How to manage osteoporosis in children

The relationship of bone mineral density and vitamin D levels with steroid use and ambulation in patients with Duchenne muscular dystrophy

Objectives

This study aims to assess the bone mineral density (BMD) and serum levels of 25(OH)-vitamin D and their relationship with steroid use and ambulation in patients with Duchenne muscular dystrophy (DMD).

Patients and methods

Between January 2017 and May 2018, medical records of a total of 67 male patients (mean age, 13.9±4.3 years; range, 8 to 25 years) who were diagnosed with definite DMD were retrospectively analyzed. Demographic data, functional activity level, steroid use, fracture history and location, serum levels vitamin D, and lumbar and hip Z-scores in BMD at the time of the initial admission were recorded.

Results

The mean level of vitamin D was 13.4±7.5 ng/mL. In terms of serum levels of vitamin D, 28 patients (41.8%) had severe deficiency, 31 (46.3%) had insufficiency, and five patients (7.5%) had deficiency. Only three (4.5%) of the patients had sufficient levels of vitamin D. The hip Z-scores were significantly lower than lumbar Z scores. There was no significant difference in the lumbar and hip BMD measurements between the patients with and without steroid use. Lumbar Z-scores were significantly lower in non-ambulatory patients than ambulatory patients.

Conclusion

It is of utmost importance to evaluate the initial serum vitamin D levels in terms of bone health and prescribe replacement in case of deficiency/insufficiency in DMD patients. Since the decrease in the BMD is evident in this patient population, maintaining the mobilization as long as possible, providing loading on the bone for a long time, may be beneficial.

Basics of bone metabolism and osteoporosis in common pediatric neuromuscular disabilities

Bone modeling is a process that starts with fetal life and continues during adolescence. Complex factors such as hormones, nutritional and environmental factors affect this process. In addition to these factors, physical conditioning and medications that have toxic effects on bony tissue should be carefully considered in patient follow-up. Osteoporosis is a significant problem in pediatric population because of ongoing growth and development of skeletal system. Two types of osteoporosis are primary and secondary types and children with neuromuscular disabilities constitute a major group with secondary osteoporosis. Low bone mass in patients with cerebral palsy, spina bifida, and Duchenne muscular dystrophy cause increased bone fragility in even slight traumas. Maximizing peak bone mass and prevention of bone loss are very important to reduce the fracture risk in neuromuscular diseases. This article aims to review the determinants of bone physiology and bone loss in children with cerebral palsy, spina bifida, and Duchenne muscular dystrophy.

Investigating the Prevalence of Low Bone Mass in Children of Southern Iran and Its Associated Factors

BACKGROUND

Improving peak bone mass and bone strength in the first years of life and enhancing it during young adulthood could prevent osteoporosis and fractures in the last years of life. We evaluated the prevalence of low bone mass in the lumbar and femoral neck and its associated factors in southern Iranian children.

METHODS

This is a cross-sectional study on healthy Iranian children aged 9 - 18 years old during 2011 - 2012. Dual energy X-ray absorptiometry (DEXA) was used for measuring bone mineral density (BMD). BMD Z-score ≤ -2 was considered as low. Anthropometric data, physical activity, sun exposure, puberty, and mineral biochemical parameters were assessed. Data were analyzed using SPSS v.15.

RESULTS

477 normal children, including 236 (49.5%) girls and 241 (50.5%) boys, aged 13.8 ± 2.7 years were enrolled. Prevalence of low bone mass (LBM) in the femoral and lumbar region was 10.7% and 18.7%, respectively. The prevalence of LBM in femur of girls is twice more than boys. Fat mass index, BMI Z-score, and physical activity were associated with lumbar low bone mass. BMI Z-score and physical activity were associated with femoral low bone mass.

CONCLUSIONS

High prevalence of low bone mineral density in children 9 to 18 years in south of the country is concerned and is needed to plan for prevention and treatment. BMI-Z score, fat mass index, and physical activity were the 3 most important preventive factors in developing low bone mass in children.

