Cyclic administration of pamidronate in children with severe osteogenesis imperfecta

Osteoporosis in premenopausal women

The development of osteoporosis and fractures in young premenopausal women is infrequent and is usually associated with secondary causes of osteoporosis. Therefore, it is recommendable to perform a clinical evaluation and a thorough laboratory study searching for possible causes of bone loss in these patients. Treatment depends on the cause of osteoporosis and the associated processes as well as the future gestational desire of the patient, all of which should be taken into account when evaluating the most adequate diagnostic and the therapeutic approach in these patients.

Osteogenesis imperfecta: shifting paradigms in pathophysiology and care in children

The formation of functional bone requires a delicate interplay between osteogenesis and osteolysis. Disturbances in this subtle balance result in an increased risk for fractures. Besides its mechanical function, bone tissue represents a key player in the regulation of calcium homeostasis. Impaired bone formation results in bone fragility, which is especially pronounced in osteogenesis imperfecta (OI). This rare genetic disorder is characterized by frequent fractures as well as extraskeletal manifestations. The current classification of OI includes 23 distinct types. In recent years, several new mutations in different genes have been identified, although the exact pathomechanisms leading to the clinical presentation of OI often remain unclear. While bisphosphonates are still the standard of care, novel therapeutic approaches are emerging. Especially, targeted antibody therapies, originally developed for osteoporosis, are increasingly being investigated in children with OI and represent a promising approach to alleviate the consequences of impaired osteogenesis and improve quality of life in OI patients. This review aims to provide insight into the pathophysiology of OI and the consequences of distinct disease-causing mutations affecting the regulation of bone homeostasis. In this context, we describe the four most recently identified OI-causing genes and provide an update on current approaches for diagnosis and treatment.

Approach to the Pediatric Patient With Glucocorticoid-Induced Osteoporosis

Glucocorticoid (GC) therapy remains the cornerstone of treatment for many conditions of childhood and an important cause of skeletal and endocrine morbidity. Here, we discuss cases that bring to life the most important concepts in the management of pediatric GC-induced osteoporosis (pGIO). Given the wide variety of underlying conditions linked to pGIO, we focus on the fundamental clinical-biological principles that provide a blueprint for management in any clinical context. In so doing, we underscore the importance of longitudinal vertebral fracture phenotyping, how knowledge about the timing and risk of fractures influences monitoring, the role of bone mineral density in pGIO assessments, and the impact of growth-mediated "vertebral body reshaping" after spine fractures on the therapeutic approach. Overall, pGIO management is predicated upon early identification of fractures (including vertebral) in those at risk, and timely intervention when there is limited potential for spontaneous recovery. Even a single, low-trauma long bone or vertebral fracture can signal an osteoporotic event in an at-risk child. The most widely used treatments for pediatric osteoporosis, intravenous bisphosphonates, are currently recommended first-line for the treatment of pGIO. It is recognized, however, that even early identification of bone fragility, combined with timely introduction of the most potent bisphosphonate therapies, may not completely prevent osteoporosis progression in all contexts. Therefore, prevention of first-ever fractures in the highest-risk settings is on the horizon, where there is also a need to move beyond antiresorptives to the study of anabolic agents.

Trabecular bone scores in children with osteogenesis imperfecta respond differently to bisphosphonate treatment depending on disease severity

Introduction

Osteogenesis imperfecta (OI) is a congenital skeletal disorder characterized by bone fragility. Bisphosphonates (BISs) have become the mainstream treatment in children with OI. However, an optimal treatment protocol has not yet been established, while BIS treatment tends to be administered to normalize bone mineral density (BMD). Bone quality is an important component of bone strength. The trabecular bone score (TBS) is a quantitative measure of the microstructure that affects bone quality. This study investigated the TBS during BIS treatment in children with OI.

Materials and methods

Twenty-nine children with OI were enrolled and classified into two groups: mild (type 1) and moderate to severe (types 3 and 4). Dual-energy x-ray absorptiometry images were retrospectively analyzed for TBS calculation. The relationship between the areal BMD (aBMD), its Z-score, height-adjusted BMD (BMDHAZ) Z-score, TBS, and TBS Z-score with the treatment duration was assessed for each group.

Results

In the mild group, the aBMD, its Z-score, and BMDHAZ Z-score showed a significant positive correlation with treatment duration (r = 0.68, 0.68, 0.72, respectively, p < 0.01). The TBS Z-score tended to increase with treatment duration, albeit without reaching significance. In the moderate to severe group, the TBS Z-score showed a significant positive correlation with treatment duration (r = 0.48, p < 0.01), in contrast to the aBMD Z-score, which did not increase. Finally, the BMDHAZ Z-score only showed a weak positive correlation with treatment duration (r = 0.37, p < 0.01).

Conclusion

Because BIS affect the BMD and TBS differently based on the severity of OI, treatment goals may need to be stratified by disease severity.

Medical Management for Fracture Prevention in Children with Osteogenesis Imperfecta

There are no licensed treatments for children with osteogenesis imperfecta. Children currently receive off-label treatment with bisphosphonates, without any consistent approach to dose, drug or route of administration. Meta-analyses suggest that anti-fracture efficacy of such interventions is equivocal. New therapies are undergoing clinical trials, and it is likely that one or more will receive marketing authorisation within the next three to five years. The long-term outcome from such interventions will need to be studied carefully well beyond the period over which the clinical trials are conducted, and a consistent approach to the collection of data in this regard will be needed as a major collaborative effort.

Analyses of Osteogenesis Imperfecta in South Korea Using the Nationwide Health Insurance Service Claim Data: A Propensity Score-Matched Study

Osteogenesis imperfecta (OI) is the most common inherited form of bone fragility and includes a heterogeneous group of genetic disorders that most commonly result from defects associated with type I collagen. Although genetic analyses have been developed, nationwide research on the incidence and associated fractures in OI is lacking. This study aimed to investigate the patterns of OI prevalence, incidence, fracture rate, etc. in South Korea using National Health Insurance Service (NHIS) claims data. We found 1596 patients newly diagnosed with OI between March 2002 and February 2020. We evaluated the incidence, prevalence, and history of fractures, fracture site, prescription of anti-osteoporosis drugs, etc. To compare medical costs, fracture rates, and scoliosis rates, we created a control group comprising patients without OI using 1:1 propensity score matching. The prevalence of OI increased slightly each year, with an annual incidence of 20.20 per 100,000 live births. Mean fracture frequency in OI patients was 17 (2-32) times per patient and the most frequent fracture site was the lower leg. A total of 21.4% patients were prescribed anti-osteoporosis drugs, and the most popular drug was pamidronate. After 1:1 propensity score matching, in terms of scoliosis, OI patients had a 3.91 times higher prevalence of scoliosis than in healthy patients which was statistically significant. The sum of medical care expenses for patients with OI was 3.5 times higher than that for patients without OI. We identified nationwide trends in OI occurrence, fractures, and medication use. This study also highlighted the real-world data of scoliosis and medical costs compared to the control group.

Optimising Health-Related Quality of Life in Children With Osteogenesis Imperfecta

Osteogenesis Imperfecta is a rare, hereditary bone condition with an incidence of 1/15,000-20,000. Symptoms include bone fragility, long bone deformity, scoliosis, hypermobility, alongside secondary features such as short stature, basilar invagination, pulmonary and cardiac complications, hearing loss, dentinogenesis imperfecta and malocclusion. Osteogenesis Imperfecta can have a large impact on the child and their family; this impact starts immediately after diagnosis. Fractures, pain, immobility, hospital admissions and the need for equipment and adaptations all influence the health-related quality of life of the individual and their family. This narrative review article aims to examine the impact the diagnosis and management of osteogenesis imperfecta has on the health-related quality of life of a child. It will touch on the effect this may have on the quality of life of their wider family and friends and identify strategies to optimise health-related quality of life in this population. Optimising health-related quality of life in children with Osteogenesis Imperfecta is often a complicated, multifaceted journey that involves the child, their extended family, school, extracurricular staff and numerous health professionals.

