Long-term effects of bisphosphonates on the growing skeleton. Studies of young patients with severe osteoporosis

Drug-induced osteopetrosis

Osteopetrosis (OPT) denotes the consequences from failure of osteoclasts to resorb bone and chondroclasts to remove calcified physeal cartilage throughout growth. Resulting impairment of skeletal modeling, remodeling, and growth compromises widening of medullary spaces, formation of the skull, and expansion of cranial foramina. Thus, myelophthisic anemia, raised intracranial pressure, and cranial nerve palsies complicate OPT when severe. Osteopetrotic bones fracture due to misshaping, failure of remodeling to weave the collagenous matrix of cortical osteons and trabeculae, persistence of mineralized growth plate cartilage, "hardening" of hydroxyapatite crystals, and delayed healing of skeletal microcracks. Teeth may fail to erupt. Now it is widely appreciated that OPT is caused by germline loss-of-function mutation(s) usually of genes involved in osteoclast function, but especially rarely of genes necessary for osteoclast formation. Additionally, however, in 2003 we published a case report demonstrating that prolonged excessive dosing during childhood of the antiresorptive aminobisphosphonate pamidronate can sufficiently block osteoclast and chondroclast activity to recapitulate the skeletal features of OPT. Herein, we include further evidence of drug-induced OPT by illustrating osteopetrotic skeletal changes from repeated administration of high doses of the aminobisphosphonate zoledronic acid (zoledronate) given to children with osteogenesis imperfecta.

Combination treatment with growth hormone and zoledronic acid in a mouse model of Osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) or brittle bone disease is a genetic disorder that results in bone fragility. Bisphosphonates such as zoledronic acid (ZA) are used clinically to increase bone mass and reduce fracture risk. Human growth hormone (hGH) has been used to promote long bone growth and forestall short stature in children with OI. The potential for hGH to improve bone quality, particularly in combination with ZA has not been robustly studied.

METHODS

A preclinical study was performed using n = 80 mice split evenly by genotype (WT, Col1a2^+/G610C). Groups of n = 10 were treated with +/-ZA and +/-hGH in a factorial design for each genotype. Outcome measures included bone length, isolated muscle mass, bone parameters assessed by microCT analysis, dynamic histomorphometry, and biomechanical testing.

RESULTS

Treatment with hGH alone led to an increase in femur length in WT but not OI mice, however bone length was increased in both genotypes with the combination of hGH/ZA. MicroCT showed that hGH/ZA treatment increased cortical BV in both WT (+15%) and OI mice (+14.3%); hGH/ZA were also found to be synergistic in promoting cortical thickness in OI bone. ZA was found to have a considerably greater positive impact on trabecular bone than hGH. ZA was found to suppress bone turnover, and this was rescued by hGH treatment in terms of cortical periosteal perimeter, but not by dynamic bone remodeling. Statistically significant improvements in long bone by microCT did not translate into improvements in mechanical strength in a 4-point bending test, nor did vertebral strength improve in L4 compression testing in WT/OI bone.

DISCUSSION/CONCLUSION

These data support hGH/ZA combination as a treatment for short stature, however the improvements granted by hGH alone and in combination with ZA on bone quality are modest. Increased periosteal perimeter does show promise in improving bone strength in OI, however a longer treatment time may be required to see effects on bone strength through mechanical testing.

SHIP1 Activator AQX-1125 Regulates Osteogenesis and Osteoclastogenesis Through PI3K/Akt and NF-κb Signaling

With the worldwide aging population, the prevalence of osteoporosis is on the rise, particularly the number of postmenopausal women with the condition. However, the various adverse side effects associated with the currently available treatment options underscore the need to develop novel therapies. In this study, we investigated the use of AQX-1125, a novel clinical-stage activator of inositol phosphatase-1 (SHIP1), in ovariectomized (OVX) mice, identifying a protective role. We then found that the effect was likely due to increased osteogenesis and mineralization and decreased osteoclastogenesis caused by AQX-1125 in a time- and dose-dependent manner. The effect against OVX-induced bone loss was identified to be SHIP1-dependent as pretreatment of BMSCs and BMMs with SHIP1 RNAi could greatly diminish the osteoprotective effects. Furthermore, SHIP1 RNAi administration in vivo induced significant bone loss and decreased bone mass. Mechanistically, AQX-1125 upregulated the expression level and activity of SHIP1, followed upregulating the phosphorylation levels of PI3K and Akt to promote osteoblast-related gene expressions, including Alp, cbfa1, Col1a1, and osteocalcin (OCN). NF-κB signaling was also inhibited through suppression of the phosphorylation of IκBα and P65 induced by RANKL, resulting in diminished osteoclastogenesis. Taken together, our results demonstrate that AQX-1125 may be a promising candidate for preventing and treating bone loss.

In vitro and in silico anti-osteoporosis activities and underlying mechanisms of a fructan, ABW90-1, from Achyranthes bidentate

Achyranthes bidentata is a traditional Chinese medicine used to treat osteoporosis. AB90, a crude saccharide from A. bidentata, showed excellent osteoprotective effects in ovariectomized rats, and ABW90-1, an oligosaccharide purified from AB90, stimulated significant differentiation of osteoblasts. However, the osteogenic effects and underlying mechanisms of ABW90-1 have remained unknown. In the present study, we found that ABW90-1 significantly promoted ALP activity, mineralization, and the expression of osteogenic markers in MC3T3-E1 cells. ABW90-1 showed strong binding with the WNT signaling complex and BMP2 based on number of interactions, hydrogen bond length, and binding energy in silico. ABW90-1 significantly increased the expression of active-β-catenin, p-GSK-3β, LEF-1, BMP2, and p-SMAD1. Importantly, the osteogenic effects of ABW90-1 were partially suppressed by DKK-1 and Noggin, which are specific inhibitors of the WNT and BMP signaling pathways, respectively. Collectively, these findings suggest that ABW90-1 has osteogenic effects through crosstalk between WNT/β-catenin and BMP2/SMAD1 signaling pathways.

Osteogenesis imperfecta in children

Osteogenesis imperfecta (OI) is a disease characterised by altered bone tissue material properties together with abnormal micro and macro-architecture and thus bone fragility, increased bone turnover and hyperosteocytosis. Increasingly appreciated are the soft tissue changes, sarcopenia in particular. Approaches to treatment are now multidisciplinary, with bisphosphonates having been the primary pharmacological intervention over the last 20 years. Whilst meta-analyses suggest that anti-fracture efficacy across the life course is equivocal, there is good evidence that for children bisphosphonates reduce fracture risk, increase vertebral size and improve vertebral shape, as well as improving motor function and mobility. The genetics of OI continues to provide insights into the molecular pathogenesis of the disease, although the pathophysiology is less clear. The complexity of the multi-scale interactions of bone tissue with cellular function are gradually being disentangled, but the fundamental question of why increased tissue brittleness should be associated with so many other changes is unclear; ER stress, pro-inflammatory cytokines, accelerated senesence and altered matrix component release might all contribute, but a unifying hypothesis remains elusive. New approaches to therapy are focussed on increasing bone mass, following the paradigm established by the treatment of postmenopausal osteoporosis. For adults, this brings the prospect of restoring previously lost bone - for children, particularly at the severe end of the spectrum, the possibility of further reducing fracture frequency and possibly altering growth and long term function are attractive. The alternatives that might affect tissue brittleness are autophagy enhancement (through the removal of abnormal type I collagen aggregates) and stem cell transplantation - both still at the preclinical stage of assessment. Preclinical assessment is not supportive of targeting inflammatory pathways, although understanding why TGFb signalling is increased, and whether that presents a treatment target in OI, remains to be established.

