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

Early Life Management of Osteogenesis Imperfecta

PURPOSE OF REVIEW

This review aims to provide a review of the multidisciplinary management of infants with osteogenesis imperfecta (OI) during the first year of life, focusing on those with severe disease. The authors draw on published literature and direct experience of working in a large paediatric centre specialising in the management of rare bone disease.

RECENT FINDINGS

Whilst understanding of the pathophysiology of OI has grown over the past decade, the evidence base for management of infants remains limited. There has been a greater recognition of certain subjects of concern including pain management, cervical spine deformity, and neurocognitive development. Both international consensus guidelines on rehabilitation and disease-specific growth charts have been welcomed by clinical teams. The early involvement of multidisciplinary specialist care is critical in ensuring optimal care for the infant with severe OI. A long-term perspective which focuses on the axial, craniofacial, and peripheral skeleton as well as on development more generally provides a framework which can guide the management of infants with severe 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.

Clinical, genetic characteristics and treatment outcomes of children and adolescents with osteogenesis imperfecta: a two-center experience

BACKGROUND

Osteogenesis imperfecta (OI), is a heritable, heterogeneous connective tissue disorder, characterized by fragile bones. There are conflicting results about genotype-phenotype correlations and efficiency of bisphosphonate treatment in this disorder.

AIM

We aimed to evaluate the clinical, genetic characteristics, and long-term follow-up results of children and adolescents with OI.

MATERIALS AND METHODS

A two-center retrospective study was conducted using demographic, clinical, and genetic data obtained from the medical records of the patients.

RESULTS

Twenty-nine patients (62% male, median age; 3.6 years) with OI diagnosis from 26 families were included in the study. Thirteen different variants (nine were novel) were described in 16 patients in COL1A1, COL1A2, and P3H1 genes. Our siblings with homozygous P3H1 variants had a severe phenotype with intrauterine and neonatal fractures. Twenty-two patients were treated with bisphosphonates (17 of them with pamidronate, five with alendronate) with a median duration of 3.0 (1.6-4.8) years. Eleven patients (50%) suffered from fractures after the treatment. Haploinsufficiency variants in COL1A1 caused a milder skeletal phenotype with less fracture count and better treatment outcomes than structural variants. When compared with the anthropometric measurements at the initial diagnosis time, height Z-scores were lower on the last clinical follow-up (p = 0.009).

CONCLUSIONS

We could not find an obvious genotype-phenotype correlation in Turkish OI patients with COL1A1 or COL1A2 variants. Treatment with pamidronate was effective in reducing fracture counts, without any long-term adverse effects.

Clinical practice guidelines for optimizing bone health in Korean children and adolescents

The Committee on Pediatric Bone Health of the Korean Society of Pediatric Endocrinology has newly developed evidence-based clinical practice guidelines for optimizing bone health in Korean children and adolescents. These guidelines present recommendations based on the Grading of Recommendations, which includes the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. These guidelines include processes of bone acquisition, definition, and evaluation of low bone mineral density (BMD), causes of osteoporosis, methods for optimizing bone health, and pharmacological treatments for enhancing BMD in children and adolescents. While these guidelines provide current evidence-based recommendations, further research is required to strengthen these guidelines.

High Bone Mineral Density Osteogenesis Imperfecta in a Family with a Novel Pathogenic Variant in COL1A2

Osteogenesis imperfecta (OI) is a heterogenous group of heritable bone dysplasias characterized by bone fragility, typically low bone mass, joint laxity, easy bruising, and variable short stature. Classical OI is caused by autosomal dominant pathogenic variants in COL1A1 or COL1A2 that result in either reduced production of normal type 1 collagen or structurally abnormal collagen molecules. Pathogenic variants in these genes generally result in low bone mass. Here, we report a family that had 2 affected individuals who presented with minimal trauma fractures and were found to have elevated bone mineral density (BMD) and a previously unreported variant in COL1A2 c.3356C>T p.(Ala1119Val). We report the change in BMD using dual-energy X-ray and peripheral quantitative computed tomography over a 2.3-year period in the proband. This case report highlights the importance of BMD studies and genetic testing in the diagnostic process for brittle bone disorders.

