Temporary brittle bone disease: association with decreased fetal movement and osteopenia

Mechanical loading due to muscle movement regulates establishment of the collagen network in the developing murine skeleton

Mechanical loading is critical for collagen network maintenance and remodelling in adult skeletal tissues, but the role of loading in collagen network formation during development is poorly understood. We test the hypothesis that mechanical loading is necessary for the onset and maturation of spatial localization and structure of collagens in prenatal cartilage and bone, using in vivo and in vitro mouse models of altered loading. The majority of collagens studied was aberrant in structure or localization, or both, when skeletal muscle was absent in vivo. Using in vitro bioreactor culture system, we demonstrate that mechanical loading directly modulates the spatial localization and structure of collagens II and X. Furthermore, we show that mechanical loading in vitro rescues aspects of the development of collagens II and X from the effects of fetal immobility. In conclusion, our findings show that mechanical loading is a critical determinant of collagen network establishment during prenatal skeletal development.

Building a Co-ordinated Musculoskeletal System: The Plasticity of the Developing Skeleton in Response to Muscle Contractions

The skeletal musculature and the cartilage, bone and other connective tissues of the skeleton are intimately co-ordinated. The shape, size and structure of each bone in the body is sculpted through dynamic physical stimuli generated by muscle contraction, from early development, with onset of the first embryo movements, and through repair and remodelling in later life. The importance of muscle movement during development is shown by congenital abnormalities where infants that experience reduced movement in the uterus present a sequence of skeletal issues including temporary brittle bones and joint dysplasia. A variety of animal models, utilising different immobilisation scenarios, have demonstrated the precise timing and events that are dependent on mechanical stimulation from movement. This chapter lays out the evidence for skeletal system dependence on muscle movement, gleaned largely from mouse and chick immobilised embryos, showing the many aspects of skeletal development affected. Effects are seen in joint development, ossification, the size and shape of skeletal rudiments and tendons, including compromised mechanical function. The enormous plasticity of the skeletal system in response to muscle contraction is a key factor in building a responsive, functional system. Insights from this work have implications for our understanding of morphological evolution, particularly the challenging concept of emergence of new structures. It is also providing insight for the potential of physical therapy for infants suffering the effects of reduced uterine movement and is enhancing our understanding of the cellular and molecular mechanisms involved in skeletal tissue differentiation, with potential for informing regenerative therapies.

Joint development recovery on resumption of embryonic movement following paralysis

Fetal activity in utero is a normal part of pregnancy and reduced or absent movement can lead to long-term skeletal defects, such as Fetal Akinesia Deformation Sequence, joint dysplasia and arthrogryposis. A variety of animal models with decreased or absent embryonic movements show a consistent set of developmental defects, providing insight into the aetiology of congenital skeletal abnormalities. At developing joints, defects include reduced joint interzones with frequent fusion of cartilaginous skeletal rudiments across the joint. At the spine, defects include shortening and a spectrum of curvature deformations. An important question, with relevance to possible therapeutic interventions for human conditions, is the capacity for recovery with resumption of movement following short-term immobilisation. Here, we use the well-established chick model to compare the effects of sustained immobilisation from embryonic day (E)4-10 to two different recovery scenarios: (1) natural recovery from E6 until E10 and (2) the addition of hyperactive movement stimulation during the recovery period. We demonstrate partial recovery of movement and partial recovery of joint development under both recovery conditions, but no improvement in spine defects. The joints examined (elbow, hip and knee) showed better recovery in hindlimb than forelimb, with hyperactive mobility leading to greater recovery in the knee and hip. The hip joint showed the best recovery with improved rudiment separation, tissue organisation and commencement of cavitation. This work demonstrates that movement post paralysis can partially recover specific aspects of joint development, which could inform therapeutic approaches to ameliorate the effects of human fetal immobility. This article has an associated First Person interview with the first author of the paper.