Effects of Bisphosphonate Therapy on Bone Mineral Density in Boys with Duchenne Muscular Dystrophy

The objective of this study was to estimate the comparative effectiveness of bisphosphonate therapy on bone mineral density (BMD) in patients with corticosteroid-treated Duchenne muscular dystrophy (DMD). A retrospective, comparative effectiveness study evaluating changes in BMD and fragility fractures in patients with DMD presenting to British Columbia Children's Hospital from 1989 to 2017 was conducted. Marginal structural generalized estimating equation models weighted by stabilized inverse-probability of treatment weights were used to estimate the comparative effectiveness of therapy on BMD. Of those treated with bisphosphonates (N = 38), 7 (18.4%), 17 (44.7%), and 14 (36.8%) cases were treated with pamidronate, zoledronic acid, or a combination of both, respectively, while 36 cases of DMD were untreated. Mean age of bisphosphonate initiation was 9.2 (SD 2.7) years. Mean fragility fractures declined from 3.5 to 1.0 following bisphosphonate therapy. Compared to the treated group, the untreated group had an additional 0.63-SD decrease (95% confidence interval [CI]: -1.18, -0.08, P = .026) in total BMD and an additional 1.04-SD decrease (95% CI: -1.74, -0.34; P = .004) in the left hip BMD, but the change in lumbar spine BMD (0.15, 95% CI: -0.36, 0.66; P = .57) was not significant. Bisphosphonate therapy may slow the decline in BMD in boys with corticosteroid-treated DMD compared to untreated counterparts. Total number of fragility fractures decreased following bisphosphonate therapy.

Pamidronate: A model compound of the pharmacology of nitrogen-containing bisphosphonates; A Leiden historical perspective

Pamidronate [3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD)] was the first nitrogen-containing bisphosphonate (N-BP) investigated in clinical studies. In contrast to other clinically used bisphosphonates, pamidronate was discovered and its properties were initially studied in an Academic Institution. On the occasion of the 50th Anniversary of the first publications on the biological effects of bisphosphonates, I review in this article the contribution of Leiden investigators to the development of pamidronate that led to the recognition of the significance of the Nitrogen atom in the side chain of bisphosphonates for their action on bone resorption and to the formulation of principles for the use of N-BPs in the management of patients with different skeletal disorders.

The Nrf2 activator RTA-408 attenuates osteoclastogenesis by inhibiting STING dependent NF-κb signaling

The dysregulation of ROS production and osteoclastogenesis is involved in the progress of osteoporosis. To identify novel and effective targets to treat this disease, it is important to explore the underlying mechanisms. In our study, we firstly tested the effect of the Nrf2 activator RTA-408, a novel synthetic triterpenoid under clinical investigation for many diseases, on osteoclastogenesis. We found that it could inhibit osteoclast differentiation and bone resorption in a time- and dose-dependent manner. Further, RTA-408 enhanced the expression and activity of Nrf2 and significantly suppressed RANKL-induced reactive oxygen species (ROS) production. Nrf2 regulates the STING expression and STING induces the production of IFN-β. Here, we found that RTA-408 could suppress STING expression, but that it does not affect Ifnb1 expression. RANKL-induced degradation of IκBα and the nuclear translocation of P65 was suppressed by RTA-408. Although this compound was not found to influence STING-IFN-β signaling, it suppressed the RANKL-induced K63-ubiquitination of STING via inhibiting the interaction between STING and the E3 ubiquitin ligase TRAF6. Further, adenovirus-mediated STING overexpression rescued the suppressive effect of RTA-408 on NF-κB signaling and osteoclastogenesis. In vivo experiments showed that this compound could effectively attenuate ovariectomy (OVX)-induced bone loss in C57BL/6 mice by inhibiting osteoclastogenesis. Collectively, we show that RTA-408 inhibits NF-κB signaling by suppressing the recruitment of TRAF6 to STING, in addition to attenuating osteoclastogenesis and OVX-induced bone loss in vivo, suggesting that it could be a promising candidate for treating osteoporosis in the future.

Bisphosphonate Combination Therapy in the Management of Postchemotherapy Avascular Necrosis of the Femoral Head in Adolescents and Young Adults: A Retrospective Study From India

Purpose

With improved survival after chemotherapy for acute lymphoblastic leukemia (ALL), it is imperative to maintain good quality of life as part of the management of post-therapy adverse effects. Avascular necrosis of the femoral head (AVNFH) is one such adverse effect. A need exists for a therapy that ameliorates discomfort, provides a productive life, is cost effective, and is joint preservative. We conducted the current study to evaluate the response to bisphosphonate in the nonsurgical management of AVNFH in adolescents and young adults (AYA) who receive treatment for ALL.

Materials and Methods

This is a retrospective study of 20 AYA patients—34 affected hips—who received zolendronic acid 5 mg intravenously each year along with oral alendronate 70 mg weekly for 3 years. Clinical evaluation was performed by using the Visual Analog Scale and the Harris Hip Score. Radiographs were used to classify the Ficat-Arlet stage, monitor radiologic collapse, and evaluate the rate of progression.

Results

Pain relief with a drop in the Visual Analog Scale score was observed at a mean duration of 5.2 weeks (range, 3 weeks to 11 weeks) after the start of therapy. Radiologic progression by one grade was observed in 12 hips (35.3%), and only one hip (2.94%) showed progression by two grades. At a mean follow-up of 50.3 months, 31 affected hips (91.1%) had a satisfactory clinical outcome and had not required any surgical intervention. The proportion of hips that required total hip arthroplasty were 0%, 5%, and 22.2% in Ficat-Arlet stage I, II, and III, respectively.

Conclusion

The combination of intravenous zolendronic acid and oral alendronate provides a pragmatic solution for the management of AVNFH after therapy for ALL in AYA patients. This therapy is safe, effective, and well tolerated.

Vertebral Fractures in Duchenne Muscular Dystrophy Patients Managed With Deflazacort

BACKGROUND

Corticosteroids are widely used in the management of patients with Duchenne muscular dystrophy (DMD). They improve quality of life in these patients by prolonging ambulation and preserving cardiorespiratory status. However, corticosteroid treatment is associated with a decrease in bone mineral density (BMD) and an increased risk of vertebral fractures (VF). The purpose of this study was to investigate the prevalence of VF in patients with DMD undergoing long-term treatment with the corticosteroid deflazacort.

METHODS

We retrospectively reviewed 49 male patients with DMD on long-term deflazacort therapy at a single institution. All patients had received deflazacort for at least 2 years. VF prevalence, age at start of deflazacort treatment, duration of treatment, BMD Z-score and patient ambulatory status at the time of fracture were evaluated.

RESULTS

Of the 49 patients on long-term deflazacort treatment, 26 had VF. Out of these patients who had VF, 19% showed evidence of VF in their third year of therapy, 50% within 5 years of starting therapy, 69% within 7 years of starting therapy, and 100% within 9 years. The first evidence of VF was observed at mean BMD Z-score, lumbar (L)=-2.2 and whole body (B)=-3.1. Eighty-five percent of these patients had at least 3 collapsed vertebrae. Mean BMD Z-score at the time of or before when multiple fractures were noted was -2.4 (L) and -3.4 (B). Patients who started deflazacort at age 3 to 5, 5 to 7 or 7 to 9 years developed a VF after a mean of 4.7, 5.4, or 5.7 years, respectively. Sixty-two percent of patients had VF by the age of 12 years and 91% of patients by age of 15 years. Twenty-one of 26 patients were ambulatory at the time of VF.

