The use of bone age in clinical practice - part 1

This review examines the role of skeletal maturity ('bone age', BA) assessment in clinical practice. BA is mainly used in children with the following conditions: short stature (addressed in part 1 of this review), tall stature, early or late puberty, and congenital adrenal hyperplasia (all addressed in part 2). Various manual and automatic methods of BA assessment have been developed. Healthy tall children tend to have advanced BA and healthy short children tend to have delayed BA in comparison to chronological age. Growth hormone (GH) treatment of children with GH deficiency leads to a catch-up in BA that is usually appropriate for the height of the child. Response to GH is dependent on BA delay in young children with idiopathic short stature, and GH dosage appears to affect BA acceleration. In chronic renal failure, BA is delayed until puberty but then increases due to increased sensitivity of the growth plate to sex steroids, thus further impairing adult height. The assessment of BA provides an important contribution to the diagnostic workup and management of children with short stature.

Measuring procedures to determine the Cobb angle in idiopathic scoliosis: a systematic review

BACKGROUND

Scoliosis of the vertebral column can be assessed with the Cobb angle (Cobb 1948). This examination is performed manually by measuring the angle on radiographs and is considered the gold standard. However, studies evaluating the reproducibility of this procedure have shown high variability in intra- and inter-observer agreement. Because of technical advancements, interests in new procedures to determine the Cobb angle has been renewed. This review aims to systematically investigate the reproducibility of various new techniques to determine the Cobb angle in idiopathic scoliosis and to assess whether new technical procedures are reasonable alternatives when compared to manual measurement of the Cobb angle.

METHOD

Systematic review. Studies examining procedures used to determine the Cobb angle were selected. Two review authors independently selected studies for inclusion, extracted data and assessed risk of bias. Statistical results of reliability and agreement were summarised and described.

RESULTS

Eleven studies of new measuring procedures were included, all reporting the reproducibility. The new procedures can be divided into computer-assisted procedures, automatic procedures and smartphone apps.

CONCLUSIONS

All investigated measuring procedures showed high degrees of reliability. In general, digital procedures tend to be slightly better than manual ones. For all other measurement procedures (automatic or smartphone), results varied. Studies implementing vertebral pre-selection and observer training achieved better agreement.

The 'Functional Muscle-Bone Unit': probing the relevance of mechanical signals for bone development in children and adolescents

The present text deals with the relationship of muscle force and mass to bone mass and geometry in the developing skeleton of children and adolescents. Recent results of the last ten years are discussed with reflection on Harold Frost's 'mechanostat hypothesis'. Bone mass and geometry follow the development of body size and muscle force in children and adolescents. Thereby, bone is adapted to the tissue strain due to biomechanical forces. This process is modified by hormonal signals (i.e., estrogens and androgens). Therefore, the quantified relationship of muscle force to bone stability is a reasonable approach to distinguish between primary and secondary bone diseases. Primary bone diseases are characterized by a disturbed adaptation of bone to biomechanical forces. In contrast, secondary bone diseases show a correct adaptation of bone to loaded forces in combination with a decline of muscle force. Therefore, the 'Functional Muscle-Bone Unit' was introduced into the diagnostics of pediatric bone diseases. The ratio of two parameters--referred to bone strength on the one and to biomechanical forces on the other side--is a reasonable diagnostic approach to distinguish between primary and secondary bone diseases.

Physical Activity for the Treatment of Adolescent Depression: A Systematic Review and Meta-Analysis