Fetal therapies - (Stem cell transplantation; enzyme replacement therapy; in utero genetic therapies)

Advances in ultrasound and prenatal diagnosis are leading an expansion in the options for parents whose fetus is identified with a congenital disease. Obstetric diseases such as pre-eclampsia and fetal growth restriction may also be amenable to intervention to improve maternal and neonatal outcomes. Advanced Medicinal Therapeutic Products such as stem cell, gene, enzyme and protein therapies are most commonly being investigated as the trajectory of treatment for severe genetic diseases moves toward earlier intervention. Theoretical benefits include prevention of in utero damage, smaller treatment doses compared to postnatal intervention, use of fetal circulatory shunts and induction of immune tolerance. New systematic terminology can capture adverse maternal and fetal adverse events to improve safe trial conduct. First-in-human clinical trials are now beginning to generate results with a focus on safety first and efficacy second. If successful, these trials will transform the care of fetuses with severe early-onset congenital disease.

Schnurri-3 inhibition rescues skeletal fragility and vascular skeletal stem cell niche pathology in the OIM model of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a disorder of low bone mass and increased fracture risk due to a range of genetic variants that prominently include mutations in genes encoding type I collagen. While it is well known that OI reflects defects in the activity of bone-forming osteoblasts, it is currently unclear whether OI also reflects defects in the many other cell types comprising bone, including defects in skeletal vascular endothelium or the skeletal stem cell populations that give rise to osteoblasts and whether correcting these broader defects could have therapeutic utility. Here, we find that numbers of skeletal stem cells (SSCs) and skeletal arterial endothelial cells (AECs) are augmented in Col1a2oim/oim mice, a well-studied animal model of moderate to severe OI, suggesting that disruption of a vascular SSC niche is a feature of OI pathogenesis. Moreover, crossing Col1a2oim/oim mice to mice lacking a negative regulator of skeletal angiogenesis and bone formation, Schnurri 3 (SHN3), not only corrected the SSC and AEC phenotypes but moreover robustly corrected the bone mass and spontaneous fracture phenotypes. As this finding suggested a strong therapeutic utility of SHN3 inhibition for the treatment of OI, a bone-targeting AAV was used to mediate Shn3 knockdown, rescuing the Col1a2oim/oim phenotype and providing therapeutic proof-of-concept for targeting SHN3 for the treatment of OI. Overall, this work both provides proof-of-concept for inhibition of the SHN3 pathway and more broadly addressing defects in the stem/osteoprogenitor niche as is a strategy to treat OI.

Alendronate treatment rescues the effects of compressive loading of TMJ in osteogenesis imperfecta mice

BACKGROUND

Osteogenesis imperfecta (OI) is a genetic disorder of connective tissue caused by mutations associated with type I collagen, which results in defective extracellular matrix in temporomandibular joint (TMJ) cartilage and subchondral bone. TMJ is a fibrocartilaginous joint expressing type I collagen both in the cartilage and the subchondral bone. In the present study the effects of alendronate and altered loading of the TMJ was analyzed both in male and female OI mice.

MATERIALS AND METHODS

Forty-eight, 10-weeks-old male and female OI mice were divided into 3 groups: (1) Control group: unloaded group, (2) Saline + Loaded: Saline was injected for 2 weeks and then TMJ of mice was loaded for 5 days, (3) alendronate + loaded: alendronate was injected for 2 weeks and then TMJ of mice was loaded for 5 days. Mice in all the groups were euthanized 24-h after the final loading.

RESULTS

Alendronate pretreatment led to significant increase in bone volume and tissue density. Histomorphometrically, alendronate treatment led to increase in mineralization, cartilage thickness and proteoglycan distribution. Increased mineralization paralleled decreased osteoclastic activity. Our immunohistochemistry revealed decreased expression of matrix metallopeptidase 13 and ADAM metallopeptidase with thrombospondin type 1 motif 5.

CONCLUSION

The findings of this research support that alendronate prevented the detrimental effects of loading on the extracellular matrix of the TMJ cartilage and subchondral bone.

Bone alterations of pamidronate therapy in children with cerebral palsy complicating orthopedic management

Cerebral palsy (CP) is a heterogeneous group of disorders with different clinical types and underlying genetic variants. Children with CP are at risk for fragility fractures secondary to low bone mineral density, and although bisphosphonates are prescribed for the treatment of children with bone fragility, there is limited information on long-term bone impact and safety. Children with CP usually present overtubulated bones, and the thickening of cortical bone by pamidronate treatment can potentially further narrow the medullary canal. Our purpose was to report bone alterations attributable to pamidronate therapy that impact orthopedic care in children with CP. The study consisted of 41 children with CP treated with pamidronate for low bone mineral density from 2006 to 2020. Six children presented unique bone deformities and unusual radiologic features attributed to pamidronate treatment, which affected their orthopedic care. The cases included narrowing of the medullary canal and sclerotic bone, atypical femoral fracture, and heterotopic ossification. Treatment with bisphosphonate reduced the number of fractures from 101 in the pretreatment period to seven in the post-treatment period ( P  < 0.001). In conclusion, children with CP treated with bisphosphonate have a reduction in low-energy fractures; however, some fractures still happen, and pamidronate treatment can lead to bone alterations including medullary canal narrowing with sclerotic bone and atypical femoral fractures. In very young children, failure to remodel may lead to thin, large femoral shafts with cystic medullary canals. More widespread use of bisphosphonates in children with CP may make these bone alterations more frequent. Level of evidence: Level IV: Case series with post-test outcomes.

An exploratory open-label multicentre phase I/II trial evaluating the safety and efficacy of postnatal or prenatal and postnatal administration of allogeneic expanded fetal mesenchymal stem cells for the treatment of severe osteogenesis imperfecta in infants and fetuses: the BOOSTB4 trial protocol

INTRODUCTION

Severe osteogenesis imperfecta (OI) is a debilitating disease with no cure or sufficiently effective treatment. Mesenchymal stem cells (MSCs) have good safety profile, show promising effects and can form bone. The Boost Brittle Bones Before Birth (BOOSTB4) trial evaluates administration of allogeneic expanded human first trimester fetal liver MSCs (BOOST cells) for OI type 3 or severe type 4.

METHODS AND ANALYSIS

BOOSTB4 is an exploratory, open-label, multiple dose, phase I/II clinical trial evaluating safety and efficacy of postnatal (n=15) or prenatal and postnatal (n=3, originally n=15) administration of BOOST cells for the treatment of severe OI compared with a combination of historical (1-5/subject) and untreated prospective controls (≤30). Infants<18 months of age (originally<12 months) and singleton pregnant women whose fetus has severe OI with confirmed glycine substitution in COL1A1 or COL1A2 can be included in the trial.Each subject receives four intravenous doses of 3×106/kg BOOST cells at 4 month intervals, with 48 (doses 1-2) or 24 (doses 3-4) hours in-patient follow-up, primary follow-up at 6 and 12 months after the last dose and long-term follow-up yearly until 10 years after the first dose. Prenatal subjects receive the first dose via ultrasound-guided injection into the umbilical vein within the fetal liver (16+0 to 35+6 weeks), and three doses postnatally.The primary outcome measures are safety and tolerability of repeated BOOST cell administration. The secondary outcome measures are number of fractures from baseline to primary and long-term follow-up, growth, change in bone mineral density, clinical OI status and biochemical bone turnover.