CONCLUSIONS

Our findings suggest that there is a high risk of VF associated with length of deflazacort use in DMD patients, regardless of age at start of therapy.

LEVEL OF EVIDENCE

Level III-retrospective therapeutic study.

Bone protective agents in children

Evaluation of bone health in childhood is important to identify children who have inadequate bone mineralisation and who may benefit from interventions to decrease their risk of osteoporosis and subsequent fracture. There are no bone protective agents that are licensed specifically for the prevention and treatment of osteoporosis in children. In this review, we discuss the mechanism of action and use of bisphosphonates and other new and established bone protective agents in children.

Clinical guidelines for the prevention and treatment of osteoporosis: summary statements and recommendations from the Italian Society for Orthopaedics and Traumatology

BACKGROUND

The Italian Society for Orthopaedics and Traumatology conceived this guidance-which is primarily addressed to Italian orthopedic surgeons, but should also prove useful to other bone specialists and to general practitioners-in order to improve the diagnosis, prevention, and treatment of osteoporosis and its consequences.

MATERIALS AND METHODS

Literature reviews by a multidisciplinary team.

RESULTS

The following topics are covered: the role of instrumental, metabolic, and genetic evaluations in the diagnosis of osteoporosis; appraisal of the risk of fracture and thresholds for intervention; general strategies for the prevention and treatment of osteoporosis (primary and secondary prevention); the pharmacologic treatment of osteoporosis; the setting and implementation of fracture liaison services for tertiary prevention. Grade A, B, and C recommendations are provided based on the main levels of evidence (1-3). Toolboxes for everyday clinical practice are provided.

CONCLUSIONS

The first up-to-date Italian guidelines for the primary, secondary, and tertiary prevention of osteoporosis and osteoporotic fractures are presented.

Outcome of Long-Term Bisphosphonate Therapy in McCune-Albright Syndrome and Polyostotic Fibrous Dysplasia

McCune-Albright syndrome (MAS) is a rare bone disorder characterized by fibrous dysplasia (FD), endocrinopathies, and café-au-lait patches. FD patients have been shown to respond favorably to treatment with bisphosphonates, but data are scarce in the more severe polyostotic form (PFD), including MAS, and factors determining treatment outcome are not known, particularly in the long-term. We evaluated the biochemical (bone turnover markers [BTMs]) and clinical (pain reduction) outcome of bisphosphonate therapy in 11 patients with MAS and 30 patients with PFD: median duration of treatment 6 years (range, 2 to 25 years). Prognostic factors for treatment outcome were identified in both groups. Patients with MAS were younger at diagnosis (p = 0.001), all had precocious puberty, and four (36%) had additional growth hormone (GH) excess associated with severe craniofacial FD. Extent of skeletal disease was more severe in MAS compared to PFD. MAS patients had higher serum alkaline phosphatase (ALP) concentrations (p = 0.005), higher skeletal burden scores (p < 0.001), and more fractures (p = 0.021). MAS patients had also higher levels of FGF-23 (p = 0.008) and higher prevalence of hypophosphatemia (p = 0.013). Twenty-four of 30 PFD patients (80%) demonstrated a complete clinical and biochemical response within a year of starting treatment (p = 0.015), compared to only four of 11 MAS patients (36%). There were no nonresponders. In the whole group, FGF-23, total ALP, P1NP, and CTX positively correlated with skeletal burden scores (all p ≤ 0.001), which was the only significant risk factor for an incomplete response to bisphosphonate therapy (p < 0.01). Our data suggest a beneficial and safe outcome of long-term bisphosphonate therapy in the majority of patients with PFD, although response to therapy was limited by the higher skeletal disease burden in MAS patients. In the PFD/MAS population studied, the only identified prognostic factor that influenced the outcome of bisphosphonate therapy was a high skeletal burden score. © 2016 American Society for Bone and Mineral Research.

Interventions to prevent and treat corticosteroid-induced osteoporosis and prevent osteoporotic fractures in Duchenne muscular dystrophy

BACKGROUND

Corticosteroid treatment is considered the 'gold standard' for Duchenne muscular dystrophy (DMD); however, it is also known to induce osteoporosis and thus increase the risk of vertebral fragility fractures. Good practice in the care of those with DMD requires prevention of these adverse effects. Treatments to increase bone mineral density include bisphosphonates and vitamin D and calcium supplements, and in adolescents with pubertal delay, testosterone. Bone health management is an important part of lifelong care for patients with DMD.

OBJECTIVES

To assess the effects of interventions to prevent or treat osteoporosis in children and adults with DMD taking long-term corticosteroids; to assess the effects of these interventions on the frequency of vertebral fragility fractures and long-bone fractures, and on quality of life; and to assess adverse events.

SEARCH METHODS

On 12 September 2016, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL Plus to identify potentially eligible trials. We also searched the Web of Science ISI Proceedings (2001 to September 2016) and three clinical trials registries to identify unpublished studies and ongoing trials. We contacted correspondence authors of the included studies in the review to obtain information on unpublished studies or work in progress.

SELECTION CRITERIA

We considered for inclusion in the review randomised controlled trials (RCTs) and quasi-RCTs involving any bone health intervention for corticosteroid-induced osteoporosis and fragility fractures in children, adolescents, and adults with a confirmed diagnosis of DMD. The interventions might have included oral and intravenous bisphosphonates, vitamin D supplements, calcium supplements, dietary calcium, testosterone, and weight-bearing activity.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed reports and selected potential studies for inclusion, following standard Cochrane methodology. We contacted study authors to obtain further information for clarification on published work, unpublished studies, and work in progress.

MAIN RESULTS

We identified 18 potential studies, of which two, currently reported only as abstracts, met the inclusion criteria for this review. Too little information was available for us to present full results or adequately assess risk of bias. The participants were children aged five to 15 years with DMD, ambulant and non-ambulant. The interventions were risedronate versus no treatment in one trial (13 participants) and whole-body vibration versus a placebo device in the second (21 participants). Both studies reported improved bone mineral density with the active treatments, with no improvement in the control groups, but the abstracts did not compare treatment and control conditions. All children tolerated whole-body vibration treatment. No study provided information on adverse events. Two studies are ongoing: one investigating whole-body vibration, the other investigating zoledronic acid.

AUTHORS' CONCLUSIONS

We know of no high-quality evidence from RCTs to guide use of treatments to prevent or treat corticosteroid-induced osteoporosis and reduce the risk of fragility fractures in children and adults with DMD; only limited results from two trials reported in abstracts were available. We await formal trial reports. Findings from two ongoing relevant studies and two trials, for which only abstracts are available, will be important in future updates of this review.

A survey of steroid-related osteoporosis diagnosis, prevention and treatment practices of pediatric rheumatologists in North America

BACKGROUND

The purpose of our study is to assess practices of North American pediatric rheumatologists regarding monitoring, prevention, and treatment of low bone mineral density (BMD) in children on long-term glucocorticoid treatment. Long-term glucocorticoid therapy is associated with accelerated bone loss. Children with JIA and lupus have low baseline BMD and incident vertebral fractures commonly occur in these groups of patients even after a relatively short period of time being on systemic glucocorticoids. There are no established guidelines for identification, prevention, and treatment of glucocorticoid-induced bone loss in children.