Vertebral fracture assessment (VFA) for monitoring vertebral reshaping in children and adolescents with osteogenesis imperfecta treated with intravenous neridronate

PURPOSE

The study was aimed at monitoring vertebral bodies changes with the use of Vertebral Fracture Assessment (VFA) in children and adolescents affected by osteogenesis imperfecta (OI) during treatment with intravenous neridronate.

METHODS

60 children and adolescents (35 males and 25 females; age 1-16 years) with OI type I, III and IV were included in the study. Intravenous neridronate was administered at the dose of 2 mg/kg every 3 months in all patients. Lumbar spine (LS) bone mineral density (BMD) and VFA by dual X-ray absorptiometry (DXA) were assessed every 6 months up to 24 months during treatment. VFA with vertebral morphometry (MXA) was used to calculate the three indices of vertebral deformity: wedging, concavity and crushing. Serum calcium, phosphate, parathyroid hormone (PTH), 25-hydroxy-vitamin D [25(OH)D], total alkaline phosphatase (ALP), bone alkaline phosphatase (BALP) and urinary C-terminal telopeptide of type 1 collagen (CTx) were measured at any time point.

RESULTS

Mean LS BMD values significantly increased at 24 months compared to baseline (p < 0.0001); the corresponding Z-score values were -1.28 ± 1.23 at 24 months vs -2.46 ± 1.25 at baseline; corresponding mean Bone Mineral Apparent Density (BMAD) values were 0.335 ± 0.206 vs 0.464 ± 0.216. Mean serum levels of ALP, BALP and CTx significantly decreased from baseline to 24 months. By MXA, we observed a significant 19.1% reduction of the mean wedging index of vertebral reshaping at 12 months, and 38.4% at 24 months (p < 0.0001) and of the mean concavity index (16.3% at 12 months and 35.9% at 24 months; p < 0.0001). Vertebral reshaping was achieved for 66/88 (75%) wedge fractures and 59/70 (84%) concave fractures, but there were 4 incident mild fractures. Finally, VF rate was reduced at 24 months compared to baseline: 37/710 (5.2%) vs 158/710 (22.2%).

CONCLUSION

Our study demonstrates the utility of VFA as a safe and alternative methodology in the follow-up of children and adolescents with OI.

Development of the Screening Tool for Everyday Mobility and Symptoms (STEMS) for skeletal dysplasia

BACKGROUND

Skeletal dysplasia are genetic disorders of cartilage and bone, characterized by impairments commonly resulting in short stature, altered movement biomechanics, pain, fatigue and reduced functional performance. While current tools quantify functional mobility performance, they have not been standardly used in this population group and do not capture patient-reported symptoms such as pain or fatigue. This study evaluated a new tool, the Screening Tool for Everyday Mobility and Symptoms (STEMS), designed to accurately and objectively assess functional mobility and associated symptomology for individuals with skeletal dysplasia.

METHODS

Individuals aged 5-75 years with a skeletal dysplasia completed the STEMS, the Functional Mobility Scale (FMS) and Six Minute Walk Test (6MWT). The correlation among the STEMS, use of mobility aides, FMS and 6MWT normalised for leg length was calculated. One-way analysis of variance compared the STEMS symptomatology to normalised 6MWT distance.

RESULTS

One hundred and fifty individuals with skeletal dysplasia (76 achondroplasia, 42 osteogenesis imperfecta, 32 other; 74 < 18 years, 76 ≥ 18 years) participated. Almost two thirds of the group reported pain and/or fatigue when mobilising at home, at work or school and within the community, but only twenty percent recorded use of a mobility device. The STEMS setting category demonstrated highly significant correlations with the corresponding FMS category (r = - 0.983 to - 0.0994, all p < 0.001), and a low significant correlation with the normalised 6MWT distance (r = - 0.323 to - 0.394, all p < 0.001). A decreased normalised 6MWT distance was recorded for individuals who reported symptoms of pain and/or fatigue when mobilising at home or at work/school (all p ≤ 0.004). Those who reported pain only when mobilising in the community had a normal 6MWT distance (p = 0.43-0.46).

