2 Z score) had normal TBS, while, in children with LS aBMD Z-score > -2 from both groups, >50% had degraded or partially degraded TBS. Degraded TBS was seen in half the control children although none of them had low Trab vBMD.

CONCLUSION

We found poor correlation between TBS and Trab vBMD in paediatric diabetic and healthy population. Our results also suggest establishing paediatric TBS cut offs in improving the classification of children having degraded trabecular bone.

Studying bone mineral density in young people: The complexity of choosing a pQCT reference database

BACKGROUND

Many chronic illnesses affect bone health, and commonly lead to mineralization abnormalities in young people. As cortical and trabecular bone may be differentially affected in certain diseases, an imaging technique that allows for detailed study of the bone structure is required. Peripheral quantitative computed tomography (pQCT) overcomes the limitations of dual energy X-ray absorptiometry (DXA) and is perhaps more widely available for use in research than bone biopsy. However, in contrast to DXA, where there are large reference datasets, this is not the case for pQCT.

METHODS

Fifty-five children and young adults aged 7 to 30 years had the non-dominant tibia scanned at the 3% & 4% sites for trabecular bone mineral density and the 38% site for cortical bone mineral density and bone mineral content. Image acquisition and analysis was undertaken according to the protocols of two of the largest reference datasets for tibial pQCT. The Z-scores generated were compared to examine the differences between protocols and the differences from the expected median of zero in a healthy population.

RESULTS

The trabecular bone mineral density Z-scores generated by the two protocols were similar. The same was true for cortical mineral content Z-scores at the 38% site. Cortical bone mineral density was significantly different between protocols and likely affected by differences in the ethnicity of our cohort compared to the reference datasets. Only one reference dataset extended from childhood to young adulthood. Only trabecular bone mineral density, periosteal and endosteal circumference Z-scores from one methodology were not significantly biased when tested for deviation of the median from zero.

CONCLUSIONS

pQCT is a useful tool for studying trabecular and cortical compartments separately but, there are variations in pQCT scanning protocols, analysis methodology, and a paucity of reference data. Reference datasets may not be generalizable to local study populations, even when analysed using identical analysis protocols.

Altered cortical bone strength and lean mass in young women with long-duration (19 years) type 1 diabetes

To investigate bone health and body composition in young women with long-duration type 1 diabetes (T1D) in relation to matched controls. Twenty-three Swedish women, age 19.2-27.9 years, with a T1D duration of 10 years or more were recruited from the Swedish National Diabetes Registry (NDR). An age-, gender- and geography-matched control group was recruited. Bone mass and body composition were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Data was retrieved from the NDR and SWEDIABKIDS registries. T1D individuals had a mean diabetes duration of 19 years. T1D individuals had reduced lean mass (40.0 ± 6.1 kg vs. 43.9 ± 4.9 kg) and were shorter (1.66 ± 0.06 m vs. 1.71 ± 0.06 m) although comparable BMI. Subjects with T1D had lower muscle area (P = 0.0045). No differences were observed for fractures; physical activity; total, lumbar spine or femur areal bone mineral density. The cortical bone strength strain index was lower for TD1 patients (1875 ± 399 mm³ vs. 2277 ± 332 mm³). In conclusion, young women with long-term diabetes duration showed reduced cortical bone strength, decreased periosteal circumference, endosteal circumference and altered body composition. These factors contribute to the health burden of TD1, which warrants further attention for advancing bone health in women with T1D.

Growth of cortical bone thickness and trabecular bone density in Japanese children

BACKGROUND

The acquisition of a high bone density at a young age is a strategy to prevent fractures/falls later in life. We therefore decided to investigate the increases in cortical thickness (CoTh) and trabecular bone density (TBD) of children.

METHODS

Subjects comprised 1314 students (678 boys and 636 girls) aged between 12 and 18 years. Lifestyle factors were examined with a self-administered questionnaire (sleep times, exercise habits, and calcium intake). Bone growth was assessed based on CoTh and TBD using an ultrasonic bone densitometer. Height, weight, and body fat percentage were also measured.

RESULTS

Increases in CoTh and TBD occurred earlier in girls than in boys. Calcium intake was not sufficient at any of the ages examined, and sleep times were shorter than those recommended by the National Sleep Foundation. Increases in CoTh and TBD occurred subsequent to increases in height. Although increases in CoTh were observed with age in both sexes, TBD increased in boys until the age of 17 years and in girls until the age of 15 years. At 18 years of age, the young adult mean value was greater than 100% for CoTh but lower than 100% for TBD. A multivariate analysis identified age, body mass index (BMI), and exercise as independent positive factors for CoTh, while body fat percentage was an independent negative factor. Age and BMI were independent positive factors for TBD in both sexes, whereas body fat percentage was a positive factor in boys only.

CONCLUSIONS

The study found that CoTH and TBD varied with age and differed in increase in boys and girls; related factors of bone increase could also be found. The results of this study may contribute to the acquisition of high bone density in children and adolescents.

Play During Growth: the Effect of Sports on Bone Adaptation

PURPOSE OF REVIEW

The development of exercise interventions for bone health requires an understanding of normative growth trends. Here, we summarize changes in bone during growth and the effect of participating in sports on structural and compositional measures in different bones in males and females.

RECENT FINDINGS

Growing females and males have similar normalized density and bone area fraction until age 16, after which males continue increasing at a faster rate than females. All metrics for both sexes tend to plateau or decline in the early 20s. Areal BMD measures indicate significant heterogeneity in adaptation to sport between regions of the body. High-resolution CT data indicate changes in structure are more readily apparent than changes in density. While adaptation to sport is spatially heterogeneous, participation in weight-bearing activities that involve dynamic muscle contractions tends to result in increased bone adaptation.

Deficits in Bone Architecture and Strength in Children Living With HIV on Antiretroviral Therapy

BACKGROUND

Reduced bone mineral mass by dual x-ray absorptiometry is reported in children living with HIV (CLWH), but few studies of bone microarchitecture, particularly in sub-Saharan Africa, have been conducted. Here, we compare bone architecture and strength in black South African CLWH and uninfected control children by peripheral quantitative computed tomography (pQCT).

SETTING AND METHODS

One hundred seventy-two CLWH on antiretroviral therapy (ART) and 98 controls in the CHANGES Bone Study in Johannesburg, South Africa received pQCT scans of the radius and tibia. Measurements included trabecular and cortical volumetric bone mineral density (vBMD) and bone strength, estimated by the polar strength strain index (SSI), a validated measure of fracture risk.

RESULTS

CLWH (51% boys) and controls (63% boys) were an average of age 10.4 years. Mean ART duration for CLWH was 9.5 years, with 70.9% on an efavirenz-based, 28.5% on a lopinavir/ritonavir-based, and 1 child on an atazanavir/ritonavir-based regimen. Male CLWH had lower trabecular vBMD at the radius than controls after adjustment for age, radial length, and Tanner stage (β = -17.3, standard error = 7.2, P = 0.018). Bone strength by polar SSI was lower in CLWH than controls (778 vs. 972 mm, P < 0.01). CLWH on an LPV/r-based regimen had lower trabecular vBMD (199 vs. 222 mg/cm, P < 0.001) and cortical vBMD (1074 vs. 1093 mg/cm, P = 0.004) than those on an efavirenz-based regimen. No difference in bone strength by polar SSI was observed between treatment groups.

