Obesity during childhood and adolescence augments bone mass and bone dimensions

Obesity is associated with greater valgus knee alignment in pubertal children, and higher body mass index is associated with greater variability in knee alignment in girls

OBJECTIVE

In adults, osteoarthritis (OA) is associated with obesity and knee alignment. Whether knee alignment differences develop during childhood and are associated with obesity is unknown. We assessed the distribution of knee alignment in children and adolescents, and determined how knee alignment differs between obese and nonobese children.

METHODS

This cross-sectional study examined knee alignment in 155 healthy weight and 165 obese subjects. Knee alignment [metaphyseal-diaphyseal angle (MDA) and anterior tibiofemoral angle (ATFA)] and fat mass were measured using whole body dual-energy X-ray absorptiometry (DEXA). National reference data were used to generate age- and sex-specific body mass index (BMI, kg/m(2)) Z-scores. Multivariable linear regression was used to identify independent factors associated with ATFA and MDA.

RESULTS

The mean MDA and ATFA were similar between obese and nonobese subjects. In stratified analyses, females had greater variability in MDA and ATFA values (p < 0.001 and p = 0.04, respectively) at higher BMI Z-scores. Compared with healthy weight controls, obese subjects had less valgus of the MDA prior to the onset of puberty (+ 2.0°, p = 0.001), but had greater valgus at later pubertal stages (-1.9°, p = 0.01).

CONCLUSION

We found significantly greater variability in knee alignment among females at higher BMI Z-scores, and greater valgus alignment in obese adolescents in late puberty. The major limitation is the use of DEXA for assessment of alignment, which needs validation against longstanding radiographs. Longitudinal studies are needed to determine whether childhood obesity is a risk factor for progressive malalignment that may predispose to pain and risk of early osteoarthritis.

Exercise, hormones and skeletal adaptations during childhood and adolescence

Although primarily considered a disorder of the elderly, emerging evidence suggests the antecedents of osteoporosis are established during childhood and adolescence. A complex interplay of genetic, environmental, hormonal and behavioral factors determines skeletal development, and a greater effort is needed to identify the most critical factors that establish peak bone strength. Indeed, knowledge of modifiable factors that determine skeletal development may permit optimization of skeletal health during growth and could potentially offset reductions in bone strength with aging. The peripubertal years represent a unique period when the skeleton is particularly responsive to loading exercises, and there is now overwhelming evidence that exercise can optimize skeletal development. While this is not controversial, the most effective exercise prescription and how much investment in this prescription is needed to significantly impact bone health continues to be debated. Despite considerable progress, these issues are not easy to address, and important questions remain unresolved. This review focuses on the key determinants of skeletal development, whether exercise during childhood and adolescence should be advocated as a safe and effective strategy for optimizing peak bone strength, and whether investment in exercise early in life protects against the development of osteoporosis and fractures later in life.

Physical activity and bone mineral accrual in boys with different body mass parameters during puberty: a longitudinal study

The aim of our longitudinal study was to investigate the relationships between physical activity and bone mass in boys with different body mass status during the years surrounding pubertal growth spurt. Two hundred and six boys entering puberty took part in this study. The subjects were divided into underweight (BMI < 15.35), normal weight (BMI ≥ 15.35-21.22), overweight (BMI ≥ 21.22-26.02) and obese (BMI > 26.02) groups at baseline according to age related categories. Whole-body DXA scans were performed at baseline, after 12 and 24 months to assess body composition (lean body mass, fat mass), and total body (TB), lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD) parameters. Physical activity was measured by 7-day accelerometry. For longitudinal analysis, multilevel fixed effects regression models were constructed. Biological age, height and lean body mass had an effect for explanation of TB BMD, FN BMD and LS BMD. Moderate to vigorous physical activity (MVPA), vigorous physical activity (VPA) and sedentary time (SED) had the significant effect only on FN BMD. Being an underweight boy at the baseline indicated greater chance (p<0.01) to have lower TB BMD in the future (2 years at follow up) development, compared to normal weight (estimates = -0.038), overweight (estimates = -0.061) and obese boys (estimates = -0.106).

Underweight, overweight, and pediatric bone fragility: impact and management

Skeletal health is modulated by a variety of factors, including genetic makeup, hormonal axes, and environment. Across all ages, extremes of body weight may exert a deleterious effect on bone accretion and increase fracture risk. The incidence of both anorexia nervosa and obesity, each involving extreme alterations in body composition, is rising among youth, and secondary osteoporosis is increasingly being diagnosed among affected children and adolescents. Compared with the elderly, the definition of osteoporosis that stems from any underlying condition differs for the pediatric population and special precautions are required with regard to treatment of young patients. Early recognition and management of both underweight and overweight youth and the accompanying consequences on bone and mineral metabolism are essential for preservation of skeletal health, although prevention of bone loss and optimization of bone mineral accrual remain the most important protective measures.

Wrist circumference as a novel predictor of hypertension and cardiovascular disease: results of a decade follow up in a West Asian cohort

No study has yet evaluated the effect of wrist circumference on risk of incident hypertension and cardiovascular disease (CVD) in an adult population. The present study included 3642 women, aged ≥30 years, free of CVD at baseline, who had undergone health examinations between January 1999 and 2001 and were followed up until March 2010. Cox proportional hazard regression was performed to assess the hazard ratios (HRs) of wrist circumference for CVD and hypertension events. During 10 years of follow-up, 284 cases of first CVD and 615 cases of incident hypertension occurred. In a model adjusted for conventional CVD risk factors, the HR of 1 cm increase in wrist circumference was 1.15 (1.06-1.25) for hypertension and was marginally significant for CVD (HR, 1.12 [1.00-1.25]; P-value 0.052). After considering body mass index and waist circumference in the model, we found significant interaction between waist circumference and wrist circumference in risk prediction of hypertension and CVD (P < .001). In non-centrally obese women (waist circumference <95 cm), in multivariable model plus body mass index and waist circumference, increase in wrist circumference was independently associated with both hypertension (HR, 1.17 [1.02-1.35]) and CVD (HR, 1.29 [1.03-1.61]). However, among centrally obese women (waist circumference ≥95 cm), wrist circumference increase could not predict either hypertension (HR, 0.97 [0.84-1.18]) or CVD events (HR, 0.90 [0.75-1.07]). Wrist circumference as a novel anthropometric measure was an independent predictor for incident hypertension and CVD events among non-centrally obese women.

Bone fractures in children: is there an association with obesity?

OBJECTIVE

To determine the relationship between body mass index (BMI) and odds of extremity bone fractures in children.

STUDY DESIGN

This was a prospective cross-sectional study conducted at 2 tertiary care pediatric emergency departments. A convenience sample of children 2-17 years of age with a nonpenetrating extremity injury was enrolled. Demographics, activity level, mechanism of injury, participant BMI, and presence of a fracture were recorded. The main outcome was the odds of an extremity bone fracture based on BMI category; logistic regression was used to estimate the odds of fracture by BMI category.

RESULTS

We enrolled 2213 children, of whom 1078 (48.7%) sustained a fracture and 316 (14.3%) were classified as obese. The mean (SD) age was 9.5 (4.2) years, and percentage of male children was 56.8%. Compared with children with a normal BMI, the adjusted odds of fracture among obese, overweight, and underweight children were 0.75 (0.58, 0.97), 1.15 (0.89, 1.48), and 1.44 (1.00, 2.07) respectively.

CONCLUSIONS

Obese children had a minor but statistically significant decreased odds of fracture relative to children with a normal BMI, but no association was observed in overweight children. However, underweight children were found to be at an increased odds of fracture. This study suggests that overweight and obese children do not have increased odds of extremity fracture.