CONCLUSIONS

The Screening Tool for Everyday Mobility and Symptoms (STEMS) is a useful new tool to identify and record mobility aide use and associated self-reported symptoms across three environmental settings for adults and children with skeletal dysplasia. The STEMS may assist clinicians to monitor individuals for changes in functional mobility and symptoms over time, identify individuals who are functioning poorly compared to peers and need further assessment, and to measure effectiveness of treatment interventions in both clinical and research settings.

Finite element analysis of bone strength in osteogenesis imperfecta

As a dedicated experimentalist, John Currey praised the high potential of finite element (FE) analysis but also recognized its critical limitations. The application of the FE methodology to bone tissue is reviewed in the light of his enthusiastic and colorful statements. In the past decades, FE analysis contributed substantially to the understanding of structure-function properties in the hierarchical organization of bone and to the simulation of bone adaptation. The systematic experimental validation of FE analysis of bone strength in anatomical locations at risk of fracture led to its application in clinical studies to evaluate efficacy of antiresorptive or anabolic treatment of bone fragility. Beyond the successful analyses of healthy or osteoporotic bone, FE analysis becomes increasingly involved in the investigation of other fragility-related bone diseases. The case of osteogenesis imperfecta (OI) is exposed, the multiscale alterations of the bone tissue and the effect of treatment summarized. A few FE analyses attempting to answer open questions in OI are then reported. An original study is finally presented that explored the structural properties of the Brtl/+ murine model of OI type IV subjected to sclerostin neutralizing antibody treatment using microFE analysis. The use of identical material properties in the four-point bending FE simulations of the femora reproduced not only the experimental values but also the statistical comparisons examining the effect of disease and treatment. Further efforts are needed to build upon the extraordinary legacy of John Currey and clarify the impact of different bone diseases on the hierarchical mechanical properties of bone.

Current status in therapeutic interventions of neonatal bone mineral metabolic disorders

Neonatal care has significantly improved in the past decade with improved survival of preterm and sick neonates. Similarly, the field of bone and mineral disorders is continuing to accelerate with better understanding of pathophysiology and genetic basis of diseases, as well as availability of newer diagnostic and therapeutic modalities. In this extensive and rapidly expanding field, metabolic bone disease specialists are frequently called upon to translate progress into better care for neonates with bone and mineral disorders. Accordingly, this chapter provides a review of clinical manifestations and evidence-based investigation and management (where available) of common, rare and ultra-rare disorders of bone and mineral metabolism manifesting in the neonatal period. Besides medical treatment we emphasise the crucial role of the multidisciplinary team, which include physical therapists, occupational therapists and dieticians, in the care of neonates with bone disorders such as osteogenesis imperfecta and achondroplasia.

The Osteocyte as the New Discovery of Therapeutic Options in Rare Bone Diseases

Osteocytes are the most abundant (~95%) cells in bone with the longest half-life (~25 years) in humans. In the past osteocytes have been regarded as vestigial cells in bone, since they are buried inside the tough bone matrix. However, during the last 30 years it has become clear that osteocytes are as important as bone forming osteoblasts and bone resorbing osteoclasts in maintaining bone homeostasis. The osteocyte cell body and dendritic processes reside in bone in a complex lacuno-canalicular system, which allows the direct networking of osteocytes to their neighboring osteocytes, osteoblasts, osteoclasts, bone marrow, blood vessels, and nerves. Mechanosensing of osteocytes translates the applied mechanical force on bone to cellular signaling and regulation of bone adaptation. The osteocyte lacuno-canalicular system is highly efficient in transferring external mechanical force on bone to the osteocyte cell body and dendritic processes via displacement of fluid in the lacuno-canalicular space. Osteocyte mechanotransduction regulates the formation and function of the osteoblasts and osteoclasts to maintain bone homeostasis. Osteocytes produce a variety of proteins and signaling molecules such as sclerostin, cathepsin K, Wnts, DKK1, DMP1, IGF1, and RANKL/OPG to regulate osteoblast and osteoclast activity. Various genetic abnormality-associated rare bone diseases are related to disrupted osteocyte functions, including sclerosteosis, van Buchem disease, hypophosphatemic rickets, and WNT1 and plastin3 mutation-related disorders. Meticulous studies during the last 15 years on disrupted osteocyte function in rare bone diseases guided for the development of various novel therapeutic agents to treat bone diseases. Studies on genetic, molecular, and cellular mechanisms of sclerosteosis and van Buchem disease revealed a role for sclerostin in bone homeostasis, which led to the development of the sclerostin antibody to treat osteoporosis and other bone degenerative diseases. The mechanism of many other rare bone diseases and the role of the osteocyte in the development of such conditions still needs to be investigated. In this review, we mainly discuss the knowledge obtained during the last 30 years on the role of the osteocyte in rare bone diseases. We speculate about future research directions to develop novel therapeutic drugs targeting osteocyte functions to treat both common and rare bone diseases.