Technique, Safety, and Yield of Bone Biopsies for Histomorphometry in Children

PURPOSE

To evaluate image-guided bone biopsy for bone histomorphometry to assess osteoporosis in children with respect to safety and yield.

MATERIALS AND METHODS

A single-center retrospective review was performed of 79 bone biopsies in 73 patients performed between 2007 and 2015. Biopsies of the iliac bone were performed under general anesthesia, after tetracycline labeling, using a Rochester needle (Medical Innovations International, Inc, Rochester, Minnesota). Ultrasound and fluoroscopic guidance were used in all procedures. Biopsy technique, technical success, safety, and histomorphometry results (complete, incomplete, none) were analyzed.

RESULTS

There were 41 male patients (51.8%). Technical success was achieved in 76/79 (96%) procedures. Of 79 biopsies, 75 (95%) were uneventful. Unplanned overnight observation was required in 3 (minor SIR grade B), and prolonged hospital stay owing to hematoma causing nerve compression pain was required in 1 (major SIR grade D). Complete histomorphometric reports were obtained in 69 (87%) procedures, incomplete reports were obtained in 7 (9%), and no reports were obtained in 3(4%). Incomplete reports were insufficient to provide a definitive diagnosis or guide treatment. Histomorphometry impacted subsequent therapy in 69 (87%) biopsies.

CONCLUSIONS

Image-guided bone biopsy for osteoporosis using the Rochester needle is a valuable and safe technique for establishing the diagnosis of osteoporosis and directing treatment based on histomorphometry results.

Beyond osteogenesis imperfecta: Causes of fractures during infancy and childhood

Fractures in infancy or early childhood require prompt evaluation with consideration of accidental or non-accidental trauma as well as a large number of genetic disorders that predispose to fractures. Bone fragility has been reported in more than 100 genetic disorders, including skeletal dysplasias, inborn errors of metabolism and congenital insensitivity to pain. Most of these disorders are rare but often have distinctive clinical or radiographic findings to assist in the diagnosis. Gene sequencing is available, albeit connective tissue and skeletal dysplasia panels and biochemical studies are only helpful in a minority of cases. This article presents the clinical, radiographic, and molecular profiles of the most common heritable disorders other than osteogenesis imperfecta with increased bone fragility. In addition, the clinicians must consider non-heritable influences such as extreme prematurity, prenatal viral infection and neoplasia in the diagnostic process.

Effects of bisphosphonates to treat osteoporosis in children with cerebral palsy: a meta-analysis

BACKGROUND

In childhood and adolescence, some patients with cerebral palsy (CP) have long-term limited mobility, which can lead to secondary osteoporosis, Prevention and treatment strategies have been evaluated for the management of low bone mineral density (BMD) and fragility fractures. Currently, however, there are no established guidelines for the stratification and individualization of therapeutic interventions. Recently, an increasing number of studies have reported on the use of bisphosphonates to increase BMD in various pediatric conditions, and bisphosphonates have been suggested as a method to treat osteoporosis and prevent fractures.

PURPOSE

We performed the current meta-analysis to assess the effects of bisphosphonates on increasing BMD in children who have CP with secondary osteoporosis.

MATERIALS AND METHODS

A search of PubMed, Cochrane, and Embase from inception to April 2014 was performed with the following keywords: (bone disease, metabolic OR osteoporosis OR osteopenia) AND (child OR pediatric OR adolescent) AND (cerebral palsy) AND (bisphosphonate). Four studies were ultimately included in the meta-analysis: one randomized, double-blinded, placebo-controlled study and three case-controlled studies.

RESULTS

The Z-score of lumbar spine was significantly improved after bisphosphonates treatment compared with pre-treatment values (standardized mean difference [SMD], 0.799; 95% confidence interval [CI], 0.499-1.100; p<0.001). The Z-score of femur was also improved significantly compared with that of the baseline value (SMD, 0.748; 95% CI, 0.382-1.114; p<0.001).

CONCLUSIONS

Bisphosphonates have a significant effect on improving BMD in children with CP. Further standardization of treatment protocols including treatment dosage and duration needs to be established, and long-term follow up studies are needed.