Background: A noticeable proportion of adolescents with depression do not respond to guideline recommended treatment options. This systematic review and meta-analysis investigated the effectiveness of physical activity interventions as an alternative or complementary treatment for adolescents (12-18 years) with depression. The characteristics of the physical activity treatment that were most effective in reducing symptoms in adolescents with depression and the impact of methodological shortcomings in the existing research were also examined. Methods: Medline, PsycINFO, SPORTDiscus, ProQuest, and CENTRAL were searched for eligible records. Effect size estimates were pooled based on the application of a random-effects model. Potential moderation by physical activity characteristics (i.e., intensity, type, context, and time frame) and methodological features (i.e., type of control group and diagnostic tool to identify depression at baseline) was investigated by means of subgroup analyses and meta-regressions. The certainty of evidence was assessed by the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The primary outcome was the antidepressant effect of physical activity at postintervention measurement time point. As secondary outcomes, the sustainability of effects after the end of physical activity treatment and the acceptability of physical activity treatments were assessed. Overall, 10 studies were included in the qualitative synthesis and 9 studies involving 431 patients were included in the quantitative synthesis. Results: A moderate, significant antidepressant effect of physical activity was found (Hedges' g = -0.47, 95% CI = -0.71 to -0.24). Heterogeneity was small (T2 = 0.0313, I 2 = 27%, p = 0.18). However, the certainty of evidence was downgraded to low because the included studies contained serious methodological limitations. Moderator analyses revealed that session intensity significantly moderated the antidepressant effect of physical activity. Moreover, noticeably smaller effect sizes were found in studies that used non-physical activity sham treatments as control treatments (e.g., playing board games), compared to studies that used no control group treatments. Only three studies assessed the sustainability of effects after the end of physical activity treatment. The results suggest that the antidepressant effects further increase after the end of physical activity interventions. There was no significant difference in dropout risk between the physical activity and control groups. Conclusions: This review suggests that physical activity is effective in treating depression in adolescents. Physical activity sessions should be at least moderately intense [rate of perceived exertion (RPE) between 11 and 13] to be effective. Furthermore, our results suggest that physical activity treatments are well accepted. However, the low methodological quality in included studies might have led to effect overestimation. Therefore, more studies with higher methodological quality are needed to confirm the recommendation for physical activity treatments in adolescents with depression.

DBS in the basolateral amygdala improves symptoms of autism and related self-injurious behavior: a case report and hypothesis on the pathogenesis of the disorder

We treated a 13-year-old boy for life-threatening self-injurious behavior (SIB) and severe Kanner's autism with deep brain stimulation (DBS) in the amygdaloid complex as well as in the supra-amygdaloid projection system. Two DBS-electrodes were placed in both structures of each hemisphere. The stimulation contacts targeted the paralaminar, the basolateral (BL), the central amygdala as well as the supra-amygdaloid projection system. DBS was applied to each of these structures, but only stimulation of the BL part proved effective in improving SIB and core symptoms of the autism spectrum in the emotional, social, and even cognitive domains over a follow up of now 24 months. These results, which have been gained for the first time in a patient, support hypotheses, according to which the amygdala may be pivotal in the pathogeneses of autism and point to the special relevance of the BL part.

De novo BK channel variant causes epilepsy by affecting voltage gating but not Ca2+ sensitivity

Epilepsy is one of the most common neurological diseases and it causes profound morbidity and mortality. We identified the first de novo variant in KCNMA1 (c.2984 A > G (p.(N995S)))-encoding the BK channel-that causes epilepsy, but not paroxysmal dyskinesia, in two independent families. The c.2984 A > G (p.(N995S)) variant markedly increased the macroscopic potassium current by increasing both the channel open probability and channel open dwell time. The c.2984 A > G (p.(N995S)) variant did not affect the calcium sensitivity of the channel. We also identified three other variants of unknown significance (c.1554 G > T (p.(K518N)), c.1967A > C (p.(E656A)), and c.3476 A > G (p.(N1159S))) in three separate patients with divergent epileptic phenotypes. However, these variants did not affect the BK potassium current, and are therefore unlikely to be disease-causing. These results demonstrate that BK channel variants can cause epilepsy without paroxysmal dyskinesia. The underlying molecular mechanism can be increased activation of the BK channel by increased sensitivity to the voltage-dependent activation without affecting the sensitivity to the calcium-dependent activation. Our data suggest that the BK channel may represent a drug target for the treatment of epilepsy. Our data highlight the importance of functional electrophysiological studies of BK channel variants in distinguishing whether a genomic variant of unknown significance is a disease-causing variant or a benign variant.

Mechanography--a new device for the assessment of muscle function in pediatrics

The development of the musculoskeletal system in children and adolescents became an important topic in the field of pediatric research when the connections between muscle force and bone diseases were revealed. The present study focused on reference values of ground reaction forces, which derive from muscle forces of the lower limbs. Specifically, the study investigated the relationship between anthropometric characteristics and peak jump force (PJF), and peak jump power (PJP). The parameters were assessed by jumping mechanography using the Leonardo Jumping Platform. The entire study group was comprised of 135 school boys (ages 7-21 y) and 177 girls (ages 6-19 y), who were enrolled in a German primary school and a German high school. The analysis of the parameters revealed that forces deriving from the motor performance of jumping follow an exponential relationship to body size parameters. Therefore, with consideration of anthropometric characteristics, the assessment of ground reaction forces might provide a novel, inexpensive, and accurate approach for the assessment motor performance in children and adolescents.