Effects of zoledronic acid on vertebral shape of children and adolescents with osteogenesis imperfecta

Vertebral compression fracture (VCF) is a common and severe complication of osteogenesis imperfecta (OI). We prospectively observe the changes of vertebral shape during zoledronic acid (ZOL) treatment and assess influence factors of VCF in OI children. 32 children with VCF and 10 children without VCF (NVCF) were included and given ZOL treatment for 2 years, who were matched in age and gender. Control group included 17 treatment naïve OI patients with VCF who were matched in age, gender and clinical severity to 17 patients in VCF group received ZOL treatment for 1 year (as ZOL treated group). We performed quantitative vertebral morphometry and calculated concavity index (mh/ph), height-length ratio (ah/LL, mh/LL, ph/LL) and projection area (PA) of vertebrae from T4 to L4 before and after treatment. At baseline, patients in VCF group had significantly lower PA, mh/ph, ah/LL, mh/LL and ph/LL than patients in NVCF group (P < 0.01). PA, mh/ph, ah/LL, mh/ LL and ph/LL of patients with VCF were raised by (35.2 ± 19.5)%, (22.9 ± 15.1)%, (19.6 ± 13.9)%, (33.6 ± 25.5)%, and (8.1 ± 8.8)% (P < 0.01) after 1-year treatment of ZOL, and were increased by (71.8 ± 28.2)%, (42.8 ± 21.8)%, (35.1 ± 20.6)%, (65.4 ± 43.2)%, and (12.5 ± 11.4)% after 2-year treatment of ZOL (P < 0.01). Compared to control group, mh/ph, ah/LL and mh/LL were significantly higher (P < 0.01) in ZOL treated group. LS-BMD and its increase were positively correlated to vertebral height and PA at baseline and the improvement of vertebral height and PA after ZOL treatment, respectively. In conclusion, the compressive vertebrae of OI children could be effectively reshaped during ZOL treatment. Low LS-BMD was an independent risk factor for VCF and its increase was positively correlated to the improvement in vertebral shape after ZOL treatment.

Cyclic pamidronate treatment for osteogenesis imperfecta: Report from a Brazilian reference center

Treatment of moderate and severe forms of osteogenesis imperfecta (OI) with cyclic pamidronate at the Reference Center for OI Treatment in Southern Brazil was studied. A retrospective cohort study was conducted from 2002 to 2012. Data were obtained during inpatient (drug infusion) and outpatient care. Clinical data, including the presence of blue sclerae, dentinogenesis imperfecta, history and site of the fractures, biochemical data, including calcium, phosphorus, and alkaline phosphatase levels, were systematically collected. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA). Forty-five patients (26 females) were included in the study, and the age of the patients at the time of diagnosis ranged from 1 to 144 months, with a median age (p25-p75) of 38 (5-96) months. Most cases presented OI-4 (51.1%), and the median age of the patients at the start of treatment was 3.3 years (25-75 percentiles: 0.5 - 8.7 years). Twenty-four patients (54.5%) had some adverse events or intercurrences during treatment, and the treatment compliance mean was 92.3% (± 10.7). The treatment with intravenous pamidronate has shown to be safe, well-tolerated, and effective in regard to the improvement of BMD and the reduction of the number of fractures in children and adolescents with OI.

