Surgical Management and Denosumab for Aneurysmal Bone Cysts of the Spine in an Australian Tertiary Paediatric Centre

Aneurysmal bone cysts (ABC) are rare osteolytic, benign but often locally aggressive tumours of the long bones or vertebrae. For spinal ABC, surgical management, embolisation or sclerotherapy alone often carry high morbidity and/or high recurrence rates. Interruption of receptor activator of nuclear factor-kappa B ligand (RANKL) signalling holds promise as an effective therapeutic strategy for these tumours. We aimed to review the approach to surgical management and evaluate the efficacy and safety of denosumab for ABC of the spine in children. Retrospective review of 7 patients treated with denosumab using a standardised protocol for ABC of the spine in a tertiary paediatric centre. Surgical intervention was only conducted if there was spinal instability or significant neurological impairment. Denosumab 70 mg/m² was given 4-weekly for at least 6 months, followed by 2 doses of zoledronate 0.025 mg/kg, aiming to prevent rebound hypercalcaemia. All patients achieved stability of the spine and resolution of neurological impairment, if present. Six patients achieved metabolic remission and have ceased denosumab without recurrence to date; the other showed clinical and radiological improvement without complete metabolic remission. Three patients developed symptomatic hypercalcaemia 5-7 months after cessation of denosumab, requiring additional bisphosphonate treatment. We present our algorithm for the surgical and medical management of paediatric spinal ABC. Denosumab produced a radiological and metabolic response in all patients, with complete remission in most. Follow-up time was not long enough to evaluate the endurance of response after cessation in some patients. Incidence of rebound hypercalcaemia in this paediatric cohort was high, prompting a change to our protocol.

Childhood type 1 diabetes is associated with abnormal bone development

OBJECTIVE

To describe bone mineral density (BMD), bone structure, and fracture prevalence in adolescents with type 1 diabetes (T1D) and explore their associations with glycemic control and microvascular complications.

RESEARCH DESIGN AND METHODS

Cross sectional study of 64 adolescents (38 males) with T1D duration >10 years who underwent dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), fracture survey, plantar fascia thickness, and microvascular complications assessment.

RESULTS

Mean age was 16.6 ± 2.1 years, diabetes duration 12.8 ± 2.2 years and HbA1c 8.9 ± 1.7% (74 mmol/mol). Fracture prevalence was 50%. DXA areal BMD (Z-score) was reduced for femoral neck (-0.5 ± 1.3, p = 0.008) and arm (-0.4 ± 1.0, p < 0.001), while total areal BMD and lumbar spine BMD were normal. In pQCT (Z-score), trabecular volumetric BMD (vBMD) was reduced for tibia (-0.4 ± 0.8, p < 0.001) and radius (-0.8 ± 1.4, p < 0.001) whereas cortical vBMD was increased at both sites (tibia: 0.5 ± 0.6, p < 0.001, radius: 0.7 ± 1.5, p < 0.001). Muscle cross-sectional area (CSA) was reduced for upper (-0.6 ± 1.2, p < 0.001) and lower (-0.4 ± 0.7, p < 0.001) limbs. DXA total areal BMD was positively correlated with BMI (p < 0.01) and age at T1D diagnosis (p = 0.04). Lower radial bone CSA, total and lumbar spine BMD were associated with autonomic nerve dysfunction. HbA1c, diabetes duration, fracture history and other microvascular complications were not significantly associated with bone parameters.

CONCLUSIONS

Adolescents with childhood-onset T1D have site-specific bone deficits in upper and lower limbs but normal total and lumbar spine BMD. T1D appears to have differential effects on trabecular and cortical bone compartments. Future longitudinal analysis is warranted to examine whether these changes translate in to increased fracture risk.

Denosumab for central giant cell granuloma in an Australian tertiary paediatric centre

BACKGROUND

Central giant cell granulomas (CGCG) are rare osteolytic, benign but often locally aggressive tumours of bone. Surgical curettage may not be possible in extensive lesions and resection carries high morbidity, especially in growing children, and previous medical therapies have had variable efficacy and high recurrence rates. Interruption of receptor activator of nuclear factor-kappa B ligand (RANKL) signalling holds promise as an effective therapeutic strategy for these tumours.

AIMS

To evaluate the efficacy and safety of our protocol for denosumab treatment of CGCG in children.

METHODS

Retrospective review of 4 patients treated with denosumab using a standardised protocol for CGCG in a tertiary paediatric centre. Denosumab 70 mg/m² was given 4-weekly, followed by 2 doses of zoledronate 0.025 mg/kg, aimed at preventing rebound hypercalcaemia.

RESULTS

Treatment of CGCG resulted in metabolic remission in all patients, but recurrence, detected by positron emission tomography (PET), occurred at 6 months in three patients and 12 months in one patient. Three patients developed symptomatic hypercalcaemia 4-5 months and one patient asymptomatic hypercalcaemia 7 months after cessation of denosumab, with 3 requiring additional bisphosphonate treatment.

CONCLUSIONS

Denosumab produced a radiological and metabolic response in our patients, but metabolic recurrence occurred in all patients. PET imaging was effective for monitoring treatment response and early detection of recurrence. Incidence of rebound hypercalcaemia in this paediatric cohort was high. We present proposed changes to our protocol with the aim of producing sustained remission and preventing rebound hypercalcaemia.

Randomized Controlled Trial Evaluating the Use of Zoledronic Acid in Duchenne Muscular Dystrophy

CONTEXT

Patients with glucocorticoid-dependent Duchenne muscular dystrophy (DMD) have increased fracture risk and reduced bone mineral density (BMD), often precipitating mobility loss.

OBJECTIVE

To investigate use of zoledronic acid (ZA) in DMD in improving BMD.

METHODS

Two arm, parallel, randomized controlled trial, set in pediatric hospitals across Australia and New Zealand. Sixty-two (31 per arm) boys with glucocorticoid-dependent DMD between 6 and 16 years were included. Five ZA infusions (0.025 mg/kg at months 0, and 3, and 0.05 mg/kg at months 6, 12, and 18), plus calcium and vitamin D, were compared with calcium and vitamin D alone. The main outcome measures were change in lumbar spine (LS) BMD raw and Z-score by dual energy absorptiometry x-ray (DXA) at 12 and 24 months, secondary outcomes assessing mobility, fracture incidence, bone turnover, peripheral quantitative computerized (pQCT) and pain scores.

RESULTS

At 12 and 24 months, mean difference in changes of LS BMD Z-score from baseline was 1.2 SD (95% CI 0.9-1.5), higher by 19.3% (14.6-24.0) and 1.4 SD (0.9-1.9), higher by 26.0% (17.4-34.5) in ZA than control arms respectively (both P < .001). Five controls developed Genant 3 vertebral fractures, 0 in the ZA arm. Mobility, pain, and bone turnover markers were similar between arms at 12 and 24 months. Trabecular BMC and vBMD pQCT at radius and tibia were greater at 12 months in the ZA cohort than control; the evidence for this difference remained at 24 months for radius but not tibia.

CONCLUSION

ZA improved BMD in glucocorticoid-dependent DMD boys. Although the small cohort precluded demonstrable fracture benefit, improved BMD might reduce incident vertebral fracture.

Long-term outcomes of warfarin versus aspirin after Fontan surgery

OBJECTIVES

Because of the nature of the Fontan physiology, patients are at an increased risk of thromboembolic complications. As such, warfarin or aspirin is generally prescribed lifelong for thromboprophylaxis. This study aimed to compare long-term rates of cerebrovascular injury, thrombosis, bleeding, bone mineral density, and quality of life in people living with Fontan circulation receiving warfarin compared with aspirin.

METHODS

This was a multicenter study of a selected cohort from the Australia and New Zealand Fontan population. Participants underwent cerebral magnetic resonance imaging to detect the presence of cerebrovascular injury (n = 84) and dual-energy X-ray absorptiometry to assess bone mineral density (n = 120). Bleeding (n = 100) and quality of life (n = 90) were assessed using validated questionnaires: Warfarin and Aspirin Bleeding assessment tool and Pediatric Quality of Life Inventory, respectively.

RESULTS

Stroke was detected in 33 participants (39%), with only 7 (6%) being clinically symptomatic. There was no association between stroke and Fontan type or thromboprophylaxis type. Microhemorrhage and white matter injury were detected in most participants (96% and 86%, respectively), regardless of thromboprophylaxis type. Bleeding rates were high in both groups; however, bleeding was more frequent in the warfarin group. Bone mineral density was reduced in our cohort compared with the general population; however, this was further attenuated in the warfarin group. Quality of life was similar between the warfarin and aspirin groups. Home international normalized ratio monitoring was associated with better quality of life scores in the warfarin group.