ETHICS AND DISSEMINATION

The trial is approved by Competent Authorities in Sweden, the UK and the Netherlands (postnatal only). Results from the trial will be disseminated via CTIS, ClinicalTrials.gov and in scientific open-access scientific journals.

TRIAL REGISTRATION NUMBERS

EudraCT 2015-003699-60, EUCT: 2023-504593-38-00, NCT03706482.

Influence of zoledronic acid and pamidronate on tooth eruption in children with osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) is a congenital disease comprising a heterogeneous group of inherited connective tissue disorders. The main treatment in children is bisphosphonate therapy. Previous animal studies have shown that bisphosphonates delay tooth eruption. The aim of this study is to determine whether patients with OI treated with pamidronate and/or zoledronic acid have a delayed eruption age compared to a control group of healthy children.

METHODS

An ambispective longitudinal cohort study evaluating the age of eruption of the first stage mixed dentition in a group of children with OI (n = 37) all treated with intravenous bisphosphonates compared with a group of healthy children (n = 89). Within the study group, the correlation (Pearson correlation test) between the type of medication administered (pamidronate and/or zoledronic acid) and the chronology of tooth eruption is established, as well as the relationship between the amount of cumulative dose received and tooth eruption.

RESULTS

The age of eruption of the study group was significantly delayed compared to the age of eruption of the control group for molars and lateral incisors (p < 0.05). Patients who received higher cumulative doses had a delayed eruption age compared to those with lower cumulative doses (p < 0.05). There is a high positive correlation between age of delayed tooth eruption and Zoledronic acid administration.

CONCLUSION

Patients with OI have a delayed eruption of the 1st stage mixed dentition compared to a control group of healthy children. This delayed eruption is directly related to the cumulative dose of bisphosphonates and the administration of zoledronic ac.

Efficacy and safety of intravenous Zolidronic acid in the treatment of pediatric osteogenesis imperfecta: a systematic review

Osteogenesis imperfecta is an inherited clinically heterogeneous disorder of bone metabolism characterized by bone and skeletal fragility and an increased risk of fractures. Pamidronate infusion was the standard treatment, but zoledronic acid is increasingly used to treat children with osteogenesis imperfecta. We conducted a systematic literature review to evaluate the efficacy and safety of intravenous zoledronic acid in the treatment of osteogenesis imperfecta in pediatric patients. A systematic review of the published literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eligible articles were clinical trials and observational studies including pediatric patients (<16 years) with osteogenesis imperfecta treated with zoledronic acid. We selected articles published during the 20 past years. The selected languages were English and French. We included articles with a minimum sample size of five patients. Six articles fulfilled the selection criteria. The majority of patients were Chinese (58%). The predominant sex was male (65%), and the age of included patients ranged from 2.5 weeks to 16.8 years. For all patients, zoledronic infusions were administrated intravenously. The zoledronic treatment duration ranged from 1 to 3 years. Densitometry parameters before and after zoledronic treatment were evaluated and showed significant improvement both in lumbar spine-bone mineral density Z -score and femoral neck-bone mineral density Z -scores. A significant decrease in fracture rate has also been noted both in vertebral and nonvertebral fracture incidence. The two most common side effects were fever and flu-like reactions. None of the patients presented severe adverse events. Zoledronic acid appeared to be well-tolerated and effective in the treatment of pediatric osteogenesis imperfecta.

Home care needs assessment among caregivers of children and adolescents with osteogenesis imperfecta: a cross-sectional study

BACKGROUND

Children and adolescents with complex medical issues need home care services; however, few studies have provided insight into the unmet home care needs of the families of patients with osteogenesis imperfecta (OI). In this study, we aimed to assess the home care needs of caregivers of children and adolescents with OI and the associated factors.

METHODS

A self-administered questionnaire was administered online to 142 caregivers of patients with OI aged 3-17 years between May and October 2022 from 25 provinces in China. The questionnaire comprised 15 questions on demographic variables and 14 questions on home care needs. Chi-square analysis was used to compare group differences for categorical variables. Multivariate binary logistic regression analysis was conducted to examine predictors of caregivers' home care needs.

RESULTS

The study findings indicated that 81.5% of caregivers had high home care needs. The three leading types of home care needs were helping the child carry out physical fitness recovery exercises at home (72.5%), understanding precautions regarding treatment drugs (72.5%), and relieving the child's pain (70.4%). OI patients' poor self-care ability (adjusted odds ratio = 5.9, 95% confidence interval = 1.8-19.0) was related to caregivers' high level of home care needs.

CONCLUSIONS

The findings of this study suggest that future scientific research and nursing guidance should focus on OI patients' physical training, medication management, pain relief, fracture prevention, and treatment. In addition, caregivers of patients with poor self-care ability should receive special attention in the development of interventions. This study can help with addressing the unmet home care needs of caregivers of children and adolescents with OI. It is vital to develop a personalized intervention plan based on patients' self-care ability.

New Perspectives of Therapies in Osteogenesis Imperfecta-A Literature Review

(1) Background: Osteogenesis imperfecta (OI) is a rare skeletal dysplasia characterized as a heterogeneous disorder group with well-defined phenotypic and genetic features that share uncommon bone fragility. The current treatment options, medical and orthopedic, are limited and not efficient enough to improve the low bone density, bone fragility, growth, and mobility of the affected individuals, creating the need for alternative therapeutic agents. (2) Methods: We searched the medical database to find papers regarding treatments for OI other than conventional ones. We included 45 publications. (3) Results: In reviewing the literature, eight new potential therapies for OI were identified, proving promising results in cells and animal models or in human practice, but further research is still needed. Bone marrow transplantation is a promising therapy in mice, adults, and children, decreasing the fracture rate with a beneficial effect on structural bone proprieties. Anti-RANKL antibodies generated controversial results related to the therapy schedule, from no change in the fracture rate to improvement in the bone mineral density resorption markers and bone formation, but with adverse effects related to hypercalcemia. Sclerostin inhibitors in murine models demonstrated an increase in the bone formation rate and trabecular cortical bone mass, and a few human studies showed an increase in biomarkers and BMD and the downregulation of resorption markers. Recombinant human parathormone and TGF-β generated good results in human studies by increasing BMD, depending on the type of OI. Gene therapy, 4-phenylbutiric acid, and inhibition of eIF2α phosphatase enzymes have only been studied in cell cultures and animal models, with promising results. (4) Conclusions: This paper focuses on eight potential therapies for OI, but there is not yet enough data for a new, generally accepted treatment. Most of them showed promising results, but further research is needed, especially in the pediatric field.

Fatality owing to pulmonary hemorrhage following pamidronate disodium administration in a neonate with osteogenesis imperfecta type 2: A case report

We report the case of a patient with osteogenesis imperfecta (OI) who developed pulmonary hemorrhage 4 d after pamidronate disodium (PA) administration, despite a relatively stable respiratory status. Bisphosphonates are introduced to reduce osteoclast activity and are now widely used in patients with OI. Bisphosphonates are typically well-tolerated in children, and the standard of care involves cyclic intravenous administration of PA. However, in practice, there is limited experience with the use of PA for severe OI during the neonatal period, and its safety remains uncertain. This report aimed to describe the respiratory events potentially associated with PA in a neonatal patient with OI type 2, suggesting that serious life-threatening complications of pulmonary hemorrhage may occur after PA administration. Further studies are required to assess the relationship between pulmonary hemorrhage and PA administration, aiming to enhance prophylaxis measures.

Effectiveness and safety of pamidronate treatment in nonambulatory children with low bone mineral density

PURPOSE

Nonambulatory pediatric patients may have low bone mineral density (BMD) and increased risk of pathologic fractures. Though bisphosphonate therapy is the mainstream medical intervention in these children, clinical data regarding this treatment are limited. Therefore, this study aimed to evaluate the effectiveness and safety of bisphosphonate therapy in such children.

