Osteogenesis imperfecta, non-accidental injury, and temporary brittle bone disease

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.

Osteogenesis Imperfecta and Child Abuse From a Forensic Point of View

Osteogenesis imperfecta (OI) also called brittle bone disease is a rare genetic disorder that results from a defect in type 1 collagen, which is a main structural protein involved in the structure of bones, tendons, ligaments, the dentin layer of teeth, and the sclera of the eye. The defect in this gene is known to be a predisposing factor to fractures. The deficiency in type 1 collagen can be either qualitative or quantitative. Due to this deficiency, the bones become so fragile and can break easily with minimal trauma, which can be coined as “imperfect bone formation.” It also leads to bruises due to the extravasation of blood in the connective tissue of the skin. Sometimes, fractures may result from the routine handling of parents. It can be misleading since fractures are considered to be the second most common sign of child abuse according to the literature. One of the main duties in forensic medicine is examining live victims, which plays a crucial role in confirming a clinical diagnosis. In this paper, a review of the literature was conducted and a summary of reported cases of osteogenesis imperfecta, which were initially diagnosed as child abuse, is presented.

The aim of this study was to review the literature for the prevalence of misdiagnosed cases of osteogenesis imperfecta as child abuse, analyzing various types of presentations in osteogenesis imperfecta that might lead a physician to a wrong diagnosis of child abuse and to clarify common findings and fracture sites seen among patients with osteogenesis imperfecta. The literature review was conducted for both conditions, osteogenesis imperfecta and child abuse, and an evaluation and analysis of case reports and case series regarding osteogenesis imperfecta cases misdiagnosed as child abuse utilizing the PubMed search engine.

Unexplained fractures in children validate the consideration of osteogenesis imperfecta and child physical abuse. A thorough and careful evaluation is recommended as soon as possible because a delay can result in psychological consequences for both the child and the family.

Tooth dentin defects reflect genetic disorders affecting bone mineralization

Several genetic disorders affecting bone mineralization may manifest during dentin mineralization. Dentin and bone are similar in several aspects, especially pertaining to the composition of the extracellular matrix (ECM) which is secreted by well-differentiated odontoblasts and osteoblasts, respectively. However, unlike bone, dentin is not remodelled and is not involved in the regulation of calcium and phosphate metabolism. In contrast to bone, teeth are accessible tissues with the shedding of deciduous teeth and the extractions of premolars and third molars for orthodontic treatment. The feasibility of obtaining dentin makes this a good model to study biomineralization in physiological and pathological conditions. In this review, we focus on two genetic diseases that disrupt both bone and dentin mineralization. Hypophosphatemic rickets is related to abnormal secretory proteins involved in the ECM organization of both bone and dentin, as well as in the calcium and phosphate metabolism. Osteogenesis imperfecta affects proteins involved in the local organization of the ECM. In addition, dentin examination permits evaluation of the effects of the systemic treatment prescribed to hypophosphatemic patients during growth. In conclusion, dentin constitutes a valuable tool for better understanding of the pathological processes affecting biomineralization.

Current and emerging treatments for the management of osteogenesis imperfecta

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

Temporary brittle bone disease: fractures in medical care

Temporary brittle bone disease is the name given to a syndrome first reported in 1990, in which fractures occur in infants in the first year of life. The fractures include rib fractures and metaphyseal fractures which are mostly asymptomatic. The radiological features of this disorder mimic those often ascribed to typical non-accidental injury. The subject has been controversial, some authors suggesting that the disorder does not exist. This study reports five infants with typical features of temporary brittle bone disease in whom all or most of the fractures took place while in hospital. A non-accidental cause can be eliminated with some confidence, and these cases provide evidence in support of the existence of temporary brittle bone disease.

Clinical-radiological features of fractures in premature infants--a review

Premature infants are more vulnerable to bone fractures than term infants for numerous reasons, directly or indirectly related to prematurity. Although the reported incidence of fractures in this vulnerable population is somewhat inconsistent, the increased risk is clear. Metabolic disorders, genetic disease, accidental trauma, and non-accidental injury can all account for fractures in premature infants, so that determining the etiology is of importance. This increased risk does not appear to continue into childhood. Thus, most of these fractures would be found in children <3 years of age, often within the first year of life. Unfortunately, this is the same age group in which the majority of non-accidental injury (NAI) cases, frequently presenting with fractures, are seen. Further confounding the diagnosis is the possibility of previously undiagnosed fractures from trauma during delivery, and fractures due to bone weakening by metabolic diseases. A multi-dimensional approach using a combination of diagnostic procedures is necessary to properly identify the location of the fractures, the bone structure and characteristics, and the history with regards to family situation and medical treatment. This paper reviews the potential factors related to fractures in premature infants and the differential diagnoses of child abuse fractures.

Classical osteogenesis imperfecta and allegations of nonaccidental injury

We report 12 patients with osteogenesis imperfecta initially diagnosed with nonaccidental injuries. As a result, formal hearings, care proceedings, and criminal proceedings ensued and seven of the children were removed from their parents. The features suggestive of osteogenesis imperfecta at the time of the initial investigation included a positive family history in six patients, scleral discoloration in nine, abnormally large anterior fontanels in four, excessive numbers of wormian bones in four, abnormal bone texture in two, and abnormal biochemical findings in three. There were discrepancies between the fractures and other clinical evidence of inflicted trauma. The seven patients removed from their homes eventually were returned. Five patients remained at home. Information was available on the subsequent history of the patients for an average of 4.8 years. Although seven patients have had additional fractures, there have been no additional allegations of nonaccidental injury. When investigating children with unexplained fractures, it is important to review carefully their clinical history, family history, physical examination findings, and radiographic findings. Misdiagnosing patients with nonaccidental injuries causes substantial harm to the family and particularly to the child.