CONCLUSIONS

Cerebrovascular injury is a frequent occurrence in the Australia and New Zealand Fontan population regardless of thromboprophylaxis type. No benefit of long-term warfarin prophylaxis could be demonstrated over aspirin; however, consideration must be given to important clinical features such as cardiac function and lung function. Furthermore, the association of reduced bone health in children receiving warfarin warrants further mechanistic studies.

Exercise Intolerance, Benefits, and Prescription for People Living With a Fontan Circulation: The Fontan Fitness Intervention Trial (F-FIT)-Rationale and Design

Background: Despite developments in surgical techniques and medical care, people with a Fontan circulation still experience long-term complications; non-invasive therapies to optimize the circulation have not been established. Exercise intolerance affects the majority of the population and is associated with worse prognosis. Historically, people living with a Fontan circulation were advised to avoid physical activity, but a small number of heterogenous, predominantly uncontrolled studies have shown that exercise training is safe-and for unique reasons, may even be of heightened importance in the setting of Fontan physiology. The mechanisms underlying improvements in aerobic exercise capacity and the effects of exercise training on circulatory and end-organ function remain incompletely understood. Furthermore, the optimal methods of exercise prescription are poorly characterized. This highlights the need for large, well-designed, multi-center, randomized, controlled trials. Aims and Methods: The Fontan Fitness Intervention Trial (F-FIT)-a phase III clinical trial-aims to optimize exercise prescription and delivery in people with a Fontan circulation. In this multi-center, randomized, controlled study, eligible Fontan participants will be randomized to either a 4-month supervised aerobic and resistance exercise training program of moderate-to-vigorous intensity followed by an 8-month maintenance phase; or usual care (control group). Adolescent and adult (≥16 years) Fontan participants will be randomized to either traditional face-to-face exercise training, telehealth exercise training, or usual care in a three-arm trial with an allocation of 2:2:1 (traditional:telehealth:control). Children (<16 years) will be randomized to either a physical activity and exercise program of moderate-to-vigorous intensity or usual care in a two-arm trial with a 1:1 allocation. The primary outcome is a change in aerobic exercise capacity (peak oxygen uptake) at 4-months. Secondary outcomes include safety, and changes in cardiopulmonary exercise testing measures, peripheral venous pressure, respiratory muscle and lung function, body composition, liver stiffness, neuropsychological and neurocognitive function, physical activity levels, dietary and nutritional status, vascular function, neurohormonal activation, metabolites, cardiac function, quality of life, musculoskeletal fitness, and health care utilization. Outcome measures will be assessed at baseline, 4-months, and 12-months. This manuscript will describe the pathophysiology of exercise intolerance in the Fontan circulation and the rationale and protocol for the F-FIT.

Impact of adiposity on clinical outcomes in people living with a Fontan circulation

BACKGROUND

To assess the association between body composition and the risk of adverse outcomes in Fontan patients.

METHODS

Participants from the Australian and New Zealand Fontan Registry with dual-energy X-ray absorptiometry scans were included. Appendicular lean mass (ALM), appendicular lean mass index (ALM divided by height squared; ALMI) and total body fat mass percentage (%BF) were calculated. ALMI and %BF z-scores were derived using age- and sex-matched reference ranges. The primary outcome was Fontan failure (death, transplantation, New York Heart Association functional class III/IV, protein-losing enteropathy, and plastic bronchitis) or moderate-or-severe ventricular dysfunction.

RESULTS

144 patients were included. Mean %BF was 29% (SD 10) with 50% having increased adiposity. Mean ALMI z-score was -1.4 (SD 1.1); one third of patients had skeletal muscle deficiency (ALMI z-score < -1 and -2) and another third had Fontan-associated myopaenia (ALMI z-score < -2). Age and %BF were associated with the risk of the endpoint in univariable regression (age: HR 1.09 per year, 95% CI 1.02-1.17, p = 0.01; %BF: HR 1.08, 95% CI 1.01-1.17, p = 0.03). On multivariable regression, every 1% increase in %BF was associated with a 10% increased risk of reaching the clinical endpoint (HR 1.10, 95% CI 1.01-1.19; p = 0.03). ALM was not associated with the endpoint (HR 1.02 per kg, 95% CI 0.88-1.20, p = 0.77).

CONCLUSIONS

Increased adiposity is associated with higher risk for adverse outcomes. Prospective studies to assess lifestyle interventions to optimise body composition should be prioritised.

Body Composition in Young Adults Living With a Fontan Circulation: The Myopenic Profile

Background

We sought to characterize body composition abnormalities in young patients living with a Fontan circulation and explore potential pathophysiologic associations.

Methods and Results

Twenty‐eight patients with a Fontan circulation were prospectively recruited in this cross‐sectional study. Participants underwent cardiopulmonary exercise testing, dual‐energy X‐ray absorptiometry, echocardiography, and biochemical assessment. Mean age was 26±7 years. Skeletal muscle mass, estimated by appendicular lean mass index Z score, was reduced compared with reference data (−1.49±1.10, P<0.001). Percentage body fat Z score overall was within normal range (0.23±1.26, P=0.35), although 46% had elevated adiposity. Those with reduced skeletal muscle mass (appendicular lean mass index Z score of −1 or lower) had lower percent predicted oxygen pulse (55±15 versus 76±16%, P=0.002). Overall agreement between body mass index and dual‐energy X‐ray absorptiometry to assess adiposity was fair only (weighted [linear] κ coefficient: 0.53; 95% CI, 0.34–0.73) and slight in the setting of muscle mass deficiency (weighted κ coefficient: 0.32; 95% CI, 0.13–0.50). Appendicular lean mass was independently associated with absolute peak VO₂ (β=70.6 mL/min, P=0.001). Appendicular lean mass index Z score was inversely associated with hemoglobin (r=−0.4, P=0.04), and the degree of muscle deficit was associated with ventricular systolic impairment.

Conclusions

Young patients with a Fontan circulation have a body composition characterized by reduced skeletal muscle mass, which is associated with peak exercise capacity. Increased adiposity is common despite a normal body mass index. Low skeletal muscle mass is associated with systolic dysfunction and compensatory erythrocytosis.

Abnormal Cortical and Trabecular Bone in Youth With Type 1 Diabetes and Celiac Disease

OBJECTIVE

This study compared bone health in youth with type 1 diabetes and celiac disease (CD) versus type 1 diabetes alone.

RESEARCH DESIGN AND METHODS

This was a case-control study of 42 youth with coexisting type 1 diabetes and CD and 40 with type 1 diabetes matched for age, sex, diabetes duration, and HbA_1c. Bone mineral density (BMD), bone mineral content (BMC), and BMC-to-lean tissue mass (LTM) ratio were measured using DXA and reported as z-scores for height. Total, trabecular, and cortical bone and muscle parameters were measured using peripheral quantitative computed tomography (pQCT) and reported as z-scores for age.

RESULTS

Mean age at assessment was 14.3 ± 3.1 years; diabetes duration, 8.0 ± 3.5 years; HbA_1c, 8.2 ± 1.5% (66 ± 5 mmol/mol); and 25-hydroxy vitamin D, 71 ± 21 nmol/L. Comparing youth with coexisting CD versus type 1 diabetes alone, DXA showed lower BMC-to-LTM ratio (0.37 ± 1.12 vs. 0.73 ± 2.23, P = 0.007) but no difference in total BMD. Youth with coexisting CD also had lower BMC-to-LTM ratio versus the general population (P = 0.04). Radial pQCT showed lower total BMC (-0.92 ± 1.40 vs. -0.26 ± 1.23, P = 0.03) despite similar bone and muscle cross-sectional area. In multivariable linear regression, lower BMC was associated with higher insulin dose (P = 0.03) but not HbA_1c.

CONCLUSIONS

Youth with both type 1 diabetes and CD have lower BMC relative to LTM and lower BMC, indicating abnormal trabecular and cortical bone development despite similar bone and muscle size. These findings suggest that the two conditions confer a lower bone turnover state. We recommend further examination of bone health in this population; future research should examine early interventions to improve bone health.

Long-term Outcomes of Adolescent Anorexia Nervosa on Bone

PURPOSE

Anorexia nervosa (AN) is a chronic and life-threatening eating disorder that can have a considerable negative impact on the growing skeleton. We hypothesized that the long-term impact on bone health may persist even after normalization of body weight.

METHODS

41 females (mean age 21.2 ± 2.9 years) with a history of adolescent-onset AN attended a follow-up bone health assessment at 5 years (T5, n = 28) or 10 years (T10, n = 13) after their first AN-related hospital admission. Assessment included dual-energy x-ray absorptiometry measurements of the total body, lumbar spine, and proximal femur, peripheral quantitative computed tomography at the radius and tibia, anthropometric measurements, serum biochemistry, fracture history, and a patient questionnaire.