Osteogenesis Imperfecta: New Perspectives From Clinical and Translational Research

Osteogenesis imperfecta (OI) is a monogenic bone fragility disorder that usually is caused by mutations in one of the two genes coding for collagen type I alpha chains, COL1A1 or COL1A2. Mutations in at least 18 other genes can also lead to an OI phenotype. As genetic testing is more widely used, mutations in these genes are also more frequently discovered in individuals who have a propensity for fractures, but who do not have other typical clinical characteristics of OI. Intravenous bisphosphonate therapy is still the most widely used drug treatment approach. Preclinical studies in OI mouse models have shown encouraging effects when the antiresorptive effect of a bisphosphonate was combined with bone anabolic therapy using a sclerostin antibody. Other novel experimental treatment approaches include inhibition of transforming growth factor beta signaling with a neutralizing antibody and the inhibition of myostatin and activin A by a soluble activin receptor 2B. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research

Assessing disease experience across the life span for individuals with osteogenesis imperfecta: challenges and opportunities for patient-reported outcomes (PROs) measurement: a pilot study

Background

Patient reported outcome (PRO) information is crucial for establishing better patient-provider communication, improving shared decision-making between clinicians and patients, assessing patient responses to therapeutic interventions, and increasing satisfaction with care. We used the Brittle Bones Disease Consortium (BBDC) Contact Registry for People with OI, managed by the Rare Disease Clinical Research Network (RDCRN) to (1) to evaluate the construct validity of the Patient-Reported Outcome Measurement Information System® (PROMIS®) to record important components of the disease experience among individuals with OI; and (2) explore the feasibility of using a registry to recruit individuals with OI to report on health status. Our long-term goal is to enhance communication of health and disease management findings back to the OI community, especially those who do not have access to major OI clinical centers.

Results

We demonstrated the construct validity of PROMIS instruments in OI. Our results confirm that the scores from most domains differ significantly from the general US population: individuals with OI have worse symptom burden and functioning. We found no excessive floor or ceiling effects. Our study demonstrates that the BBDC Contact Registry can be used to recruit participants for online health status surveys. However, there are numerous challenges that must be addressed: lack of self-knowledge of OI type, under-representation of men, limited ethnic diversity, and imperfect questionnaire completion rates.

Conclusion

Our pilot study demonstrated the feasibility of using a contact registry to recruit respondents from the OI community and to obtain analyzable PROMIS data regarding disease experience. Because the results differ from the general population and avoid excessive floor and ceiling effects, PROMIS instruments can be used to assess response to therapeutic interventions in individuals with OI. Future directions will include (1) development and validation of an OI-specific patient-based classification system that aggregates persons with similar clinical characteristics and risks for complications to identify treatment needs; and (2) integrating these PRO tools into routine patient care and research studies.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1004-x) contains supplementary material, which is available to authorized users.

Responsiveness to pamidronate treatment is not related to the genotype of type I collagen in patients with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heritable disorder characterized by increased bone fragility, low bone mass, dentinogenesis imperfecta, and blue sclerae. Most patients with OI have a mutation in either COL1A1 or COL1A2, which encode type I collagen. We screened these genes in Japanese patients with OI and compared their genotype and phenotype, focusing on the clinical response to treatment with pamidronate. Sequencing analysis of the genes in 19 families revealed 15 mutations, of which ten were missense mutations, thee were nonsense mutations, and two were frameshift mutations. Each of the 15 mutations was found in unrelated families, even though the patients were from a contiguous region surrounding our hospital. Substitutions of serine for glycine were the commonest mutation in both genes; notably, dentinogenesis imperfecta and fractures at birth were detected with higher frequencies in patients with this substitution when compared with other genotypes. The Z score of the bone mineral density of patients with this substitution was also lower than that of patients with other genotypes. Pamidronate treatment significantly increased the Z score in all patients, and increases in the Z score did not correlate with the OI types, causative genes, or genotype. In conclusion, the efficacy of pamidronate treatment does not seem to be related to the genotype of type I collagen in patients with OI.

Consensus guidelines on the use of bisphosphonate therapy in children and adolescents

Bisphosphonate therapy is the mainstay of pharmacological intervention in young people with skeletal fragility. The evidence of its use in a variety of conditions remains limited despite over three decades of clinical experience. On behalf of the Australasian Paediatric Endocrine Group, this evidence-based consensus guideline presents recommendations and discusses the graded evidence (using the GRADE system) for these recommendations. Primary bone fragility disorders such as osteogenesis imperfecta are considered separately from osteoporosis secondary to other clinical conditions (such as cerebral palsy, Duchenne muscular dystrophy). The use of bisphosphonates in non-fragility conditions, such as fibrous dysplasia, avascular necrosis, bone cysts and hypercalcaemia, is also discussed. While these guidelines provide an evidence-based approach where possible, further research is required in all clinical applications in order to strengthen the recommendations made.