Bone density and alendronate effects in Duchenne muscular dystrophy patients

INTRODUCTION

Patients with DMD have low bone mineral density (BMD) and are at high risk for fractures. We examined changes in BMD and the effects of alendronate in DMD patients treated at our institution in the last decade.

METHODS

Retrospective cohort study of 39 DMD patients.

RESULTS

Patients had screening dual energy x-ray absorptiometry (DXA) at an average age of 12 years. The vast majority had low Z-scores at the total hip and lumbar spine. Patients treated with glucocorticoids had a significantly lower Z-score at the spine than those not treated with glucocorticoids. Z-scores at the hip trended down without alendronate (P = 0.07) and trended up with alendronate (P = 0.4).

CONCLUSIONS

By age 12 years, most patients with DMD had low Z-scores. They may have benefitted from earlier screening. Z-score at the hip trended downward without alendronate and trended upward (stabilized) with alendronate, but these trends were not statistically significant.

IGF-1 Signaling is Essential for Differentiation of Mesenchymal Stem Cells for Peak Bone Mass

Survival of children with chronic medical illnesses is leading to an increase in secondary osteoporosis due to impaired peak bone mass (PBM). Insulin-like growth factor type 1 (IGF-1) levels correlate with the pattern of bone mass accrual and many chronic illnesses are associated with low IGF-1 levels. Reduced serum levels of IGF-1 minimally affect the integrity of the skeleton, whereas recent studies suggest that skeletal IGF-I regulates PBM. To determine the role of IGF-1 in postnatal bone mass accrual regardless of source, we established an inducible type 1 Igf receptor Cre/lox knockout mouse model, in which the type 1 Igf receptor was deleted inducibely in the mesenchymal stem cells (MSCs) from 3-7 weeks of age. The size of the mouse was not affected as knockout and wild type mice had similar body weights and nasoanal and femoral lengths. However, bone volume and trabecular bone thickness were decreased in the secondary spongiosa of female knockout mice relative to wild type controls, indicating that IGF-1 is critical for bone mass. IGF-1 signaling in MSCs in vitro has been implicated to be involved in both migration to the bone surface and differentiation into bone forming osteoblasts. To clarify the exact role of IGF-1 in bone, we found by immunohistochemical analysis that a similar number of Osterix-positive osteoprogenitors were on the bone perimeter, indicating migration of MSCs was not affected. Most importantly, 56% fewer osteocalcin-positive mature osteoblasts were present on the bone perimeter in the secondary spongiosa in knockout mice versus wild type littermates. These in vivo data demonstrate that the primary role of skeletal IGF-1 is for the terminal differentiation of osteoprogenitors, but refute the role of IGF-1 in MSC migration in vivo. Additionally, these findings confirm that impaired IGF-1 signaling in bone MSCs is sufficient to impair bone mass acquisition.

Efficacy of pamidronate in children with low bone mineral density during and after chemotherapy for acute lymphoblastic leukemia and non-Hodgkin lymphoma

Background

Reduced bone mineral density (BMD) is a significant sequelae in children receiving chemotherapy for acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). Reduced BMD is associated with an increased risk for fractures. Pamidronate, a second-generation bisphosphonate, has been used to treat osteoporosis in children. This study evaluated the safety and efficacy of pamidronate in children with low BMD during and after chemotherapy for ALL and NHL.

Methods

Between April 2007 and October 2011, 24 children with ALL and NHL were treated with pamidronate. The indication was a decreased BMD Z-score less than -2.0 or bone pain with a BMD Z-score less than 0. Pamidronate was infused at 1 mg/kg/day for 3 days at 1-4 month intervals (pamidronate group, cases). The BMD Z-scores of the cases were compared with those of 10 untreated patients (control group). Lumbar spine BMDs were measured every 6 cycles using dual energy X-ray absorptiometry and Z-scores were calculated. Bone turnover parameters (25-hydroxyvitamin D, alkaline phosphatase, parathyroid hormone, osteocalcin, and type I collagen c-terminal telopeptide) were analyzed.