RESULTS

A recovery in body weight and BMI was seen for both the T5 and T10 cohorts (BMI at intake 16.6, BMI at T5-T10 21.2-21.3). Dual-energy x-ray absorptiometry body composition indicated a recovery of fat mass and lean tissue mass. Total BMD was unaffected, but reductions were seen at the femoral neck and arms. Peripheral quantitative computed tomography showed reduced trabecular and cortical bone in the radius, and cortical thinning in the tibia. AN patients showed a statistically significant reduction in measures of radiographic bone health at follow up, although not to a degree that necessitated clinical intervention. Serum insulin-like growth factor 1 was also positively correlated with total BMD and BMC measures. While fracture risk was not increased, a subset of participants (8%) showed multiple (>4) fractures.

CONCLUSION

A longitudinal study of adolescent AN showed persisting negative effects on bone health.

Diagnosis of Recurrent Fracture in a Pediatric Cohort

Significant fracture history in children is defined as having at least one vertebral fracture, at least 2 fractures by age 10, or at least 3 fractures by age 19. Between September 2011 and December 2014, clinical data were collected on children with a significant fracture history that attended a major Australian children's hospital. Fifty-six patients were identified as having 305 fractures in total, including 44 vertebral fractures. 18% of patients (10/56) were diagnosed with osteogenesis imperfecta (OI) by a bone health expert, molecular testing or both, and they sustained 23% of all fractures (71/305). Analysis of serum bone biochemistry showed all median values to be within a normal range and no clinically significant differences between patients with and without OI. The DXA and pQCT derived bone mineral density (BMD) and bone mineral content (BMC) Z scores were reduced overall. DXA derived total body and lumbar spine areal BMD-for-age and BMC-for-age Z scores were significantly lower in children who had vertebral fractures or who were later diagnosed with OI. Similarly, pQCT performed on radii and tibiae showed Z scores significantly less than zero. pQCT-derived limb muscle cross sectional area Z scores were significantly lower in the OI subgroup. In conclusion, this study describes the bone phenotype of children referred to a tertiary hospital clinic for recurrent fractures and highlights a subset of children with previously undiagnosed OI, but a larger cohort without classic OI. Thus it can be clinically challenging to differentiate between children with OI type 1 (mild phenotype) and non-OI children without bone densitometry and genetic testing. We conclude that recurrent fractures in children should prompt a comprehensive bone and systemic health assessment to eliminate an underlying pathology.

Novel variant in Sp7/Osx associated with recessive osteogenesis imperfecta with bone fragility and hearing impairment

Osteogenesis imperfecta (OI) is a connective tissue disorder characterized by low bone density and recurrent fractures with a wide genotypic and phenotypic spectrum. Common features include short stature, opalescent teeth, blue sclerae and hearing impairment. The majority (>90%) of patients with OI have autosomal dominant variants in COL1A1/COL1A2, which lead to defects in type 1 collagen. More recently, numerous recessive variants involving other genes have also been identified. Sp7/Osx gene, is a protein coding gene that encodes a zinc finger transcription factor, osterix, which is a member of the Sp subfamily of sequence-specific DNA-binding proteins. Osterix is expressed primarily by osteoblasts and has been shown to be vital for bone formation and bone homeostasis by promoting osteoblast differentiation and maturation. In animal models, Sp7/Osx has also been shown to regulate biomineralization of otoliths, calcium carbonate structures found in the inner ear of vertebrates. Until recently, only one report of a boy with an Sp7/Osx pathogenic variant presenting with bone fragility, limb deformities and normal hearing has been described in the literature. We have identified a novel Sp7/Osx variant in another sibship that presented with osteoporosis, low-trauma fractures and short stature. Progressive moderate-to-severe and severe-to-profound hearing loss secondary to otospongiosis and poor mineralization of ossicles and petrous temporal bone was also noted in two of the siblings. A homozygous pathogenic variant in exon 2 of the Sp7/Osx gene was found in all affected relatives; c.946C>T (p.Arg316Cys). Bone biopsies in the proband and his male sibling revealed significant cortical porosity and high trabecular bone turnover. This is the second report to describe children with OI associated with an Sp7/Osx variant. However, it is the first to describe the bone histomorphometry associated with this disorder and identifies a significant hearing loss as a potential feature in this OI subtype. Early audiology screening in these children is therefore warranted.

Incomplete total body protein recovery in adolescent patients with anorexia nervosa

Background

Bone health and growth during adolescence require adequate total body protein (TBPr). Renutrition for patients with anorexia nervosa (AN) should aim to normalize body composition and to recover both fat mass and TBPr.

Objective

We intended to analyze predictors of protein status, including exercise status, in adolescents with AN and to investigate whether weight gain would replenish body protein deficits.

Methods

We assessed TBPr in a longitudinal, observational study as height-adjusted nitrogen index (NI) using in vivo neutron activation analysis in 103 adolescents with AN [mean ± SD age, 15.6 ± 1.4 y; body mass index (BMI, in kg/m2), 16.5 ± 1.6] at the commencement of inpatient refeeding (T0), in 56 of these patients 7 mo thereafter as outpatients (T1), and in age-matched controls (C; n = 51, 15.5 ± 2.1 y, BMI 20.7 ± 1.9). Lean tissue and fat mass were assessed by dual-energy X-ray absorptiometry. BMI, BMI standard deviation score, and lean tissue mass were tested as predictors of protein status using receiver operating characteristic analysis.

Results

At T0, NI was decreased in AN (AN, 0.88 ± 0.10 compared with C, 1.00 ± 0.08, P < 0.001). In 34%, the patients showed protein depletion. Patients classified as ``exercisers'' had a higher NI than did ``nonexercisers'' (0.89 ± 0.11 compared with 0.85 ± 0.08, P = 0.045). BMI, BMI standard deviation score, and lean tissue mass did not show potential as predictors of protein status. Despite increases in weight (+6.9 ± 4.5 kg), and BMI (+2.5 ± 1.7), protein status did not improve (TBPr T0, 8.0 ± 1.1 kg; T1, 8.1 ± 1.0 kg, P = 0.495). In an AN subgroup at 7 mo matched with controls in age (AN, 16.5 ± 1.1 y; C, 16.2 ± 1.8 y) and BMI (AN, 20.5 ± 1.4; C, 20.7 ± 1.3), protein status was still not normalized in AN (NI: AN, 0.89 ± 0.09 compared with C, 1.00 ± 0.07, P < 0.001).

Conclusions

Adolescents recovering from AN remained protein depleted at 7 mo after baseline assessment, even though they were weight restored.

Improved insulin sensitivity and body composition, irrespective of macronutrient intake, after a 12 month intervention in adolescents with pre-diabetes; RESIST a randomised control trial

Background

A higher protein to carbohydrate ratio in the diet may potentiate weight loss, improve body composition and cardiometabolic risk, including glucose homeostasis in adults. The aim of this randomised control trial was to determine the efficacy of two structured lifestyle interventions, differing in dietary macronutrient content, on insulin sensitivity and body composition in adolescents. We hypothesised that a moderate-carbohydrate (40-45% of energy), increased-protein (25-30%) diet would be more effective than a high-carbohydrate diet (55-60%), moderate-protein (15%) diet in improving outcomes in obese, insulin resistant adolescents.

Methods

Obese 10–17 year olds with either pre-diabetes and/or clinical features of insulin resistance were recruited at two hospitals in Sydney, Australia. At baseline adolescents were prescribed metformin and randomised to one of two energy restricted diets. The intervention included regular contact with the dietician and a supervised physical activity program. Outcomes included insulin sensitivity index measured by an oral glucose tolerance test and body composition measured by dual-energy x-ray absorptiometry at 12 months.

Results

Of the 111 adolescents recruited, 85 (77%) completed the intervention. BMI expressed as a percentage of the 95th percentile decreased by 6.8% [95% CI: −8.8 to −4.9], ISI increased by 0.2 [95% CI: 0.06 to 0.39] and percent body fat decreased by 2.4% [95% CI: −3.4 to −1.3]. There were no significant differences in outcomes between diet groups at any time.

Conclusion

When treated with metformin and an exercise program, a structured, reduced energy diet, which is either high-carbohydrate or moderate-carbohydrate with increased-protein, can achieve clinically significant improvements in obese adolescents at risk of type 2 diabetes.

Trial registration

Australian New Zealand Clinical Trail Registry ACTRN12608000416392. Registered 25 August 2008.

Intravenous zoledronic Acid given every 6 months in childhood osteoporosis

AIM

To evaluate the safety and efficacy of 12 months of zoledronic acid (ZA) administered every 6 months to children with osteoporosis.