METHODS

A cross-sectional online survey was conducted with 199 physicians who were listed in the ACR database as practicing pediatric rheumatology in North America.

RESULTS

86 physicians (43%) responded; 87% were board-certified in pediatric rheumatology. 95% used dual energy X-ray absorptiometry as their primary modality for assessing BMD. 79% "rarely" or "never" obtained a baseline BMD measurement prior to initiation of glucocorticoid therapy. 42% of respondents followed BMD annually. 93% "frequently" or "always" prescribed calcium for patients on long-term corticosteroid therapy; 81% "frequently" or "always" prescribed vitamin D. In patients diagnosed with osteoporosis, 35%-50 % of the practitioners "sometimes", "frequently" or "always" prescribed bisphosphonates. Bisphosphonates are prescribed at similar rates for male and female patients, and slightly more frequently for pubertal than for pre-pubertal patients. 96% of respondents "rarely" or "never" prescribed calcitonin for patients on long-term glucocorticoid therapy; 92% "rarely" or "never" prescribe this medication for patients with known osteopenia or osteoporosis.

CONCLUSIONS

Utilization of DXA in children on long-term corticosteroid therapy varies greatly among North American pediatric rheumatologists. Most respondents do not screen for low BMD on a regular basis despite acknowledging the risks of bone loss in this population. Broad consensus appears to be present among practitioners favoring the prescription of calcium and vitamin D for patients receiving long-term corticosteroid therapy. Relatively few respondents consistently recommend bisphosphonate therapy, even for patients with known low bone density; calcitonin is rarely used. These data underscore the need for studies to acquire specific data on bone loss, and its prevention and treatment in young patients on long-term glucocorticoid therapy.

Bisphosphonates and connexin 43: a critical review of evidence

Bisphosphonates (BPs) are drugs commonly used in the treatment of various disease arising or affecting bone tissue. There is a standard use in bone neoplasia and metastasis, hormonal and developmental disorders as well as for compensation of adverse effects in several medical therapies. Many in-vivo and in-vitro studies have assessed the efficacy of this drug and its function in cellular scale. In this concern, BPs are described to inhibit the resorptive function of osteoclasts and to prevent apoptosis of osteoblasts and osteocytes. They can preserve the osteocytic network, reduce fracture rate, and increase the bone mineral content, which is therapeutically used. Connexin 43 (Cx43) is a crucial molecule for basal regulation of bone homeostasis, development, and differentiation. It is described for signal transduction in many physiological and pathological stimuli and recently to be involved in BP action.

Effect of bisphosphonates on the rapidly growing male murine skeleton

Bisphosphonates are effective for preventing and treating skeletal disorders associated with hyperresorption. Their safety and efficacy has been studied in adults where the growth plate is fused and there is no longitudinal bone growth and little appositional growth. Although bisphosphonate use in the pediatric population was pioneered for compassionate use in the treatment of osteogenesis imperfecta, they are being increasingly used for the treatment and prevention of bone loss in children at risk of hyperresorptive bone loss. However, the effect of these agents on the growing skeleton in disorders other than osteogenesis imperfecta has not been systematically compared. Studies were, therefore, undertaken to examine the consequences of bisphosphonate administration on the growth plate and skeletal microarchitecture during a period of rapid growth. C57Bl6/J male mice were treated from 18 to 38 days of age with vehicle, alendronate, pamidronate, zoledronate, or clodronate at doses selected to replicate those used in humans. Treatment with alendronate, pamidronate, and zoledronate, but not clodronate, led to a decrease in the number of chondrocytes per column in the hypertrophic chondrocyte layer. This was not associated with altered hypertrophic chondrocyte apoptosis or vascular invasion at the growth plate. The effects of pamidronate on trabecular microarchitecture were less beneficial than those of alendronate and zoledronate. Pamidronate did not increase cortical thickness or cortical area/total area relative to control mice. These studies suggest that bisphosphonate administration does not adversely affect skeletal growth. Long-term investigations are required to determine whether the differences observed among the agents examined impact biomechanical integrity of the growing skeleton.

RANK-Ligand inhibitor associated osteonecrosis of the jaw

Osteonecrosis of the jaw may be caused by many different triggers. One of them is described to be the drug or medication related osteonecrosis of the jaw. Since many years bisphosphonates induced the dreaded diagnosis. Recently a drug named denosumab is reported to show similar effects on the jaw. In this case report we present a RANK-Ligand inhibitor associated osteonecrosis of the lower jaw and discuss the lights and shadows of this newly introduced drug.

What you need to know about bisphosphonates: an overview and general recommendations for orthodontic treatment

The orthodontic treatment of patients on bisphosphonates is becoming an increasing aspect of contemporary practice. This article will draw attention to the chemical structure and effects of these drugs on bone and will provide the latest recommendations to avoid potential sequelae.

Idiopathic juvenile osteoporosis: a cross-sectional single-centre experience with bone histomorphometry and quantitative computed tomography

BACKGROUND

Idiopathic juvenile osteoporosis (IJO) is a rare condition of poorly understood etiology and pathophysiology that affects otherwise healthy children. This condition is characterized clinically by bone pain and vertebral fractures; spontaneous recovery is observed after puberty in the majority of cases. Although decreased trabecular bone turnover has been noted previously, cortical and trabecular bone characteristics as determined by quantitative computed tomography (QCT) and their relationship to bone histomorphometry are unknown.

METHODS

All children with a clinical diagnosis of IJO who were followed in our center since 1995 and who had undergone at least one diagnostic bone biopsy were included in this cross-sectional analysis.

RESULTS

Fifteen patients (11 males/4 females) with median ages of 5.8 and 10.2 years at first symptoms and at referral, respectively, were included in the analysis. Histomorphometric analysis demonstrated decreased trabecular bone turnover (BFR/BS) in the majority of patients with heterogeneous parameters of trabecular mineralization and volume. QCTresults demonstrated that bone mineral density (BMD) was reduced in both trabecular/lumbar and cortical/femoral bone: Z score: -2.1 (-3.6;-1.0) and -0.9 (-8.2;1.4)in the two compartments, respectively. In the eight patients who underwent both bone biopsy and QCT, cortical BMD was associated with trabecular separation and with trabecular bone formation rate (r = 0.898 and -0.881, respectively, both p < 0.05).

CONCLUSIONS

This series confirms that IJO is characterized by impaired trabecular architecture that can be detected by both bone biopsy and QCT. The association between bone biopsy and QCT results may have implications for diagnosis, treatment, and follow-up of these children.

The use of intravenous bisphosphonate therapy to treat vertebral fractures due to osteoporosis among boys with Duchenne muscular dystrophy

The impact of intravenous bisphosphonate treatment to treat painful vertebral fractures in boys with DMD has not been documented. In this retrospective observational study of seven boys, 2 years of intravenous bisphosphonate therapy was associated with back pain improvement and stabilization or increases in the height ratios of fractured vertebrae.

INTRODUCTION

Boys with Duchenne muscular dystrophy (DMD) are at risk for vertebral fractures. We studied the impact of intravenous bisphosphonate therapy for the treatment of painful vertebral fractures in DMD.

METHODS

This was a retrospective observational study in seven boys with DMD (median 11.6 years, range 8.5 to 14.3) treated with intravenous pamidronate (9 mg/kg/year) or zoledronic acid (0.1 mg/kg/year) for painful vertebral fractures.

