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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

The effect of local unemployment on health: A longitudinal study of Irish mothers 2001-2011

The relationship between economic conditions and health is mixed, with some evidence from the most recent financial crisis finding a positive effect of periods of unemployment on heath behaviours. This study uses longitudinal data spanning the periods before, during and after the Irish crisis of 2007, to test the impact of economic expansion and contraction on mothers physical and mental health and health behaviours. Three waves of data from the Irish Lifeways Cohort Study for the period 2001-2011, and local area employment rates from the Irish Census, are used to capture the impact of a period of increased unemployment on health before, during and after the Irish recession, independent of individual employment status. The results from fixed effect linear probability models demonstrate that an additional unit of local area unemployment increases the probability of reporting poor self-rated health by 1-1.8 percentage points and of reporting poor mental well-being by 1.4 and 2.7 percentage points depending on the instrument used. There are decreases in the probability of consuming cigarettes by 3.3 percentage points, self-describing as a regular smoker by 2.9 percentage points and obesity by 0.9 percentage points. The probability of engaging in at least 20 minutes of strenuous or moderate exercise per week declines by 7.8 and 8.7 percentage points respectively, while the probability of engaging in at least 20 minutes of mild exercise rises by 10 percentage points. These results are largely consistent with the US literature, which is predominantly based on working men, thus demonstrating the universal impact of economic vulnerability on health.

Parental unemployment during the Great Recession and childhood adiposity

The incidence of adiposity in the early years of life has outgrown the prevalence in older children and adolescents globally; however, the factors influencing weight gain are predominantly studied in adults. This study examines the relationship between changing economic conditions during the Irish recession and child weight in a nationally representative sample of 10,011 Irish children studied at 9 months, 3 years and 5 years old. This study is the first to use longitudinal anthropometric measurements to estimate the impact of direct parental unemployment on children's weight. Fixed effect logistic regression is used to examine the effects of parental unemployment on weight using the Growing up in Ireland infant cohort from 2008 to 2013. Weight and length/height measured by trained interviewers and child growth charts are used to quantify children's weight status according to BMI-for-age and weight-for-age measures. For BMI-for-age, the probability of a child being classified as overweight/obese is 8 percentage points higher if either parent experiences unemployment. A sensitivity analysis of weight-for-age indicates that the probability is of similar magnitude across several alternative growth charts and definitions of adiposity (the WHO standard, British Growth Reference, and Centers for Disease Control). The analysis is repeated, cross-sectionally, for physical activity and diet to clarify mechanisms of effect. The probability of a child consuming healthy food and physical activity with an implied cost is lower if either parent becomes unemployed. A focus on overweight/obesity in the early years is of crucial importance as if current trends are not addressed, a generation of children may grow up with a higher level of chronic disease.

Epidemiological transition: a historical analysis of immigration patterns by country of origin (1861-1986) related to circulatory system diseases and all-cause mortality in twentieth-century Australia

BACKGROUND AND OBJECTIVES

Circulatory system disease (CSD) patterns vary over time and between countries, related to lifestyle risk factors, associated in turn with socioeconomic circumstances. Current global CSD epidemics in developing economies are similar in scale to those observed previously in the USA and Australasia. Australia exhibits an important macroeconomic phenomenon as a rapidly transitioning economy with high immigration throughout the nineteenth and twentieth centuries. We wished to examine how that historical immigration related to CSD patterns subsequently.

METHODS AND SETTING

We provide a novel empirical analysis employing census-derived place of birth by age bracket and sex from 1891 to 1986, in order to map patterns of immigration against CSD mortality rates from 1907 onwards. Age-specific generalised additive models for both CSD mortality in the general population, and all-cause mortality for the foreign-born (FB) only, from 1910 to 1980 were also devised for both males and females.

RESULTS

The percentage of FB fell from 32% in 1891 to 9.8% in 1947. Rates of CSD rose consistently, particularly from the 1940s onwards, peaked in the 1960s, then declined sharply in the 1980s and showed a strong period effect across age groups and genders. The main effects of age and census year and their interaction were highly statistically significant for CSD mortality for males (p<0.001, each term) and for females (p<0.001, each term). The main effect of age and year were statistically significant for all-cause mortality minus net migration rates for the FB females (each p<0.001), and for FB males, age (p<0.001) was significant.

CONCLUSIONS

We argue our empirical calculations, supported by historical and socioepidemiological evidence, employing immigration patterns as a proxy for epidemiological transition, affirm the life course hypothesis that both early life circumstances and later life lifestyle drive CSD patterns.

Economic evaluation of CPD activities for healthcare professionals: A scoping review

CONTEXT

Continuing professional development (CPD) activities for healthcare professionals are central to the optimisation of patient safety and person-centred care. Although there is some evidence on the economics of healthcare professionals training, very little is known about the costs and benefits of CPD.

METHODS

This study aimed to review the research evidence on economic evaluations of CPD activities for healthcare professionals. CINAHL, MEDLINE/PubMed, Scopus, Econlit and Web of Science databases were used to identify articles published between 2010 and 2021.

RESULTS

Of the 6791 titles identified, 119 articles met the inclusion criteria and were included in this scoping review. The majority of articles were partial economic evaluations of CPD programmes (n = 70); half were from the USA. Studies that included multiple professions were most prevalent (n = 54), followed by nurses (n = 34) and doctors (n = 23). Patient outcomes were the most commonly reported outcome (n = 51), followed by change in clinical practice (n = 38) and healthcare professionals' knowledge gain (n = 19).

CONCLUSIONS

There is an urgent call for more evidence regarding the economic evaluations of CPD. This is particularly important in view of the rising costs of healthcare globally. The majority of studies included in this review did not provide detailed information on the evaluations and many focused exclusively on the cost of CPD activities rather than outcomes.