METHODS

Retrospective cohort study of 27 patients (16 male, 11 female) treated with ZA (0.05 mg/kg/dose) every 6 months for 1 year. 20 were immobile, 4 steroid-induced osteoporosis, 2 idiopathic osteoporosis and 1 neurofibromatosis type 1. 16 had long bone fractures and 12 had vertebral wedging at baseline. Mineral homeostasis, bone mineral density (BMD) and vertebral morphometry were evaluated at baseline and 12 months. Results were compared to published data on 3-monthly ZA treatment.

RESULTS

Median age at ZA start was 10.5 years (range 6.2-13.3). Following the first infusion, 2 developed asymptomatic hypocalcemic, 14 developed temperature > 38°C, 13 aches/pain and 6 nausea. At 12 months, there was reduction in bone turnover and improvement in BMD and vertebral shape. No patient fractured after starting ZA. Growth was normal. Outcomes were similar to 3-monthly ZA.

CONCLUSION

ZA administered 6-monthly was associated with acute phase reaction to the first dose and improvement in BMD, reduction in bone turnover and improved vertebral shape at 12 months.

Intravenous pamidronate treatment in children with moderate-to-severe osteogenesis imperfecta started under three years of age

OBJECTIVE

Evaluate clinical outcome of early cyclic intravenous pamidronate treatment in children with moderate-to-severe osteogenesis imperfecta (OI), commenced before three years of age.

METHODS

A retrospective review of 17 patients with moderate-to-severe OI. Development, anthropometry, fracture history, bone mineral density (BMD) and biochemistry were collected at baseline, 12 and 24 months.

RESULTS

Four had OI type I, eleven had type III, one OI-FKBP10 type and one OI type V. Mean age at start of pamidronate was 14 ± 11 months. Pamidronate ranged from 6 to 12 mg/kg/year. No adverse reaction apart from fever and vomiting was noted. Long bone fracture decreased from a mean of 10.4/year to 1.2/year after 12 months and 1.4/year after 24 months (p = 0.02). Lumbar spine age- and height-matched BMD Z-scores increased (p < 0.005). Sixteen with vertebral compression fractures at baseline all showed improved vertebral shape (p < 0.001). Concavity index, likewise, improved (p < 0.005). Motor milestones compared to historical data show earlier attainment in rolling over, crawling, pulling to stand and walking independently but not sitting.

CONCLUSION

Cyclic intravenous pamidronate, started under 3 years of age in children with moderate-to-severe OI, was well tolerated and associated with an increase in lumbar spine BMD, reduced fracture frequency, vertebral remodelling and attainment of motor milestones at an earlier age.

The impact of dysglycaemia on bone mineral accrual in young people with cystic fibrosis

OBJECTIVE

The effect of dysglycaemia on bone mineral density (BMD) has not been studied in young people with CF. We examined factors associated with BMD in a tertiary paediatric CF clinic.

DESIGN

Retrospective, clinic-based study at The Children's Hospital at Westmead, Sydney.

PATIENTS

Young people with CF aged ≤ 18 years.

MEASUREMENTS

Bone mineral density was measured by dual-energy X-ray absorptiometry; main outcome measures were total body (TB), lumbar spine (LS) and femoral neck (FN) BMD and bone mineral content (BMC), and LS volumetric BMD (vBMD), reported as z scores for height. Dysglycaemia, based on oral glucose tolerance test, was defined as CF-related diabetes (CFRD) or impaired glucose tolerance (IGT).

RESULTS

Overall, 14 of 81 (17%) had CFRD, 6 (7%) IGT and 61 (76%) normal glucose tolerance (NGT). Mean age was 14.9 ± 2.4 years and mean height z score -0.68 ± 1.39. Osteopenic (z score ≤-2) TB, LS or FN BMD was present in 30 of 81 (37%), BMC in 42 (52%) and vBMD in 10 (5%). Across the three groups, there were differences in LS vBMD (CFRD, -0.67 ± 0.76; IGT, -0.52 ± 0.76; NGT, -0.05 ± 1.39; P = 0.04), LS BMD (P < 0.01), LS BMC (P = 0.01) and TB BMD (P = 0.01). In multivariate linear regression, LS BMC was associated with dysglycaemia (β = 0.56; 95% CI, 0.00-1.13; P = 0.05) and approached significance for FEV(1) (β = 0.01; 95% CI, 0.00-0.02; P = 0.06).

CONCLUSIONS

Dysglycaemia is associated with reduced bone mass accrual in youth with CF, in addition to recognized factors such as abnormal lung function, poor nutritional status and disease severity. Bone health assessment is essential in youth with CF.

Zoledronic acid improves bone mineral density in pediatric spinal cord injury

Spinal cord injury (SCI) is associated with rapid and sustained bone loss and increase risk of fracture. Disuse is the primary cause for bone loss, although neural and hormonal changes may also contribute via different mechanisms. Bisphosphonates are used widely to treat osteoporosis in adults and are used increasingly for primary and secondary osteoporosis in children. Current data are insufficient to recommend routine use of bisphosphonates for fracture prevention in adult patients post-SCI and there are no available data in pediatric SCI. We report a 12-year-old boy with non-traumatic SCI who was treated with six monthly zoledronic acid (0.05 mg/kg/dose) for 18 months. The patient (AA) was diagnosed with transverse myelitis at 8.1 years of age, resulting in ventilator-dependent incomplete C3 tetraplegia. Following a fragility fracture to the surgical neck of the right humerus at 9.5 years of age, he was started on zoledronic acid. Bone turnover decreased and bone densitometry data (dual-energy X-ray absorptiometry [DXA] and peripheral quantitative computed tomography [pQCT]) showed improvement in metaphyseal and diaphyseal bone mineral content (BMC), volumetric bone mineral density (vBMD), and size, after 18 months of treatment. In the growing skeleton post-SCI, zoledronic acid potentially increases vertebral and long-bone strength by preserving trabecular bone (increased BMC and vBMD) and increasing cortical vBMD and cross-sectional area (CSA).

SPECT/CT scans allow precise anatomical location of sentinel lymph nodes in breast cancer and redefine lymphatic drainage from the breast to the axilla

BACKGROUND

Historical studies of lymphatic drainage of the breast have suggested that the lymphatic drainage of the breast was to lymph nodes lying in the antero-pectoral group of nodes in the axilla just lateral to the pectoral muscles. The purpose of this study was to confirm this is not correct.

METHODS

The hybrid imaging method of SPECT/CT allows the exact anatomical position of the sentinel lymph node (SLN) in the axilla to be documented during pre-operative lymphoscintigraphy (LS) in patients with breast cancer. We have done this in a series of 741 patients. The Level I axillary nodes were defined as anterior, mid or posterior. This was related to the anatomical location of the primary cancer in the breast.

RESULTS

A SLN was found in the axilla in 97.8% of our patients. Just under 50% of SLNs located in the axilla were not in the anterior group and lay in the mid or posterior group of Level I axillary nodes. There was a SLN in a single node field in 460 patients (63%), two node fields in 261(36%), three node fields in 6 and four node fields in 1 patient.

CONCLUSION

Axillary lymphatic drainage from the breast is not exclusively to the anterior (or antero-pectoral) group of Level I nodes.

SYNOPSIS

SPECT/CT lymphoscintigraphy shows that the breast does not always drain to the anterior group of Level I lymph nodes in the axilla but may drain to the mid axilla and/or posterior group in about 50% of patients with breast cancer regardless of the location of the cancer in the breast. These data redefine lymph drainage from the breast to axillary lymph nodes.

Zoledronic acid improves bone mineral density, reduces bone turnover and improves skeletal architecture over 2 years of treatment in children with secondary osteoporosis

There are limited data on the use of bisphosphonate therapy for secondary osteoporoses in childhood, and no previous reports of the use of zoledronic acid in this group. We report 20 children with a variety of underlying primary diagnoses with associated secondary osteoporosis, who were treated with 3 monthly zoledronic acid for 2 years (annualised dose 0.1mg/kg/year). There was a significant improvement in lumbar spine (by 1.88 SD±1.24 over first 12 months, p<0.001) and total bone mineral density as assessed by dual energy absorptiometry (DXA) scans, with a similar increase in bone mineral content for lean tissue mass (mean increase 1.34 SD in first 12 months, p<0.001). Bone turnover was reduced with a suppression of both osteocalcin and alkaline phosphatase in the first 12 months of treatment. Skeletal architecture was improved, with increased second metacarpal cortical thickness from 2.44mm to 2.72mm (p<0.001) and improved vertebral morphometry, with 7 patients who had vertebral wedging at baseline showing improved anterior (p=0.017) and middle (p=0.001) vertebral height ratios. Aside from well reported transient side effects with the first dose, there were no adverse effects reported. No adverse effects on anthropometric parameters were seen over the course of the study. Despite all patients having sustained fragility fractures prior to treatment, no fractures were reported during the study period. Further evidence is required to confirm efficacy, with long term follow up required to assess the impact of treatment on fracture risk.