RESULTS

At baseline, 27 vertebral fractures were evident in the seven boys. After 2 years of bisphosphonate therapy, 17 of the fractures had an increase in the most severely affected vertebral height ratio, 10 vertebrae stabilized, and none showed a decrease in height ratio. Back pain resolved completely (N = 3) or improved (N = 4). The median change in lumbar spine volumetric bone mineral density Z-score was 0.5 standard deviations (interquartile range, -0.3 to 1.7). Two boys had three incident vertebral fractures in previously normal vertebral bodies that developed over the observation period. There was a decline in the trabecular bone formation rate on trans-iliac bone biopsy but no evidence of osteomalacia. First-dose side effects included fever and malaise (N = 4), hypocalcemia (N = 2), and vomiting (N = 1); there were no side effects with subsequent infusions.

CONCLUSIONS

Intravenous bisphosphonate therapy was associated with improvements in back pain and stabilization to improvement in vertebral height ratios of previously fractured vertebral bodies. At the same time, such therapy does not appear to completely prevent the development of new vertebral fractures in this context.

A phase I study of zoledronic acid and low-dose cyclophosphamide in recurrent/refractory neuroblastoma: a new approaches to neuroblastoma therapy (NANT) study

BACKGROUND

Zoledronic acid, a bisphosphonate, delays progression of bone metastases in adult malignancies. Bone is a common metastatic site of advanced neuroblastoma. We previously reported efficacy of zoledronic acid in a murine model of neuroblastoma bone invasion prompting this Phase I trial of zoledronic acid with cyclophosphamide in children with neuroblastoma and bone metastases. The primary objective was to determine recommended dosing of zoledronic acid for future trials.

PROCEDURE

Escalating doses of intravenous zoledronic acid were given every 28 days with oral metronomic cyclophosphamide (25 mg/m(2)/day). Toxicity, response, zoledronic acid pharmacokinetics, bone turnover markers, serum IL-6, and sIL-6R were evaluated.

RESULTS

Twenty-one patients, median age 7.5 (range 0.8-25.6) years were treated with 2 mg/m(2) (n = 4), 3 mg/m(2) (n = 3), or 4 mg/m(2) (n = 14) zoledronic acid. Fourteen patients were evaluable for dose escalation. A median of one (range 1-18) courses was given. Two dose limiting toxicities (grade 3 hypophosphatemia) occurred at 4 mg/m(2) zoledronic acid. Other grades 3-4 toxicities included hypocalcemia (n = 2), elevated transaminases (n = 1), neutropenia (n = 2), anemia (n = 1), lymphopenia (n = 1), and hypokalemia (n = 1). Osteosclerosis contributed to fractures in one patient after 18 courses. Responses in evaluable patients included 1 partial response, 9 stable disease (median 4.5 courses, range 3-18), and 10 progressions. Zoledronic acid pharmacokinetics were similar to adults. Markers of osteoclast activity and serum IL-6 levels decreased with therapy.

CONCLUSIONS

Zoledronic acid with metronomic cyclophosphamide is well tolerated with clinical and biologic responses in recurrent/refractory neuroblastoma. The recommended dose of zoledronic acid is 4 mg/m(2) every 28 days.

Approach to the child with fractures

Evaluation of the child with fractures is challenging, as no clear guidelines exist to distinguish traumatic from pathological fractures. Although most fractures in childhood are benign, recurrent fractures may be associated with a wide variety of primary skeletal diseases as well as secondary causes, necessitating a careful history and physical exam to guide the evaluation. There is no "gold standard" for the evaluation and treatment of children with fractures and low bone mineral density (BMD); therefore, the diagnosis of osteoporosis in a pediatric patient should be made using a combination of clinical and radiographic features. Interpretation of bone densitometry in growing patients presents a unique set of challenges because areal BMD measured by dual-energy x-ray absorptiometry depends on multiple dynamic variables. Interpretation of pediatric dual-energy x-ray absorptiometry should be based on Z-scores (sd scores compared to age, sex, and ethnicity-matched controls), using normative databases specific to the brand of densitometer and the patient population. Given the skeleton's ability to recover from low BMD through modeling and remodeling, optimizing management of underlying conditions leading to bone fragility is the initial step. Conservative measures including calcium and vitamin D supplementation and weight-bearing physical activity are important interventions that should not be overlooked. The use of bisphosphonates in children and adolescents is controversial due to lack of long-term efficacy and safety data and should be limited to clinical trials and compassionate therapy in children with significantly compromised quality of life. Close monitoring is required, and further study is necessary to assess their long-term safety and efficacy in children.

A bisphosphonate that does not affect osteoclasts prevents osteoblast and osteocyte apoptosis and the loss of bone strength induced by glucocorticoids in mice

Although a major effect of bisphosphonates on bone is inhibition of resorption resulting from their ability to interfere with osteoclast function, these agents also prevent osteoblast and osteocyte apoptosis in vitro and in vivo. However, the contribution of the latter property to the overall beneficial effects of the drugs on bone remains unknown. We compared herein the action on glucocorticoid-induced bone disease of the classical bisphosphonate alendronate with that of IG9402, a bisphosphonate analog that preserves osteoblast and osteocyte viability but does not induce osteoclast apoptosis in vitro. The bisphosphonates were injected daily (2.3 μmol/kg) to 5-month-old Swiss Webster mice (6-11 per group), starting 3 days before implantation of pellets releasing the glucocorticoid prednisolone (2.1 mg/kg/day). IG9402 did not affect levels of circulating C-telopeptide or osteocalcin, markers of resorption and formation, respectively, nor did it decrease mRNA levels of osteocalcin or collagen 1a1 in bone. On the other hand, alendronate decreased all these parameters. Moreover, IG9402 did not reduce cancellous mineralizing surface, mineral apposition rate, or bone formation rate, whereas alendronate induced a decrease in each of these bone formation measures. These findings demonstrate that, in contrast to alendronate, IG9402 does not inhibit bone turnover. Both alendronate and IG9402, on the other hand, activated survival kinase signaling in vivo, as evidenced by induction of ERK phosphorylation in bone. Furthermore, both bisphosphonates prevented the increase in osteoblast and osteocyte apoptosis as well as the decrease in vertebral bone mass and strength induced by glucocorticoids. We conclude that a bisphosphonate that does not affect osteoclasts prevents osteoblast and osteocyte apoptosis and the loss of bone strength induced by glucocorticoids in mice.

The use of zoledronic acid in pediatric cancer patients

BACKGROUND

The third generation bisphosphonate zoledronic acid has demonstrated efficacy in reducing skeletal-related events in adult patients with multiple cancer types that have skeletal disease. The use of zoledronic acid in pediatric oncology patients with bone metastases for the purpose of reducing pain, improving bone strength and altering the progression of metastatic disease has not been thoroughly evaluated.

PROCEDURE

From October 2005 to December 2008, 19 patients at the Aflac Cancer Center received one or more doses of zoledronic acid as part of their therapy. A retrospective review of these patients was performed and information was collected including indication for treatment, toxicities, and outcomes.

RESULTS

Most patients (n = 15) received zoledronic acid following relapse of their malignancy with metastatic disease present in one or more bony sites. Hypocalcemia and hypophosphatemia were frequent, but did not result in clinical symptoms. More significant toxicities associated with zoledronic acid, including clinically apparent renal insufficiency and osteonecrosis of the jaw, were not seen. Overall, zoledronic acid was well tolerated in this population.

CONCLUSIONS

The benefits of zoledronic acid seen in randomized trials of adults with bone metastases have sparked interest in its use for children with metastatic cancer. The administration of zoledronic acid in pediatric oncology appears safe, and may result in improved bone strength and pain control. Further evaluation is warranted to prospectively evaluate its efficacy and long-term safety in pediatric patients with cancer and skeletal metastases.