Higher circulating parathormone is associated with smaller and weaker bones in obese children

Obese children have disadvantageous bone geometry, bone of low quality, and reduced strength at non-weight-bearing skeletal sites. The aim of our study was to investigate the role of parathormone (PTH) and the Wnt/β-catenin signaling pathway and its inhibitors, sclerostin and Dickkopf-1 (DKK1), as negative modulators of fat mass on bone. This was a cross-sectional observational study performed in 44 (26 males and 18 females) obese subjects, aged 11.41 ± 2.61 years. Thirty-seven normal-weight, healthy children (22 males and 15 females) of the same chronological age served as controls for the biochemical parameters and bone markers, while the data on bone geometry were evaluated according to our normative data obtained previously in a group of 325 control children. Digitalized X-rays were evaluated at the level of the second metacarpal bone for the determination of bone geometry: total cross-sectional area (TCSA), cortical area (CA), medullary area (MA), and bone strength (bending breaking resistance index [BBRI]). Serum bone markers (intact procollagen-1N-terminal propeptide [P1NP] and serum carboxy-terminal telopeptide of collagen-1 [CTX]), sclerostin, DKK1, PTH, 25-hydroxyvitamin D and were also measured. Data for TCSA, CA, MA, and BBRI are expressed as a standard deviation score in order to normalize them for age and sex. TCSA (mean ± SD, -2.92 ± 2.71), CA (-0.60 ± 0.82), MA (-0.45 ± 1.14), and BBRI (-2.65 ± 2.31) were all significantly smaller than in controls (p < 0.01). Serum PTH (36.27 ± 23.89 vs. 19.33 ± 11.37 pg/mL) and CTX (1.55 ± 0.44 vs. 1.34 ± 0.46 ng/mL) were significantly increased (p < 0.05) in the obese children compared to controls, while sclerostin was significantly decreased (24.67 ± 10.06 vs. 30.42 ± 11.01 pmol/L, p < 0.05). P1NP was also significantly increased (p < 0.01). PTH was negatively correlated with TCSA, CA, and BBRI. Bone turnover is higher in obese children than in controls, and this is associated with smaller and apparently weaker bones. Higher PTH and lower sclerostin levels may be responsible for these findings.

High bone density in adolescents with obesity is related to fat mass and serum leptin concentrations

OBJECTIVES

Obesity has been associated with increased bone mass, but the mechanisms involved are still poorly understood. We aimed to explore the relation between bone mineral density and factors known to influence bone formation in obese and lean adolescents.

METHODS

We recruited 24 obese and 25 lean adolescents in a case-control study. Total body bone mineral density (TB-BMD) z scores and body composition were determined using dual-energy x-ray absorptiometry. We measured 25-hydroxyvitamin D (25-OH-D), glucose, insulin, and leptin concentrations. Physical activity (PA) level was quantified using accelerometer.

RESULTS

TB-BMD z score was higher, whereas 25-OH-D and PA levels were lower in obese compared with lean subjects (TB-BMD z score 1.06 ± 0.96 vs 0.26 ± 0.91, P = 0.004; 25-OH-D 9.9 ± 6.4 vs 18.5 ± 7.4 ng mL, P < 0.001; PA level 308.3 ± 22.1 vs 406.8 ± 29.2 count min, P = 0.01). TB-BMD z score was not related to 25-OH-D or PA levels, but was positively correlated with leptin concentration and fat mass (P < 0.05). Vitamin D concentration was negatively correlated with fat mass (P < 0.001).

CONCLUSIONS

Despite lower serum vitamin D and PA levels, BMD was higher in adolescents with obesity and associated with higher serum leptin concentrations. Furthermore, adolescents with obesity have lower vitamin D serum concentrations than lean controls, probably owing to its distribution in adipose tissue.

Dual-energy X-ray absorptiometry interpretation and reporting in children and adolescents: the revised 2013 ISCD Pediatric Official Positions

The International Society for Clinical Densitometry Official Revised Positions on reporting of densitometry results in children represent current expert recommendations to assist health care providers determine which skeletal sites should be measured, which, if any, adjustments should be made, reference databases to be used, and the elements to include in a dual-energy X-ray absorptiometry report. The recommended scanning sites remain the total body less head and the posterior-anterior spine. Other sites such as the proximal femur, lateral distal femur, lateral vertebral assessment, and forearm are discussed but are only recommended for specific pediatric populations. Different methods of interpreting bone density scans in children with short stature or growth delay are presented. The use of bone mineral apparent density and height-adjusted Z-scores are recommended as suitable size adjustment techniques. The validity of appropriate reference databases and technical considerations to consider when upgrading software and hardware remain unchanged. Updated reference data sets for all contemporary bone densitometers are listed. The inclusion of relevant demographic and health information, technical details of the scan, Z-scores, and the wording "low bone mass or bone density" for Z-scores less than or equal to -2.0 standard deviation are still recommended for clinical practice. The rationale and evidence for the development of the Official Positions are provided. Changes in the grading of quality of evidence, strength of recommendation, and worldwide applicability represent a change in current evidence and/or differences in opinion of the expert panelists used to validate the position statements for the 2013 Position Development Conference.

Obesity and its effects on pediatric supracondylar humeral fractures

BACKGROUND

This study evaluates the effects of childhood obesity on fracture complexity and associated injuries in pediatric supracondylar humeral fractures.

METHODS

A billing query identified all patients who were two to eleven years of age and had undergone operative treatment for extension-type supracondylar humeral fractures over a 12.5-year period. Records were reviewed for demographic data, body mass index percentile, and injury data. Complex fractures were defined as type-3 supracondylar humeral fractures, supracondylar humeral fractures with intercondylar extension, or supracondylar humeral fractures with ipsilateral upper-extremity fractures. Logistic regression analyses were used to test relationships among body mass index subgroups, fracture complexity, elbow motion, preoperative and postoperative neurovascular status, and complications.

RESULTS

Three hundred and fifty-four patients met our inclusion criteria. Forty-one children were underweight (BMI in the <5th percentile), 182 were normal weight (BMI in the 5th to 85th percentile), sixty-three were overweight (BMI in the >85th to 95th percentile), and sixty-eight were obese (BMI in the >95th percentile). There were 149 patients, eleven of whom were obese, with isolated type-2 fractures and 205 patients, fifty-seven of whom were obese, with complex fractures. Thirty-two patients had preoperative nerve palsies and twenty-eight patients had postoperative nerve palsies. Using logistic regression, obesity was associated with complex fractures (odds ratio, 9.19 [95% confidence interval, 4.25 to 19.92]; p < 0.001), preoperative nerve palsies (odds ratio, 2.69 [95% confidence interval, 1.15 to 6.29]; p = 0.02), postoperative nerve palsies (odds ratio, 7.69 [95% confidence interval, 2.66 to 22.31]; p < 0.001), and postoperative complications (odds ratio, 4.03 [95% confidence interval, 1.72 to 9.46]; p < 0.001). Additionally, obese patients were more likely to sustain complex fractures from a fall on an outstretched hand than normal-weight patients (odds ratio, 13.00 [95% confidence interval, 3.44 to 49.19]; p < 0.001).

CONCLUSIONS

Obesity is associated with more complex supracondylar humeral fractures, preoperative and postoperative nerve palsies, and postoperative complications. To our knowledge, this study is the first to assess the implications of obesity on supracondylar humeral fracture complexity and associated injuries and it validates public health efforts in combating childhood obesity.