Bone mineral content and density in Rett syndrome and their contributing factors

This study used densitometry to investigate the areal bone mineral density (aBMD) and bone mineral content (BMC) in an Australian Rett syndrome cohort and to assess how factors such as genotype, epilepsy, BMI, and mobility affect these parameters. The influence of lean tissue mass (LTM) and bone area (BA) on total body BMC (TBBMC) was also investigated. Participants, recruited from the Australian Rett Syndrome Database (ARSD), had TBBMC and lumbar spine (LS) and femoral neck (FN) aBMD measured using Dual energy x-ray absorptiometry. Mean height standardized Z scores and CIs for the bone outcomes were obtained from multiple regression models. The mean height Z score for the FN aBMD was low at -2.20, while the LS aBMD was -0.72. The TBBMC mean height Z score was -0.62, although once adjusted for BA and LTM, the mean was above zero, suggesting that low BMC can be explained by narrow bones and decreased muscle mass, likely secondary to decreased mobility. Multiple linear regression identified the p.R168× and p.T158M mutations as the strongest predictors of low aBMC and BMD for all bone outcomes. The strong relationship between genotype, BMC, and aBMD is likely underpinned by the strong relationship between LTM, mobility, and bone outcome measures.

The natural history and osteodystrophy of mucolipidosis types II and III

AIM

To assess the natural history and impact of the secondary bone disease observed in patients with mucolipidosis (ML) II and III.

METHODS

Affected children and adults were ascertained from clinical genetics units around Australia and New Zealand. Diagnoses were confirmed by the National Referral Laboratory in Adelaide. The study encompassed all patients ascertained between 1975 and 2005. Data focussing on biochemical parameters at diagnosis, and longitudinal radiographic findings were sought for each patient. Where feasible, patients underwent clinical review and examination. Examinations included skeletal survey, bone densitometry, and measurement of serum and urine markers of bone metabolism. In a subset of patients, functional assessment using the Pediatric Evaluation and Disability Inventory (PEDI) and molecular analysis of GNPTAB were performed.

RESULTS

Twenty-five patients with mucolipidosis were ascertained over a 30-year period. Morbidity and functional outcomes on living patients were described. Serum calcium and phosphate were normal. All, but one patient, had normal alkaline phosphatase. Serum osteocalcin and urine deoxypyridinoline/creatinine were elevated. Two radiological patterns were observed (i) transient neonatal hyperparathyroidism in infants with ML II and (ii) progressive osteodystrophy in patients with ML intermediate and ML III. Molecular analyses of GNPTAB in nine subjects are reported.

CONCLUSION

ML is characterised by a progressive bone and mineral disorder which we describe as the 'osteodystrophy of mucolipidosis'. The clinical and radiographic features of this osteodystrophy are consistent with a syndrome of 'pseudohyperparathyroidism'. Much of the progressive skeletal and joint pathology is attributable to this bone disorder.

The successful use of pamidronate in an 11-year-old girl with complex regional pain syndrome: response to treatment demonstrated by serial peripheral quantitative computerised tomographic scans

Complex regional pain syndrome (CRPS) is a disorder that can cause significant functional morbidity. While it usually presents in adulthood, it has also been reported in children. Multiple treatment modalities have been reported with mixed success. Bisphosphonate therapy has been shown to be effective in adult patients, but there are limited data in children. We report the successful use of intravenous pamidronate therapy in diminishing pain, improving function, and restoring bone mass in an 11-year-old girl with CRPS of her left lower limb following a tibial fracture. Previous treatment with intense physiotherapy and regional sympathetic blockade had not improved her symptoms. Pain improved within weeks of the first pamidronate infusion, with subsequent improvement in function. The benefit in pain reduction and function was sustained during the 2-year treatment regime. Improvement in bone mass and density was demonstrated by dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computerised tomography (pQCT). pQCT scans showed marked improvement in bone size and geometry and muscle bulk on the affected side. No adverse affects were reported. We conclude that intravenous pamidronate was associated with reduced pain, a return of function, and recovery of bone and muscle parameters in a child with CRPS. Before definitive conclusions can be drawn, a randomised controlled trial similar to those undertaken in adults previously is required to fully validate this approach.

Systemic effects of zoledronic acid in children with traumatic femoral head avascular necrosis and Legg-Calve-Perthes disease

BACKGROUND

Intravenous bisphosphonate therapy is associated with preservation of femoral head sphericity and congruence in 77% of children with traumatic avascular necrosis. The aim was to describe the systemic effects of intravenous zoledronic acid (ZA) on bone and mineral metabolism in otherwise normal children and adolescents with femoral head AVN.

MATERIAL AND METHODS

37 children (age 10.8+/-2.76 years) diagnosed with avascular necrosis AVN (Slipped Capital Femoral Epiphysis (SCFE), N=20 or Legg-Calve-Perthes disease (LCPD), N=17) were treated with at least 12 months of ZA. Bone mineral density (BMD) by DXA, bone morphometry and mineral homeostasis were evaluated at baseline, 6, 12 and 18 months. Data was retrieved retrospectively.

RESULTS

All children maintained height SD during treatment. BMI SD increased in the SCFE subgroup during the first 12 month period. Bone age increased appropriately. Age adjusted total body BMD, lumbar spine BMD and lean tissue mass adjusted bone mineral content (BMC) Z-scores increased significantly over the 18 months of treatment. The LS.BMD increase was greater in LCPD than in SCFE leading to more individuals with LCPD having a LS.BMD((age))Z-score over 2 SD at 12 months follow-up. Biochemical markers of bone turnover were decreased and PTH increased during the first 12 months of treatment and bone modeling was reduced. All markers stabilised over the next 6 months. There were no incidences of fracture, spondylolisthesis or osteonecrosis of the jaw.

CONCLUSION

We here report that ZA in otherwise healthy children with femoral head AVN increases BMD - most pronounced in the LCPD group - and reduces bone modeling and turnover. Further efficacy and safety data are required before this therapy can be widely recommended.

Abdominal fat assessment in adolescents using dual-energy X-ray absorptiometry

BACKGROUND

Abdominal obesity is an increasing problem in adolescents, often persisting into adulthood. Reliable assessment has been restricted to techniques limited by relatively high radiation doses or cost.

AIM

To investigate the reliability of several abdominal regions using dual-energy X-ray absorptiometry (DXA), and to assess the construct validity of these methods against metabolic profile.

METHODS

Inter- and intra-rater precision of two assessors were examined, for fat mass analysis in six different abdominal regions using DXA in overweight/obese and normal weight adolescents. Construct validity was examined in overweight/obese individuals.

RESULTS

All methods had acceptable intra- and inter-rater reliability. Region 1 was most precise in overweight/obese individuals, while Region 6 was most precise in normal weight individuals. In all regions, assessments were less precise in overweight/obese individuals. All regions were equally predictive of insulin outcomes.

CONCLUSIONS

Abdominal adiposity can be reliably assessed in adolescents using DXA, and the most precisely assessed regions were identified. All regions predicted insulin outcomes.

Childhood chronic recurrent multifocal osteomyelitis: pamidronate therapy decreases pain and improves vertebral shape

OBJECTIVE

Chronic relapsing multifocal osteomyelitis (CRMO) results in significant morbidity, especially in those with vertebral collapse. Symptomatic benefit with intravenous pamidronate (PAM) has been shown; however, few studies have demonstrated radiological benefit. We describe clinical and radiological data on 7 pediatric cases of CRMO treated with PAM.

METHODS

Retrospective chart review on all children with CRMO treated with PAM. Response to PAM was measured by subjective reports and radiology including vertebral morphometry.

RESULTS

Seven patients (1 male) presented with bone pain at a median age of 8 years (range 5-14). Symptoms had been present for a median of 18 months (range 11-51) before PAM therapy. All patients had involvement of multiple nonspinal sites, 5 children had spinal involvement with vertebral fractures, and 5 had joint involvement. Six cases had symptomatic improvement within 6 months of starting PAM, which was sustained during PAM therapy (median 26 mo, range 6-41) and persisted in the 4 cases who had ceased treatment for the duration of followup (27 mo, range 18-51). The least benefit was seen in the 3 cases with synovial joint involvement. The 3 cases with spinal radiological followup showed modeling of vertebral fractures and in one patient improvement in kyphosis. No radiological improvement in nonspinal lesions was seen.

CONCLUSION

PAM therapy was associated with symptomatic improvement and vertebral modeling in children with CRMO. We suggest that children with bone pain and/or spinal involvement be considered for PAM therapy early after diagnosis.