Osteogenesis imperfecta: practical treatment guidelines

Osteogenesis imperfecta (OI), an inherited connective tissue disorder of remarkable clinical variability, is caused by a quantitative or qualitative defect in collagen synthesis and is characterised by bone fragility. The number of fractures and deformities, and the age at which they begin greatly influence the prognosis and the achievement of walking and autonomy. A multidisciplinary team approach is essential for diagnosis, for communication with patient and parents, and to tailor treatment needs to the severity of the disease and the age of the patient. Three types of treatment are available: nonsurgical management (physical therapy, rehabilitation, bracing and splinting), surgery (intramedullary rod positioning, spinal and basilar impression surgery), and drugs to increase the strength of bone and decrease the number of fractures. An aggressive rehabilitative approach is indicated to optimise functional ability and walking capacity; appropriately timed surgery to insert intramedullary rods provides improved function of extremities. Despite a high rate of complications, intramedullary telescopic roding has proven to be the most successful method for preventing and correcting fractures and deformities of long bones, improving walking capability and leading to successful rehabilitation of even severely affected patients. Surgery may be required in patients with progressive spinal deformity and in those with symptomatic basilar impression. Hearing function, dentinogenesis imperfecta, cardiac and respiratory function, and neurological changes must be monitored. The causal defect of the disease cannot be corrected with medical treatment and, currently, only symptomatic therapy is available. In recent years growth hormone (GH) and bisphosphonate agents have been used in OI therapy. GH is beneficial in patients with moderate forms of OI, showing a positive effect on bone turnover, bone mineral density and height velocity rate. Bisphosphonates have proved beneficial in children with severe OI, increasing bone mineral density and reducing the fracture rate and pain with no adverse effects reported. These data require confirmation in double-blind controlled studies; however, bisphosphonates have markedly improved morbidity in patients with OI. Future developments in genetic therapy may be directed towards either replacing cells carrying the mutant gene with normal cells or silencing the mutant allele using antisense suppression therapy, thus transforming a biochemically severe form of OI into a mild form.

The relationship of genotype to cognitive outcome in galactosaemia

AIMS

To evaluate the cognitive outcome of a cohort of children with galactosaemia in relation to genotype.

METHODS

The cohort was drawn from children notified to the British Paediatric Surveillance Unit galactosaemia study which ran from 1988 to 1990. Cognitive outcome was assessed using the Wechsler Intelligence Scale for Children or the Wechsler Preschool and Primary Scale of Intelligence. Parents completed a questionnaire detailing educational status, and the attending paediatrician returned a questionnaire regarding age at diagnosis and biochemical outcome over the previous two years.

RESULTS

A total of 45 children were genotyped: 30 were homoallelic for the Q188R mutation, the remainder being heteroallelic for Q188R with K285N (n = 4), L195P (n = 4), or other mutations (n = 7). Psychometric evaluation was available in 34 cases: mean full scale IQ was 79, verbal quotient 79, and performance quotient 82. Genotype was not related to galactose-1-phosphate (Gal-1-P) concentrations. However, children homoallelic for the Q188R mutation had significantly lower IQ scores than those who were heteroallelic (73. 6 v 94.8). This difference was independent of social and demographic influences and Gal-1-P concentrations over the previous two years.

CONCLUSIONS

In children with galactosaemia, cognitive outcome appears to relate to genotype rather than metabolic control, as reflected by Gal-1-P concentrations. The value of measuring Gal-1-P concentrations routinely once successfully established on a galactosaemia diet is questionable as concentrations do not appear to affect outcome. In the UK population, homozygosity for the Q188R mutation is invariably associated with a poor outcome, and there is evidence that variability in neurocognitive outcome is at least part dependent on allelic heterogeneity.

Temporary brittle bone disease: a true entity?

Temporary brittle bone disease is a recently described phenotype of increased fracture susceptibility in the first year of life in which there are multiple unexplained fractures without evidence of other internal or external injury. Most child abuse experts do not accept the existence of temporary brittle bone disease and presume these cases are child abuse. The author reviewed 26 cases of infants with multiple unexplained fractures that fit the criteria of temporary brittle bone disease and studied nine of them with either computed tomography or radiographic bone density measurements. The results show a striking association between temporary brittle bone disease and decreased fetal movement, usually from intrauterine confinement, and low bone density measurements in eight of the nine infants. The association with decreased fetal movement and intrauterine confinement is in keeping with the mechanostat-mechanical load theory of bone formation. The author feels that temporary brittle bone disease is a real entity and that historical information related to decreased fetal movement or intrauterine confinement and the use of bone density measurements can be helpful in making this diagnosis.

Non-accidental injury or brittle bones

When a child presents with one or more unexplained fractures, non-accidental injury (NAI) should be considered in the differential diagnosis. This article reviews some of the other differential diagnoses, particularly osteogenesis imperfecta and the alleged "temporary brittle bone disease".