Effects of weight-bearing activities on bone mineral content and density in children and adolescents: a meta-analysis

Osteoporosis and associated fractures are a major health concern in Western industrialized nations. Exercise during growth is suggested to oppose the involutional bone loss later in life by increasing peak bone mass. The primary aim of the present meta-analysis was to provide a robust estimate of the effect of weight-bearing activities (WBAs) on bone mineral content (BMC) and areal bone mineral density (aBMD), during childhood and adolescence. To locate relevant studies up to June 2012, computerized searches of multiple bibliographic databases and hand searches of key journals and reference lists were performed. Results were extracted by two independent reviewers. The quality of the included trials was assessed via the Physiotherapy Evidence Database (PEDro) score. The study group effect was defined as the difference between the standardized mean change for the treatment and control groups divided by the pooled pretest SD. From 109 potentially relevant studies, only 27 met the inclusion criteria. The analyzed training programs were capable of significantly increasing BMC and aBMD during growth. However, the weighted overall effect sizes (ESs) for changes in BMC (ES 0.17; 95% confidence interval [CI], 0.05-0.29; p < 0.05) and aBMD (ES 0.26; 95% CI, 0.02-0.49) were small. Stepwise backward regression revealed that more than one-third of the observed variance (r(2)  = 0.35) between subgroups of the BMC dataset could be explained by differences in the amount of habitual calcium intake per day (beta 0.54, p < 0.01) and the maturational stage (beta -0.28, p < 0.01) at baseline. No significant moderators were identified for aBMD, possibly due to the small number of trials investigating WBAs on aBMD. The results of this meta-analysis conclude that WBAs alongside high calcium intake provide a practical, relevant method to significantly improve BMC in prepubertal children, justifying the application of this exercise form as an osteoporosis prophylaxis in this stage of maturity.

Body fat in children does not adversely influence bone development: a 7-year longitudinal study (EarlyBird 18)

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Both negative and positive associations have been reported between body fat and bone density. Extra mechanical loading from excess fat may lead to greater bone mass. Excess ectopic fat may lead to bone demineralisation through inflammatory pathways.

WHAT THIS STUDY ADDS

Longitudinally collected data from narrow-angle beam densitometry gives a novel insight into bone growth through adolescence. There is no evidence of a deleterious effect of body fat on children's growing bones after adjustment for height and age. Body fat, mediated by puberty, is associated with larger bones in boys and bones that are both denser and larger in girls.

OBJECTIVE

Bone growth is an important determinant of peak bone mass and fracture risk, but there is limited data on the impact of fat-on-bone development at a time when childhood obesity is reaching epidemic proportions. Accordingly, we explored the effect of body fat (BF) on bone growth over time in the context of age, pubertal tempo and gender.

METHOD

A cohort of 307 children was measured biannually from 9-16 years for height and weight, and every 12 months for percent BF, bone area (BA), bone mineral content and areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry. Pubertal tempo was determined quantitatively by age at peak height velocity.

RESULTS

Percent BF increased and then fell in the boys, but increased throughout in the girls. aBMD and BA increased in both genders (P < 0.001). Greater BF was associated with higher aBMD and BA in girls (P < 0.001), but only BA in boys (P < 0.001). The extra aBMD associated with increased BF was greater in older girls. The rise in aBMD and BA was associated with earlier puberty in both genders (P < 0.001). The impact of BF on aBMD was greater in later puberty in girls (0.0025 g cm(-2) per 10% BF at 10 years versus 0.016 g cm(-2) per 10% BF at 14 years, P < 0.001).

CONCLUSION

Greater BF is associated with larger bones, but also denser bones in girls. The effects of fat and puberty are complex and gender specific, but BF of contemporary UK children does not appear to be deleterious to bone quality.

Prevention of Osteoporosis and Bone Fragility

The importance of optimal bone growth in childhood and adolescence has been recognized as one of the key strategies in osteoporotic fracture prevention. Low birth size, poor childhood growth, and low peak bone mass at the cessation of growth have been linked to the later risk of osteoporosis and hip fracture. Formerly, the focus was merely on maximizing bone mineral accrual because a high peak bone mineral mass may prevent attainment of a critical “fracture threshold” associated with age-related bone loss and osteoporosis. More recently, the focus has shifted away from bone mineral accrual—as measured by dual-energy X-ray absorptiometry (DXA)—toward the optimization of bone strength. This is partly because of the advances in bone imaging that have enabled estimation of bone strength beyond bone mass. In this review, we briefly describe long-bone growth and structural development and our abilities to assess bone properties by medical imaging tools. In addition, we summarize the evidence of factors contributing to skeletal growth, bone fragility, and the development of strong, healthy bones.

Low dietary calcium and obesity: a comparative study in genetically obese and normal rats during early growth

PURPOSE

A low calcium intake (LCaI) may predispose to obesity, and excessive fat mass may be detrimental to bone. The impact of Ca inadequacy would be greater in subjects predisposed to obesity. LCaI effect on obesity development during the rapid growth period was compared in two strains of rats: spontaneously obese IIMb/β (O) and Wistar (W). Pregnant rats were fed 0.5% (N) or 0.2% (L) of Ca (OLCa, ONCa, WLCa and WNCa). Male pups were fed the maternal diet until day 60.

METHODS

Body composition, lipid profile, glucose homeostasis, 25 hydroxyvitamin D, Ca-phosphorus, and bone metabolism were evaluated.

RESULTS

BW and body fat were higher, whereas body protein was lower in OLCa versus ONCa (p < 0.05). OLCa presented the highest body fat, glucose, non-HDL and total cholesterol, TGL, insulin levels, and HOMA-IR, liver weight, and adipose perigonadal plus retroperitoneal pads (p < 0.05). WLCa did not exhibit an increase BW and only showed a slight change in body composition with minor biochemical alterations compared to WNCa (p < 0.05). Osteocalcin, CTX, and proximal tibia and lumbar spine BMDs were lower in O than in W rats fed the same Ca diet (p < 0.05). Body ash and Ca content, and total skeleton BMC/BW were lower in OLCa and WLCa versus their corresponding NCa groups (p < 0.05).

CONCLUSION

The negative effect of a low Ca diet on fat mass accumulation and lipid profile may be more evident in rats predisposed to obesity. Nevertheless, low CaI interferes with the normal glucose homeostasis leading to an increase in insulin resistance. Low CaI during early growth may be an obesogenic factor that may persist into adult life and may account for the development of obesity and some of its co-morbidities.

Application of body mass index according to height-age in short and tall children

Background

In children with either delayed or accelerated growth, expressing the body mass index (BMI) to chronological age might lead to invalid body composition estimates. Reference to height-age has been suggested for such populations; however its validity has not been demonstrated.

Methods

Anthropometric data of healthy children were obtained from the German KiGGS survey. We selected three samples with different height distributions representing short stature (mean height SDS: -1.6), normal stature (height SDS: 0), and tall stature (height SDS: +1.6), and compared BMI-for-age and BMI-for-height-age between these samples across the paediatric age range. Differences between samples were tested using Kruskal-Wallis one-way analysis of variance and permutation tests.

Results

At a given age, BMI was distributed towards lower values in short, and towards higher values in tall subjects as compared to a population with average height distribution. Expressing BMI to height-age eliminated these differences in boys with a short stature from 4 years to 14 years of age, in tall boys from 4 to 16 years, in short girls aged 2-10 years or tall girls aged 2-17 years.

Conclusion

From late infancy to adolescent age, BMI distribution co-varies with height distribution and referencing to height-age appears appropriate within this age period. However, caution is needed when data about pubertal status are absent.

Bone size and bone strength are increased in obese male adolescents

CONTEXT

Controversy exists on the effect of obesity on bone development during puberty.

OBJECTIVE

Our objective was to determine differences in volumetric bone mineral density (vBMD) and bone geometry in male obese adolescents (ObAs) in overlap with changes in bone maturation, muscle mass and force development, and circulating sex steroids and IGF-I. We hypothesized that changes in bone parameters are more evident at the weight-bearing site and that changes in serum estradiol are most prominent.

DESIGN, SETTING, AND PARTICIPANTS

We recruited 51 male ObAs (10-19 years) at the entry of a residential weight-loss program and 51 healthy age-matched and 51 bone-age-matched controls.

MAIN OUTCOME MEASURES

vBMD and geometric bone parameters, as well as muscle and fat area were studied at the forearm and lower leg by peripheral quantitative computed tomography. Muscle force was studied by jumping mechanography.