Results

The median cycle of pamidronate treatment was 12. Increases in BMD Z-scores were significantly higher in the pamidronate group than in the control group (P<0.001). BMD (mg/cm²) increased in all pamidronate-treated cases. Twenty patients who complained of bone pain reported pain relief after therapy. The treatment was well tolerated.

Conclusion

Pamidronate appears to be safe and effective for the treatment of children with low BMD during and after chemotherapy for ALL and NHL.

Selected risk factors of fractures in children — own observation

Bone fractures may depend on Vitamin D Receptor Gene (VDR), bone mineral density, bone turnover markers. Patients and methods. 161 patients were recruited and underwent: skeletal densitometry (DXA) method and bone turnover studies (Osteocalcin and Ntx).The study group was evaluated using restriction enzyme digestion at BsmI (rs1544410), FokI (rs2228570), ApaI (rs7975232) and TaqI (rs731236), polymorphic sites of the VDR gene. Multivariate logistic regression was used to assess factor significance. The model included variables with sex- and age-standardized parameters, VDR genotypes, and bone metabolism marker levels. Results. Factors associated with fractures were: osteocalcin concentration and Z-score BMDt. Odds Ratio (OR) values equaled: 1.01 (95%Confidence Interval (95%CI) 1.00–1.02) for osteocalcin (p=0.006), and 0.66 (95%CI 0.42-1.03; p=0.07) for Z-score BMDt. In patients with reduced bone mass, factors related to fractures were: osteocalcin (0.04) and carriage of BsmI b (0.07) or ApaI a alleles (0.08). ORs were 1.01 (95%CI 1.00–1.02) for OC, 0.29 (95%CI 0.07–1.14) for BsmI, and 2.13 (95%CI 0.91–4.99) for ApaI polymorphic allele carriage. Conclusions. Carriage of BsmI b allele reduces, while carriage of ApaI a allele and heightened osteoclacin level increase the risk of fractures in study children with reduced bone mass. VDR polymorphism, bone mineral density and bone formation’s marker — osteocalcin maybe considered as risk factor for fracure in children from Lodz region.

Informing evidence-based clinical practice guidelines for children with cerebral palsy at risk of osteoporosis: a systematic review

AIM

The aim of this systematic review was to inform evidence-based clinical practice guidelines for children with cerebral palsy (CP) and low bone mineral density (BMD).

METHOD

A computer-assisted literature search was focused on low BMD in children with CP, and was limited to the following interventions: weight-bearing activities, bisphosphonate use, and vitamin D or calcium supplementation. Articles were classified according to American Academy of Neurology guidelines and recommendation classifications were given based on the evidence for the intervention increasing BMD and decreasing fragility fractures. Studies were included if they were English-language full-text studies, focused on children with CP, and included at least 10 participants receiving the studied interventions.

RESULTS

Twenty-one articles underwent full-text review and data abstraction, including seven studies of weight-bearing activities, five studies of vitamin D or calcium supplementation, and nine studies of bisphosphonates administration. Overall, the evidence that bisphosphonates administration increases BMD was assessed as level B (probable) while the evidence that vitamin D or calcium supplementation does so was assessed as level C (possible); there was insufficient evidence to suggest that weight-bearing activities are an effective intervention to improve BMD. The evidence that bisphosphonates help to prevent fragility fractures was assessed as level C (possible); there was inadequate evidence to support the use of weight-bearing activities or vitamin D or calcium supplementation to decrease fragility fractures.

INTERPRETATION

Evidence-based clinical practice guidelines were created outlining the suggested role of weight-bearing activities, vitamin D and calcium supplementation, and bisphosphonate use for children with CP with low BMD at risk of fragility fractures.