CONCLUSION

CLWH initiated on ART early in life with well-controlled HIV have deficits in bone architecture and reductions in bone strength as detected by pQCT.

Intensive weight gain therapy in patients with anorexia nervosa results in improved serum tartrate-resistant acid phosphatase (TRAP) 5a and 5b isoform protein levels

AIM

Tartrate-resistant acid phosphatase (TRAP) exists as isoforms 5a and 5b. TRAP 5a is a biomarker of chronic inflammation and influences adipose tissue and 5b associates with bone metabolism/pathologies. The aim was to investigate the association of serum TRAP 5a/5b isoforms with fat and bone markers and anthropometric parameters in patients with anorexia nervosa (AN) during weight gain therapy.

METHODS

Twenty-five Swedish female AN patients, age 16-24 years, were treated for 12 weeks with a high-energy diet with six meals daily. Serum TRAP 5a/5b, markers of fat/glucose metabolism, markers of bone resorption and formation were measured. Parameters of bone and body composition were assessed by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography.

RESULTS

BMI increased from median 15.4 kg/m² to 19.0 kg/m², p < 0.0001. TRAP 5a and 5a/5b ratio increased but TRAP 5b decreased during the study. TRAP Δ5a and Δ5b correlated with Δinsulin and Δadiponectin, respectively. TRAP 5b correlated with trabecular density at start but not at week 12. At 12 weeks, TRAP 5b correlated with CTX, and Δ decrease in TRAP 5b correlated to Δ increase in bone-specific alkaline phosphatase.

CONCLUSIONS

This clinical interventional study resulted in increased BMI in patients with AN. The decreased TRAP 5b protein levels confirm a role for TRAP 5b as a marker of bone resorption, whereas increased TRAP 5a seemed to derive from systemic changes in bone as well as metabolic changes. The combined detection of TRAP 5a and TRAP 5b in serum could be an indicator of improved bone metabolism.

LEVEL OF EVIDENCE

Level III, prospective interventional cohort study.

Bone Microarchitecture Assessed by Trabecular Bone Score Is Independent of Mobility Level or Height in Pediatric Patients with Cerebral Palsy

Bone strength and fracture risk do not only depend on bone density, but also on bone structure. The trabecular bone score (TBS) evaluates homogeneity of bone microarchitecture indirectly by measuring gray-level variations of two-dimensional (2D) DXA images. Although TBS is well-established for adults, there have been only few publications in pediatrics. In this monocentric retrospective analysis, we investigated TBS in children and adolescents with cerebral palsy (CP), a patient group vulnerable to low bone mineral mass due to impaired mobility. The influence of different parameters on TBS and areal BMD (aBMD) were evaluated, as well as the relationship between TBS and aBMD. We compared TBS values of our study population to a reference population. A total of 472 lumbar spine-dual-energy X-ray absorptiometry (LS-DXA) scans of children and adolescents with CP (205 female), aged between 4 and 18 years, were analyzed. The DXA-scans were part of the routine examination. The children had no records of fractures or specific bone diseases. Our study population with CP had similar TBS as the reference population. TBS did not increase with age until an inflection point at 10 years in females, and 12 years in males. Girls had significantly higher TBS than boys (p = .049) and pubertal girls aged 8 to 13 years had significantly higher TBS than prepubertal girls (p = .009). TBS standard deviation score for age (SDS-TBS) and aBMD Z-scores correlated weakly (p < .001; R = 0.276 [males], R = 0.284 [females]). Other than for aBMD Z-scores, SDS-TBS was not influenced by age-adjusted height Z-scores and there was no significant difference in SDS-TBS when grouped by mobility levels, using the Gross Motor Function Classification System (GMFCS). Our results indicate that children with CP have a similar homogeneous distribution of trabecular microarchitecture as controls. Puberty initiation appears to be essential for increase of TBS with age and for sex differences. TBS seems less influenced by body composition, height, and mobility than aBMD. © 2020 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Bone Mineral Reference Values for Athletes 11 to 20 Years of Age

Objectives. Training for sport is associated with the development of bone minerals, and the need for reference data based on athletes is often indicated. The purpose of this study was to develop a reference for bone mineral density (BMD) and content (BMC) specific for youth athletes of both sexes participating in several sports. Methods DEXA (dual energy X-ray absorptiometry) was used for total body measurements of bone minerals in 1385 athletes 11 to 20 years, 1019 males and 366 females. The athletes were training in several sports at Hungarian academies. Reference values for total bone mineral density and bone mineral content, and also BMD excluding the head (total body less head, TBLH) were developed using the LMS chartmaker pro version 2.3. Results. The centile distributions for BMD and BMC of the athletes differed significantly from those of the age- and sex-specific references for the general population. The youth athletes had higher BMD and BMC than those of the reference for the general population. Conclusion. The potential utility of the DEXA reference for male and female youth athletes may assist in monitoring changes in the BMC and BMD associated with normal growth and maturation, and perhaps more importantly, may be useful in monitoring changes specific to different phases of sport-specific training protocols.

How to manage osteoporosis before the age of 50

This narrative review discusses several aspects of the management of osteoporosis in patients under 50 years of age. Peak bone mass is genetically determined but can also be affected by lifestyle factors. Puberty constitutes a vulnerable period. Idiopathic osteoporosis is a rare, heterogeneous condition in young adults due in part to decreased osteoblast function and deficient bone acquisition. There are no evidence-based treatment recommendations. Drugs use can be proposed to elderly patients at very high risk. Diagnosis and management of osteoporosis in the young can be challenging, in particular in the absence of a manifest secondary cause. Young adults with low bone mineral density (BMD) do not necessarily have osteoporosis and it is important to avoid unnecessary treatment. A determination of BMD is recommended for premenopausal women who have had a fragility fracture or who have secondary causes of osteoporosis: secondary causes of excessive bone loss need to be excluded and treatment should be targeted. Adequate calcium, vitamin D, and a healthy lifestyle should be recommended. In the absence of fractures, conservative management is generally sufficient, but in rare cases, such as chemotherapy-induced osteoporosis, antiresorptive medication can be used. Osteoporosis in young men is most often of secondary origin and hypogonadism is a major cause; testosterone replacement therapy will improve BMD in these patients. Diabetes is characterized by major alterations in bone quality, implying that medical therapy should be started sooner than for other causes of osteoporosis. Primary hyperparathyroidism, hyperthyroidism, Cushing's syndrome and growth hormone deficiency or excess affect cortical bone more often than trabecular bone.

Assessing bone mineralisation in children with chronic kidney disease: what clinical and research tools are available?