Long-Term Bisphosphonate Therapy in Osteogenesis Imperfecta

PURPOSE OF REVIEW

Osteogenesis imperfecta (OI) is a genetic bone disorder resulting in bone fragility. It has a heterogeneous phenotype which typically includes reduced bone mass, multiple fractures, deformity, and chronic disability. Bisphosphonate treatment remains the first-line medical management, but there is still debate on aspects of its effectiveness. This review summarizes current knowledge about long-term bisphosphonate use in OI with recommendations on clinical application.

RECENT FINDINGS

Bisphosphonates increase bone mineral density, most notably of the vertebrae, and reduce fracture risk in the pediatric OI population. Gains in strength and mobility, together with the permissive effect on orthopedic surgery (e.g., in combination with intramedullary rodding) and physiotherapy, have resulted in improved quality of life for those with OI. As experience in its use continues, the risks and benefits of long-term bisphosphonate treatment in OI are slowly emerging. Patient registries containing data on genotype, phenotype, fractures, bisphosphonate treatment, orthopedic intervention, and functional outcomes are essential for systematic evaluation given the lack of large multi-centered randomized control trials.

Skeletal dysplasia: Respiratory management during infancy

BACKGROUND

Skeletal dysplasia encompasses a variety of developmental disorders of the bone and cartilage that manifest as disproportionate shortening of limbs and trunk in the neonate. Many types of skeletal dysplasia are complicated by respiratory failure at or soon after birth and require intensive care and prolonged hospitalization. Respiratory complications in these infants are complex and are characterized by airway anomalies, restrictive lung disease due to a narrow and abnormally compliant chest wall, pulmonary hypoplasia, and central apnea. Appropriate management of these unique patients requires a clear understanding of the pathophysiology and use of pulmonary function tests for early recognition and management of complications.

CONCLUSION

This review provides an overview of the underlying respiratory pathology and a practical guide to the newborn care provider for the diagnosis and management of respiratory complications in infants with skeletal dysplasia.

Osteogenesis imperfecta in children and adolescents-new developments in diagnosis and treatment

Osteogenesis imperfecta (OI) is the most prevalent heritable bone fragility disorder in children. It has been known for three decades that the majority of individuals with OI have mutations in COL1A1 or COL1A2, the two genes coding for collagen type I alpha chains, but in the past 10 years defects in at least 17 other genes have been linked to OI. Almost all individuals with a typical OI phenotype have a mutation in one of the currently known genes. Regarding medical treatment, intravenous bisphosphonate therapy is the most widely used medical approach. This has a marked effect on vertebra in growing children and can lead to vertebral reshaping after compression fractures, but there is little effect of bisphosphonate therapy on the development of scoliosis. Bisphosphonate treatment decreases long-bone fracture rates, but such fractures are still frequent. Newer medications with anti-resorptive and bone anabolic action are being investigated in an attempt to improve on the efficacy of bisphosphonates but the safety and efficacy of these new approaches in children with OI is not yet established.

The long-term effects of switching from active intravenous bisphosphonate treatment to low-dose maintenance therapy in children with osteogenesis imperfecta

BACKGROUND/AIMS

Intravenous bisphosphonate therapy is the first-line treatment in moderate-to-severe osteogenesis imperfecta (OI), but there are varied treatment protocols with little data on long-term efficacy. This study evaluates the clinical outcomes when transitioning from active bisphosphonate treatment to maintenance therapy.

METHODS

A retrospective review was conducted on 17 patients before treatment, following active treatment (zoledronate 0.05 mg/kg 6-monthly or pamidronate 6-9 mg/kg/year) and after establishment on maintenance treatment for more than 2 years (zoledronate 0.025 mg/kg 6-monthly or pamidronate <4 mg/kg/year).