RESULTS

In addition to an advanced bone maturation, differences in trabecular bone parameters (higher vBMD and larger trabecular area) and cortical bone geometry (larger cortical area and periosteal and endosteal circumference) were observed in ObAs both at the radius and tibia at different pubertal stages. After matching for bone age, all differences at the tibia, but only the difference in trabecular vBMD at the radius, remained significant. Larger muscle area and higher maximal force were found in ObAs compared with controls, as well as higher circulating free estrogen, but similar free testosterone and IGF-I levels.

CONCLUSIONS

ObAs have larger and stronger bones at both the forearm and lower leg. The observed differences in bone parameters can be explained by a combination of advanced bone maturation, higher estrogen exposure, and greater mechanical loading resulting from a higher muscle mass and strength.

Fat and lean BMI reference curves in children and adolescents and their utility in identifying excess adiposity compared with BMI and percentage body fat

BACKGROUND

Body mass index (BMI) and percentage body fat (%BF) are widely used to assess adiposity. These indexes fail to account for independent contributions of fat mass (FM) and lean body mass (LBM) to body weight, which vary according to age, sex, pubertal status, and population ancestry in the pediatric population.

OBJECTIVE

The objective was to develop pediatric reference curves for fat mass index (FMI) and lean body mass index (LBMI) and evaluate the effects of population ancestry and LBM on measures of excess adiposity (BMI, %BF, and FMI).

DESIGN

Sex-specific FMI and LBMI reference curves relative to age for children and adolescents aged 8-20 y were generated from cross-sectional body-composition data measured by dual-energy X-ray absorptiometry from NHANES.

RESULTS

The mean LBMI z score was higher in blacks (males: 0.26; females: 0.45) than in whites (males: -0.07; females: -0.09) and Mexican Americans (males: 0.05; females: -0.09). The positive predictive value of overweight by BMI to identify excess adiposity defined by FMI was lower in blacks (males: 35.9%; females: 30.3%) than in whites (males: 65.4%; females: 52.2%) and Mexican Americans (males: 73.3%; females: 68.3%). Participants classified as having excess adiposity by FMI but normal adiposity by %BF had significantly higher BMI, LBMI, and height z scores than did those classified as having excess adiposity by %BF but normal adiposity by FMI.

CONCLUSIONS

Relative to FMI, the prevalence of excess adiposity is overestimated by BMI in blacks and underestimated by %BF in individuals with high LBM. The use of FMI and LBMI improves on the use of %BF and BMI by allowing for the independent assessment of FM and LBM.

Geometric indices of hip bone strength in obese, overweight, and normal-weight adolescent girls

The aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight adolescent girls using hip structure analysis (HSA). This study included 64 postmenarcheal adolescent girls (14 obese, 21 overweight, and 29 normal weight). The 3 groups (obese, overweight, and normal weight) were matched for maturity (years since menarche). Body composition and bone mineral density (BMD) of whole body, lumbar spine, and proximal femur were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN) at its narrow neck (NN) region, the intertrochanteric (IT), and the femoral shaft (FS) by the HSA program. Cross-sectional area and section modulus were measured from hip BMD profiles. Total hip BMD and FN BMD were significantly higher in obese and overweight girls in comparison with normal-weight girls (p < 0.05). However, after adjusting for weight, using a one-way analysis of covariance, there were no significant differences among the 3 groups regarding HSA variables. This study suggests that in obese and overweight adolescent girls, axial strength and bending strength indices of the NN, IT, and FS are adapted to the increased body weight.

Does excess weight interfere with bone mass accumulation during adolescence?

Obesity and osteoporosis are important global health problems characterized by increasing prevalence with high impact on morbidity and mortality. The objective of this review was to determine whether excess weight during adolescence interferes with bone mass accumulation. If bone mineral gain can be optimized during puberty, adults are less likely to suffer from the devastating complications of osteoporosis. The increased fracture risk in obese children has also been attributed to a lower bone mass for weight compared to non-obese children. Thus, adiposity present in this age group may not result in the protection of bone mass, in contrast to what has been observed in adults. However, studies involving adolescents have reported both protective and detrimental effects of obesity on bone. The results and mechanisms of these interactions are controversial and have not been fully elucidated, a fact highlighting the extreme relevance of this topic and the need to monitor intervening and interactive variables.

Distinct relationships of intramuscular and subcutaneous fat with cortical bone: findings from a cross-sectional study of young adult males and females

CONTEXT

Intracellular fat within muscle and visceral tissue has been suggested to adversely influence bone development.

OBJECTIVE

The aim of the study was to evaluate associations between im fat, as reflected by muscle density as measured by peripheral quantitative computed tomography, and cortical bone parameters in young adults.

DESIGN/SETTING/PARTICIPANTS

We conducted a cross-sectional analysis of 1703 males and 2243 females aged 17.8 years from the Avon Longitudinal Study of Parents and Children.

OUTCOME MEASURES

We measured cortical bone parameters from midtibial peripheral quantitative computed tomography scans.

RESULTS

Muscle density (inversely related to im fat) was inversely associated with periosteal circumference (PC) (beta = -0.07 [95% confidence interval (CI), -0.1, -0.04]), cortical bone mineral density (BMDC) (beta = -0.21 [95% CI, -0.26, -0.17]), and cortical thickness (CT) (beta = -0.37 [95% CI, -0.42, -0.33]) (males and females combined, adjusted for age, height, gender, and muscle cross-sectional area). In contrast, sc fat area was positively associated with PC (beta = 0.10 [95% CI, 0.07, 0.12]), but no association was seen with BMDC or CT. To examine the role of candidate intermediary metabolic pathways, analyses were repeated after adjustment for insulin, C-reactive protein, and β-C-telopeptides of type I collagen. Whereas similar associations were observed after adjustment for insulin and C-reactive protein, the association between muscle density and BMDC was partially attenuated by adjustment for β-C-telopeptides of type I collagen (beta = -0.14 [95% CI, -0.20, -0.08]).

CONCLUSION

Although im and sc fat were both positively associated with cortical bone mass, the nature of these relationships differed in that im fat was predominantly associated with CT and BMDC, whereas sc fat was mainly associated with PC. These relationships were largely independent of candidate metabolic pathways, such as altered bone resorption, insulin resistance, or inflammation.

Childhood obesity is associated with increased risk of most lower extremity fractures

BACKGROUND

A number of studies have found an increased risk of lower extremity injuries in obese patients. Most studies, however, are unable to provide stable population-based estimates based on the degree of obesity and few assess the risk pertaining to more detailed fracture location in the lower extremities.

QUESTIONS/PURPOSES

We therefore investigated the relationship between obesity and lower extremity fractures in different age and fracture locations in a stable population.

METHODS

This is a population-based, cross-sectional study from the electronic medical records of 913,178 patients aged 2 to 19 years. The body mass index (BMI) for each patient in the cohort was used to stratify patients into five weight classes (underweight, normal weight, overweight, moderate obesity, and extreme obesity) based on BMI for age. Records were assessed for the occurrence of lower extremity fractures for each cohort member. The associations among the five weight classes and specific lower extremity fractures were estimated using multiple logistic regression models and expressed with odds ratios (ORs) and 95% confidence intervals (CIs) using multivariate analysis to adjust for patient demographic variables.

RESULTS

Overweight, moderately obese, and extremely obese patients all had an increased OR of fractures of the foot (OR, 1.14, 1.23, and 1.42, respectively, with 95% CI, 1.04-1.24, 1.12-1.35, and 1.26-1.61, respectively) along with the ankle, knee, and leg (OR, 1.27, 1.28, and 1.51, respectively, with 95% CI, 1.16-1.39, 1.15-1.42, and 1.33-1.72, respectively). The association was strongest in the 6- to 11-year-old age group. We found no association between increasing BMI and increased risk of fractures of the femur and hip.