Bone biopsy findings and correlation with clinical, radiological, and biochemical parameters in children with fractures

In children the diagnosis of osteoporosis is based on fracture history and DXA-derived BMD. Bone biopsy is an invasive but accurate method for studying bone characteristics. In this study we evaluated bone biopsy findings and their correlation with noninvasive measures of bone health. Transiliac bone biopsy was performed on 24 consecutive children (17 boys, median age 12 years, range 6 to 16 years) evaluated for suspected primary osteoporosis. Biopsy findings were compared with normative data and correlated with clinical, radiological, biochemical, and densitometric findings. The patients had sustained altogether 64 nonvertebral fractures (median 2.5) from low- or moderate-energy traumas, and 14 patients (58%) had vertebral fractures. The median lumbar spine BMD Z-score was -1.2 (range -3.1 to +1.0). Hypovitaminosis D was present in 58%. Histomorphometry showed low bone volume in 7 patients and normal bone volume in 17. Bone turnover was high in 7, low in 7, and normal in 10 patients. Histomorphometric findings correlated poorly with fracture history, serum bone turnover markers, and DXA findings. Vitamin D deficiency and low lumbar BMD were associated with high bone turnover in the biopsy. These findings underscore the difficulties in diagnosing pediatric osteoporosis. Bone histomorphometry gives additional information and may be useful when considering bisphosphonate treatment in children with suspected primary osteoporosis.

Updated recommendations for the diagnosis and management of osteoporosis: a local perspective

Postmenopausal osteoporosis and osteoporosis in elderly men are major health problems, with a significant medical and economic burden. Although osteopenia and osteoporosis are more common locally than in the West, fracture rates are generally less than in Western countries. Vitamin D deficiency is common in the region and contributes adversely to bone health. Vitamin D deficiency should be suspected and treated in all subjects with ostopenia or osteoporosis. The use of risk factors to determine fracture risk has been adopted by the World Health Organization and many international societies. Absolute fracture risk methodology improves the use of resources by targeting subjects at higher risk of fractures for screening and management. The King Faisal Specialist Hospital Osteoporosis Working Group recommends screening for women 65 years and older and for men 70 years and older. Younger subjects with clinical risk factors and persons with clinical evidence of osteoporosis or diseases leading to osteoporosis should also be screened. These guidelines provide recommendations for treatment for postmenopausal women and men older than 50 years presenting with osteoporotic fractures for persons having osteoporosis-after excluding secondary causes-or for persons having low bone mass and a high risk for fracture. The Working Group has suggested an algorithm to use at King Faisal Specialist Hospital that is based on the availability, cost, and level of evidence of various therapeutic modalities. Adequate calcium and vitamin D supplement are recommended for all. Weekly alendronate (in the absence of contraindications) is recommended as first-line therapy. Alternatives to alendronate are raloxifene or strontium ranelate. Second-line therapies are zoledronic acid intravenously once yearly, when oral therapy is not feasible or complicated by side effects, or teriparatide in established osteoporosis with fractures.

Fenretinide prevents the development of osteoporosis in Cftr-KO mice

BACKGROUND

The most recently described phenotype associated with Cystic Fibrosis (CF) is reduced bone mineral density which results in osteopenia and osteoporosis. The etiology of the early onset of osteoporosis in CF patients has remained to be established. It has been suggested that inadequate nutritional absorption of essential fatty acids may play a role in the altered bone metabolism. In this study, we characterized the protective effect of fenretinide [N-(4-hydroxyphenyl) retinamide], a vitamin A derivative, on the early onset of osteoporosis in cystic fibrosis transmembrane conductance regulator knockout (Cftr-KO) mice.

METHODS

Using micro-computed-tomography we examined the effect of fenretinide on the bone composition and architecture in a Cftr-KO mouse model which was then confirmed with histological analyses. Plasma fatty acids were quantified using thin layer chromatography-ELISA method.

RESULTS

Twice-weekly treatments with fenretinide, over four weeks dramatically increased trabecular bone volume compared to controls. This increase in bone volume was also related to an increased concentration of ceramide in the plasma resulting in the down regulation of phospholipid-bound AA in Cftr-KO mice.

CONCLUSIONS

To our knowledge, this is the first time that fenretinide's protective effect against osteoporosis has been demonstrated. The results of this study strongly suggest that fenretinide has potential to be used as a prophylaxis by preventing the early onset of osteoporosis.