Vascular endothelial growth factor genetic polymorphisms and haplotypes in female patients with bisphosphonate-related osteonecrosis of the jaws

OBJECTIVE

To investigate the polymorphisms of the vascular endothelial growth factor (VEGF) gene in relation to female patients who developed bisphosphonate-related osteonecrosis of the jaws (BRONJ).

METHODS

Test subjects were 30 Italian female patients with BRONJ (Group A). Control subjects were 30 female patients with a history of intravenous bisphosphonate use without any evidence of osteonecrosis (Group B) and 125 unrelated healthy volunteers (Group C). Three single-nucleotide polymorphisms were investigated: -634 G>C, occurring in 5' untranslated region (UTR); +936 C>T, occurring in 3' UTR; and -2578 C>A of the promoter region.

RESULTS

The frequency of the VEGF CAC (+936/-2578/-634) haplotype was increased in patients with BRONJ, compared with female disease-negative controls [odds ratio (OR) = 2.76, 95% CI = 1.09-4.94, P = 0.039; corrected P value: P(c) = 0.117], and was also increased compared with female healthy controls (OR = 2.11, 95% CI = 1.14-3.89, P = 0.024; corrected P value: P(c) = 0.072). The CC homozygotes of -634G>C of VEGF gene and AA homozygotes of -2578C>A have also been significantly correlated in female patients who developed BRONJ compared with healthy controls (OR = 2.04, 95% CI = 1.12-3.70, P = 0.008; corrected P value: P(c) = 0.024).

CONCLUSIONS

These results suggest a possible haplotype effect of VEGF polymorphisms expression in BRONJ Italian female patients. Studies with different and larger populations possibly using TagSNP to represent all haplotypes within the VEGF gene are needed to further delineate the genetic contribution of this gene to BRONJ.

Current and emerging treatments for the management of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is the most common bone genetic disorder and it is characterized by bone brittleness and various degrees of growth disorder. Clinical severity varies widely; nowadays eight types are distinguished and two new forms have been recently described although not yet classified. The approach to such a variable and heterogeneous disease should be global and therefore multidisciplinary. For simplicity, the objectives of treatment can be reduced to three typical situations: the lethal perinatal form (type II), in which the problem is survival at birth; the severe and moderate forms (types III-IX), in which the objective is 'autonomy'; and the mild form (type I), in which the aim is to reach 'normal life'. Three types of treatment are available: non-surgical management (physical therapy, rehabilitation, bracing and splinting), surgical management (intramedullary rod positioning, spinal and basilar impression surgery) and medical-pharmacological management (drugs to increase the strength of bone and decrease the number of fractures as bisphosphonates or growth hormone, depending on the type of OI). Suggestions and guidelines for a therapeutic approach are indicated and updated with the most recent findings in OI diagnosis and treatment.

Osteoporosis in anorexia nervosa

Anorexia nervosa is a condition associated with reduced bone mass and increased bone fragility, for which there is no known effective treatment. Anorexia nervosa usually has its onset during adolescence, the critical time when peak bone mass is accrued. Low bone mass is caused by reduced bone formation, as well as accelerated bone resorption. The etiology is multifactorial and includes poor nutrition, low bodyweight, sex hormone deficiency and hypercortisolism. Weight gain and resumption of menses is accompanied by some improvement in bone mass, but may not restore it to normal levels. Oral estrogen-replacement therapy is not effective in increasing bone mass in this disorder. The bisphosphonates, used in conjunction with nutritional rehabilitation and weight gain, have shown promise, but concerns about safety have limited their use. The aim of this article is to highlight recent recommendations regarding the assessment of fracture risk in children and adolescents, summarize the evidence for low bone mass and increased fracture risk in anorexia nervosa, and discuss approaches to the management of low bone mass in this disorder.

Bisphosphonates in patients with autoimmune rheumatic diseases: Can they be used in women of childbearing age?

Autoimmune rheumatic diseases (ARD) are prevalent in women during their childbearing age. For their treatment, high doses of corticosteroid (CS) for long-term periods are often required, increasing the risk of bone loss. According to recent guidelines, bisphosphonates (BP) should be used as first line treatment to prevent CS induced osteoporosis. However, due to their long-term release from bone and their ability to cross the placenta, it has been suggested to avoid BP in women during their fertile years. BP seem to decrease foetus bone length in pregnant animals, but not in humans, at least, when they are administered at therapeutic dosage. BP are embryo toxic in animals when used at high dosage. In a systematic literature review, we found 58 women treated with BP close before or during pregnancy, showing no related congenital malformations. However, the Unit of Clinical and Epidemiological Genetics in University of Padova collected ten cases of women treated with BP during pregnancy, reporting 20% of congenital malformations. Thus, we suggest to avoid BP during pregnancy and caution with their use in fertile women. When they have to be given before pregnancy, specific affinities of the BP have to be considered to plan the washout period beforehand.

Langerhans cell histiocytosis: Current concepts and treatments

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder of cells with the phenotype of activated Langerhans cells. The diagnosis of LCH is often delayed or missed. Many questions about LCH remain to be answered, including whether it is caused by a malignancy or by immune dysregulation. Data from the early 1990s showed that LCH consisted of an accumulation of monoclonal LCH cells, suggesting a neoplastic disorder. However, further investigations with current sophisticated techniques have not shown consistent genomic aberrations. Recent data which suggests a role for an IL-17A dependant pathway of dendritic cell fusion in LCH remains to be proven. The most recent data taken together swing the pendulum towards an immunologic aberration. The clinical course of LCH is highly variable, ranging from a self-healing solitary bone lesion to widely disseminated life-threatening disease. Patients with multisystem (MS) disease with organ dysfunction, particularly those refractory to front line therapy, and those with multiple reactivations of disease associated with significant permanent sequelae represent the greatest challenge. Early switch of refractory patients to salvage therapies has contributed to the improvement in survival of MS-LCH patients. Due to the rarity of LCH in children and adults, patients must be enrolled on multi-national clinical trials, whenever possible, to advance our knowledge of the optimal therapeutic strategies and long-term outcomes.

Cyclic pamidronate therapy in children with osteogenesis imperfecta

BACKGROUND

Severe osteogenesis imperfecta (OI) is a disorder characterized by osteopenia, frequent fractures, progressive deformity, loss of mobility, and chronic bone pain. There has been no effective therapy for the disorder until recently. The main objective of this study was to determine the efficacy and safety of pamidronate in improving bone mineralization and reducing fracture incidence in osteogenesis imperfecta.

METHODS

Intravenous pamidronate was administered to 64 children (from 21 months to 10 years old) with severe OI, in a 1 mg/kg single daily dose for 3 sequential days at 4-month intervals, over 24-48 months duration. Clinical status, biochemical characteristics including bone turnover markers, bone mineral density of the lumbar spine and femoral neck, and radiological changes were assessed regularly during treatment.

RESULTS

The number of fractures decreased from a median of 8 (range 4-11) to 0 fractures/year (range 0-4) (p <0.05). After 16 months of treatment, there was significant improvement in bone mineral density (BMD-DEXA) z-score of the lumbar spine from a median of -5.90 (range -7.01 to -4.76) to -2.70 (range -4.46 to -1.98) (p <0.001). Serum alkaline phosphatase (ALP) (bone formation marker) decreased from a median of 731.0 U/l (range 438-998 U/l) to 183 U/l (range 95-286 U/l) (p <0.001), implying a significant reduction in bone turnover and resorption and increase in bone mineralization. There was no improvement in growth velocity or height SDS. Mobility and ambulation improved in all but five children (all five had taken the drug for less than 2.5 years). There was a significant relief of chronic pain and fatigue but no adverse effects in all children using the drug.