METHODS

We conducted a retrospective study of 21 nonambulatory children (Gross Motor Function Classification System level V) with BMD z-score ≤ -2.0 who were treated with intravenous pamidronate for at least 1 year. These patients received pamidronate every 4 months at a dose of 1.0 to 3.0 mg/kg for each cycle and had regular follow-ups for at least 1 year. The main outcome measures were changes in BMD, risk rate of fracture, biochemical data, and adverse events.

RESULTS

The average duration of pamidronate treatment was 2.0±0.9 years, and the mean cumulative dose of pamidronate according to body weight was 7.7±2.5 mg/kg/yr. After treatment, the mean lumbar spine bone mineral content, BMD, and height-for-age-z-score-adjusted BMD z-score (BMDhazZ) significantly improved. The relative risk of fracture after treatment was 0.21 (p=0.0032), suggesting that pamidronate treatment reduced fracture incidence significantly. The increase in the average dose per body weight in each cycle significantly increased the changes in BMDhazZ.

CONCLUSION

Pamidronate treatment improved the bone health of nonambulatory children with low bone density without any significant adverse events. Independent of cumulative dosage and duration of treatment, the effectiveness of pamidronate increased significantly with an increase in the average dose per body weight in subsequent cycles.

Effects of novel raloxifene analogs alone or in combination with mechanical loading in the Col1a2G610c/+ murine model of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a hereditary bone disease in which gene mutations affect collagen formation, leading to a weak, brittle bone phenotype that can cause severe skeletal deformity and increased fracture risk. OI interventions typically repurpose osteoporosis medications to increase bone mass, but this approach does not address compromised tissue-level material properties. Raloxifene (RAL) is a mild anti-resorptive used to treat osteoporosis that has also been shown to increase bone strength by a-cellularly increasing bone bound water content, but RAL cannot be administered to children due to its hormonal activity. The goal of this study was to test a RAL analog with no estrogen receptor (ER) signaling but maintained ability to reduce fracture risk. The best performing analog from a previous analog characterization project, named RAL-ADM, was tested in an in vivo study. Female wildtype (WT) and Col1a2G610C/+ (G610C) mice were randomly assigned to treated or untreated groups, for a total of 4 groups (n = 15). Starting at 10 weeks of age, all mice underwent compressive tibial loading 3×/week to induce an anabolic bone formation response in conjunction with RAL-ADM treatment (0.5 mg/kg; 5×/week) for 6 weeks. Tibiae were scanned via microcomputed tomography then tested to failure in four-point bending. RAL-ADM had reduced ER affinity, and increased post-yield properties, but did not improve bone strength in OI animals, suggesting some properties can be improved by RAL analogs but further development is needed to create an analog with decidedly positive impacts to OI bone.

A practical guide to the diagnosis and management of osteoporosis in childhood and adolescence

Osteoporosis in childhood distinguishes itself from adulthood in four important ways: 1) challenges in distinguishing otherwise healthy children who have experienced fractures due to non-accidental injury or misfortunate during sports and play from those with an underlying bone fragility condition; 2) a preponderance of monogenic "early onset" osteoporotic conditions that unveil themselves during the pediatric years; 3) the unique potential, in those with residual growth and transient bone health threats, to reclaim bone density, structure, and strength without bone-targeted therapy; and 4) the need to benchmark bone health metrics to constantly evolving "normal targets", given the changes in bone size, shape, and metabolism that take place from birth through late adolescence. On this background, the pediatric osteoporosis field has evolved considerably over the last few decades, giving rise to a deeper understanding of the discrete genes implicated in childhood-onset osteoporosis, the natural history of bone fragility in the chronic illness setting and associated risk factors, effective diagnostic and monitoring pathways in different disease contexts, the importance of timely identification of candidates for osteoporosis treatment, and the benefits of early (during growth) rather than late (post-epiphyseal fusion) treatment. While there has been considerable progress, a number of unmet needs remain, the most urgent of which is to move beyond the monotherapeutic anti-resorptive landscape to the study and application of anabolic agents that are anticipated to not only improve bone mineral density but also increase long bone cross-sectional diameter (periosteal circumference). The purpose of this review is to provide a practical guide to the diagnosis and management of osteoporosis in children presenting to the clinic with fragility fractures, one that serves as a step-by-step "how to" reference for clinicians in their routine clinical journey. The article also provides a sightline to the future, emphasizing the clinical scenarios with the most urgent need for an expanded toolbox of effective osteoporosis agents in childhood.

Emerging Landscape of Osteogenesis Imperfecta Pathogenesis and Therapeutic Approaches

Osteogenesis imperfecta (OI) is an uncommon genetic disorder characterized by shortness of stature, hearing loss, poor bone mass, recurrent fractures, and skeletal abnormalities. Pathogenic variations have been found in over 20 distinct genes that are involved in the pathophysiology of OI, contributing to the disorder's clinical and genetic variability. Although medications, surgical procedures, and other interventions can partially alleviate certain symptoms, there is still no known cure for OI. In this Review, we provide a comprehensive overview of genetic pathogenesis, existing treatment modalities, and new developments in biotechnologies such as gene editing, stem cell reprogramming, functional differentiation, and transplantation for potential future OI therapy.

Clinical Characteristics and Therapeutic Management of Osteogenesis Imperfecta in Iraqi Children

Background: Osteogenesis imperfecta (OI) is a rare congenital condition that results in bone fragility, recurrent fractures, and various extra-skeletal manifestations. Currently, intravenous bisphosphonate is the mainstay of medical treatment in OI. Objective: To identify the effect of current management strategies on Iraqi children diagnosed with OI. Methods: A retrospective study enrolled OI patients who were registered in Central Child Teaching Hospital, Baghdad, Iraq, from January 2015 to December 2022. We enrolled confirmed OI cases (either clinically and/or radiologically) who received cyclic pamidronate therapy for at least 3 cycles. They neither received other types of bisphosphonates nor underwent surgical intervention. Results: A total of 52 cases of OI had been identified, but only 36 patients were eligible for the current study. The mean age of the patients was 6.64±4.22 years. A statistically significant drop in the annual fracture rate in OI patients who received intravenous pamidronate cycles was seen, along with a significant rise in weight for age Z-score, lumbar spine bone mineral density DEXA Z-score, and alkaline phosphate levels. No significant improvement was documented in height for age Z-score in OI patients. Conclusions: Intravenous pamidronate cycles for Iraqi children with osteogenesis imperfecta work to lower their risk of breaking bones every year and raise their weight, lumbar spine bone mineral density, and alkaline phosphate levels. Pamidronate did not result in an improvement in the height of OI children.