Osteoporosis in children and adolescents

In recent years, the issue of low bone density in children and adolescents has attracted much attention. The classical definition of osteoporosis should be valid at any age, yet its practical applicability to children and adolescents remains a matter of debate and there is no consensus on a diagnosis based solely on the BMD value. The clinical relevance of uncomplicated low bone density in the young and its long-term consequences remain difficult to evaluate and there is only preliminary evidence that the BMD value is a predictor of fracture risk in growing subjects. Moreover, the interpretation of densitometric data in the young is difficult because the "normal" BMD values to be used for comparison are continuously changing with age, and in addition, depend on several variables, such as gender, body size, pubertal stage, skeletal maturation and ethnicity. Although Z-score values below -2 are generally considered a serious warning, most bone specialists make a diagnosis of osteoporosis in children and adolescents only in the presence of low BMD and at least one fragility fracture. The scope of this review is limited to presenting a picture of the available knowledge. The literature on fractures will be presented in detail, since fractures are one of the key elements in the debate. There are countless papers on fractures in childhood and adolescence, but very few of them attempt to identify fragility fractures, and still fewer develop the concept of osteoporosis in the young in relation to fractures. The different forms of primary and secondary osteoporosis, the more technical aspects of bone densitometry in pediatrics, and the delicate issue of treatment will be discussed only briefly.

Pediatric bone density and fracture

As children grow, they accumulate bone mineral, which serves as a "bone bank" for the future. Any condition that interferes with normal bone mineral accrual during childhood has the potential to reduce peak bone mass and subsequently increase future risk for fracture. In contrast to adults, for whom dual-energy x-ray absorptiometry (DXA) has become the standard clinical instrument for assessing bone mineral density and criteria have been developed to define osteopenia and osteoporosis, information for children is still limited. Numerous issues confound the interpretation of DXA-derived bone mineral density measurements in children, and clinicians often find themselves caught between the limitations of these methods and the practical issue of taking care of their pediatric patient. The explosion of treatment options for postmenopausal osteoporosis has resulted in new options for the treatment of children and adolescents. However, most of these agents have not been sufficiently well studied in children to permit the development of standardized treatment guidelines.

Fractures in children with Pompe disease: a potential long-term complication

BACKGROUND

Pompe disease (glycogen storage disease type II or acid maltase deficiency) is an autosomal recessive disorder caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). Classic infantile-onset disease, characterized by cardiomegaly and profound weakness, leads to death in the first year of life from cardiorespiratory failure. Reversal of cardiomyopathy and improved motor function have been shown in clinical trials of rhGAA enzyme replacement therapy (ERT) with alglucosidase alfa (Myozyme), recently approved for clinical use. Increased survival potentially unmasks long-term complications of this previously lethal disease, including risk of skeletal fracture, recently identified at our institution and not previously reported in children with Pompe disease.

OBJECTIVE

To report the risk of fracture in children with Pompe disease with increased survival with ERT.

MATERIALS AND METHODS

We present four cases of fracture in patients with classic infantile Pompe disease treated with ERT at our institution, and review a study database for additional reports of fracture in this population.

RESULTS

We review 19 fractures in 14 children with Pompe disease on ERT.

CONCLUSION

Radiologists should be familiar with and vigilant for the association of fractures and increased survival on ERT in children with Pompe disease. We discuss potential mechanisms, implications for radiographic surveillance, potential intervention, and needs for further research.

[Osteoporosis in children and adolescents]

There is currently no consensus definition of osteopenia and osteoporosis in children according to bone mineral density (BMD) values measured by dual energy x-ray absorptiometry (DXA); interpretation of BMD measures must take into account the child's weight and pubertal status. In children, primary forms of osteoporosis--juvenile idiopathic osteoporosis and osteogenesis imperfecta--are rare; on the other hand, the frequency of secondary osteoporosis is increasing. Fractures, especially of the forearm, are frequent in children. During the peak growth period, bone growth and mineralization are dissociated; in consequence temporary bone fragility promotes fractures. Several recent studies show that children with fractures have reduced BMD and that the occurrence of fractures in children may constitute a risk factor for osteoporosis and fracture during adulthood. In cases of secondary osteoporosis, close monitoring of the causal disease is the key element of treatment; there are very few controlled studies of the prevention or treatment of osteoporosis in children.