Mineral and bone disorder in chronic kidney disease (CKD-MBD) is a triad of biochemical imbalances of calcium, phosphate, parathyroid hormone and vitamin D, bone abnormalities and soft tissue calcification. Maintaining optimal bone health in children with CKD is important to prevent long-term complications, such as fractures, to optimise growth and possibly also to prevent extra-osseous calcification, especially vascular calcification. In this review, we discuss normal bone mineralisation, the pathophysiology of dysregulated homeostasis leading to mineralisation defects in CKD and its clinical consequences. Bone mineralisation is best assessed on bone histology and histomorphometry, but given the rarity with which this is performed, we present an overview of the tools available to clinicians to assess bone mineral density, including serum biomarkers and imaging such as dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. We discuss key studies that have used these techniques, their advantages and disadvantages in childhood CKD and their relationship to biomarkers and bone histomorphometry. Finally, we present recommendations from relevant guidelines-Kidney Disease Improving Global Outcomes and the International Society of Clinical Densitometry-on the use of imaging, biomarkers and bone biopsy in assessing bone mineral density. Given low-level evidence from most paediatric studies, bone imaging and histology remain largely research tools, and current clinical management is guided by serum calcium, phosphate, PTH, vitamin D and alkaline phosphatase levels only.

Associations between serum levels of insulin-like growth factor-I and bone mineral acquisition in pubertal children: a 3-year follow-up study in Hamamatsu, Japan

BACKGROUND

Epidemiological data regarding the association between serum levels of IGF-I and bone mineral acquisition during childhood are scarce. Here, we investigated the association between serum levels of IGF-I and bone status during puberty.

METHODS

We analyzed prospective 3-year follow-up data of 254 community-dwelling children who completed both baselines (at age 11.2 years) and follow-up (at age 14.2 years) surveys in Hamamatsu, Japan. Total body (TB) bone area and bone mineral parameters were assessed using dual-energy X-ray absorptiometry.

RESULTS

During the 3-year follow-up period, there were significant (P < 0.05) increases in total body less head (TBLH) areal bone mineral density (aBMD), TBLH bone mineral content (BMC), and TB bone area, and a significant decrease in TB bone mineral apparent density (BMAD, volumetric bone mineral density, vBMD). IGF-I levels showed significant positive relationships with TBLH BMC and TBLH aBMD at both baseline and follow-up. TBLH aBMD in boys and TB BMAD in girls at follow-up showed significant increases from the lowest to highest quartiles of baseline IGF-I levels after adjusting for confounding factors. Similarly, changes in TBLH aBMD in boys and TB BMAD in girls during the 3-year follow-up period showed significant increases from the lowest to highest quartiles of baseline IGF-I levels after adjusting for confounding factors.

CONCLUSIONS

These results suggest that pubertal children with high levels of serum IGF-I tended to have high bone mineral acquisition later on.

Diagnosis of osteoporotic vertebral fractures in children

Osteoporosis is a generalised disorder of the skeleton with reduced bone density and abnormal bone architecture. It increases bone fragility and renders the individual susceptible to fractures. Fractures of the vertebrae are common osteoporotic fractures. Vertebral fractures may result in scoliosis or kyphosis and, because they may be clinically silent, it is imperative that vertebral fractures are diagnosed in children accurately and at an early stage, so the necessary medical care can be implemented. Traditionally, diagnosis of osteoporotic vertebral fractures has been from lateral spine radiographs; however, a small number of studies have shown that dual energy x-ray absorptiometry is comparable to radiographs for identifying vertebral fractures in children, while allowing reduced radiation exposure. The diagnosis of vertebral fractures from dual energy x-ray absorptiometry is termed vertebral fracture assessment. Existing scoring systems for vertebral fracture assessment in adults have been assessed for use in children, but there is no standardisation and observer reliability is variable. This literature review suggests the need for a semiautomated tool that (compared to the subjective and semiquantitative methods available) will allow more reliable and precise detection of vertebral fractures in children.

Suboptimal bone status for adolescents with low motor competence and developmental coordination disorder-It's sex specific

BACKGROUND

Australian adolescents with low motor competence (LMC) have higher fracture rates and poorer bone health compared to European normative data, but currently no normative data exists for Australians.

AIMS

To examine whether there were bone health differences in Australian adolescents with LMC or Developmental Coordination Disorder (DCD) when compared to typically developing age-matched Australian adolescents.

METHODS AND PROCEDURES

Australian adolescents aged 12-18 years with LMC/DCD (n = 39; male = 27; female = 12) and an Australian comparison sample (n = 188; boys = 101; girls = 87) undertook radial and tibial peripheral Quantitative Computed Tomography (pQCT) scans. Stress Strain Index (SSI (mm³)), Total Bone Area (TBA (mm²)), Muscle Density (MuD [mgcm³]), Muscle Area (MuA [cm²]), Subcutaneous Fat Area (ScFA [cm²]), Cortical Density (CoD [mgcm³]), Cortical Area (CoD [mm²]), cortical concentric ring volumetric densities, Functional Muscle Bone Unit Index (FMBU: (SSI/bone length)) and Robustness Index (SSI/bone length^3), group and sex differences were examined.

OUTCOME AND RESULTS

The main finding was a significant sex-x-group interaction for Tibial FMBU (p = .021), Radial MuD (p = .036), and radial ScFA (p = .002). Boys with LMC/DCD had lower tibial FMBU scores, radial MuD and higher ScFA than the typically developing age-matched sample.

CONCLUSION AND IMPLICATIONS

Comparisons of bone measures with Australian comparative data are similar to European findings however sex differences were found in the present study. Australian adolescent boys with LMC/DCD had less robust bones compared to their well-coordinated Australian peers, whereas there were no differences between groups for girls. These differences may be due to lower levels of habitual weight-bearing physical activity, which may be more distinct in adolescent boys with LMC/DCD compared to girls.

Persistence of Muscle-bone Deficits Following Anti-tumour Necrosis Factor Therapy in Adolescents With Crohn Disease

OBJECTIVES

The aim of the study is to assess change in the muscle-bone unit in adolescents with Crohn disease (CD) on anti-tumour necrosis factor (anti-TNFα).

METHODS

Prospective study following anti-TNFα in 19 adolescents with CD with a median age (range) of 15.1 years (11.2, 17.2). At baseline, 6 and 12 months, subjects had a biochemical assessment of insulin growth factor axis, bone turnover and muscle-bone health by dual energy absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and dynamic isometry.

RESULTS

Significant clinical improvement in disease activity was observed by 2 weeks (P = 0.004 vs baseline) and maintained at 12 months (P = 0.038 vs baseline). Median bone specific alkaline phosphatase standard deviation score (SDS) increased from -1.7 (-3.6 to -1.0) to -1.2 (-3.6 to -0.5) by 6 weeks (P = 0.01). At baseline, DXA total body and lumbar spine bone mineral density (BMD) SDS was -0.9 (-2.3 to 0.5) and -1.1 (-2.9 to 0.4), respectively. At baseline, pQCT trabecular BMD SDS at 4% tibia and muscle cross-sectional area SDS at 66% radius was -1.6 (-3.2 to 1.1) and -2.4 (-4.3 to -0.3), respectively. At baseline, maximal isometric grip force (MIGF) of the non-dominant hand adjusted for height was -1.5 (-4.5 to 0.49). All these deficits in muscle-bone persisted at 6 and 12 months.