CONCLUSIONS

Increasing BMI is associated with increased odds of foot, ankle, leg, and knee fractures in children.

LEVEL OF EVIDENCE

Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

How does bone quality differ between healthy-weight and overweight adolescents and young adults?

BACKGROUND

Overweight youth have greater bone mass than their healthy-weight peers but sustain more fractures. However, it is unclear whether and how excess body fat influences bone quality in youth.

QUESTIONS/PURPOSES

We determined whether overweight status correlated with three-dimensional aspects of bone quality influencing bone strength in adolescent and young adult females and males.

METHODS

We categorized males (n=103; mean age, 17 years) and females (n=85; mean age, 18 years) into healthy-weight and overweight groups. We measured lean mass (LM) and fat mass (FM) with dual-energy x-ray absorptiometry (DXA). We used high-resolution peripheral quantitative CT to assess the distal radius (7% site) and distal tibia (8% site). Bone quality measures included total bone mineral density (Tt.BMD), total area (Tt.Ar), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), separation (Tb.Sp), and thickness (Tb.Th). We used multiple regression to compare bone quality between healthy-weight and overweight adolescents adjusting for age, ethnicity, limb length, LM, and FM.

RESULTS

Overweight males had higher (10%-21%) Tt.BMD, BV/TV, and Tb.N and lower Tb.Sp at the tibia and lower Tt.Ar at the radius than healthy-weight males. No differences were observed between overweight and healthy-weight females. LM attenuated the differences in bone quality between groups in males while FM negatively predicted Tt.BMD, BV/TV, Tb.N, and Tb.Th.

CONCLUSIONS

Our data suggest overweight males have enhanced bone quality compared with healthy-weight males; however, when group differences are interpreted in the context of the mechanostat theory, it appears bone quality of overweight adolescents adapts to LM and not to greater FM.

Does obesity affect fracture healing in children?

BACKGROUND

Obesity is a risk factor for various orthopaedic diseases, including fractures. Obesity's influence on circulating hormones and cytokines and bone mineralization ultimately influences the body's osteogenic response and bone mineralization, potentially increasing the risk of fracture and impacting fracture healing.

QUESTIONS/PURPOSES

Does obesity delay fracture recovery in overweight or obese children as measured by the time to release to normal activity? Is this average time for return to activity influenced by the mechanism of the injury? Does obesity's effect on mineralization and loading in overweight or obese children lead to a greater proportion of upper extremity fracture versus lower extremity fracture?

METHODS

We prospectively followed 273 patients with nonpathologic long bone fractures treated from January 2010 to October 2011. Patients were stratified into obese/overweight, normal weight, and underweight groups. All patients were followed until release to regular activities (mean, 41 days; range, 13-100 days).

RESULTS

Release to regular activities occurred sooner in obese/overweight than in normal weight patients: 39 and 42 days, respectively. A greater proportion of obese/overweight patients had low to moderate energy mechanisms of injury than did normal weight patients, but we found no difference between the groups in terms of return to activity when stratified by mechanism. There was also no difference in the proportion of upper extremity injuries between the two groups.

CONCLUSIONS

Obese/overweight children did not have a delay in release to activities compared with children of normal weight.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Effect of obesity on linear growth

PURPOSE OF REVIEW

To describe our current understanding of the mechanisms involved in the regulation of linear growth in childhood obesity.

RECENT FINDINGS

The developmental origins hypothesis has focused on low birth weight individuals with subsequent obesity, identifying a cascade of neuroendocrine regulatory factors involved in the progressive increase in body fat and metabolic risk. Yet, tall stature is the common clinical outcome of childhood obesity. Recent data have expanded our understanding of environmental influences on developing systems. Here, we review the elements of neuroendocrine systems contributing to the integration of metabolic controls involved in growth regulation in the obese child with particular emphasis on growth hormone, ghrelin, insulin-like growth factors and insulin.

SUMMARY

Growth patterns of obesity during childhood are well described, documenting increased linear growth in early childhood associated with accelerated pubertal maturation resulting in normal adult height. Despite recent data suggesting that ghrelin and the growth hormone secretagogue receptor, as well as the insulin-like growth factors, their binding proteins and insulin have potential to be mediators of nutrient exposure and linear growth, it remains to be determined how these systems interrelate and determine growth. This is an area of ongoing investigation.

Skeletal maturation in obese patients

INTRODUCTION

The objective of this study was to compare skeletal maturation in obese patients and in subjects of normal weight to evaluate the best timing for orthopedic and orthodontic treatment. The null hypothesis was that obese and normal-weight patients show similar degrees of skeletal maturation.

METHODS

The sample for this retrospective study consisted of 50 white patients (28 boys, 22 girls) whose x-rays (hand-wrist and lateral cephalometric radiographs) were already available. The test group included 25 obese patients (11 girls, 14 boys; average age, 9.8 ± 2.11 years), and the control group included 25 subjects of normal weight (11 girls, 14 boys; average age, 9.9 ± 2.5 years). Skeletal maturation was determined by using the carpal analysis method and the cervical vertebral maturation method.

RESULTS

According to the carpal analysis, there was a significant difference between skeletal and chronologic ages between the test group (11.8 ± 11.4 months) and the control group (-2.9 ± 3.1 months). Furthermore, the obese subjects exhibited a significantly higher mean cervical vertebral maturation score (2.8 ± 0.7) than did the control subjects (2 ± 0.6) (P <0.05).

CONCLUSIONS

Compared with the normal-weight subjects, the obese subjects showed a higher mean discrepancy between skeletal and chronologic ages according to the carpal analysis and had a significantly higher cervical vertebral maturation score. Thus, to account for the growth in obese patients with skeletal discrepancies, it might be necessary to perform examinations and dentofacial and orthopedic treatments earlier than in normal-weight subjects.

A high-fat diet induces obesity and impairs bone acquisition in young male mice

The postnatal development of obesity is highly associated with the excessive consumption of a high-calorie, high-fat diet (HFD). However, the correlation between HFD-induced pediatric obesity and skeletal development remains to be elucidated. In the present study, postnatal day 17 (PND17) mice were weaned on a HFD for eight weeks ad libitum to induce obesity. The HFD mice showed a significant increase in the total body weight and gonadal and abdominal fat mass compared with the control animals. Peripheral quantitative (pQ) CT scans of the tibial bone revealed that the bone mineral density (BMD), including the total, trabecular and cortical BMD, was unchanged between the HFD and control diet groups, but that it was inversely associated with body fat. By contrast, the bone mineral content (BMC) and trabecular area were significantly decreased in the HFD group compared with the control. RNA and protein were isolated from the femur. qPCR and western blot analyses showed a significant downregulation in the gene expression of the key canonical Wnt signaling molecule β-catenin, the osteoblastic cell differentiation marker Runt-related transcription factor 2 (Runx2) and also in the β-catenin gene encoded protein levels of the HFD mice when compared with the controls. Consistent with the increased fat mass in the HFD-induced obese animals, the expression of the adipogenic genes and aP2 was increased compared with the controls. Bone marrow cells were aspirated and the ex vivo bone marrow cell cultures showed that the number of colony-forming unit osteoblasts (CFU-OBs) per bone was significantly decreased in the samples from the HFD mice compared with those from the controls. These observations suggested that HFD-induced obesity in growing animals may affect the total available osteoblastic cell differentiation progenitors in the bone, while increasing adipogenesis. This may result in negative consequences for the bone later on in adult life.

Small metacarpal bones of low quality in obese children

OBJECTIVE

It is still not known whether fat mass excess could exert a positive effect on bone. The aim of our study was to evaluate bone strength and quality in a group of overweight and obese children and adolescents by assessing bone geometry at metacarpal bones and ultrasound at phalangeal level.