CONCLUSION

Cyclic pamidronate administration is effective in improving bone mineralization and reducing fracture incidence in childhood osteogenesis imperfecta.

Comparative tolerability of treatments for juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) includes several forms of chronic arthritis in children. Treatments are chosen according to the type and severity of the disease. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids remain the mainstays of therapy. Traditional slower acting anti-rheumatic drugs, such as gold therapy, penicillamine, sulfasalazine, tiopronin and hydroxychloroquine, are usually poorly active in children. In addition, adverse effects are common, including severe macrophage activation syndrome with gold therapy or sulfasalazine. Low dose, once weekly methotrexate has emerged as the therapeutic agent of choice for children who fail to respond adequately to the administration of an NSAID, especially in those with the extended oligoarticular subtype of the disease. Other immunosuppressive agents, such as cyclosporin, are sometimes combined with methotrexate. In recent years, novel treatments have been developed. Autologous hematopoietic stem cell transplantation is effective in a number of children with severe JIA, whose disease has been refractory to conventional therapy. However, only short term follow-up data are currently available for this novel therapy. In addition, severe infections complicated by macrophage activation syndrome and death have been reported. Finally, anti-tumour necrosis factor-alpha therapy has shown efficacy in more than two-thirds of children with JIA and polyarthritis, and other cytokine inhibitors may be soon available.

Pregnancy outcome following in utero exposure to bisphosphonates

BACKGROUND AND AIM

The safety of bisphosphonates in human pregnancy has not been well established. To characterize pregnancy outcome in women receiving bisphosphonates, we conducted a multi-centre, prospective cohort study with a comparison group.

METHODS

Patients were recruited through 3 teratogen information centres in Canada and South Korea. We followed 21 women exposed to bisphosphonates during or <3 months before pregnancy, and 21 matched-comparison group women without exposure to known teratogens. Pregnancy/neonatal outcome data were collected by interview. The primary endpoint was neonatal outcome including major birth defects. The secondary endpoints included other pregnancy outcomes such as spontaneous abortions.

RESULTS

Indication of the therapy was osteoporosis in all patients. There was no difference in the maternal demographics between the 2 groups. In the bisphosphonate group, there were 18 live births, 2 spontaneous abortions and 1 therapeutic abortion, which were not significantly different from the comparison group. The mean gestational age (mean+/-SD) of the bisphosphonate group was 38.7+/-1.9 weeks (comparison group: 39.3+/-1.9 weeks; P=0.42), and the mean birth weight was 3.1+/-0.3 kg (comparison group: 3.3+/-0.5 kg; P=0.11). In the bisphosphonate group, there was a child diagnosed with Apert syndrome, an autosomal dominant acrocephalosyndactyly, with a fibroblast growth factor 2 mutation.

CONCLUSION

Coupled with existing data in the literature, our findings suggest that preconceptional and first-trimester use of bisphosphonates may not pose substantial fetal risks.

Effects of bisphosphonates in children with osteogenesis imperfecta: an AACPDM systematic review

This systematic review of the effects of bisphosphonate treatment in children with osteogenesis imperfecta was conducted using the American Academy for Cerebral Palsy and Developmental Medicine methodology for developing systematic reviews of treatment interventions (Revision 1.1) 2004. Despite a large body of published literature, there have been only eight studies with a sufficiently high level of internal validity to be truly informative. These studies confirm improvement in bone density. Many, but not all studies, demonstrate reduction in fracture rate and enhanced growth. There has been extremely limited evaluation of broader treatment impacts such as deformity, need for orthopedic surgery, pain, functioning, or quality of life. Short-term side effects were minimal. Which medication and dosing regimen is optimal and how long patients should be treated are unclear. This body of evidence would be strengthened by a larger controlled trial, because many studies lacked adequate power to evaluate stated outcomes. These studies do not address the impacts of bisphosphonates in children with milder forms of osteogenesis imperfecta and severe forms that are not due to mutations in the type I pro-collagen gene (e.g. types VII and VIII). Additional research is needed into treatment of infants. More studies evaluating medication choices, optimal dosing, duration of treatment, post-treatment impacts, and long-term side effects are necessary.

Bisphosphonate-induced osteopetrosis: novel bone modeling defects, metaphyseal osteopenia, and osteosclerosis fractures after drug exposure ceases

In 2003, we reported on a 12-yr-old boy who had developed osteopetrosis (OPT) while receiving pamidronate (PMD) for idiopathic bone pain and enigmatic elevation in circulating bone alkaline phosphatase. Now 17 yr of age, he was re-evaluated 6.5 yr after PMD exposure stopped. Our patient described less bone pain but further limb fractures. His growth plates were fused, yet hyperphosphatasemia persisted. Radiographs documented interval fractures of a metacarpal, an osteosclerotic distal radius, and a dense diaphyseal segment of an ulna where a "chalkstick" break remained incompletely healed after 2 yr. There was new L(4) spondylolysis, and previous L(5) spondylolysis had caused spondylolisthesis. Modeling disturbances of OPT persisted, but partial recovery was shown by metaphyseal surfaces with a unique concave shape. Metaphyseal osteosclerosis had remodeled imperfectly to become focal areas of dense, diaphyseal bone. Newer metaphyseal bone was unexpectedly osteopenic, especially in his distal femurs where cortices were thin and a paucity of trabeculae was documented by CT. Femoral necks had become short and wide with an abnormal contour. A "bone-within-bone" configuration was now present throughout his skeleton. In vertebrae, endplates were thin, and trabecular osteopenia was present central and peripheral to the bands of osteosclerosis. BMD Z-scores assessed by DXA had decreased into the normal range in his spine, hip, and whole body. Iliac crest biopsy showed active bone formation, with much less accumulated primary spongiosa than during the PMD infusions. Osteoclasts that had been dysmorphic, round cells without polarization and off of bone surfaces were now unremarkable in number, location, and appearance. In conclusion, bisphosphonate toxicity during childhood can impair skeletal modeling and remodeling with structural changes that evolve and carry into adult life.

Successful results of pamidronate treatment in children with osteogenesis imperfecta with emphasis on the interpretation of bone mineral density for local standards

AIM

To assess the long-term effect of pamidronate therapy on bone mineral metabolism and bone mineral density (BMD) in children with osteogenesis imperfecta (OI) and to evaluate BMD results with respect to national standards.

METHODS

Pamidronate was administered intravenously on 3 consecutive days every 3 to 4 months at a dose of 1 mg/kg/d in 35 patients. Infusion cycles ranged from 4 to 17. Serum calcium, phosphorus, bone turnover markers, L1-L4 areal BMD (aBMD), and fracture rate were evaluated. Areal BMD Z scores were compared with national sex-specific reference data and volumetric BMD Z scores.

RESULTS

In all children, linear growth continued along the same percentile during treatment. All parameters of bone turnover showed a decrease. L1 to L4 aBMD and Z score increased markedly, and fracture rate decreased in all patients during therapy. The mean annual percent gain in aBMD was highest in the first year and slowed down in subsequent years. Mean L1 to L4 aBMD Z scores according to Turkish reference data were higher than that of manufacturer values (P = 0.004). Correction of L1 to L4 vertebrae for bone size yielded to a decrease in osteoporosis in OI patients (41.5% vs 22.3%).