CONCLUSIONS

Despite improvement in disease and osteoblast activity, bone and muscle deficits, as assessed by DXA, pQCT, and grip strength in adolescents with CD did not improve following twelve months of anti-TNFα.

A Review of Pediatric Lower Extremity Data for Pedestrian Numerical Modeling: Injury Epidemiology, Anatomy, Anthropometry, Structural, and Mechanical Properties

Pedestrian injuries are the fourth leading cause of unintentional injury-related death among children aged 1 to 19. The lower extremity represents the most frequently injured body region in car-to-pedestrian accidents. The goal of this study was to perform a systematic review of the data related to pedestrian lower extremity injuries, anatomy, anthropometry, structural, and mechanical properties, which can be used in the development of new pediatric computational models. The study began with a review of epidemiologic data related to pediatric pedestrian accidents. Anatomy of the child lower extremity and age-related anthropometry data were presented as well. Then, both the mechanical and structural properties of the lower extremity main components (e.g., bones, cartilages, knee ligaments, muscles, tendons, and growth plates) available in literature were summarized. The study concluded with a brief description of current child pedestrian models, which included a discussion about their limitations. We believe that data included in this review study can help in improving the biofidelity of current child models and support the development and validation of new child models used by safety researchers for protection of pediatric population.

Sex-, Ethnic-, and Age-Specific Centile Curves for pQCT- and HR-pQCT-Derived Measures of Bone Structure and Strength in Adolescents and Young Adults

There are presently no adolescent centile curves for bone parameters at the tibial midshaft using peripheral quantitative computed tomography (pQCT) or at the distal radius and tibia using high-resolution pQCT (HR-pQCT). Thus, we aimed to develop sex-, ethnic-, site-, and age-specific centile curves for pQCT and HR-pQCT-derived bone outcomes for youth and young adults aged 10 to 21 years. We acquired pQCT scans (XCT3000 or XCT2000) at the tibial midshaft (50% site) and HR-pQCT scans (XtremeCT) at the distal radius (7% site) and tibia (8% site) in a convenience sample of participants in the mixed-longitudinal University of British Columbia Healthy Bones III Study. We scanned 778 10- to 21-year-olds annually for a maximum of 11 years using pQCT (413 girls, 56% Asian; 365 boys, 54% Asian; n = 3160 observations) and 349 10- to 21-year-olds annually for a maximum of 4 years using HR-pQCT (189 girls, 51% Asian; 165 boys, 50% Asian; n = 1090 observations). For pQCT, we report cortical bone mineral density (BMD), total bone cross-sectional area, and polar strength-strain index. For HR-pQCT, we report standard measures (total BMD, trabecular number, thickness, and bone volume fraction) and automated segmentation measures (total bone cross-sectional area, cortical BMD, porosity, and thickness). We applied finite element analysis to estimate failure load. We applied the lamda, mu, sigma (LMS) method using LMS ChartMaker Light (version 2.5, The Institute of Child Health, London, UK) to construct LMS tables and centile plots. We report sex- and age-specific centiles (3rd, 10th, 25th, 50th, 75th, and 97th) for whites and Asians for pQCT bone parameters at the tibial midshaft and HR-pQCT bone parameters at the distal radius and tibia. These centile curves might be used by clinicians and scientists to interpret values or better understand trajectories of bone parameters in clinical populations, those from different geographic regions or of different ethnic origins. © 2018 American Society for Bone and Mineral Research.

Averaged head phantoms from magnetic resonance images of Korean children and young adults

Increased use of mobile phones raises concerns about the health risks of electromagnetic radiation. Phantom heads are routinely used for radiofrequency dosimetry simulations, and the purpose of this study was to construct averaged phantom heads for children and young adults. Using magnetic resonance images (MRI), sectioned cadaver images, and a hybrid approach, we initially built template phantoms representing 6-, 9-, 12-, 15-year-old children and young adults. Our subsequent approach revised the template phantoms using 29 averaged items that were identified by averaging the MRI data from 500 children and young adults. In females, the brain size and cranium thickness peaked in the early teens and then decreased. This is contrary to what was observed in males, where brain size and cranium thicknesses either plateaued or grew continuously. The overall shape of brains was spherical in children and became ellipsoidal by adulthood. In this study, we devised a method to build averaged phantom heads by constructing surface and voxel models. The surface model could be used for phantom manipulation, whereas the voxel model could be used for compliance test of specific absorption rate (SAR) for users of mobile phones or other electronic devices.

Bone mineral density reference standards for Chinese children aged 3-18: cross-sectional results of the 2013-2015 China Child and Adolescent Cardiovascular Health (CCACH) Study

OBJECTIVES

No nationwide paediatric reference standards for bone mineral density (BMD) are available in China. We aimed to provide sex-specific BMD reference values for Chinese children and adolescents (3-18 years).

METHODS

Data (10 818 participants aged 3-18 years) were obtained from cross-sectional surveys of the China Child and Adolescent Cardiovascular Health in 2015, which included four municipality cities and three provinces. BMD was measured using Hologic Discovery Dual Energy X-ray Absorptiometry (DXA) scanner. The DXA measures were modelled against age, with height as an independent variable. The LMS statistical method using a curve fitting procedure was used to construct reference smooth cross-sectional centile curves for dependent versus independent variables.

RESULTS

Children residing in Northeast China had the highest total body less head (TBLH) BMD while children residing in Shandong Province had the lowest values. Among children, TBLH BMD was higher for boys as compared with girls; but, it increased with age and height in both sexes. Furthermore, TBLH BMD was higher among US children as compared with Chinese children. There was a large difference in BMD for height among children from these two countries. US children had a much higher BMD at each percentile (P) than Chinese children; the largest observed difference was at P50 and P3 and the smallest difference was at P97.

CONCLUSIONS

This is the first study to present a sex-specific reference dataset for Chinese children aged 3-18 years. The data can help clinicians improve interpretation, assessment and monitoring of densitometry results.

Imaging methods for bone mass evaluation during childhood and adolescence: an update

The objective of the work was to prepare an update on imaging methods for bone evaluation during childhood and adolescence. The text was based on original and review articles on imaging methods for clinical evaluation of bone mass in children and adolescents up to 20 years old. They were selected from BIREME and PUBMED by means of the following keywords: bone density; osteoporosis/diagnosis; densitometry; tomography; ultrasonography; magnetic resonance imaging; and radiogrammetry and published in Portuguese or English, in the last 10 years (2006-2016). The article was organized into topics with the description of peculiarities, advantages and disadvantages of each imaging method and their possible clinical applicability. Despite the emergence of new technologies, dual energy X-ray absorptiometry (DXA) remains the gold standard method for low bone mass diagnosis in all age groups. However, interpretation is complex in children and adolescents and demands skilled people. Quantitative computed tomography (QCT) [central QCT, peripheral QCT (pQCT) and high resolution-pQCT (HR-pQCT)] and magnetic resonance imaging (MRI) evaluate real bone density, but are not yet available for routine use. Quantitative bone ultrasound (QUS) shows good perspectives for its use in primary prevention actions. Automated radiogrammetry shows promise as a method able to flag individuals who might benefit from a complete bone assessment, but the clinical value of the measures still needs to be established.