RESULTS

There was a significant reduction in mean fracture rate from 1.5 ± 1.1 fractures/year at baseline to 0.7 ± 0.7 fractures/year on active treatment. Z-scores for lumbar spine bone mineral density, bone mineral content, volumetric bone mineral density and bone mineral content for lean tissue mass increased during active treatment. These improvements were maintained during the period of maintenance treatment. Vertebral height improved in fractured thoracic vertebrae from pre-treatment to active therapy and improved further during maintenance treatment. Metacarpal cortical thickness and relative cortical area also increased over the treatment periods.

CONCLUSION

Maintenance intravenous bisphosphonate therapy preserved the beneficial effects of active treatment at the doses stated above. Further studies are required to determine the optimal bisphosphonate treatment regimen in the management of children with OI.

New therapeutic targets in rare genetic skeletal diseases

Introduction: Genetic skeletal diseases (GSDs) are a diverse and complex group of rare genetic conditions that affect the development and homeostasis of the skeleton. Although individually rare, as a group of related diseases, GSDs have an overall prevalence of at least 1 per 4,000 children. There are currently very few specific therapeutic interventions to prevent, halt or modify skeletal disease progression and therefore the generation of new and effective treatments requires novel and innovative research that can identify tractable therapeutic targets and biomarkers of these diseases.

Areas covered: Remarkable progress has been made in identifying the genetic basis of the majority of GSDs and in developing relevant model systems that have delivered new knowledge on disease mechanisms and are now starting to identify novel therapeutic targets. This review will provide an overview of disease mechanisms that are shared amongst groups of different GSDs and describe potential therapeutic approaches that are under investigation.

Expert opinion: The extensive clinical variability and genetic heterogeneity of GSDs renders this broad group of rare diseases a bench to bedside challenge. However, the evolving hypothesis that clinically different diseases might share common disease mechanisms is a powerful concept that will generate critical mass for the identification and validation of novel therapeutic targets and biomarkers.

Beneficial effects of intravenous pamidronate treatment in children with osteogenesis imperfecta under 24 months of age

Osteogenesis imperfecta (OI) is an inherited disorder characterized by bone fragility and low bone mass. Low bone density and fracture is a cause of morbidity. Limited data exists on bisphosphonate treatment in patients under 24 months of age. The objective of the study was to examine the safety and efficacy of pamidronate in children under 24 months with OI. To do so, we carried out a retrospective chart review and analysis of OI patients started on intravenous pamidronate under 24 months of age. Pamidronate was administered in three-day cycles. Growth, the number of fractures, and lumbar bone mineral densities were recorded both prior to and after treatment initiation. A total of 18 patients were reviewed. Five were classified as OI type I, seven were type III, and six were type IV. The mean age at treatment initiation was 12 months (range 11 days to 23 months). The mean lumbar z score at baseline was -3.63, which improved to -1.53 at one year (P < 0.01) and 0.79 (P < 0.01) at the end of the study. The fracture rate improved from 68 fractures in 209 months (0.32 fractures/patient-month) before treatment to 41 fractures in 1,248 months (0.03 fractures/patient-month) post-treatment (P < 0.05). Height standard deviation score (SDS) was conserved from baseline to end of study (-2.12 ± 2.45 vs. -2.45 ± 2.73) (P = 0.05) with an average follow-up of 73 months. The only adverse effect recorded in six infants was fever during the initial pamidronate infusion. Treatment with intravenous pamidronate is safe, significantly improves lumbar bone mineral density (L-BMD), and reduces fracture rates in young infants with OI while preserving linear growth.

Association between joint hypermobility, scoliosis, and cranial base anomalies in paediatric Osteogenesis imperfecta patients: a retrospective cross-sectional study

BACKGROUND

Joint hypermobility is a common clinical characteristic of patients with Osteogenesis imperfecta (OI), a disorder with serious comorbidities of scoliosis and cranial base anomalies. This study aimed at evaluating how prevalent joint hypermobility is in paediatric OI patients, and to find out whether it serves as a potential predictive marker of the different spinal complications; scoliosis and craniovertebral anomalies (basilar impression and basilar invagination).

METHODS

In this cross-sectional one-center study we analysed retrospectively clinical patient records and radiographs of 47 OI patients, aged 1-19 years, some of whom were treated with bisphosphonates. Presence of joint hypermobility, scoliosis, and craniovertebral anomalies was recorded and possible connections between the phenomena were explored with correlation analysis.