Acute phase response and mineral status following low dose intravenous zoledronic acid in children

INTRODUCTION

Previous reports have shown a high frequency of hypocalcaemia and flu-like symptoms following an initial first zoledronic acid dose of 0.02-0.025 mg/kg in children.

METHODS

We systematically evaluated the mineral status and symptomatology of 63 children with a variety of bone disorders treated with an initial zoledronic acid dose of 0.0125 mg/kg. The Mann-Whitney U test, chi-squared test and Fisher's exact test were used as appropriate.

RESULTS

0.0125 mg/kg zoledronic acid reduced the incidence and intensity of hypocalcaemia but not the incidence of the flu-like symptoms compared to higher doses. Within the low dose cohort, flu-like symptoms were associated with an acute inflammatory response. Children who became hypocalcaemic received a higher dose in relation to their body mass index and body surface area.

CONCLUSION

Reducing the initial zoledronic acid dose in children decreased the incidence of hypocalcaemia and thus improved safety. Dosing on the basis of body mass index or body surface area instead of body weight may further reduce the incidence of hypocalcaemia.

Decreased bone mineral density in neurofibromatosis type 1: results from a pediatric cohort

Neurofibromatosis type 1 (NF1) is a common genetic disorder affecting 1 in 3000 live births. It is well documented to be associated with bony deformities and other orthopaedic problems. Based on our observation that NF1 patients undergoing orthopaedic surgery often had osteopenic bone, we performed a study to assess the bone mineral density of a cohort of children with NF1 without orthopaedic defects.Twenty-three patients were recruited from the neurofibromatosis clinic. The bone mineral density of the total body, lumbar spine, and proximal femur was measured using dual-energy x-ray absorptiometry. Quantitative ultrasound was used to measure broadband ultrasonic attenuation at both heels. The group's mean dual-energy x-ray absorptiometry sex- and age-matched Z scores were below normal (-0.8 +/- 1.1, -0.8 +/- 1.2, -0.7 +/- 0.8, -0.6 +/- 1.1, -0.6 +/- 0.9, -0.6 +/- 1.1 for the total body, arms, legs, lumbar spine, and right and left femoral neck, respectively; all P < 0.01). Although some individuals had normal bone mass, 30% had total body Z scores below -1.5. The mean heel broadband ultrasonic attenuation Z score was also lower than normal (-0.8 +/- 0.6; P < 0.001). Children with NF1 have a general tendency toward osteopenia, suggesting an abnormal underlying bone phenotype. This may be relevant when considering operative intervention and, if better understood, may partially explain poor bone healing associated with NF1.

Bisphosphonate rescue in distraction osteogenesis: a case series

Distraction osteogenesis is a powerful stimulus for new bone (and tissue) generation (anabolism). Biomechanical stimulation by distraction of the regenerate region results in a high rate of tissue and bone production. However, catabolism (bone resorption) can also occur, the process potentially accentuated in a stress-shielded environment of an external fixator. Regenerate insufficiency can result in regenerate bending or fracture after frame removal. Experimental evidence has demonstrated that bisphosphonates may mediate improved local limb bone mineral density (BMD) and regenerate strength in animal models. Seven patients who had undergone limb lengthening using an Ilizarov device were found to have regenerate insufficiency. Poor regenerate quality led to consideration for intervention. With informed consent, patients received a therapeutic regime of intravenous pamidronate (n = 3) or zoledronic acid (n = 4).The mean age was 13.8 years (SD, +/-3.6 years), with a minimum follow-up period of 4 months after fixator removal. The sites of regenerate insufficiency were the proximal tibia (n = 6) and the distal femur (n = 1). The mean time interval in the fixator before bisphosphonate treatment was 170 days (range, 124-252 days), with an average length increase of 4.8 cm (SD, +/-1.1 cm). At time of intravenous bisphosphonate treatment, dual-energy x-ray absorptiometry measurements demonstrated a reduced BMD (mean, 62.1%; SD, +/-12.6%) in the bone adjacent to the lengthening site of the nonoperated side. Mean healing index was high at 79.6 days/cm (range, 64.4-108.0 days/cm), reflecting the observed regenerate insufficiency. No significant systemic complications were encountered. Six of the patient's fixators were removed without requirement for other intervention, demonstrating a rapid and sustained improvement in local BMD, increasing to a mean of 85.6% (SD, +/-13.3%) of the healthy side. One patient did not respond and subsequently healed after percutaneous osteogenic protein 1 (bone morphogenetic protein 7) and bone marrow injection. Most failed regenerate cases maintain some underlying anabolic activity and can be treated successfully with bisphosphonate therapy, which reduces catabolism. Only 1 case required percutaneous administration of an anabolic therapy to achieve union. These minimally invasive approaches may lessen the need for surgery in a group where significant surgical reintervention could otherwise be required.

Bone changes in adolescent girls with anorexia nervosa

PURPOSE

To clarify the effect of chronological age, height, lean tissue mass, and menstrual status on standard reported DXA (dual-energy x-ray absorptiometry) measures.

METHODS

Growth and DXA data from a retrospective longitudinal cohort of 30 adolescent females with anorexia nervosa (AN) were examined. Areal bone mineral density (aBMD), total body bone mineral content (BMC) and total body bone area were measured and standardized for age, height, lean tissue mass, and total bone area. We then examined the changes in these parameters after 12 months of multidisciplinary treatment.

RESULTS

The subjects had lower BMC and aBMD than the age- and height-matched reference population at baseline, there were further decreases in these parameters with treatment. BMC adjusted for lean tissue mass and bone area were normal at baseline and there was no significant change with treatment. Bone area adjusted for height was low at baseline and decreased despite treatment.

CONCLUSION

Our data suggest that the low age- and height-adjusted bone mineral content and bone mineral density in females with AN is secondary to poor bone growth leading to low bone area. These subjects had relatively normal bone mineral content for their bone size and lean tissue mass. Changes in bone size were proportional to changes in lean tissue mass.

Effect of zoledronic acid in an L6-L7 rabbit spine fusion model

Previous studies have shown that zoledronic acid administration can increase mineral content and strength in distraction osteogenesis. Of the few studies that have examined the use of bisphosphonates in spinal arthrodesis, none have assessed the effect of single dose treatment. The objective of this study was to evaluate the feasibility of enhancing spinal fusion rate using single dose zoledronic acid (ZA) to increase fusion-mass size and mineral density. Forty-eight New Zealand white rabbits underwent an L6-L7 intertransverse process fusion. The L6-L7 model is more challenging than the more commonly used level of L5-L6. Animals were randomly allocated to one of three groups, one received iliac crest bone graft alone, one group received iliac crest bone graft with locally administered zoledronic acid, 20 microg, and one group received iliac crest bone graft with a single dose of systemically administered zoledronic acid, 0.1 mg/kg. ZA doses were administered at the time of surgery. Twenty-four rabbits were culled at 6 weeks and 24 rabbits were culled at 12 weeks. Success of spinal fusion was determined by manual palpation. Specimens were evaluated radiographically, underwent quantitative computerised tomography analysis and were tested biomechanically in flexion and extension. In the six-week group, only five of the 24 spines fused with no noticeable trend with respect to treatment. In the 12-week group there was a trend toward increased fusion in the systemically administered ZA group (63%) versus the other two groups (25%) but was not statistically significant (p = 0.15). Radiographically, the local ZA treatment group showed a delay in remodelling with the presence of unremodelled bone chips. The 12-week systemic ZA group exhibited an 86% increase in BMC, a 31% increase in vBMD and a 41% increase in the volume of the fusion-mass (p < 0.05). The 12-week local ZA group also showed significant increases in BMC (69%), vBMD (31%) and total fusion-mass volume (29%) (p < 0.05). Biomechanical testing showed that the range of motion in flexion decreased to 4.5 (+/-2.5) degrees and 4.8 (+/-4.7) degrees for the local and systemic groups respectively compared to 9.6 (+/-4.9) degrees for the control group (p < 0.05). This study has shown that zoledronic acid increased fusion-mass size and bone mineral content. Systemic ZA led to an increased fusion rate; however the fusion rate remained below 100%. We suggest that bisphosphonate treatment may require an anabolic conjunctive therapy to ensure enhanced successful fusion.