Fibroblast Growth Factor 23 Concentrations Reflect Sex Differences in Mineral Metabolism and Growth in Early Infancy

BACKGROUND

The role of fibroblast growth factor 23 (FGF23) in the regulation of mineral homeostasis in early life is inadequately understood. We aimed to explore the effects of vitamin D supplementation on serum FGF23 and to elucidate longitudinal changes in FGF23, in addition to studying its association with mineral metabolism in early infancy.

METHODS

Altogether 113 healthy infants received vitamin D3 10, 30 or 40 µg/day from age 0.5 to 3.0 months. Cord blood at birth and capillary blood samples at 3 months were analyzed for serum 25-hydroxyvitamin D, parathyroid hormone, phosphate, calcium and intact and C-terminal FGF23.

RESULTS

In repeated-measures ANCOVA, intact FGF23 concentration increased with time (p < 0.001) and C-terminal FGF23 decreased (p < 0.001). At 3 months, girls had a higher concentration of intact FGF23 (51 vs. 26 pg/ml, p < 0.001) and a greater increase over time (x0394;FGF23 intact 45 vs. 16 pg/ml, p = 0.001) than boys. Vitamin D did not affect serum intact or C-terminal FGF23 concentrations. Girls showed a positive correlation between phosphate and intact FGF23 (p = 0.004), whereas in boys phosphate and C-terminal FGF23 correlated inversely (p = 0.006).

CONCLUSIONS

A substantial sex-related difference in intact FGF23 concentration exists during early infancy, possibly related to differences in skeletal growth between boys and girls.

Analysis of the functional muscle-bone unit of the forearm in patients with phenylketonuria by peripheral quantitative computed tomography

Bone disease in patients with phenylketonuria (PKU) is incompletely characterized. We therefore analyzed, in a cross-sectional study radius macroscopic bone architecture and forearm muscle size by peripheral quantitative computed tomography (pQCT) and muscle strength by hand dynamometry in a large cohort (n = 56) of adolescent and adult patients with PKU aged 26.0 ± 8.9 (range, 11.8-41.5) years. Data were compared with a reference population (n = 700) from the DONALD study using identical methodology. We observed a significant reduction of cortical thickness (z-score -1.01 ± 0.79), Strength-Strain Index (SSI) (z-score -0.81 ± 1.03), and total bone mineral density (BMD) of the distal radius (z-score -1.05 ± 1.00). Mean muscle cross-sectional area (z-score -0.98 ± 1.19) and muscle grip force (z-score -0.64 ± 1.26) were also significantly reduced, indicating an impaired muscular system as part of the clinical phenotype of PKU. SSI positively correlated (r = 0.53, P < 0.001) with the corresponding muscle cross-sectional area in the reference population; however, the regression line slope in PKU patients was less steep (P < 0.001), indicating that bone strength is not adequately adapted to muscle force. In conclusion, the radial bone in PKU patients is characterized by reduced bone strength in relation to muscular force, decreased cortical thickness, and impaired total BMD at the metaphyseal site. These alterations indicate a mixed bone defect in PKU, both of which are due to primary alterations of bone metabolism and to secondary alterations in response to neuromuscular abnormalities.

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.

Bone Traits Seem to Develop Also During the Third Decade in Life-Normative Cross-Sectional Data on 1083 Men Aged 18-28 Years

By identifying individuals with low peak bone mass (PBM) at young age, early targeted interventions to reduce future fracture risk could be possible. Peripheral quantitative computed tomography (pQCT) is in many ways superior to the gold standard dual-energy X-ray absorptiometry (DXA), as cortical and trabecular compartments as well as the volumetric density and bone structure can be examined separately. Because each of these traits contributes independently to bone strength, it is probable that pQCT provides an even better fracture risk estimation than DXA. Currently, the clinical applications of pQCT are limited partly because comprehensive normative pQCT data, especially in young men, are not readily available. We therefore set up a study in young men with the following objectives: (1) to identify peak ages in pQCT bone traits with special reference to PBM and peak bone strength; and (2) to provide normative pQCT data. We measured volumetric bone mineral density and structural parameters at ultradistal (trabecular bone) and diaphyseal radius and tibia (cortical bone) by pQCT scans (Stratec XCT2000®; Stratec Medizintechnik GmbH, Pforzheim, Germany) in a population-based age-stratified sample of 1083 men aged 18-28 yr residing in greater Malmö, Sweden. Group differences in 1-yr classes were evaluated by analysis of variance. We found similar bone traits in age groups at ultradistal sites whereas most bone traits at diaphyseal sites were higher with higher ages, however with different increment patterns depending on the specific trait. In Swedish young adult men, we found that different bone traits continued to change after age 18, but at different rates, indicating that peak areal bone mineral density (as measured by DXA) and peak bone strength may be reached at different ages.

Muscle and skeletal health in children and adolescents with GH deficiency

In addition to promoting linear growth, GH plays a key role in the regulation of bone and muscle development and metabolism. Although GH deficiency is frequently listed among the causes of secondary osteoporosis in children, its impact on bone and muscle health and on fracture risk is still not completely established. Current data suggest that childhood-onset GH deficiency can affect bone and muscle mass and strength, with GH replacement therapy exerting beneficial effects. Moreover, GH withdrawal at final height can result in reduced peak bone and muscle mass, potentially leading to increased fracture risk in adulthood. Thus, the muscle-bone unit in GH deficient subjects should be monitored during childhood and adolescence in order to prevent osteoporosis and increased fracture risk and GH replacement should be tailored to ensure an optimal bone and muscle health.

The effect of loading and ethnicity on annual changes in cortical bone of the radius and tibia in pre-pubertal children

BACKGROUND

It is unclear what effect habitual physical activity or ethnicity has on annual changes in bone size and strength in pre-pubertal children.

AIM

To determine whether the annual relative change in bone size and strength differed between high and low bone loaders and also between black and white pre-pubertal children.

SUBJECTS AND METHODS

Peripheral quantitative computed tomography (pQCT) scans of the 65% radius and tibia were completed on 41 black and white children (15 boys, 26 girls) between the ages of 8-11 years, at baseline and 1 year later. Children were categorised into either a high or low bone loading group from a peak bone strain score obtained from a bone-specific physical activity questionnaire. Total area (ToA), cortical area (CoA), cortical density (CoD), strength-strain index (SSI), periosteal circumference (PC), endosteal circumference (EC) and cortical thickness (CT) were assessed.

RESULTS

There was no difference in annual relative change in radial or tibia bone size and strength between the low and high bone loaders. Black children had a greater annual relative change in CoD (p = 0.03) and SSI (p = 0.05) compared to the white children.