The use of bone age in clinical practice - part 2

If height-limiting treatment is being considered for a child with tall stature, skeletal maturity is invaluable in the selection of appropriate patients for treatment, determining appropriate age of treatment commencement, monitoring progress of treatment, and determining the expected treatment effect on adult height. In precocious puberty, bone maturation can be usefully assessed at initial diagnosis and start of treatment and at regular intervals thereafter during treatment monitoring. Together with height, bone maturation is an essential parameter for long-term treatment monitoring in congenital adrenal hyperplasia. Bone age (BA) determination in children with skeletal dysplasia is only feasible in a few disorders and estimations should be treated with caution. Radiographs of the left hand and wrist are, however, essential in the diagnosis of many skeletal disorders. Bone mineralization and measures of bone lengths, width, thickness and cortical thickness should always be evaluated in relation to a child's height and BA, especially around puberty. The use of skeletal maturity, assessed on a radiograph alone to estimate chronological age for immigration authorities or criminal courts is not recommended.

Mechanical influences on bone development in children

This review focuses on methodological concepts in the evaluation of skeletal muscle function and on adaptation. It is now thought that the critical property of bone is strength rather than weight, and that control of bone strength is mainly exercised through the effect of the mechanical loads brought to bear on bone. Muscle contraction places the greatest physiological load on bone, and so the stability of bone must be adapted to muscle strength (the functional muscle-bone unit). The described suggestions and recommendations outline a new concept: bone mass and strength should not be related to age. There is now more and more evidence that bone mass and strength should be related to muscle function. Thus analyzed, there is no such entity as 'peak bone mass'. Many studies are presently under way to evaluate whether these novel approaches increase the sensitivity and specificity of fracture prediction in an individual. Furthermore, the focus of many bone researchers is shifting away from bone mass to bone geometry or bone strength and their relationship with the driving muscle system.

Results of a prospective pilot trial on mobility after whole body vibration in children and adolescents with osteogenesis imperfecta

OBJECTIVE

To evaluate the effect of whole body vibration on the mobility of long-term immobilized children and adolescents with a severe form of osteogenesis imperfecta. Osteogenesis imperfecta is a hereditary primary bone disorder with a prevalence from 1 in 10000 to 1 in 20000 births. Most of these children are suffering from long-term immobilization after recurrent fractures. Due to the immobilization they are affected by loss of muscle (sarcopenia) and secondary loss of bone mass.

SUBJECTS

Whole body vibration was applied to eight children and adolescents (osteogenesis imperfecta type 3, N=5; osteogenesis imperfecta type 4, N=3) over a period of six months.

INTERVENTIONS AND RESULTS

Whole body vibration was applied by a vibrating platform (Galileo Systems) constructed on a tilting-table. Success of treatment was assessed by measuring alterations of the tilting-angle and evaluating the mobility (Brief Assessment of Motor Function). All individuals were characterized by improved muscle force documented by an increased tilting-angle (median = 35 degrees) or by an increase in ground reaction force (median at start=30.0 [N/kg] (14.48-134.21); median after six months = 146.0 [N/kg] (42.46-245.25).

CONCLUSIONS

Whole body vibration may be a promising approach to improve mobility in children and adolescents severely affected with osteogenesis imperfecta.

Reshaping of vertebrae during treatment with neridronate or pamidronate in children with osteogenesis imperfecta

BACKGROUND/AIMS

Osteogenesis imperfecta (OI) is a hereditary disease causing increased bone fragility. Pamidronate (PAM), which has to be administered as a 3-day course according to the original protocol by Glorieux, is the most frequently used therapy. Other bisphosphonates like neridronate (NER), which can be infused during an outpatient visit, have also proven to be effective. This is the first analysis comparing the effect of PAM and NER using vertebral morphometry.

METHODS

28 patients with OI type III and IV were retrospectively analyzed by matched pairs.