Effect of growth hormone therapy and puberty on bone and body composition in children with idiopathic short stature and growth hormone deficiency

The state of bone health and the effect of growth hormone (GH) therapy on bone and body composition in children with idiopathic short stature (ISS) are largely unknown. A direct role of GH deficiency (GHD) on bone density is controversial. Using dual-energy X-ray absorptiometry, this study measured total body bone mineral content (TB BMC), body composition, and volumetric bone mineral density (vBMD) at the lumbar spine (LS) and femoral neck (FN) in 77 children (aged 3-17 years) with ISS (n = 57) and GHD (n = 20). Fifty-five children (GHD = 13) receiving GH were followed over 24 months including measurement of bone turnover. At diagnosis, size-corrected TB BMC SDS was greater (P <or= 0.002) and LSvBMD SDS lower (P < 0.03) than zero in both prepubertal ISS and GHD subjects, but FNvBMD SDS was reduced only in the GHD group (P < 0.05). The muscle-bone relation, as assessed by the BMC/lean mass (LTM) ratio SDS was not different between groups. During GH therapy, prepubertal GHD children gained more height (1.58 [0.9] SDS) and LTM (0.87 [0.63] SDS) compared to prepubertal ISS children (0.75 [0.27] and 0.17 [0.25] SDS, respectively). Percent body fat decreased in GHD (-5.94% [4.29]) but not in ISS children. Total body BMC accrual was less than predicted in all groups accompanied by an increase in bone turnover. Puberty led to the greatest absolute, but not relative, increments in weight, LTM, BMI, bone mass, and LSvBMD. Our results show that children with ISS and GHD differ in their response to GH therapy in anthropometry, body composition, and bone measures. Despite low vBMD values at diagnosis in both prepubertal groups, size-corrected regional or TB bone data were generally within the normal range and did not increase during GH therapy in GHD or ISS children. Growth hormone had great effects on the growth plate and body composition with subsequent gains in height, LTM, bone turnover, and bone mass accrual, but no benefit for volumetric bone density over 2 years.

Altered body composition and metabolism in the male offspring of high fat-fed rats

An intrauterine environment may play a role in predisposing a developing fetus to metabolic diseases during adulthood. We investigated the hypothesis that a maternal diet high in omega-6 polyunsaturated fat can modify the programming of an offspring's glucose tolerance, insulin sensitivity, body composition, lipid metabolism, and insulin signaling. High omega-6 polyunsaturated fat diets were fed to female rats 4 weeks before mating and throughout the gestation period. The offspring were maintained on chow diet. At 3 months of age, indirect calorimetry, oral glucose tolerance tests, and dual x-ray absorptiometry measurements were performed. Triglyceride content and beta-hydroxyacyl coenzyme A dehydrogenase activity were determined in the liver and quadriceps muscle. Expression levels of key insulin signaling pathway proteins were measured in the liver and quadriceps muscle of the 3-month-old offspring. Offspring from the fat-fed dams had significantly increased proportions of both total body fat and abdominal fat. All offspring displayed normal insulin sensitivity and glucose tolerance, although the offspring from the fat-fed dams were significantly more hyperinsulinemic 15 minutes after an oral glucose challenge. Whole body fuel oxidation was not altered. The offspring of fat-fed dams had significantly elevated liver triglyceride content. Insulin signaling protein expression levels in the offspring of fat-fed dams were consistent with reduced hepatic insulin sensitivity but increased quadriceps insulin sensitivity. A maternal diet high in omega-6 polyunsaturated fat evokes programming within the metabolic processes of the offspring that may predispose the offspring to the development of metabolic diseases.

The skeletal phenotype of men with previous constitutional delay of puberty

It is presently unclear whether men with a history of constitutional delay (CD) of puberty are osteopenic. This study compares auxology, bone mass, size, and density of 32 men (age, 21-33 yr) with previous CD with 45 controls. Using dual-energy x-ray absorptiometry, areal bone mineral density (aBMD) and volumetric bone mineral density at the lumbar spine (LS) and femoral neck (FN), hip strength analysis, and total-body and body segment (arms, legs, trunk) measurements were determined. Auxological variables, body composition, the muscle-bone relation, and the effect of prior androgen treatment were studied. Men with previous CD were shorter (P < 0.001) and had shorter height-adjusted arms compared with controls. Height-adjusted total-body bone mineral content (BMC) (P = 0.004), aBMD (P = 0.016), and bone area (P = 0.006) but not lean tissue mass (P = 0.507) were lower in CD men compared with controls; consequently, their BMC to lean tissue mass ratio was reduced (P < 0.001). Segment length-adjusted BMC and bone area of arms (P < 0.001) and legs (P < 0.03), but not trunk were lower in CD men than in controls. They had lower LS aBMD (P = 0.044) but normal LS and FN volumetric bone mineral density. Size-adjusted LS width and the hip cross-sectional area were lower than in controls. There was no difference in anthropometric or dual-energy x-ray absorptiometry results between untreated (n = 15) and androgen-treated (n = 17) CD men.We conclude that men with previous CD have normal LS and FN volumetric density but reduced total-body bone mass, which was explained by reduced limb bone mass and size. Together with the reduced LS bone width and hip crosssectional area, these skeletal characteristics suggest impaired periosteal expansion during puberty. The skeletal phenotype of CD males may be altered by their late onset of puberty.

Importance of estrogen on bone health in Turner syndrome: a cross-sectional and longitudinal study using dual-energy X-ray absorptiometry

Osteoporosis and fractures are features in adults with Turner syndrome (TS). Using dual-energy x-ray absorptiometry, correcting bone mineral content (BMC) for height and lean mass (LTM) avoids misclassification of short children as osteopenic. Total body (TB), lumbar spine (LS), and femoral neck (FN) dual-energy x-ray absorptiometry scans were performed on 83 patients with TS (aged 4-24 yr). A prepubertal subgroup (n = 17) receiving GH was followed for 24 months. Age z-scores for height, TB BMC, LTM, the BMC/LTM ratio, and LS volumetric bone mineral density (vBMD) decreased significantly (P < 0.001) with age in prepubertal subjects (n = 51) but were constant in the combined pubertal and postmenarchal group (n = 32). Osteopenia was found in 14.5% (TB), 15.8% (LS), and 28.4% (FN) of patients. In the longitudinal subgroup, TB BMC z-scores decreased by -0.28 (0.31) in subjects remaining prepubertal (n = 11) but increased by 0.71 (0.56) in subjects entering puberty (n = 6; P = 0.007). The z-scores for height and LTM increased in both groups. Our results show a height-independent prepubertal decrease in bone mass accrual, which ceased with puberty. Optimizing bone mass in TS may require earlier induction of puberty than currently recommended. However, reduced FN volumetric bone mineral density and a dissociation of bone and muscle measures were age independent, suggesting an additional intrinsic bone defect.

A comparison of bone geometry and cortical density at the mid-femur between prepuberty and young adulthood using magnetic resonance imaging

In upper extremity bones, a sexual dimorphism exists in the development of periosteal and endocortical bone surfaces during growth. Little is known about developmental patterns of bone geometry at weight-bearing bones like the femur. Using MRI and dual energy X-ray absorptiometry (DXA), this study assessed the differences in mid-femoral total (TA), cortical (CA) and medullary areas (MA), cortical thickness, and cortical density (BMD(compartment)) between prepuberty and young adulthood in 145 healthy subjects (94 females) 6 to 25 years old. Additionally, agreement between mid-femoral total bone volume (TV) measurements by DXA and MRI were investigated. In both sexes, TA, CA, MA, and cortical thickness were significantly larger in adults compared to prepubertal subjects (P < 0.001), and males had greater values than females. This sex difference persisted for TA, CA, and cortical thickness (P < 0.05), but not MA, after adjusting for femur length and weight. Mean (SD) cortical BMD increased from 1.05 (0.07) and 1.09 (0.10) g/cm(3) in prepubertal children to 1.46 (0.14) and 1.42 (0.1) g/cm(3) in young adults, females and males, respectively (P < 0.001). TV measurements by DXA were significantly greater than by MRI (P < 0.001) in young adults. In conclusion, periosteal and endocortical expansion and increasing cortical BMD are the growth processes found at the mid-femur in both sexes. Our findings contrast to that in upper extremity bones, where MA is constant in females during growth. The difference in femoral bone development may be due to higher strains caused by weight bearing and genetic factors. DXA, in contrast to MRI, is inaccurate in the determination of mid-femoral TV measures.

Importance of lean mass in the interpretation of total body densitometry in children and adolescents

OBJECTIVE

Most studies that use total body dual energy x-ray absorptiometry (DEXA) in children rely on areal bone mineral density (BMD=bone mineral content [BMC]/bone area [BA]) and compare the output with age- and sex-specific normative data. Because this approach is prone to size-related misinterpretation, this study focuses on the interrelations among BMC, body size (height), and lean tissue mass (LTM).

STUDY DESIGN

This cross-sectional study presents normative total body LTM data in relation to height and BMC for 459 healthy white subjects (249 female), 3 to 30 years of age. Guidelines for DEXA interpretation in children are provided and illustrated for patients with growth hormone deficiency (n=5) and anorexia nervosa (n=5).