CONCLUSION

Children who performed high bone loading activities over a 1-year period had similar bone growth to children who did low bone loading activities over the same period. Rapid maturational growth over this period may have resulted in bone adapting to the strains of habitual physical activity placed on it. Black children may have greater tibial bone strength compared to white children due to a greater annual increase in cortical density.

Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional 'muscle-bone unit', defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton's health follow-up.

Patient-specific fracture risk assessment of vertebrae: A multiscale approach coupling X-ray physics and continuum micromechanics

While in clinical settings, bone mineral density measured by computed tomography (CT) remains the key indicator for bone fracture risk, there is an ongoing quest for more engineering mechanics-based approaches for safety analyses of the skeleton. This calls for determination of suitable material properties from respective CT data, where the traditional approach consists of regression analyses between attenuation-related grey values and mechanical properties. We here present a physics-oriented approach, considering that elasticity and strength of bone tissue originate from the material microstructure and the mechanical properties of its elementary components. Firstly, we reconstruct the linear relation between the clinically accessible grey values making up a CT, and the X-ray attenuation coefficients quantifying the intensity losses from which the image is actually reconstructed. Therefore, we combine X-ray attenuation averaging at different length scales and over different tissues, with recently identified 'universal' composition characteristics of the latter. This gives access to both the normally non-disclosed X-ray energy employed in the CT-device and to in vivo patient-specific and location-specific bone composition variables, such as voxel-specific mass density, as well as collagen and mineral contents. The latter feed an experimentally validated multiscale elastoplastic model based on the hierarchical organization of bone. Corresponding elasticity maps across the organ enter a finite element simulation of a typical load case, and the resulting stress states are increased in a proportional fashion, so as to check the safety against ultimate material failure. In the young patient investigated, even normal physiological loading is probable to already imply plastic events associated with the hydrated mineral crystals in the bone ultrastructure, while the safety factor against failure is still as high as five. Copyright © 2016 John Wiley & Sons, Ltd.

Sex- and Maturity-Related Differences in Cortical Bone at the Distal Radius and Midshaft Tibia Evaluated by Quantitative Ultrasonography

Boys usually have higher values of bone mineral density measured by dual-energy X-ray absorptiometry than girls, but contradictorily also have a greater incidence of fractures during growth. The purpose of this study was to investigate sex- and maturity-related differences in bone speed of sound (SoS) at the radius and tibia in a sample of 625 healthy children aged 10-14 y and to analyze the contributions of physical activity (PA) to possible dissimilarities. Radial and tibial SoS was evaluated by quantitative ultrasound, maturity was estimated as the years of distance from the peak height velocity age, and PA was assessed by accelerometry. Comparisons between sexes and maturity groups (low: below average [<-2.5 y], high: average or above [≥-2.5 y]) were made by two-sample t-tests with unequal variances. Girls in the high-maturity group had higher SoS at the radius and tibia compared with girls in the low-maturity group (p < 0.001). There were no SoS differences at the radius or tibia between the high- and low-maturity groups in boys. Within high-maturity children, girls had higher SoS than boys at the radius and tibia (p < 0.001). There were no differences at the radius and tibia between girls and boys with low maturity. The results were not modified after controlling for PA. Regardless of PA, the results provide insight into sex- and maturity-related differences in bone SoS at the distal radius and midshaft tibia from maturity less than 2.5 y from the peak height velocity age, with boys having lower SoS.

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).

A Critical Comparison Between Two Scanning Protocols of High-Resolution Peripheral Quantitative Computed Tomography at the Distal Radius in Adolescents

High-resolution peripheral quantitative computed tomography (HR-pQCT) is a unique technology for assessing bone mineral density and bone microarchitecture. Currently, no universally accepted protocol for selecting the region of interest (ROI) at the distal radius has been established for growing subjects. This study aimed (1) to investigate the differences in HR-pQCT measurements of 2 different ROI protocols applied to the distal radius of healthy adolescents and (2) to identify the least common area of ROI (the least common ROI) between the protocols. Twenty-six boys and 26 girls aged between 13 and 16 yr old were recruited. Nondominant distal radius was scanned by 2 HR-pQCT protocols, namely, the "5-mm protocol," where the distal end of ROI started at 5 mm proximal to a reference line, and the "4% protocol," where the ROI started at 4% of the ulnar length proximal to another reference line. The least common ROI between the 2 protocols was identified and the slice numbering within the common ROI was determined. Bland-Altman plots were used to check the agreement of the least common ROIs between the 2 protocols. Paired t-test and Wilcoxon signed-rank test were used for analysis. In boys, significant differences between protocols were found in most parameters with the maximum difference observed in the cortical area (25.0%, p < 0.001). In girls, differences were observed only for total volumetric bone mineral density (3.6%, p = 0.032). The number of slices in the least common ROI was 66 (60.0%) and 57 (51.8%) in boys and girls, respectively. Good agreements on all HR-pQCT parameters from the least common ROI between the 2 protocols were found. Significant differences in bone parameters were noted between the 2 protocols. When comparing the 2 protocols, observed gender differences could reflect the differences in skeletal growth at the peripubertal period between genders. Least common ROI could be useful for cross-center comparisons and when merging datasets from different centers.

Improving Vitamin D Status and Related Health in Young Women: The Safe-D study - Part B

BACKGROUND

Vitamin D deficiency is highly prevalent and associated with increased risk of a number of chronic health conditions including cardiovascular disease, poor bone and muscle health, poor mental health, infection, and diabetes. Vitamin D deficiency affects millions of Australians, potentially causing considerable suffering, economic loss, and mortality.

OBJECTIVE

To measure the effectiveness of a (1) mobile-based app (behavioral) and (2) pharmacological intervention to increase circulating 25-hydroxyvitamin D (serum 25 OHD) levels and health outcomes over 4 months of intervention compared with usual care in a cohort of young women with suboptimal serum 25 OHD levels (25-75 nmol/L).

METHODS

Participants with 25 OHD levels 25 to 75 nmol/L are invited to participate in this study. Participants are randomized to one of three groups in 1:1:1 ratio: a mobile phone-based application, vitamin D supplementation (1000 IU/day), and a control group. Data collection points are at baseline, 4, and 12 months post baseline with the major endpoints being at 4 months. A wide-range of information is collected from participants throughout the course of this study. General health, behavioral and demographic information, medications, smoking, alcohol and other substance use, health risk factors, nutrition, eating patterns and disorders, and mental health data are sourced from self-administered, Web-based surveys. Clinical data include anthropometric measurements, a silicone skin cast of the hand, cutaneous melanin density, bone mineral density, and body composition scans obtained through site visits. Main analyses will be conducted in two ways on an intention-to-treat (ITT) basis using the last observation carried forward approach as an imputation for missing data, and on a per protocol basis to compare the intervention arms against the control group at 4 and 12 months.

RESULTS

Publication of trial results is anticipated in 2017.

CONCLUSIONS

The study will allow assessment of the effects of a mobile-based app behavioral intervention and vitamin D supplementation on vitamin D status and will evaluate the effects of improving vitamin D levels on several health outcomes.