DESIGN AND PATIENTS

This is a cross sectional observational study performed in 123 subjects, aged 11.2 ± 2.9 years.

MEASUREMENTS

Digitalized X-rays were evaluated at the level of the 2nd metacarpal bone for the determination of the outer (D) and inner (d) diameter, cortical area (CA), medullary endocortical area (EA), metacarpal index (MI) and bone strength (Bending Breaking Resistance Index; BBRI). A total of 98 subjects underwent amplitude dependent speed of sound (Ad-SOS) and bone transmission time (BTT) assessment by phalangeal ultrasonography.

RESULTS

SDs for each measured parameter were as follows: Males: D = -0.71 ± 0.95, d = -0·29 ± 0.86, CA = -0.69 ± 0.69, EA = -0.32 ± 0.79, Ad-SOS = -1.14 ± 0.91, BTT = -1.17 ± 1.11 and BBRI (417 ± 151 vs 495 ± 174 mm(3) ) were all significantly lower than in controls (P < 0.05). Females: D = -1.03 ± 1.06, d = -0.38 ± 0.92, CA = -0.91 ± 0.72, EA = -0.46 ± 0.79, Ad-SOS = -1.08 ± 1.11, BTT = -0.97 ± 1.07 and BBRI (342 ± 117 vs 649 ± 318 mm(3) ) were all significantly lower than in controls (P < 0.05).

CONCLUSIONS

Obese children show an unfavourable bone geometry and a bone of low quality and reduced strength compared to controls at a nonweight bearing skeletal site. This finding seems to support a detrimental effect of fat mass on bone and explain the frequent occurrence of wrist fractures in this group of children.

The role of pro/anti-inflammatory adipokines on bone metabolism in NAFLD obese adolescents: effects of long-term interdisciplinary therapy

To investigate the role of pro- and anti-inflammatory adipokines in the bone metabolism of non-alcoholic fatty liver disease (NAFLD) obese adolescents as well as the effects of long-term interdisciplinary therapy on metabolic-related risk factors. Forty post-puberty obese adolescents were randomly assigned into two groups: (1) NAFLD group and (2) non-NAFLD group (diagnosis by ultrasonography) and submitted to a weight loss therapy. Body composition was analyzed by air displacement plethysmography, bone mineral density (BMD) and content by dual-energy X-ray absorptiometry, blood samples were collected to measure lipid profile, hepatic enzymes, and adipokines. Leptin and adiponectin concentrations were measured by ELISA. A decrease in total body mass, BMI, body fat, visceral and subcutaneous fat, insulin concentration, HOMA-IR, total cholesterol and an increase in lean body mass were observed in both groups after therapy. It was found positive correlation between the Δ BMD and the Δ fat mass (%) (r = 0.31, P = 0.01) and negative correlations between Δ BMC with Δ HOMA-IR (r = -0.34, P = 0.02) and Δ HOMA-IR with Δ leptin (r = -0.34, P = 0.02). In addition, increased levels of adiponectin and reduction in leptin concentrations were observed in NAFLD group. In the simple regression analysis, the HOMA-IR was an independent predictor changes in BMC in total obese adolescents and in the non-NAFLD group. One year of interdisciplinary weight loss therapy for obese adolescents with or without NAFLD, could regulate bone mineral metabolism as result of an increased BMC and improved inflammatory state.

Assessing bone health in children and adolescents

During normal childhood and adolescence, the skeleton undergoes tremendous change. Utilizing the processes of modeling and remodeling, the skeleton acquires its adult configuration and ultimately achieves peak bone mass. Optimization of peak bone mass requires the proper interaction of environmental, dietary, hormonal, and genetic influences. A variety of acute and chronic conditions, as well as genetic polymorphisms, are associated with reduced bone density, which can lead to an increased risk of fracture both in childhood and later during adulthood. Bone densitometry has an established role in the evaluation of adults with bone disorders, and the development of suitable reference ranges for children now permits the application of this technology to younger individuals. We present a brief overview of the factors that determine bone density and the emerging role of bone densitometry in the assessment of bone mass in growing children and adolescents.

Trends in Height and BMI of 6-Year-Old Children during the Nutrition Transition in Chile

OBJECTIVE

We analyzed trends in height and BMI and their interaction in 6-year-old Chilean children over the last 15 years.

RESEARCH METHODS AND PROCEDURES

We calculated height for age z-score (HAZ), BMI z-score, prevalence of obesity, underweight, and stunting from cross-sectional national school-based annual population surveys in 1987, 1990, 1993, 1996, 2000, and 2002. Using mixed model analysis, we determined the risk of obesity according to height over time as odds ratios (ORs) and 95% confidence interval and the potential influence of height and year of study on BMI z-score.

RESULTS

Over the study period, height increased by 2.8 cm in boys and 2.6 cm in girls, whereas stunting declined from 5% to 2% in both. Tallness increased by approximately 2%, BMI z-score increased from +0.3 to +0.65 in boys and to +0.62 in girls, and HAZ increased from -0.47 in boys and -0.45 in girls to 0 in 2002. Underweight declined from 4% to 3%, whereas obesity rose from 5% to approximately 14%. The probability of obesity among tall children was significantly greater than that for normal height children (OR, 2.3 to 3.5). The lowest obesity risk was observed between -2 and -1 HAZ. The OR for obesity in the stunted relative to normal height children was variable, ranging from 1.23 to 0.65, whereas it was significant and consistently positive (1.1 to 1.7) for boys and girls when it was compared with the lowest obesity risk according to height.

DISCUSSION

Tallness is significantly associated with increased obesity risk in children, while stunting is also associated, but to a lesser degree.

Prevalence of overweight in children with bone fractures: a case control study

BACKGROUND

Children's fractures have been enlisted among orthopaedics complaints of childhood obesity. Unhealthy lifestyle behaviours may contribute to increased risk. This study described the prevalence of overweight/obesity in children and adolescents reporting a recent fracture in relation to gender, dynamic of trauma, and site of fracture.

METHODS

Four-hundred-forty-nine children and adolescents with fracture and 130 fracture-free controls were recruited from a large children's hospital. The interaction between overweight and gender, dynamic of trauma, site of fracture was explored. Sports participation, television viewing, and calcium intake were also investigated.

RESULTS

Overweight/obesity rate was increased in girls with fracture either at the upper or the lower limb (p= 0.004), while it was increased only in boys with fracture at the lower limb (p <0.02). Overweight/obesity rate did not differ between groups with low or moderate trauma. TV viewing ≥ 2 hrs was more frequent in children with fractures than controls (61.5% vs 34.5%, p =0.015) in the overweight/obese group.

CONCLUSIONS

The increased prevalence of overweight/obesity in children with fractures is related to gender and site of fracture. Higher levels of sedentary behaviours characterize overweight children reporting fractures.

Correlation between body mass index and orthodontic treatment outcome

OBJECTIVE

To determine whether there is a correlation between body mass index (BMI), patient cooperation, and treatment success during multibracket (MB) appliance therapy.

MATERIALS AND METHODS

All adolescent MB patients started and finished between 2007 and 2010 were analyzed. The pretreatment BMI was calculated and negative file entries such as bad oral hygiene, missed appointments, and appliance breakage were recorded. According to the number of negative entries, cooperation was classified as good, bad, or poor. Additionally, the treatment duration and the number of appointments were recorded. For the evaluation of treatment success, the pretreatment and posttreatment PAR (peer assessment rating) scores were measured.

RESULTS

Of the 77 subjects, 61 had a normal BMI (79.2%) and 16 were considered overweight (20.8%). Whereas 51.7% of the normal-weight children had a good cooperation, only 25% of the overweight patients cooperated sufficiently. Consequently, the number of patients exhibiting bad or poor cooperation was higher in the overweight group (37.5% bad, 37.5% poor) than in the normal-weight group (30.6% bad, 17.7% poor). Patients with an increased BMI had a slightly longer treatment duration (21.4 months) and needed more appointments (19.9) than their normal-weight peers (18.9 months, 18.1 appointments). The PAR (peer assessment rating) score reduction, however, was comparable (normal BMI: 17.8 points, 64.0%; increased BMI: 15.2 points, 65.3%).