Tensile Mechanical Properties of Dry Cortical Bone Extracellular Matrix: A Comparison Among Two Osteogenesis Imperfecta and One Healthy Control Iliac Crest Biopsies

Osteogenesis imperfecta (OI) is a genetic, collagen-related bone disease that increases the incidence of bone fractures. Still, the origin of this brittle mechanical behavior remains unclear. The extracellular matrix (ECM) of OI bone exhibits a higher degree of bone mineralization (DBM), whereas compressive mechanical properties at the ECM level do not appear to be inferior to healthy bone. However, it is unknown if collagen defects alter ECM tensile properties. This study aims to quantify the tensile properties of healthy and OI bone ECM. In three transiliac biopsies (healthy n = 1, OI type I n = 1, OI type III n = 1), 23 microtensile specimens (gauge dimensions 10 × 5 × 2 μm3) were manufactured and loaded quasi-statically under tension in vacuum condition. The resulting loading modulus and ultimate strength were extracted. Interestingly, tensile properties in OI bone ECM were not inferior compared to controls. All specimens revealed a brittle failure behavior. Fracture surfaces were graded according to their mineralized collagen fibers (MCF) orientation into axial, mixed, and transversal fracture surface types (FST). Furthermore, tissue mineral density (TMD) of the biopsy cortices was extracted from micro-computed tomogra[hy (μCT) images. Both FST and TMD are significant factors to predict loading modulus and ultimate strength with an adjusted R 2 of 0.556 (p = 2.65e-05) and 0.46 (p = 2.2e-04), respectively. The influence of MCF orientation and DBM on the mechanical properties of the neighboring ECM was further verified with quantitative polarized Raman spectroscopy (qPRS) and site-matched nanoindentation. MCF orientation and DBM were extracted from the qPRS spectrum, and a second mechanical model was developed to predict the indentation modulus with MCF orientation and DBM (R 2 = 67.4%, p = 7.73e-07). The tensile mechanical properties of the cortical bone ECM of two OI iliac crest biopsies are not lower than the one from a healthy and are primarily dependent on MCF orientation and DBM. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Schnurri-3 inhibition rescues skeletal fragility and vascular skeletal stem cell niche pathology in a mouse model of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a disorder of low bone mass and increased fracture risk due to a range of genetic variants that prominently include mutations in genes encoding type collagen. While it is well known that OI reflects defects in the activity of bone-forming osteoblasts, it is currently unclear whether OI also reflects defects in the many other cell types comprising bone, including defects in skeletal vascular endothelium or the skeletal stem cell populations that give rise to osteoblasts and whether correcting these broader defects could have therapeutic utility. Here, we find that numbers of skeletal stem cells (SSCs) and skeletal arterial endothelial cells (AECs) are augmented in Col1a2oim/oim mice, a well-studied animal model of moderate to severe OI, suggesting that disruption of a vascular SSC niche is a feature of OI pathogenesis. Moreover, crossing Col1a2oim/oim mice to mice lacking a negative regulator of skeletal angiogenesis and bone formation, Schnurri 3 (SHN3), not only corrected the SSC and AEC phenotypes but moreover robustly corrected the bone mass and spontaneous fracture phenotypes. As this finding suggested a strong therapeutic utility of SHN3 inhibition for the treatment of OI, a bone-targeting AAV was used to mediate Shn3 knockdown, rescuing the Col1a2oim/oim phenotype and providing therapeutic proof-of-concept for targeting SHN3 for the treatment of OI. Overall, this work both provides proof-of-concept for inhibition of the SHN3 pathway and more broadly addressing defects in the stem/osteoprogentior niche as is a strategy to treat OI.

Pharmacological options in the treatment of osteogenesis imperfecta: A comprehensive review of clinical and potential alternatives

Osteogenesis imperfecta (OI) is a genetically heterogeneous connective tissue disorder characterized by bone fragility and different extra-skeletal manifestations. The severity of these manifestations makes it possible to classify OI into different subtypes based on the main clinical features. This review aims to outline and describe the current pharmacological alternatives for treating OI, grounded on clinical and preclinical reports, such as antiresorptive agents, anabolic agents, growth hormone, and anti-TGFβ antibody, among other less used agents. The different options and their pharmacokinetic and pharmacodynamic properties will be reviewed and discussed, focusing on the variability of their response and the molecular mechanisms involved to attain the main clinical goals, which include decreasing fracture incidence, improving pain, and promoting growth, mobility, and functional independence.

Approach to the Patient: Pharmacological Therapies for Fracture Risk Reduction in Adults With Osteogenesis Imperfecta

CONTEXT

Osteogenesis imperfecta (OI) is a genetic disorder characterized by increased bone fragility largely caused by defects in structure, synthesis, or post-translational processing of type I collagen. The effectiveness of medications used for fracture reduction in adults with OI is understudied and practice recommendations are not well established. Drugs currently used to improve skeletal health in OI were initially developed to treat osteoporosis. Oral and intravenous bisphosphonates have been shown to improve bone mineral density (BMD) in adults with OI and are commonly used; however, conclusive data confirming fracture protection are lacking. Similarly, teriparatide appears to increase BMD, an effect that seems to be limited to individuals with type I OI. The role of denosumab, abaloparatide, romosozumab, and estradiol/testosterone in adult OI have not been systematically studied. Anti-sclerostin agents and transforming growth factor-beta antagonists are under investigation in clinical trials.

OBJECTIVE

This review summarizes current knowledge on pharmacologic treatment options for reducing fracture risk in adults with OI.

METHODS

A PubMed online database search of all study types published in the English language using the terms "osteogenesis imperfecta," "OI," and "brittle bone disease" was performed in June 2022. Articles screened were restricted to adults. Additional sources were identified through manual searches of reference lists.

CONCLUSION

Fracture rates are elevated in adults with OI. Although clinical trial data are limited, bisphosphonates and teriparatide may be useful in improving BMD. Further research is needed to develop medications for adults with OI that will lead to definite fracture rate reduction.

Denosumab use in osteogenesis imperfecta: an update on therapeutic approaches

Osteogenesis imperfecta (OI) is an inherited skeletal disorder that leads to bone fragility and multiple fractures. Given advances in the genetic understanding of existing phenotypes and newly discovered mutations, therapeutic management of OI has become challenging. Denosumab, a monoclonal antibody that inhibits the interaction between the receptor activator of nuclear factor kappa B ligand (RANKL) and its receptor RANK, has been approved to treat postmenopausal osteoporosis and emerged as an important therapy for malignancies and other skeletal disorders, including pediatric skeletal conditions such as OI. This review summarizes information about denosumab therapy in OI by exploring its mechanisms of action, main indications, and safety and efficacy. Several case reports and small series have been published about the short-term use of denosumab in children with OI. Denosumab was considered a strong drug candidate for OI patients with bone fragility and a high risk of fracture, particularly for patients with the bisphosphonate (BP)-unresponsive OI-VI subtype. The evidence for denosumab's effects in children with OI indicates that it effectively improves bone mineral density but not fracture rates. A decrease in bone resorption markers was observed after each treatment. Safety was assessed by tracking the effects on calcium homeostasis and reporting side effects. No severe adverse effects were reported. Hypercalciuria and moderate hypercalcemia were reported, suggesting that BPs be used to prevent the bone rebound effect. In other words, denosumab can be used as a targeted intervention in children with OI. The posology and administration protocol require more investigation to achieve secure efficiency.

Cyclic intravenous pamidronate for an infant with osteogenesis imperfecta type II

A woman in her 30s underwent a 17-week ultrasound which revealed short bowed long bones. Fetal CT at 28 weeks' gestation showed decreased ossification of the skull, a small bell-shaped thorax, hypoplastic vertebrae, and shortening and bowing of the long bones, leading to the diagnosis of osteogenesis imperfecta (OI) type II. The newborn was delivered via caesarean delivery, and tracheal intubation was performed due to the respiratory distress. A heterozygous variant in COL1A1 (c.1679G>T, p. Gly358Val) was ascertained, confirming the diagnosis of OI type II.Cyclic intravenous pamidronate was started at 41 days old with dose modification and was successfully administered every month. Currently, the infant is 8 months old without any new bone fracture. He was extubated successfully at 7 months of age and is now stable using high flow nasal cannula. The efficacy, safety, and optimal dose and timing of cyclic pamidronate for OI type II remain undefined. We report our experience of successful cyclic intravenous pamidronate treatment for an infant with OI type II.

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.

Zoledronic Acid Treatment in Infants and Toddlers with Osteogenesis Imperfecta is Safe and Effective: A Tertiary Care Centre Experience

Context

Osteogenesis imperfecta (OI) is a genetic disorder of the extracellular matrix of bone characterized by low bone mass manifesting as frequent fractures, delayed motor development, pain, and impaired quality of life. The intravenous bisphosphonate, pamidronate is an established treatment for OI. Recently, zoledronic acid (ZA) has been used for the management of OI.