RESULTS

No differences were detected between patients treated with PAM or NER at the start of therapy: mean age 4.4 years (p = 0.730), mean height 86.8 cm/85.3 cm (p = 0.854), lumbar vertebral area 208.9 mm(2)/206.0 mm(2) (p = 0.555), and in all vertebral indices. After 1 year of treatment (mean 1.16 years; p = 0.854) both groups showed a significant increase in the vertebral area and improved vertebral indices. Again there were no differences between the groups in the vertebral area (p = 0.590).

CONCLUSION

In this study there was no difference between patients treated with PAM or NER regarding vertebral morphometry during the first year of therapy. Because of the possibility of an outpatient setting, NER is convenient for these children.

Speed of sound: relation to geometric characteristics of bone in children, adolescents, and adults

OBJECTIVES

To investigate the relation between volumetric bone mineral density (vBMD) and speed of sound (SOS).

STUDY DESIGN

Total and trabecular vBMD were measured by peripheral quantitative computed tomography at the forearm in a population of 216 individuals of a pediatric outpatient clinic. Moreover, SOS was measured by a quantitative ultrasound device (QUS) at the thumb, patella, and os calcis.

RESULTS

Linear regression analysis revealed that the prediction of SOS by vBMD is relatively weak (R2 < 0.1). Moreover, body height and measures of bone size have a stronger influence on SOS than vBMD. The influence of bone size on SOS also depends on the location of measurement (highest prediction of SOS by body height at patella with R2 = 0.56). Anthropometric characteristics have a stronger influence on SOS than measures of bone mineral density at the thumb and patella in comparison to os calcis (body height predicts SOS at os calcis, with R2 = 0.03). Conclusions QUS is not a suitable method to assess bone density. If QUS is applied for the assessment of bone development and of bone fracture risk, the measurement should be performed with consideration of anthropometric measurements.

Analysis of cancellous bone turnover by multiple slice analysis at distal radius: a study using peripheral quantitative computed tomography

We compared the results of peripheral quantitative computed tomography (pQCT) measurements (XCT-900; Stratec) at the 4% site of the distal radius (section 1; slice thickness of 2 mm) and in two proximally adjacent sections (sections 2 and 3). The study population consisted of 138 ambulatory patients (age 16.4 +/- 5.6 yr; mean +/- SD; 71 female) who were referred to a pediatric densitometry unit. Total volumetric bone mineral density (BMD) increased, whereas the area of the radial cross-section decreased in a proximal direction. There was a decrease in bone mineral content between sections 1 and 3, which was more pronounced in subjects under age 16. Cancellous BMD significantly decreased from section 1 to 3 only under the age of 16. In 12 patients under age 17 who suffered from increased bone fragility, cancellous BMD decreased about 2.5 times more between sections 1 and 3 than in age-matched patients who received anticonvulsant therapy but had a normal neurologic and musculoskeletal status (-21.4% +/- 16.9 vs -8.1% +/- 6.3; p = 0.02). This suggests that in the bone fragility group, trabeculae were removed faster during longitudinal growth of the radius. In conclusion, multiple slice analysis may provide information on the dynamic turnover of metaphyseal trabeculae during growth.

Local body composition is associated with gender differences of bone development at the forearm in puberty

BACKGROUND/AIMS

The present analyses intend to clarify if gender and puberty modify the relationship between bone development (modeling and remodeling) and fat mass at the forearm.

METHODS

Data were collected from participants (139 males, 157 females, age = 5-19 years) of the Dortmund Nutritional and Anthropometric Longitudinally Designed study in a cross-sectional investigation. The main outcome measures were total and trabecular bone mineral density (BMDtot and BMDtrab), strength strain index (SSI) and parameters associated with modeling (cortical area, CA; periosteal circumference, CP) and remodeling (cortical bone mineral density, BMDcort, endosteal circumference, CE) were analyzed in their relationship to cross-sectional fat (FA) and muscle area (MA) at the forearm.

RESULTS

BMDtot was correlated with FA in pubertal males (r = -0.25). BMDtrab was contrarily predicted by FA in pubertal males and females (r = -0.28 vs. 0.31). FA was correlated with BMDcort (r = -0.32) and CE (r = 0.26) in pubertal females. MA was positively correlated with CA, CP and SSI.

CONCLUSIONS

Modeling and bone strength were primarily predicted by MA. Markers of remodeling were positively correlated with FA in pubertal females, but not in prepubertal individuals and pubertal males. Therefore, gender and puberty modify the relationship between FA and bone development.