CONCLUSION

In the present study, children with increased BMI did not cooperate as well during MB therapy as their normal-weight peers, but the treatment outcome was comparable in the two groups.

Relationship between markers of body fat and calcaneal bone stiffness differs between preschool and primary school children: results from the IDEFICS baseline survey

The aim of this study was to investigate the relationship between markers of body fat and bone status assessed as calcaneal bone stiffness in a large sample of European healthy pre- and primary school children. Participants were 7,447 children from the IDEFICS study (spread over eight different European countries), age 6.1 ± 1.8 years (range 2.1-9.9), 50.5 % boys. Anthropometric measurements (weight, height, bioelectrical impedance, waist and hip circumference, and tricipital and subscapular skinfold thickness) as well as quantitative ultrasonographic measurements to determine calcaneal stiffness index (SI) were performed. Partial correlation analysis, linear regression analysis, and ANCOVA were stratified by sex and age group: preschool boys (n = 1,699) and girls (n = 1,599) and primary school boys (n = 2,062) and girls (n = 2,087). In the overall study population, the average calcaneal SI was equal to 80.2 ± 14.0, ranging 42.4-153. The results showed that preschool children with higher body fat had lower calcaneal SI (significant correlation coefficients between -0.05 and -0.20), while primary school children with higher body fat had higher calcaneal SI (significant correlation coefficients between 0.05 and 0.13). After adjusting for fat-free mass, both preschool and primary school children showed an inverse relationship between body fat and calcaneal stiffness. To conclude, body fat is negatively associated with calcaneal bone stiffness in children after adjustment for fat-free mass. Fat-free mass may confound the association in primary school children but not in preschool children. Muscle mass may therefore be an important determinant of bone stiffness.

Laparoscopic sleeve gastrectomy in 108 obese children and adolescents aged 5 to 21 years

OBJECTIVE

To report experience with laparoscopic sleeve gastrectomy (LSG) in 108 severely obese children and adolescents.

BACKGROUND

Obesity during childhood and adolescence can be accompanied by serious long-term adverse health and longevity outcomes. With increased use of bariatric surgery to treat obesity in these patients, diverse guidelines have been published, most of which exclude children aged younger than 14 years. Few reports describe LSG in children and adolescents, delaying determining its safety and effectiveness and developing guidance regarding its use.

METHODS

A retrospective review of LSG performed from March 2008 through February 2011 by a single surgeon at King Saud University Hospitals, Riyadh, Saudi Arabia, included 108 patients aged 5 through 21 years.

RESULTS

Patients attending follow-up visits at 3 (n = 88), 6 (n = 76), 12 (n = 41), and 24 (n = 8) months postoperatively experienced median excess weight loss (EWL) of 28.9%, 48.1%, 61.3%, and 62.3%, respectively. At 6 and 12 months follow-up, 42.1% (n = 32) and 73.2% (n = 30) of patients achieved at least 50% EWL, whereas 7.9% (n = 6) and 4.9% (n = 2) had 25% or less EWL, respectively. There were no serious postoperative complications and no adverse sequelae developed during the current follow-up. Available comorbidity data indicate resolution of dyslipidemia, 21 of 30 (70.0%); hypertension, 27 of 36 (75.0%); prehypertension, 15 of 18 (83.3%); symptoms of obstructive sleep apnea, 20 of 22 (90.9%); diabetes, 15 of 16 (93.8%); and prediabetes, 11 of 11 (100.0%).

CONCLUSIONS

LSG resulted in successful short-term weight loss in more than 90% of pediatric patients and 70% or more comorbidity resolution during up to 24 months of follow-up. Long-term data are necessary to evaluate persistence of weight loss and maturation to adulthood.

The role of pro/anti-inflammatory adipokines on bone metabolism in NAFLD obese adolescents: effects of long-term interdisciplinary therapy

To investigate the role of pro- and anti-inflammatory adipokines in the bone metabolism of non-alcoholic fatty liver disease (NAFLD) obese adolescents as well as the effects of long-term interdisciplinary therapy on metabolic-related risk factors. Forty post-puberty obese adolescents were randomly assigned into two groups: (1) NAFLD group and (2) non-NAFLD group (diagnosis by ultrasonography) and submitted to a weight loss therapy. Body composition was analyzed by air displacement plethysmography, bone mineral density (BMD) and content by dual-energy X-ray absorptiometry, blood samples were collected to measure lipid profile, hepatic enzymes, and adipokines. Leptin and adiponectin concentrations were measured by ELISA. A decrease in total body mass, BMI, body fat, visceral and subcutaneous fat, insulin concentration, HOMA-IR, total cholesterol and an increase in lean body mass were observed in both groups after therapy. It was found positive correlation between the Δ BMD and the Δ fat mass (%) (r = 0.31, P = 0.01) and negative correlations between Δ BMC with Δ HOMA-IR (r = -0.34, P = 0.02) and Δ HOMA-IR with Δ leptin (r = -0.34, P = 0.02). In addition, increased levels of adiponectin and reduction in leptin concentrations were observed in NAFLD group. In the simple regression analysis, the HOMA-IR was an independent predictor changes in BMC in total obese adolescents and in the non-NAFLD group. One year of interdisciplinary weight loss therapy for obese adolescents with or without NAFLD, could regulate bone mineral metabolism as result of an increased BMC and improved inflammatory state.

Human biology at the interface of paediatrics: measuring bone mineral accretion during childhood

BACKGROUND

Professor Tanner established a paradigm for the study of growth and development that demands precise growth measurements, description of normal variability through development to adulthood, consideration of the effects of tempo and the study of factors that influence growth outcomes. The relatively new field of paediatric bone health assessment fits this paradigm and reflects the collaboration of human biologists and paediatricians in understanding the growth of the human skeleton.

REVIEW

This review describes the reasons for clinical assessment of bone density in children, the technological developments in bone health assessment in children, the development of reference curves and the effects of growth, body composition, pubertal timing, genetics and lifestyle on bone health outcomes.

Weak genetic relationship between trabecular bone morphology and obesity in mice

Obesity, in addition to being associated with metabolic diseases, such as diabetes, has also been found to lower the risk of osteoporotic fractures. The relationship between obesity and bone trabecular structure is complex, involving responses to mechanical loading and the effects of adipocyte-derived hormones, both directly interacting with bone tissue and indirectly through central nervous system signaling. Here we examine the effects of sex, a high fat diet, and genetics on the trabecular density and structure of the lumbar and caudal vertebra and the proximal tibia along with body weight, fat pad weight, and serum leptin levels in a murine obesity model, the LGXSM recombinant inbred (RI) mouse strains. The sample included 481 mice from 16 RI strains. We found that vertebral trabecular density was higher in males while the females had higher tibial trabecular density. The high fat diet led to only slightly higher trabecular density in both sexes despite its extreme effects on obesity and serum leptin levels. Trait heritabilities are moderate to strong and genetic correlations among trabecular features are high. Most genetic variation contrasts strains with large numbers of thick, closely-spaced, highly interconnected, plate-like trabeculae with a high bone volume to total volume ratio against strains displaying small numbers of thin, widely-spaced, sparsely connected, rod-like trabeculae with a low bone volume to total volume ratio. Genetic correlations between trabecular and obesity-related traits were low and not statistically significant. We mapped trabecular properties to 20 genomic locations. Only one-quarter of these locations also had effects on obesity. In this population obesity has a relatively minor effect on trabecular bone morphology.