Aim

To assess the efficacy and safety of ZA in children below five years of age with OI.

Settings and Design

A hospital-based prospective observational study.

Methods and Material

Patients with OI aged less than five years attending our centre were treated with intravenous ZA at a dose of 0.05 mg/kg every six months. Subjects were closely monitored for clinical and biochemical variables, adverse events, and new-onset fractures. The response to therapy was assessed by monitoring clinical variables including the degree of bony pains, number of fractures, height/length standard deviation score (SDS), and motor developmental milestones. All patients were analysed at baseline and at the end of two years for biochemical parameters and clinical severity score (CSS) as proposed by Aglan et al. with modifications.

Results

After two years of treatment, OI patients showed a significant decline in the rate of fractures (p < 0.001), improvement in ambulation (p = 0.005), alleviation of pain (p < 0.001), and improvement in height SDS (p < 0.05). There was a significant improvement in CSS after two years of therapy. Apart from mild flu-like symptoms and mild asymptomatic hypocalcaemia immediately post-infusion, no other adverse effect was noted.

Conclusion

ZA therapy in infants and children below five years of age with OI was effective and safe and a more convenient alternative to pamidronate.

Bisphosphonates: From Pharmacology to Treatment

Bisphosphonates are among the most widely used drugs in the world for their many clinical indications. Their mechanism of action is based on the increase in the level of bone mineralization through the inhibition of osteoclastic activity and the induction of osteoblastic activity. Recent studies also attribute to bisphosphonates an antineoplastic activity, due to the ability of these drugs to inhibit neo angiogenesis, inhibiting the proliferation of endothelial cells. Bisphosphonates have several common properties, including poorly absorbed orally, high affinity for bone mineral, inhibitory effects on osteoclastic bone resorption, prolonged bone retention, and elimination in the urine. Bisphosphonates are generally well tolerated but their use can be, however, burdened by serious side effects such as hypocalcaemia, renal impairment, and aseptic osteonecrosis of the jaw.

Osteoporosis in children and adolescents: how to treat and monitor?

Osteoporosis is a condition of increased bone fragility associated with fractures. Apart from primary genetic osteoporotic conditions, secondary osteoporosis in children is being increasingly recognized. As a result, there is growing interest in its prevention and treatment. Important goals of care are to prevent fractures, increase bone mass and trabecular and cortical thickness, reshape vertebral fractures, prevent (or correct) skeletal deformities, and improve mobility, independence, and quality of life. Secondary pediatric osteoporosis is often of multifactorial origin since affected children frequently have more than one acquired factor that is detrimental to bone health. Typical conditions causing osteoporosis are leukemias, progressive muscle or neurological disorders, as well as chronic inflammatory conditions and their treatment. Management of children with osteoporosis involves a multidisciplinary team involving pediatric experts from different subspecialties. With regard to prevention and early intervention, it is important to provide optimal management of any underlying systemic conditions including avoidance, or dose-reduction, of osteotoxic medications. Basic supporting life-style measures, such as appropriate nutrition, including adequate calcium intake and vitamin D, and physical activity are recommended, where possible. When pediatric treatment criteria for osteoporosis are met, antiresorptive drugs constitute the first pharmacological line treatment.

CONCLUSION

This clinical review focuses on the prevention, treatment, and follow-up of children with, or at risk of developing, osteoporosis and the transition from pediatric to adult care.

WHAT IS KNOWN

• Osteoporosis and associated fractures can cause significant morbidity and reduce the quality of life. • The developing skeleton has huge potential for recovery and reshaping, thus early detection of fractures, assessment of recovery potential, and treatment of children with osteoporosis can prevent future fractures, deformities, and scoliosis, improve function and mobility, and reduce pain.

WHAT IS NEW

• Osteoporosis in children and adolescents requires a multidisciplinary approach with a thorough assessment of recovery potential, and indication for therapy should be personalized. • Although bisphosphonates still represent the drug most commonly used to increase bone mass, improve mobility, and reduce pain and recurrence of fractures, new agents are being developed and could be beneficial in children with specific conditions.

ИССЛЕДОВАНИЕ СОСТОЯНИЯ КОСТНОЙ ТКАНИ У ЛИЦ С НЕСОВЕРШЕННЫМ ОСТЕОГЕНЕЗОМ МОЛОДОГО ВОЗРАСТА

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Bisphosphonates for osteoporosis in people with cystic fibrosis

BACKGROUND

Osteoporosis is a disorder of bone mineralisation occurring in about one third of adults with cystic fibrosis. Bisphosphonates can increase bone mineral density and decrease the risk of new fractures in post-menopausal women and people receiving long-term oral corticosteroids. This is an updated version of a previous review.

OBJECTIVES

To assess the effects of bisphosphonates on the frequency of fractures, bone mineral density, quality of life, adverse events, trial withdrawals, and survival in people with cystic fibrosis.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Trials Register of references (identified from electronic database searches and hand searches of journals and abstract books) on 5 May 2022. We performed additional searches of PubMed, clinicaltrials.gov and the WHO ICTRP (International Clinical Trials Registry Platform) on 5 May 2022.

SELECTION CRITERIA

Randomised controlled trials of at least six months duration studying bisphosphonates in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Authors independently selected trials, extracted data and assessed risk of bias in included studies. Trial investigators were contacted to obtain missing data. We judged the certainty of the evidence using GRADE.

MAIN RESULTS

We included nine trials with a total of 385 participants (272 adults and 113 children (aged five to 18 years)). Trial durations ranged from six months to two years. Only two of the studies were considered to have a low risk of bias for all the domains.  Bisphosphonates compared to control in people with cystic fibrosis who have not had a lung transplant Seven trials included only adult participants without lung transplants, one trial included both adults and children without lung transplantation (total of 238 adults and 113 children). We analysed adults (n = 238) and children (n = 113) separately. Adults Three trials assessed intravenous bisphosphonates (one assessed pamidronate and two assessed zoledronate) and five trials assessed oral bisphosphonates (one assessed risedronate and four assessed alendronate). Bisphosphonates were compared to either placebo or calcium (with or without additional vitamin D). Data showed no difference between treatment or control groups in new vertebral fractures at 12 months (odds ratio (OR) 0.22, 95% confidence interval (CI) 0.02 to 2.09; 5 trials, 142 participants; very low-certainty evidence) and two trials (44 participants) reported no vertebral fractures at 24 months. There was no difference in non-vertebral fractures at 12 months (OR 2.11, 95% CI 0.18 to 25.35; 4 trials, 95 participants; very low-certainty evidence) and again two trials (44 participants) reported no non-vertebral fractures at 24 months. There was no difference in total fractures between groups at 12 months (OR 0.57, 95% CI 0.13 to 2.50; 5 trials, 142 participants) and no fractures were reported in two trials (44 participants) at 24 months. At 12 months, bisphosphonates may increase bone mineral density at the lumbar spine (mean difference (MD) 6.31, 95% CI 5.39 to 7.22; 6 trials, 171 participants; low-certainty evidence) and at the hip or femur (MD 4.41, 95% 3.44 to 5.37; 5 trials, 155 participants; low-certainty evidence). There was no clear difference in quality of life scores at 12 months (1 trial, 47 participants; low-certainty evidence), but bisphosphonates probably led to more adverse events (bone pain) at 12 months (OR 8.49, 95% CI 3.20 to 22.56; 7 trials, 206 participants; moderate-certainty evidence). Children The single trial in 113 children compared oral alendronate to placebo. We graded all evidence as low certainty. At 12 months we found no difference between treatment and placebo in new vertebral fractures (OR 0.32, 95% CI 0.03 to 3.13; 1 trial, 113 participants) and non-vertebral fractures (OR 0.19, 95% CI 0.01 to 4.04; 1 trial, 113 participants). There was also no difference in total fractures (OR 0.18, 95% CI 0.02 to 1.61; 1 trial, 113 participants). Bisphosphonates may increase bone mineral density at the lumbar spine at 12 months (MD 14.50, 95% CI 12.91 to 16.09). There was no difference in bone or muscle pain (MD 3.00, 95% CI 0.12 to 75.22), fever (MD 3.00, 95% CI 0.12 to 75.22) or gastrointestinal adverse events (OR 0.67, 95% CI 0.20 to 2.26). The trial did not measure bone mineral density at the hip/femur or report on quality of life.  Bisphosphonates compared to control in people with cystic fibrosis who have had a lung transplant One trial of 34 adults who had undergone lung transplantation compared intravenous pamidronate to no bisphosphonate treatment. It did not report at 12 months and we report the 24-month data (not assessed by GRADE). There was no difference in the number of fractures, either vertebral or non-vertebral. However, bone mineral density increased with treatment at the lumbar spine (MD 6.20, 95% CI 4.28 to 8.12) and femur (MD 7.90, 95% CI 5.78 to 10.02). No participants in either group reported either bone pain or fever. The trial did not measure quality of life.