Mechanographic characteristics of adolescents and young adults with congenital heart disease

The present study comprised 29 adolescents and young adults (15 females, 14 males; aged 14.1-23.9 years) with congenital heart disease (CHD) and focused on the interaction between the biomechanical system and CHD. Individuals were characterized by auxological (height, weight), dynamometric (MIGF, maximal isometric grip force) and mechanograpic parameters (Vmax, maximal velocity; PJF, peak jump force; PJP, peak jump power; time of five stand-ups in chair-rising test). PJF, PJP and MIGF were transformed into height-related SD-scores. MIGF-SDS and PJP-SDS were lower in the CHD patients than in reference individuals. PJP-SDS was lower than PJF-SDS. PJP-SDS was correlated to Vmax (r = 0.62) and to the time of five-stand-ups in chair-rising (r = -0.62). Transcutaneous oxygen saturation and NYHA classes were correlated to Vmax (r = 0.42 and r = -0.57, respectively) and to chair-rising performance (r = -0.60 and r = 0.50, respectively). To conclude, individuals with CHD are characterized by an impaired inter- and intramuscular coordination, which is characterized by a greater decrease in muscular power than muscle force.

Subcutaneous fat and body fat mass have different effects on bone development at the forearm in children and adolescents

The present study investigated whether subcutaneous fat differs in the impact on bone development from fat mass (FM). We analyzed 295 healthy children and adolescents (age 5-19 years, 139 males) for FM by measuring four skinfold thicknesses and for bone development and body composition at the forearm by peripheral quantitative computed tomography in a cross-sectional investigation. Relative cross-sectional fat area (FA) was a surrogate for relative subcutaneous FM at the forearm and was associated positively with percent fat in prepubertal individuals and pubertal females but negatively in pubertal males. Percent FM was associated with trabecular bone mineral density (BMDtrab) in prepubertal individuals (females r = 0.394, males r = 0.242) and pubertal individuals (females r = 0.215, males r = -0.275). Bone mineral count was correlated with percent FM in pubertal males (r = -0.287). FA was correlated with BMDtrab (r = 0.285) and with cortical bone mineral density (BMDcort, r = -0.296) in pubertal females. The ratio FA/ FM was negatively correlated with BMDcort (r = -0.299) in pubertal females. Pubertal females with relatively high subcutaneous fat area (high ratio FA/FM) were characterized by lower bone strength (P = 0.047). FM and the relative amount of subcutaneous fat have effects on bone formation and resorption that depend on gender and puberty. Especially in pubertal females, higher levels of subcutaneous fat may decrease bone strength due to increased cortical remodeling.

The regulation of bone development as a biological system

A large number of molecular, cellular, and epidemiologic factors have been implicated in the regulation of bone development. A major unsolved problem is how to integrate these disparate findings into a concept that explains the development of bone as an organ. Often, events at the organ level are simply presented as the cumulative effect of all factors that individually are known to influence bone development. In such a cumulative model it must be assumed that each bone cell carries the construction plan of the entire skeletal anatomy in its genes. This scenario is implausible, because it would require an astronomical amount of positional information. We therefore propose a functional model of bone development, which is based on Frost's mechanostat theory. In this model, the genome only provides positional information for the basic outline of the skeleton as a cartilaginous template. Thereafter, bone cell action is coordinated by the mechanical requirements of the bone.

Cybernetic principles in the systematic concept of hypothalamic feeding control

Research on biological mechanisms of eating behavior and related disorders, such as obesity and anorexia nervosa, has become a large field of research in the last 15 years. With the discovery of peptides related to hypothalamic control of food intake (e.g. leptin and ghrelin) the search for the biological 'master key' of feeding control was renewed. As a result, mid-20th century biological concepts based on systematic and cybernetic thoughts fell into oblivion. This review highlights discoveries of hypothalamic-controlled feeding and eating behavior with a cybernetic and systematic perspective. Interestingly, older ideas of hypothalamic function offer possibilities for the incorporation of new molecular discoveries into systematic concepts of feeding behavior.