Impact of obesity on orthopaedics

The prevalence of obesity among children and adults is increasing worldwide. There are substantial health risks and financial costs associated with the obesity epidemic that impact the practice of orthopaedic surgery. Patients with increased body mass index are more prone to sustaining distal extremity injuries than are those with a normal body mass index. Obese individuals are more likely than nonobese individuals to seek treatment for osteoarthritis of the knee.

Effects of obesity on pediatric fracture care and management

Obese children have a theoretically increased risk of sustaining an extremity fracture because of potential variations in their bone mineral density, serum leptin levels, and altered balance and gait. Trauma databases suggest an increased rate of extremity fractures in obese children and adolescents involved in polytrauma compared with nonobese children and adolescents. Anesthetic and other perioperative concerns for obese pediatric trauma patients undergoing surgery include higher baseline blood pressures, increased rates of asthma, and obstructive sleep apnea. A child's weight must be considered when choosing the type of implant for fixation of pediatric femoral fractures. Fracture prevention strategies in obese pediatric patients consist of ensuring properly sized safety gear for both motor vehicles and sporting activities and implementing structured weight-loss programs.

Geometric indices of hip bone strength in obese, overweight, and normal-weight adolescent boys

The aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight adolescent boys using hip structure analysis. After adjusting for weight, obese boys displayed lower intertrochanteric cross-sectional moment of inertia and femoral shaft cross-sectional moment of inertia and section modulus in comparison to normal-weight and overweight boys. This study suggests that in obese adolescent boys, femoral shaft bending strength is not adapted to the increased body weight.

INTRODUCTION

The influence of being obese or overweight on bone strength in adolescents remains controversial. The main aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight adolescent boys using hip structure analysis. The second aim of this study was to explore the influence of lean mass and fat mass on hip bone strength indices in the same population.

METHODS

This study included 70 adolescent boys (25 obese, 25 normal weight, and 20 overweight). The three groups (obese, overweight, and normal weight) were matched for maturity (Tanner stage) and age. Body composition and bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN), the intertochanteric (IT), and the femoral shaft (FS) by the Hip Structure Analysis (HSA) program. Cross-sectional area (CSA), an index of axial compression strength, section modulus (Z), an index of bending strength, and cross-sectional moment of inertia (CSMI), an index of structural rigidity were measured from bone mass profiles.

RESULTS

Body weight, lean mass, fat mass and BMI were significantly higher in obese and overweight boys in comparison to normal-weight boys (P < 0.05). Total hip (TH) BMD and femoral neck (FN) BMD were significantly higher in obese and overweight boys in comparison to normal-weight boys (P < 0.05). After adjusting for age or maturation index, obese and overweight boys displayed significantly higher TH and FN BMD, CSA, CSMI, and Z of the three sites (FN, IT, and FS) in comparison to normal-weight boys (P < 0.05). However, after adjusting for weight, obese boys displayed significantly lower IT CSMI and FS CSMI and Z in comparison to normal-weight and overweight boys (P < 0.05).

CONCLUSIONS

This study suggests that in obese adolescent boys, intertrochanteric structural rigidity and femoral shaft structural rigidity and bending strength are not adapted to the increased body weight.

Overweight in childhood and bone density and size in adulthood

We evaluated the adult bone structural traits in relation to childhood overweight in 832 men and women. Childhood overweight was associated with larger cross-sections at long bones in both sexes. Excess weight in childhood may also lead to higher trabecular density in females and somewhat lower cortical density in men.

INTRODUCTION

Excess body weight in childhood may impose more loading on growing skeleton and thus lead to more robust structure in adulthood.

METHODS

This prospective cohort study evaluated the adult bone structural traits in relation to childhood overweight in a subgroup of 456 women and 376 men from the population-based cohort of Cardiovascular Risks in Young Finns Study. Between-group differences were evaluated with analysis of covariance.

RESULTS

According to established body mass index (BMI) criterion at the age of 12 years, 31 women and 34 men were classified overweight in childhood. At the mean age (SD) of 36.1 (2.7) years, total cross-sectional (ToA) and cortical area (CoA) at the distal and shaft sites and cortical (shaft CoD) and trabecular (distal TrD) bone density of the nonweight-bearing radius and weight-bearing tibia were evaluated with pQCT. Despite being taller in adolescence, the adult body height of overweight children was similar. In both sexes, childhood overweight was consistently associated with 5-10% larger ToA at all bone sites measured in adulthood. CoA did not show such a consistent pattern. Women, who were overweight in childhood, had ~5% denser TrD with no difference in CoD. In contrast, TrD in men who were overweight in childhood was not different but their CoD was ~1% lower.

CONCLUSIONS

Childhood overweight was consistently associated with larger long bone cross-sections in both sexes. Excess weight in childhood may also lead to higher trabecular density in women and somewhat lower cortical density in men. Specific mechanisms underlying these associations are not known.

DXA femoral neck strength analysis in Chinese overweight and normal weight adolescents

The aim of this study was to compare femoral neck (FN) strength in Chinese overweight adolescents with gender-matched normal weight controls and investigate the relationship of total body soft tissue composition (lean and fat masses) to indices of FN strength. Dual-energy X-ray absorptiometry (DXA) measurements of the proximal femur and total body were made in 65 Chinese overweight adolescents and 89 gender-matched normal weight controls using Lunar Prodigy DXA bone densitometer (GE Healthcare, Madison, WI). FN bone mineral density (BMD), total body lean mass, fat mass, and bone mineral content (BMC) were measured. Using FN BMD values derived from DXA measurements, hip structural analysis (HSA) was performed using Lunar enCORE (GE Healthcare), version 10.5 software. Structural parameters derived by HSA were bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and the section modulus (Z). Data were analyzed by Student's t-test, Pearson correlation coefficients (r), and one-way analysis of covariance (ANCOVA). Overweight boys and girls had higher body weight, lean mass, fat mass, and body mass index (p<0.001) than normal controls. CSA, CSMI, and Z were higher in overweight groups compared with controls (p<0.05). Lean mass correlated well with all HSA parameters (range of r: 0.501--0.714) for both genders. ANCOVA test showed no significant differences between overweight and normal weight groups regarding HSA variables in both genders after adjustment for lean mass. However, the differences remain significant after adjustment for fat mass in boys but not in girls. This study supports the conclusion that overweight individuals have greater hip neck strength in comparison with normal weight controls in Chinese adolescents. Lean mass is a major determinant for FN strength.

Adiposity and bone health in Spanish adolescents. The HELENA study

While the association of lean mass (LM) with bone mass is well understood, the association of fat mass (FM) with bone mass is controversial. Our results support that adolescents with higher levels of adiposity have greater bone mass, but this association is fully explained by their higher levels of LM.

INTRODUCTION

We aimed (1) to study the independent association of FM and LM with bone mass and (2) to study the differences in bone mass by weight status in adolescents, after controlling for relevant confounders, such as physical activity (PA), calcium intake, and LM.

METHODS

Participants were 330 adolescents (167 boys, 12.5-17.5 years) from the HELENA study. The relationships of FM (DXA, n = 330; BodPod, n = 282) and LM (DXA, n = 330) with different bone variables (whole body, total hip, lumbar spine, and femoral neck) were analyzed by linear regression, and differences between weight status were analyzed by ANCOVA.

RESULTS

Fat mass (DXA) was positively associated with bone variables in both sexes, after adjustment for height, calcium intake, and sexual maturation. Additional adjustment by PA slightly increases the associations. However, adjustment for LM inverted these associations. Similar results were obtained using BodPod instead of DXA for assessing FM. Overweight/obese adolescents had higher BMC than their non-overweight peers in most of regions studied. Additional adjustment for PA slightly increased the differences between weight status groups, while adjusting for LM inverted the associations. LM was strong and positively associated with all bone variables in both sexes. Additional adjustment for PA or FM did not change the results.

CONCLUSIONS

Adolescents with higher levels of adiposity have greater bone mass, but this association is explained by their higher levels of LM.