A Piece of the Puzzle: The Bone Health Index of the BoneXpert Software Reflects Cortical Bone Mineral Density in Pediatric and Adolescent Patients

INTRODUCTION

Suspected osteopathology in chronically ill children often necessitates the assessment of bone mineral density. The most frequently used methods are dual-energy X-ray-absorption (DXA) and peripheral quantitative computed tomography (pQCT). The BoneXpert software provides an automated radiogrammatic method to assess skeletal age from digitalized X-rays of the left hand. Furthermore, the program calculates the Bone Health Index (BHI), a measure of cortical thickness and mineralization, which is obtained from indices of three metacarpal bones. In our study, we analyzed the manner in which BHI information provided by BoneXpert compares with DXA or pQCT measurements in youths.

STUDY DESIGN

The BHI was retrospectively obtained using digitalized X-rays of the left hand and compared with the results of 203 corresponding DXA readings (Lunar Prodigy, GE Healthcare) of the lumbar vertebrae and femur as well as 117 pQCT readings (XCT 900, Stratec) of the distal radius.

RESULTS

The BHI values showed a strong positive correlation with the DXA readings at each and all lumbar vertebrae (L1 -L4: r = 0.73; P < 0.0001). The age-adjusted Z-score of L1 -L4 and the height-adjusted score showed a positive correlation with the BHI-SDS (standard deviation score, r = 0.23; P < 0.002 and r = 0.27; P < 0.001, respectively). Total bone mineral density, as assessed via pQCT, also positively correlated with the BHI (r = 0.39; P < 0.0001), but the trabecular values displayed only a weak correlation.

CONCLUSIONS

The BHI obtained using BoneXpert can be a useful parameter in the assessment of bone health in children in most cases. This technique provides observer-independent information on cortical thickness and mineralization based on X-ray imaging of the hands.

Bone's responses to mechanical loading are impaired in type 1 diabetes

Diabetes adversely impacts many organ systems including the skeleton. Clinical trials have revealed a startling elevation in fracture risk in diabetic patients. Bone fractures can be life threatening: nearly 1 in 6 hip fracture patients die within one year. Because physical exercise is proven to improve bone properties and reduce fracture risk in non-diabetic subjects, we tested its efficacy in type 1 diabetes. We hypothesized that diabetic bone's response to anabolic mechanical loading would be attenuated, partially due to impaired mechanosensing of osteocytes under hyperglycemia. Heterozygous C57BL/6-Ins2(Akita)/J (Akita) male and female diabetic mice and their age- and gender-matched wild-type (WT) C57BL/6J controls (7-month-old, N=5-7 mice/group) were subjected to unilateral axial ulnar loading with a peak strain of 3500 με at 2 Hz and 3 min/day for 5 days. The Akita female mice, which exhibited a relatively normal body weight and a mild 40% elevation of blood glucose level, responded with increased bone formation (+6.5% in Ct.B.Ar, and 4 to 36-fold increase in Ec.BFR/BS and Ps.BFR/BS), and the loading effects, in terms of changes of static and dynamic indices, did not differ between Akita and WT females (p ≥ 0.1). However, loading-induced anabolic effects were greatly diminished in Akita males, which exhibited reduced body weight, severe hyperglycemia (+230%), diminished bone formation (ΔCt.B.Ar: 0.003 vs. 0.030 mm(2), p=0.005), and suppressed periosteal bone appositions (ΔPs.BFR/BS, p=0.02). Hyperglycemia (25 mM glucose) was further found to impair the flow-induced intracellular calcium signaling in MLO-Y4 osteocytes, and significantly inhibited the flow-induced downstream responses including reduction in apoptosis and sRANKL secretion and PGE2 release. These results, along with previous findings showing adverse effects of hyperglycemia on osteoblasts and mesenchymal stem cells, suggest that failure to maintain normal glucose levels may impair bone's responses to mechanical loading in diabetics.

Peripheral quantitative computed tomography (pQCT) reveals low bone mineral density in adolescents with motor difficulties

This is the first reported study to describe local bone mineral density, assess parameters of fracture risk and report history of fractures in adolescents with motor difficulties. Motor difficulties evidenced by poor coordination in adolescence should be considered a new risk factor for below-average bone strength and structure and fracture risk.

INTRODUCTION

Adolescents with motor difficulties are characterised by poor coordination and low levels of physical activity and fitness. It is possible these deficits translate into below-average bone strength and structure. The objectives of this study were to describe local bone mineral density (BMD), assess parameters of fracture risk (stress-strain index, SSI) and report history of fractures in this group.

METHODS

Thirty-three adolescents (13 females), mean age of 14.3 (SD = 1.5) years, with motor difficulties underwent peripheral quantitative computed tomography (pQCT) measurements at proximal (66 %) and distal (4 %) sites of the non-dominant radius (R4 and R66) and tibia (T4 and T66). One sample t test was used to compare Z-scores for total BMD, trabecular density, cortical density and stress strain index (SSI) against standardized norms.

RESULTS

Significant differences were present at R4 total density mean Z-score = -0.85 (SD = 0.7, p < 0.001), R66 cortical density mean Z-score = -0.74 (SD = 1.97, p = 0.038), R66 SSI mean Z-score = -1.00 (SD = 1.08, p < 0.001) and T66 SSI mean Z-score = -0.70 (SD = 1.15, p < 0.001). There was a higher incidence of fractures (26.9 %) compared to the normal population (3-9 %).

CONCLUSIONS

Motor difficulties in adolescence should be considered a risk factor for below-average bone strength and structure and fracture risk. Strategies are needed to improve bone health in this high-risk-group.

Sexual difference in bone geometry of adult patients with classical congenital adrenal hyperplasia: data using peripheral quantitative computed tomography

BACKGROUND/AIMS

Glucocorticoid treatment may influence bone and muscle development in patients with congenital adrenal hyperplasia (CAH). This study evaluated bone mineral density (BMD), bone geometry and muscle mass.

METHODS

73 adult patients with classical CAH were followed. BMD, bone geometry and muscle mass were measured using peripheral quantitative computed tomography (pQCT). Glucocorticoid-equivalent doses throughout life were calculated and at the time pQCT androgen levels were measured.

RESULTS

In males the mean standard deviation (SD) score for trabecular BMD (-0.33 ± 0.71) was reduced, whereas mean cortical BMD (1.05 ± 1.11) was elevated. Mean total (0.86 ± 1.12) and medullary cross-sectional area (CSA; 1.12 ± 1.17) were significantly increased (p < 0.001). In all patients SD scores for cortical thickness (-0.65 ± 0.91) and muscle CSA (-0.83 ± 0.91) were reduced. Treatment duration was associated with lower trabecular BMD in males (r = -0.63, p < 0.001). Suppressed androgens and simple virilizing CAH had an adverse effect on the muscle CSA SD score (OR 0.58 and 0.46, respectively, p < 0.05).

CONCLUSION

There was a sexual difference with enlarged total and medullary CSA in females, whereas in males trabecular BMD was reduced and cortical BMD elevated. Cortical thickness and muscle CSA were reduced in all CAH patients with a possible long-term impact on bone development and stability. Monitoring of bone and muscle development might be warranted.