Effects of a 6-week, whole-body vibration strength-training on depression symptoms, endocrinological and neurobiological parameters in adolescent inpatients experiencing a major depressive episode (the "Balancing Vibrations Study"): study protocol for a randomized placebo-controlled trial

BACKGROUND

Moderate to vigorous endurance and strength-training exercise was suggested as a treatment option for major depression. However, there is little evidence to support this suggestion in adolescent patients. The present study investigates the effects of a whole-body vibration strength-training intervention on symptoms in medication-naïve adolescent inpatients experiencing a major depressive episode. Potential underlying endocrinological and neurobiological mechanisms are explored.

METHODS/DESIGN

A double-blinded randomized controlled trial is conducted at the University Hospital of Cologne in Germany, comparing a 6-week, whole-body vibration strength-training with a 6-week placebo-intervention, as add-on therapy to inpatient treatment as usual. Forty-one subjects (13-18 years of age) will be included in each of the two groups. The study is powered to detect (α = .05, β = .2) a medium effect size difference between the two groups (d = .5) in terms of patients' change in the Children's Depression Rating Scale raw-score, from baseline until the end of the intervention. As secondary endpoints, the effects of exercise treatment on patients' cortisol awakening response as well as on brain-derived neurotrophic factor, insulin-like growth factor 1 and inflammatory markers (tumor necrosis factor-alpha, interleukin-6 and C-reactive protein) serum levels will be assessed.

DISCUSSION

This study will provide evidence on the effectiveness of whole-body vibration strength-training as an add-on therapy in adolescent inpatients experiencing a major depressive episode. After completion of data collection, the present study will be the largest randomized controlled trial so far to investigate the effectiveness of an exercise intervention in inpatient adolescents suffering from a major depressive episode. Moreover, the present study may help to determine the underlying mechanisms of potential anti-depressant effects of exercise in depressed adolescent inpatients.

TRIAL REGISTRATION

DRKS.de, German Clinical Trials Register (DRKS), Identifier: DRKS00011772 . Registered on 20 March 2017.

Relationship of muscle function to auxology in preterm born children at the age of seven years

BACKGROUND/AIMS

To characterize the relationship between muscle function and auxology in preterm born children.

METHODS

Forty-five preterm born children (birth weight < or =1,500 g with mean +/- SD: 1,069 +/- 281 g; median of gestational age: 29 weeks; 50% multiple births) were analyzed for auxological parameters (weight, height) and muscle function at the age of 7 years. Maximal isometric grip force (MIGF) and ground reaction forces of goal-directed counter-movement jumping were measured using the Preston dynamometer and the Leonardo force plate. MIGF, peak jump force (PJF), peak jump power (PJP) and the maximal velocity of take-off (V(max)) were analyzed for their relationship to perinatal risk factors and actual auxological parameters.

RESULTS

With reference to age, weight-standard deviation score (SDS) and height-SDS were lower than in the reference population. With reference to height, MIGF-SDS and PJP-SDS were lower than in reference individuals. Children with intraventricular hemorrhage (IVH) had lower PJP-SDS and V(max) than children without IVH. PJP-SDS was lower than PJF-SDS in children with IVH.

CONCLUSION

Analyses showed a discrepancy between maximal force and power due to a decline of V(max) in children with IVH.

Do bone mineral density, bone geometry and the functional muscle-bone unit explain bone fractures in healthy children and adolescents?

BACKGROUND/AIMS

Because the increasing fracture incidence has not been understood, the present study compares variables of the muscle-bone interaction to examine the hypothesis that an impaired adaptation of bone strength to muscle forces explains this phenomenon.

METHODS

The forearm of 220 individuals (mean age 11.1 ± 3.2 years; range 5.5-17.4 years) was analyzed by peripheral quantitative computed tomography. Bone mineral content (BMC), bone mineral density, periosteal circumference, cortical area, strength strain index (SSI) and muscle area (MA) were measured at the distal and proximal radius of the non-dominant forearm. Maximum isometric grip force was measured by a dynamometer. The fracture history was evaluated by a questionnaire after a period of 5 ± 1.7 years.

RESULTS

During the observational period at least one fracture appeared in 78 children and adolescents (35.5%). Individuals with and without fractures were not different in age, height, weight, and body mass index. Variables of bone mineral density, bone geometry and muscle force were not different between both groups. BMC, MA and SSI were dependent on age and sex.

CONCLUSION

Fracture risk in healthy children and adolescents is not sufficiently explained by volumetric bone mineral density, the skeletal phenotype and indices of the functional muscle-bone unit.