RESULTS

Joint hypermobility was found in 70% of the patients. Scoliosis and cranial base anomalies had developed in 26%. The presence of spinal complications was independent of the bisphosphonate treatment status and joint hypermobility.

CONCLUSIONS

Scoliosis and craniovertebral anomalies are strongly associated in paediatric OI patients. Joint hypermobility that is much more common appears, however, to be a poor predictor.

Osteogenesis imperfecta: diagnosis and treatment

Osteogenesis imperfecta (OI) is a genetic bone fragility disorder characterized by low bone mass, skeletal deformity, and variable short stature. OI is predominantly caused by dominant mutations affecting type 1 collagen synthesis, with a number of other genes implicated in OI over recent years. The clinical severity of OI can vary greatly, even within families who share a common mutation. Optimal management of OI requires a multidisciplinary approach involving pediatrician, endocrinologist (bone and mineral physician), rehabilitation specialist, orthopedic surgeon, dentist, geneticist, social worker/psychologist, physiotherapist, and occupational therapist. Bisphosphonate therapy remains the mainstay of medical treatment in OI and has been shown to decrease bone pain, enhance well-being, improve muscle strength and mobility and decrease fracture incidence. Novel therapies are beginning to emerge as more is understood about the signaling pathways involved in bone formation. The following summarizes the diagnosis, genetic heterogeneity and management of OI in pediatric practice.

Treatment of osteogenesis imperfecta in adults

BACKGROUND

Osteogenesis imperfecta (OI) is a heterogeneous rare connective tissue disorder commonly caused by mutations in the collagen type I genes. Pharmacological treatment has been most extensively studied in children, and there are only few studies comprising adult OI patients.

OBJECTIVES

i) To review the literature on the current medical management of OI in children and adults, and thereby identify unmet medical needs and ii) to present an overview of possible future treatment options.

RESULTS

Individualization and optimization of OI treatment in adults remain a challenge, because available treatments do not target the underlying collagen defect, and available literature gives weak support for treatment decisions for adult patients.

CONCLUSIONS

Bisphosphonates are still the most widely used pharmacological treatment for adult OI, but the current evidence supporting this is sparse and investigations on indications for choice and duration of treatment are needed.

The ever-expanding conundrum of primary osteoporosis: aetiopathogenesis, diagnosis, and treatment

In recent years, as knowledge regarding the etiopathogenetic mechanisms of bone involvement characterizing many diseases has increased and diagnostic techniques evaluating bone health have progressively improved, the problem of low bone mass/quality in children and adolescents has attracted more and more attention, and the body evidence that there are groups of children who may be at risk of osteoporosis has grown. This interest is linked to an increased understanding that a higher peak bone mass (PBM) may be one of the most important determinants affecting the age of onset of osteoporosis in adulthood. This review provides an updated picture of bone pathophysiology and characteristics in children and adolescents with paediatric osteoporosis, taking into account the major causes of primary osteoporosis (PO) and evaluating the major aspects of bone densitometry in these patients. Finally, some options for the treatment of PO will be briefly discussed.

Osteogenesis imperfecta: clinical diagnosis, nomenclature and severity assessment

Recently, the genetic heterogeneity in osteogenesis imperfecta (OI), proposed in 1979 by Sillence et al., has been confirmed with molecular genetic studies. At present, 17 genetic causes of OI and closely related disorders have been identified and it is expected that more will follow. Unlike most reviews that have been published in the last decade on the genetic causes and biochemical processes leading to OI, this review focuses on the clinical classification of OI and elaborates on the newly proposed OI classification from 2010, which returned to a descriptive and numerical grouping of five OI syndromic groups. The new OI nomenclature and the pre-and postnatal severity assessment introduced in this review, emphasize the importance of phenotyping in order to diagnose, classify, and assess severity of OI. This will provide patients and their families with insight into the probable course of the disorder and it will allow physicians to evaluate the effect of therapy. A careful clinical description in combination with knowledge of the specific molecular genetic cause is the starting point for development and assessment of therapy in patients with heritable disorders including OI. © 2014 The Authors. American Journal of Medical Genetics Published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution–NonCommercial–NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.