Cystic fibrosis-related bone disease in children: Examination of peripheral quantitative computed tomography (pQCT) data

BACKGROUND

The investigation of skeletal health data beyond dual X-ray absorptiometry (DXA) is limited in young individuals with CF. We assessed volumetric bone mineral densities (BMD), and bone and muscle parameters using peripheral quantitative computed tomography (pQCT) in individuals with CF and controls, 7.00-17.99 years.

METHODS

Peripheral QCT (XCT 3000, Stratec) measurements were made in 53 individuals with CF and 53 controls. Bone mineral content (BMC), total volumetric BMD (vBMD) and cross sectional area (CSA) of the bone were measured at the 4% and 66% sites of the non-dominant tibia and radius. Additionally, trabecular vBMD and bone strength index (BSIc) were measured at the 4% sites, and cortical vBMD, muscle CSA (mCSA) and strength strain index (SSI) were measured at the 66% sites.

RESULTS

Pre-pubertal males with CF had greater trabecular vBMD (p=0.01) and total vBMD (p=0.00) at 4% tibia, and greater total vBMD (p=0.02) at 4% radius. Pre-pubertal females with CF had greater total vBMD at 66% tibia (p=0.02) and radius (p=0.04), and cortical vBMD (p=0.04) at the radius. At puberty, the CF cohort had less BMC at 4% tibia (males, p=0.02; females, p=0.01), and smaller mCSA at 66% tibia (males, p=0.02; females, p=0.01). Pubertal CF females had a smaller bone CSA (p=0.01) at 4% tibia, and lower bone strength (SSI) at the tibia (p=0.00) and radius (p=0.05) sites.

CONCLUSIONS

Bone strength parameters were not compromised prior to puberty in this CF cohort. At puberty, the bone phenotype changed for this CF cohort, showing several deficits compared to the controls. However, bone strength was adapting to the mechanical demands of the muscle. Altered bone parameters and their implications for lowered bone strength with increased age may be greatly influenced by: the CF cohort remaining smaller for age and/or a reduced bone strain, secondary to reduced muscle force.

Family resemblance of bone turnover rate in mothers and daughters--the MODAM study

We studied bone turnover markers (BTM) and bone microarchitecture (using high-resolution peripheral quantitative computed tomography (HR-pQCT)) in 171 postmenopausal women and their 210 premenopausal daughters. BTM levels correlated positively between mothers and daughters. The mother-daughter pairs with high BTM levels had lower cortical density than those with low BTM levels.

INTRODUCTION

We assessed the correlation of serum bone turnover markers (BTM) between postmenopausal mothers and their premenopausal daughters as well as possible determinants of this association and its impact on resemblance of bone microarchitecture between mothers and their daughters.

METHODS

Cross-sectional analysis was performed in 171 untreated postmenopausal mothers (54 sustained fragility fractures) and their 210 premenopausal daughters. Intact N-terminal propeptide of type I collagen (PINP) and β-isomerized C-terminal crosslinking telopeptide of type I collagen (CTX-I) were measured in the fasting status. Bone microarchitecture was assessed using HR-pQCT.

RESULTS

After adjustment for age, weight, lifestyle factors, hormones, and mother's fracture status, BTM levels correlated positively between mothers and daughters (Intraclass Correlation Coefficient = 0.22-0.27, p <0.005). Average BTM levels were ∼ 0.6 SD higher among daughters of mothers in the highest BTM quartile vs. the ones in the lowest BTM quartile. The variability of BTM levels explained ≤ 10 and ≤ 14% of variability of bone microarchitecture in the daughters and mothers, respectively. Cortical density was lower by 2.3-2.9% (0.6 SD, p <0.05 to <0.005) in the daughters from the mother-daughter pairs with high BTM levels (defined by generation-specific quartiles) than in the daughters from the pairs with low BTM levels. Corresponding differences for the mothers were 4.5-4.8% (0.5 SD, p <0.05 to <0.01).

CONCLUSION

BTM levels correlated between postmenopausal mothers and their premenopausal daughters after adjustment for age, weight, mother's fracture status, lifestyle, and hormonal factors. Family resemblance of BTM levels may contribute to family resemblance of some bone microarchitectural parameters, especially of cortical density.

Relation of adrenal-derived steroids with bone maturation, mineral density and geometry in healthy prepubertal and early pubertal boys

BACKGROUND

Little is known about the effects of adrenal steroids on skeletal maturation and bone mass acquisition in healthy prepubertal boys.

OBJECTIVE

To study whether adrenal-derived steroids within the physiological range are associated with skeletal maturation, areal and volumetric bone mineral density (aBMD and vBMD) and bone geometry in healthy prepubertal and early pubertal boys.

METHODS

98 healthy prepubertal and early pubertal boys (aged 6-14 y) were studied cross-sectionally. Androstenedione (A) and estrone (E1) were determined by liquid chromatography tandem mass spectrometry and DHEAS was determined by immunoassay. Whole body and lumbar spine aBMD and bone area were determined by dual-energy X-ray absorptiometry. Trabecular (distal site) and cortical (proximal site) vBMD and bone geometry were assessed at the non-dominant forearm and leg using peripheral QCT. Skeletal age was determined by X-ray of the left hand.

RESULTS

Adrenal-derived steroids (DHEAS, A and E1) are positively associated with bone age in prepubertal and early pubertal children, independently of age. There are no associations between the adrenal-derived steroids and the studied parameters of bone size (lumbar spine and whole body bone area, trabecular or cortical area at the radius or tibia, periosteal circumference and cortical thickness at the radius or tibia) or BMD (aBMD or vBMD).

CONCLUSION

In healthy prepubertal and early pubertal boys, serum adrenal-derived steroid levels, are associated with skeletal maturation, independently of age, but not with bone size or (v)BMD. Our data suggest that adrenal derived steroids are not implicated in the accretion of bone mass before puberty in boys.

Bone densitometry in children and adolescents

PURPOSE OF REVIEW

Abnormalities in bone health are increasingly recognized in the pediatric population. Although the methodologies for assessing bone mineral density were originally developed for adults, great strides have been made in recent years, improving their applicability to children. Understanding these technologies, their interpretation, utility, and limitations is critical when assessing a child or adolescent with a suspected abnormality in bone mineral density.

RECENT FINDINGS

Improved normative databases that address some of the confounding variables in the growing and maturing child have solidified dual-energy X-ray absorptiometry as the preferred method for the assessment of bone mineral density in children. Consensus statements by expert panels now provide specific guidance to clinicians seeking to evaluate children with fractures or at risk for fractures. Although still primarily a research tool, continued development of quantitative computed tomography applications in pediatrics suggests there may be a complementary role for clinical use in the future.

SUMMARY

In the child or adolescent with a significant fracture history or a potential for fractures because of an underlying cause, clinicians now have guidelines and normative data to better focus their evaluation. Likewise, researchers can use this information to improve clinical trial design and interpretation of results.