AUTHORS' CONCLUSIONS

Oral and intravenous bisphosphonates may increase bone mineral density in people with cystic fibrosis, but there are insufficient data to determine whether treatment reduces fractures. Severe bone pain and flu-like symptoms may occur with intravenous bisphosphonates. Before any firm conclusions can be drawn, trials in larger populations, including children, and of longer duration are needed to determine effects on fracture rate and survival. Additional trials are needed to determine if bone pain is more common or severe (or both) with the more potent zoledronate and if corticosteroids can ameliorate or prevent these adverse events. Future trials should also assess gastrointestinal adverse effects associated with oral bisphosphonates.

Transition of young adults with metabolic bone diseases to adult care

As more accurate diagnostic tools and targeted therapies become increasingly available for pediatric metabolic bone diseases, affected children have a better prognosis and significantly longer lifespan. With this potential for fulfilling lives as adults comes the need for dedicated transition and intentional care of these patients as adults. Much work has gone into improving the transitions of medically fragile children into adulthood, encompassing endocrinologic conditions like type 1 diabetes mellitus and congenital adrenal hyperplasia. However, there are gaps in the literature regarding similar guidance concerning metabolic bone conditions. This article intends to provide a brief review of research and guidelines for transitions of care more generally, followed by a more detailed treatment of bone disorders specifically. Considerations for such transitions include final adult height, fertility, fetal risk, heritability, and access to appropriately identified specialists. A nutrient-dense diet, optimal mobility, and adequate vitamin D stores are protective factors for these conditions. Primary bone disorders include hypophosphatasia, X-linked hypophosphatemic rickets, and osteogenesis imperfecta. Metabolic bone disease can also develop secondarily as a sequela of such diverse exposures as hypogonadism, a history of eating disorder, and cancer treatment. This article synthesizes research by experts of these specific disorders to describe what is known in this field of transition medicine for metabolic bone diseases as well as unanswered questions. The long-term objective is to develop and implement strategies for successful transitions for all patients affected by these various conditions.

Sickle cell bone disease and response to intravenous bisphosphonates in children

Children with sickle cell disease (SCD) have the potential for extensive and early-onset bone morbidity. This study reports on the diversity of bone morbidity seen in children with SCD followed at three tertiary centers. IV bisphosphonates were effective for bone pain analgesia and did not trigger sickle cell complications.

INTRODUCTION

To evaluate bone morbidity and the response to intravenous (IV) bisphosphonate therapy in children with SCD.

METHODS

We conducted a retrospective review of patient records from 2003 to 2019 at three Canadian pediatric tertiary care centers. Radiographs, magnetic resonance images, and computed tomography scans were reviewed for the presence of avascular necrosis (AVN), bone infarcts, and myositis. IV bisphosphonates were offered for bone pain management. Bone mineral density was assessed by dual-energy X-ray absorptiometry (DXA).

RESULTS

Forty-six children (20 girls, 43%) had bone morbidity at a mean age of 11.8 years (SD 3.9) including AVN of the femoral (17/46, 37%) and humeral (8/46, 17%) heads, H-shaped vertebral body deformities due to endplate infarcts (35/46, 76%), and non-vertebral body skeletal infarcts (15/46, 32%). Five children (5/26, 19%) had myositis overlying areas of AVN or bone infarcts visualized on magnetic resonance imaging. Twenty-three children (8/23 girls) received IV bisphosphonate therapy. They all reported significant or complete resolution of bone pain. There were no reports of sickle cell hemolytic crises, pain crises, or stroke attributed to IV bisphosphonate therapy.

CONCLUSION

Children with SCD have the potential for extensive and early-onset bone morbidity. In this series, IV bisphosphonates were effective for bone pain analgesia and did not trigger sickle cell complications.

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.

Osteogenesis Imperfecta Type 3 in a 10-Year-Old Child With Acute Respiratory Distress Syndrome

Osteogenesis imperfecta (OI) represents a group of rare connective tissue disorders characterized by excessive bone fragility. Type 3 is a rare form with new mutations; osteopenia and bone fragility are significant with numerous fractures, continuous and severe deformity of the spine, and long bones. Our case study concerns a 10-year-old male child admitted to the pediatric department of the State University of Haiti Hospital. OI type 3 was diagnosed based on both clinical and radiological assessments. Multidisciplinary care was initiated. Although the evolution was still unsatisfactory, characterized by intermittent episodes of dyspnea and left lung hypoplasia, he was stabilized after 28 days of hospitalization and referred to the orthopedics department for follow-up care.

Targeting transforming growth factor- β (TGF-β) for treatment of osteogenesis imperfecta

BACKGROUND

Currently, there is no disease-specific therapy for osteogenesis imperfecta (OI). Preclinical studies have shown that excessive TGF-β signaling is a driver of pathogenesis in OI. Here, we evaluated TGF-β signaling in children with OI and translated this discovery by conducting a phase 1 clinical trial of TGF-β inhibition in adults with OI.

METHODS

Histology and RNASeq were performed on bones obtained from children affected (n=10) and unaffected (n=4) by OI. Gene Ontology (GO) enrichment assay, gene set enrichment analysis (GSEA), and Ingenuity Pathway Analysis (IPA) were used to identify key dysregulated pathways. Reverse-phase protein array (RPPA), Western blot (WB), and Immunohistochemistry (IHC) were performed to evaluate changes at the protein level. A phase 1 study with a single administration of fresolimumab, a pan-anti-TGF-β neutralizing antibody, was conducted in 8 adults with OI. Safety and effects of fresolimumab on bone remodeling markers and lumbar spine areal bone mineral density (LS aBMD) were assessed.

RESULTS

OI bone demonstrated woven structure, increased osteocyte density, high turnover, and reduced bone maturation. SMAD phosphorylation was the most significantly up-regulated GO molecular event. GSEA identified TGF-β pathway as top activated signaling pathway in OI. IPA showed that TGF-β was the most significant activated upstream regulator mediating the global changes identified in OI bone. Treatment with fresolimumab was well-tolerated and associated with increase in LS aBMD in participants with OI type IV, while those with more severe OI type III and VIII had unchanged or decreased LS aBMD.

CONCLUSIONS

Our data confirm that TGF-β signaling is a driver pathogenic mechanism in OI bone and that anti-TGF-β therapy could be a potential disease-specific therapy with dose-dependent effects on bone mass and turnover.