CONCLUSIONS

Bone mineral density increased and fracture rate decreased in children and infants with OI during pamidronate treatment. Prevalence of osteoporosis decreased after correction for national standard and volumetric BMD. Use of an appropriate reference database and method of data analysis are very important for correct evaluation of osteoporosis.

Treatment and management of osteoporosis-pseudoglioma syndrome

Osteoporosis-pseudoglioma syndrome (OPPG; MIM 259770) is a very rare genetic disorder with an autosomal recessive mode of inheritance, characterized by congenital or infancy-onset visual loss and skeletal fragility, diagnosed during childhood. This syndrome can lead to severe disability and chronic bone pain. Low-density lipoprotein receptor-related protein 5 (LRP5) is the gene mutated and inactivated in OPPG, and plays a pivotal role in bone accrual and skeletal remodeling by controlling bone formation through activators, such as Wnt proteins, or inhibitors, such as DKK1. OPPG should be differentiated from osteogenesis imperfecta and child abuse by clinicians. Eye examination, coupled to bone phenotype and research of LRP5 mutation, are key points to diagnose OPPG. Chronic pain should be managed correctly in this syndrome with severe functional disability. Bisphosphonates allows fracture prevention, the catch-up of bone mineral density and improvement in mobility in children with OPPG. New drugs favoring osteoblast function and osteoclast inhibition are potential candidates in the treatment of OPPG.

Effects of alendronate and pamidronate on cultured rat metatarsal bones: failure to prevent dexamethasone-induced growth retardation

Bisphosphonates are widely used anti-resorptive drugs in the adult population. In children, their use has mainly been limited to patients with osteogenesis imperfecta. However, the powerful effects of bisphosphonates on bone turnover have raised concern about their long-term effects on the growing skeleton. We aimed to study the effects of two commonly used bisphosphonates, alendronate (Aln) and pamidronate (Pam) on normal bone growth as well as their potential to prevent glucocorticoid-induced growth retardation. Effects on bone growth were studied in fetal rat metatarsal bones (day E20) that were cultured for 5-47 days and measured every 2-7 days. Cellular mechanisms were investigated in metatarsal bones and also in the human chondrocytic cell line HCS-2/8. Chondrocyte viability (WST-1), proliferation (BrdU incorporation), differentiation (collagen type X immunohistochemistry) and apoptosis (TUNEL and Cell Death ELISA) were determined. At a clinically relevant concentration of bisphosphonates (1 microM), metatarsal bone growth was stimulated by both Aln (p<0.001 for length and p<0.05 for width) and Pam (p<0.05 for both length and width) from day 19 of culture. The growth-stimulatory effect was associated with increased chondrocyte proliferation (+21% with Aln and +24% with Pam), while cell differentiation and apoptosis were not affected. Despite the finding that both Aln and Pam (1 muM) rescued HCS-2/8 cells from undergoing dexamethasone-induced apoptosis, neither of them was able to prevent dexamethasone-induced growth retardation of fetal rat metatarsal bones. Aln and Pam have the capacity to stimulate the growth of cultured fetal rat metatarsal bones; an effect associated with increased proliferation of growth plate chondrocytes. Our experimental data suggest that bisphosphonates are ineffective in preventing glucocorticoid-induced growth retardation. Nevertheless, based on our in vitro data, both Aln and Pam appear safe to use in growing children, at least with regard to their effects on linear bone growth.

Use of weekly alendronate to treat osteoporosis in boys with muscular dystrophy

Three boys with muscular dystrophy with known osteoporosis were each treated for 1 yr with weekly alendronate and daily calcium and vitamin D. Measurements of lumbar spine and proximal femur using dual-energy x-ray absorptiometry were obtained at the initiation of the alendronate, at 6 mos, and at 1 yr. All three boys demonstrated increases in bone mineral density, with z scores improving from baseline to 1-yr follow-up. Improvements were observed at the lumbar spine, femoral neck, and greater trochanter. In this small case series, weekly oral alendronate for 1 yr plus daily vitamin D and calcium was effective in improving bone mineral density.

Efficacy of intravenous alendronate for the treatment of glucocorticoid-induced osteoporosis in children with autoimmune diseases

Our objective was to investigate the efficacy of intravenous alendronate for the treatment of glucocorticoid-induced osteoporosis (GIOP) in children with autoimmune diseases. Five children with autoimmune disease and GIOP were treated with 5 mg intravenous alendronate once every 3 months. After 1 and 2 years, we evaluated the changes in the Z score of the femoral neck bone mineral density (BMD), serum bone alkaline phosphatase, and urinary deoxypyridinoline. Six patients with GIOP, whose BMD could be observed over a 1-year period without alendronate treatment, were defined as controls. After 1 and 2 years of treatment, intravenous treatment significantly inhibited bone loss. The efficacy of alendronate demonstrated a significant correlation with a high level of bone turnover markers before alendronate treatment. Intravenous alendronate is considered to be a good choice for the treatment of GIOP because of its excellent efficacy. In addition, our study suggests that the efficacy of alendronate depends on the bone turnover of patients before treatment. Intervention with bisphosphonates during periods of high bone turnover may be recommended.

The effects of RANKL inhibition on fracture healing and bone strength in a mouse model of osteogenesis imperfecta

Currently, the standard treatment for osteogenesis imperfecta (OI) is bisphosphonate therapy. Recent studies, however, have shown delayed healing of osteotomies in a subset of OI patients treated with such agents. The current study sought to determine the effects of another therapy, RANKL inhibition, on bone healing and bone strength in the growing oim/oim mouse, a model of moderate to severe OI. Mice [73 oim/oim and 69 wild-type (WT)] were injected twice weekly with either soluble murine RANK (RANK-Fc) (1.5 mg/kg) or saline beginning at 6 weeks of age. At 8 weeks of age, the animals underwent transverse mid-diaphyseal osteotomies of the right femur. Therapy was continued until sacrifice at 2, 3, 4, or 6 weeks postfracture. At 6 weeks post-fracture, greater callus area (6.59 +/- 3.78 mm(2) vs. 2.67 +/- 2.05 mm(2), p = 0.003) and increased radiographic intensity (mineral density) (0.48 +/- 0.14 vs. 0.30 +/- 0.80, p = 0.005) were found in the RANK-Fc versus saline oim/oim group, indicating a delay in callus remodeling. Despite this delay, mechanical tests at 6 weeks postfracture revealed no significant differences in whole bone properties of stiffness and failure moment. Further, RANKL inhibition resulted in a greater failure moment and greater work to failure for the nonfractured contralateral WT bones compared to the nonfractured saline WT bones. Together, these results demonstrate that RANKL inhibition does not adversely affect the mechanical properties of healing bone in the oim/oim mice, and is associated with increased strength in intact bone in the WT mice.

Pamidronate treatment of hypercalcemia caused by vitamin D toxicity

We present a 16 month-old previously healthy boy with refractory hypercalcemia due to an overdose of an over-the-counter vitamin supplement. The patient presented to the emergency department with a few weeks' history of irritability, constipation and intermittent vomiting. His serum calcium was found to be 18 mg/dl. He was first treated with intravenous fluids, furosemide and glucocorticoids without significant improvement, but became eucalcemic within 24 hours after receiving a single dose of pamidronate. This case highlights the potential danger of high dose vitamin supplements in children, and the salutary effects of treatment with bisphosphonate.