RESULTS

LTM/height tended to be greater in male than in girls. The BMC/LTM ratio was greater in female than in boys (P<.001), even after adjustment for age and height. Sex-specific reference curves were created for LTM/height, the BMC/LTM ratio, BA/height, and BMC/BA.

CONCLUSIONS

We recommend that total body DEXA in children should be interpreted in 4 steps: (1) BMD or BMC/age, (2) height/age, (3) LTM/height, and (4) BMC/LTM ratio for height. This allows differentiation of the origin of a low BMD or BMC/age, for example, short stature and primary, secondary, and mixed bone defects.

Zoledronic acid improves the mechanical properties of normal and healing bone

OBJECTIVE

To determine the effects of the bisphosphonate zoledronic acid on the mechanical properties of normal and regenerating bone in a rabbit model of distraction osteogenesis.

BACKGROUND

Bisphosphonate therapy is used for treating osteoporosis and, more recently, to enhance bone healing and reduce stress-shielding osteoporosis in distraction osteogenesis.

METHODS

Thirty eight rabbits underwent 14 days of distraction osteogenesis on the right rear limb. They received either zero, one or two doses of intravenous zoledronic acid. Four point bending tests were performed to collect mechanical data.

RESULTS

The peak load capacity of the regenerating bone was significantly increased by bisphosphonate therapy, but a similar trend in normal bone was not significant. The energy absorbed to failure did not vary significantly in either group.

CONCLUSIONS

These data suggest that bisphosphonate therapy has a beneficial effect on the load capacity of regenerating bone, without increasing the brittleness of either new or existing bone.

RELEVANCE

Zoledronic acid administration may be a potentially valuable adjunct to distraction osteogenesis treatment, to enhance bone strength, thus reducing refracture complications.

Effect of pamidronate on distraction osteogenesis and fixator-related osteoporosis

We examined the effect on bone mineral density (BMD), bone mineral content (BMC) and mechanical properties of a single 1.0 mg/kg dose of the bisphosphonate pamidronate (Novartis), in a distraction osteogenesis model in immature rabbits. Twenty rabbits underwent a tibial osteotomy. Ten rabbits received pamidronate 1.0 mg/kg via ear vein intra-operatively while 10 received saline infusions only. After a 24 h latency, all underwent distraction of 0.375 mm twice daily for 15 days. The animals were culled at 42 days. After culling, the distracted and non-distracted tibiae were examined by quantitative computer tomography (QCT). The volumetric bone mineral density (vBMD, mg/cm(3)) in the bone proximal and distal to the regenerate in the operated limb was increased by a mean of 11 and 14%, respectively, compared to controls (P<0.05). The vBMD of the regenerate bone was increased by a mean of 8% over controls (NS, P=0.17). The bone mineral content (BMC, mg) was increased by 23% (proximal and distal) (P<0.05) in the bone surrounding the lengthening and there was a 17% trend towards an increase in the regenerate (NS, P=0.3). Four-point bending analysis documented that the load to failure was increased by 32% from 436 to 574 N (P<0.01) in the pamidronate group. The modulus of elasticity was not different between the control and pamidronate groups (P=0.3), and in both groups was only approximately one-third of the intact tibiae (P<0.001). The administration of a single dose of pamidronate can improve the bone mineral density, content and mechanical properties of a bone undergoing distraction osteogenesis.

Intravenous pamidronate reduces osteoporosis and improves formation of the regenerate during distraction osteogenesis. A study in immature rabbits

We examined the effect on bone mineral density (BMD) of a single dose of 3 mg/kg of the bisphosphonate, pamidronate (Novartis) in distraction osteogenesis in immature rabbits. Seventeen rabbits (9 control, 8 given pamidronate) were examined by dual-energy x-ray absorptiometry. There was a significant increase in the BMD in the pamidronate group compared with the control animals. The mean areal BMD (g/cm2) in the bone proximal and distal to the regenerate was increased by 40% and 39%, respectively, compared with the control group (p < 0.05). The BMD of the regenerate bone was increased by a mean of 43% (p < 0.05). There was an increase of 22% in the mean area of regenerate formed in the pamidronate group (p < 0.05). Histological examination of bone in nine rabbits (5 control, 4 pamidronate) showed an increase in osteoblastic rimming and mineralisation of the regenerate, increased formation of bone around the pin sites and an increase in the cortical width of the bone adjacent to the regenerate in the rabbits given pamidronate. Pamidronate had a markedly positive effect. It reduced the disuse osteoporosis normally associated with lengthening using an external fixator and increased the amount and density of the regenerate bone. Further study is required to examine the mechanical properties of the regenerate after the administration of pamidronate.

Intravenous pamidronate reduces osteoporosis and improves formation of the regenerate during distraction osteogenesis

We examined the effect on bone mineral density (BMD) of a single dose of 3 mg/kg of the bisphosphonate, pamidronate (Novartis) in distraction osteogenesis in immature rabbits.

Seventeen rabbits (9 control, 8 given pamidronate) were examined by dual-energy x-ray absorptiometry. There was a significant increase in the BMD in the pamidronate group compared with the control animals. The mean areal BMD (g/cm2) in the bone proximal and distal to the regenerate was increased by 40% and 39%, respectively, compared with the control group (p < 0.05). The BMD of the regenerate bone was increased by a mean of 43% (p < 0.05). There was an increase of 22% in the mean area of regenerate formed in the pamidronate group (p< 0.05).

Histological examination of bone in nine rabbits (5 control, 4 pamidronate) showed an increase in osteoblastic rimming and mineralisation of the regenerate, increased formation of bone around the pin sites and an increase in the cortical width of the bone adjacent to the regenerate in the rabbits given pamidronate.

Pamidronate had a markedly positive effect. It reduced the disuse osteoporosis normally associated with lengthening using an external fixator and increased the amount and density of the regenerate bone. Further study is required to examine the mechanical properties of the regenerate after the administration of pamidronate.

Osteoporosis: A possible aetiological factor in the development of Scheuermann's disease

The aim of this study was to test the hypothesis that spinal osteoporosis is an aetiological factor in the development of Scheuermann's disease in adolescents. Clinical and radiological data was collected on 12 individuals with Scheuermann's disease (SD). Lumbar spine bone mineral density (L2-4) was measured using dual energy X-ray absorptiometry. Age and sex-matched adolescents were used as controls. The number of standard deviations from the mean of age and sex-matched controls were calculated. In regards to results, SD patients demonstrated high bone densities of between 1 and 1.5 standard deviations above the mean of age-matched controls. These results suggest that osteoporosis is not an aetiological factor in Scheuermann's disease and that bone density measurements may indeed be higher than aged-matched controls in the general population.

Vitamin D receptor alleles predict growth and bone density in girls

OBJECTIVES

Polymorphism of the vitamin D receptor (VDR), collagen alpha I type I (Col I alpha I), and oestrogen receptor (ER) genes have been shown to account for some of the heritability of bone mineral density (BMD) in adults. This study examined this relation in prepubertal children.

METHODS AND SUBJECTS

The relation between genotypes of VDR gene (Taq I, Bsm I, Fok I), Col I alpha I gene (Msc I), and ER gene (Pvu II) with areal BMD, volumetric BMD, and growth were examined in 114 (68 girls) healthy 7 year old, white children.

RESULTS

The genotype of the VDR gene (Taq I) correlated with lumbar spine (L1-4) volumetric BMD in girls only, but at no other bone sites. In girls, VDR genotype affected areal BMD at all sites. After adjusting for height and weight, however, this effect was explained completely by the independent effect of the VDR genotype on growth. Girls with genotype TT, were 3.9 kg heavier and 4.1 cm taller than those with tt, but this relation was not present at birth. No relation was found between genotypes of the VDR gene (Fok I), Col I alpha I gene (Msc I), or ER gene (Pvu II) and BMD or growth variables.

CONCLUSIONS

In prepubertal girls, VDR alleles contribute to lumbar spine volumetric BMD variance, but the areal BMD effect reflects the relation between areal BMD and growth. VDR alleles might affect postnatal growth regulation.

Fat distribution in children and adolescents--the influence of sex and hormones

A significant proportion of the morbidity related to obesity is now recognized to be related to the regional distribution of fat. The advent of dual energy X-ray absorptiometry has facilitated the assessment of body composition in a number of investigations on body fat. From current data, including the authors' own study of trunk and leg fat in 335 children and young adults, it is evident that gender differences for total body fat, percentage of body fat and distribution of fat occur after the pubertal years. Males develop a distribution of fat which favours central deposition of fat irrespective of their total body fat--a distribution that is, unfortunately, associated with a number of adverse implications on health. Furthermore, this tendency to increasing abdominal fat is independent of adipose tissue mass. Hormonal regulators of adipose tissue, including growth hormone which is already known to increase free fatty acids and decrease fat cell mass, need to be studied to account for these gender differences.