TRIAL REGISTRATION

NCT03064074 FUNDING. This work was supported by the Brittle Bone Disorders Consortium (BBDC) (U54AR068069). The BBDC is a part of the National Center for Advancing Translational Science's (NCATS') RDCRN. The BBDC is funded through a collaboration between the Office of Rare Disease Research (ORDR) of NCATS, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institute of Dental and Craniofacial Research (NIDCR), National Institute of Mental Health (NIMH) and National Institute of Child Health and Human Development (NICHD). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. The BBDC was also supported by the OI Foundation. The work was supported by The Clinical Translational Core of BCM IDDRC (P50HD103555) from the Eunice Kennedy Shriver NICHD. Funding from the USDA/ARS under Cooperative Agreement No. 58-6250-6-001 also facilitated analysis for the study procedures. The contents of this publication do not necessarily reflect the views or policies of the USDA, nor does mention of trade names, commercial products, or organizations imply endorsement by the US Government. The study was supported by a research agreement with Sanofi Genzyme.

Safety and Efficacy of Pamidronate in Neonatal Hypercalcemia Caused by Subcutaneous Fat Necrosis: A Case Report

Subcutaneous fat necrosis of the newborn (SCFN) is a panniculitis that develops in fatty areas after fetal or perinatal distress. Prognosis is generally good with complete regression, but it can be complicated by metabolic abnormalities like hypoglycemia, hypertriglyceridemia, thrombocytopenia, and also potentially life-threatening hypercalcemia. Treatments have included hydration, furosemide and corticosteroids. These treatments can be prolonged for several days and can have complications such as nephrocalcinosis. Use of bisphosphonates has been rarely reported in newborn. We describe a case of severe hypercalcemia complicating subcutaneous fat necrosis in a newborn successfully treated by a single dose of pamidronate after having obtained partial response by therapy with hyperhydration, furosemide and hydrocortisone. When high levels of calcium do not respond to first line therapy with hyperhydration and diuretic therapy, bisphosphonates treatment could be considered a valid choice to treat hypercalcemia and to avoid corticosteroids. Further studies are needed to understand if pamidronate and other bisphosphonates can be considered the first choice in hypercalcemia due to SCFN.

Comprehensive pain management strategy for infants with moderate to severe osteogenesis imperfecta in the perinatal period

Osteogenesis imperfecta (OI) is a rare genetic heterogeneous disorder that causes increased bone fragility and recurrent fractures. For infants with OI and diffuse fractures, pain management, which is nuanced and specific for this population, is of the utmost importance to their neonatal care. Through experience at our center, we have developed a standard approach that has been successful in optimizing survival for these infants during this tenuous period. In this paper, we outline our multidisciplinary approach to pain management for infants with moderate to severe OI during the neonatal period, with emphasis on promotion of fracture healing and adequate pain control.

Long-term vascular access for infants with moderate to severe osteogenesis imperfecta

PURPOSE

Osteogenesis imperfecta (OI) is a genetic disorder that causes skeletal fragility. For the most fragile infants and young children with OI, intravenous (IV) bisphosphonate administration is essential, but IV access attempts often cause fractures. Port-a-caths help prevent these events, but some surgeons are hesitant to insert these devices in these infants due to lack of data on their safety.

METHODS

Retrospective study of pediatric patients with OI who underwent port-a-cath placement from 1999 to 2018; incidence of complications such as infection and thrombosis and need for reoperation or replacement are described.

RESULTS

Port-a-caths were placed in 17 patients with OI (median age, 8 mos [5-23 mos]; median weight, 5.8 kg [3.96-9.08 kg]) and remained in place for a median of 53.5 mos (10-127 mos). One port-a-cath was replaced because of thrombosis. Two port-a-caths were removed because of malfunction, one for skin erosion, and one for infection. In these five cases, replacement was not needed because patients could safely tolerate IV access. Two patients have their port-a-cath in place and the remaining ten patients had theirs removed electively as it was no longer needed.

CONCLUSION

Port-a-cath placement in pediatric patients with OI is safe and efficacious for durable central access, enabling reliable IV bisphosphonate delivery and reducing iatrogenic trauma.

The Role of Bisphosphonates in Childhood Diseases

Bisphosphonates have found in recent years an increasingly wide application in adult neoplastic diseases and osteoporosis. Their mechanism of action is based on the inhibition of bone turnover favouring, in particular, the mineralization and the reduction of the frequency of the remodelling cycles. The fields of application of bisphosphonates in paediatric age are constantly evolving although new trials are needed to define the schedule of administration and their long-term side effects.

Efficacy of Romosozumab for Osteoporosis in a Patient With Osteogenesis Imperfecta: A Case Report

The efficacy of romosozumab for severe osteoporosis is uncertain in patients with osteogenesis imperfecta (OI). This report introduced a severe osteoporotic case of OI to examine the effect of romosozumab on bone fragility. A 64-year-old man with OI was referred to our department for finding out the cause of his repeated fractures. He was medicated with alendronate for only one year, eight years ago, but it did not prevent repeated fractures, and thus he had not received any treatments for osteoporosis since then. However, recently, the frequency of fractures had become increased. At presentation, his lumbar and bilateral total hip bone mineral density (BMD) values were severely decreased at 0.546 and 0.209 g/cm2, respectively. Because of his severe osteoporosis, we started romosozumab treatment with eldecalcitol. Romosozumab (210 mg) was injected subcutaneously every month. At 12 months after drug initiation, his lumbar and total hip BMD increased by 22.0% and 136.4% versus pre-treatment levels, respectively. Bone formation markers increased, and bone resorption markers decreased at 12 months of the therapy. Neither hypocalcemia nor any other severe adverse effects were observed in this severe osteoporotic case. This study revealed good responses of BMD and bone turnover markers to romosozumab treatment, which can be considered as an effective treatment option for osteoporotic OI patients.

Surgical Outcome of Spinal Fusion for Osteogenesis Imperfecta With Scoliosis: Is the Hybrid System With Pedicle Screws Applicable to Weak, Tiny, and Fragile Vertebrae?

INTRODUCTION

Corrective surgery for spinal deformity associated with osteogenesis imperfecta (OI) is challenging due to the severe and rigid deformity combined with extreme bone fragility. However, surgical outcomes still remain unclear. In addition, the applicability of pedicle screws (PSs) to the tiny and fragile vertebrae in patients with OI is poorly understood. This study evaluated the surgical outcome, and the accuracy and safety of PS placement in patients with OI.

METHODS

Twenty-five patients with OI were included in this study. Mean age was 21.0±9.3 (10 to 49) years. Mean follow-up was 5.8±2.0 years. The Sillence classification showed 16 patients had the mildest type I, 1 patient had moderate type IV, and 8 patients had the most severe type III. Fifteen patients underwent anterior release followed by posterior fusion, and 10 patients underwent only posterior fusion. The accuracy of PS placement was evaluated with postoperative computed tomography.

RESULTS

Scoliosis was corrected from 95.6 to 65.8 degrees after surgery (correction rate 32.5%) and 68.1 degrees at final follow-up (both, P<0.01). Space available for the lung was improved from 76.3% to 84.9% (P<0.05). No implant dislodgement occurred after surgery. A total of 290 screws were placed, of which 213 screws (73.4%) were placed completely. However, 30 screws (10.3%) penetrated >2 mm. In particular, rates of >2 mm penetration was much higher in type III than type I and IV (27.8% vs. 3.0%; P<0.01). Complications related to spinal surgery included 2 transient neurological disturbances.

CONCLUSIONS

PSs were applicable to spinal fusion surgery in patients with OI. However special care should be taken in placing PSs because of the weakness of the pedicle cortex, which was easily penetrated especially in Sillence type III.

LEVEL OF EVIDENCE

Level IV.

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.