Findings of metabolic bone disease in infants with unexplained fractures in contested child abuse investigations: a case series of 75 infants

Background Infants who present with multiple unexplained fractures (MUF) are often diagnosed as victims of child abuse when parents deny wrongdoing and cannot provide a plausible alternative explanation. Herein we describe evidence of specific and commonly overlooked radiographic abnormalities and risk factors that suggest a medical explanation in such cases. Methods We evaluated such infants in which we reviewed the radiographs for signs of poor bone mineralization. We reviewed medical, pregnancy and family histories. Results Seventy-five of 78 cases showed poor bone mineralization with findings of healing rickets indicating susceptibility to fragility fractures that could result from a wide variety of causes other than child abuse. We found risk factors that could explain the poor bone mineralization: maternal and infant vitamin D deficiency (VDD), decreased fetal bone loading, prematurity and others. Most infants had more than one risk factor indicating that this bone disorder is a multifactorial disorder that we term metabolic bone disease of infancy (MBDI). Maternal and infant VDD were common. When tested, 1,25-dihydroxyvitamin D levels were often elevated, indicating metabolic bone disease. Conclusions Child abuse is sometimes incorrectly diagnosed in infants with MUF. Appreciation of the radiographic signs of MBDI (healing rickets), risk factors for MBDI and appropriate laboratory testing will improve diagnostic accuracy in these cases.

Brief Review on Metabolic Bone Disease

Metabolic bone disease (MBD) is a broad term that describes a clinically heterogeneous group of diseases that are only united by a common denominator of an aberrant bone chemical milieu leading to a defective skeleton and bone abnormalities. From a forensic pathologist's perspective, MBDs create a challenging diagnostic dilemma in differentiating them from child abuse, particularly when the victim is an infant. Through this brief narrative review on MBD, bone pathophysiology and two relatively challenging pediatric MBDs will be discussed.

The importance of foetal movement for co-ordinated cartilage and bone development in utero : clinical consequences and potential for therapy

Construction of a functional skeleton is accomplished through co-ordination of the developmental processes of chondrogenesis, osteogenesis, and synovial joint formation. Infants whose movement in utero is reduced or restricted and who subsequently suffer from joint dysplasia (including joint contractures) and thin hypo-mineralised bones, demonstrate that embryonic movement is crucial for appropriate skeletogenesis. This has been confirmed in mouse, chick, and zebrafish animal models, where reduced or eliminated movement consistently yields similar malformations and which provide the possibility of experimentation to uncover the precise disturbances and the mechanisms by which movement impacts molecular regulation. Molecular genetic studies have shown the important roles played by cell communication signalling pathways, namely Wnt, Hedgehog, and transforming growth factor-beta/bone morphogenetic protein. These pathways regulate cell behaviours such as proliferation and differentiation to control maturation of the skeletal elements, and are affected when movement is altered. Cell contacts to the extra-cellular matrix as well as the cytoskeleton offer a means of mechanotransduction which could integrate mechanical cues with genetic regulation. Indeed, expression of cytoskeletal genes has been shown to be affected by immobilisation. In addition to furthering our understanding of a fundamental aspect of cell control and differentiation during development, research in this area is applicable to the engineering of stable skeletal tissues from stem cells, which relies on an understanding of developmental mechanisms including genetic and physical criteria. A deeper understanding of how movement affects skeletogenesis therefore has broader implications for regenerative therapeutics for injury or disease, as well as for optimisation of physical therapy regimes for individuals affected by skeletal abnormalities.

Cite this article: Bone Joint Res 2015;4:105–116

Bone mass and bone quality are altered by hypoactivity in the chicken

Disuse induces a rapid bone loss in adults; sedentarity is now recognized as a risk factor for osteoporosis. Hypoactivity or confinement also decrease bone mass in adults but their effects are largely unknown and only few animal models have been described. We have used 10 chickens of the rapidly growing strain 857K bred in a large enclosure (FREE group); 10 others were confined in small cages with little space to move around (HYPO group). They were sacrificed at 53 days and femurs and tibias were evaluated by texture analysis, dual energy X-ray densitometry, microcomputed tomography (microCT) and histomorphometry. Hypoactivity had no effect on the length and diameter of the bones. Bone mineral density (BMD), microCT (trabecular bone volume and trabecular microarchitecture) and texture analysis were always found significantly reduced in the animals of the HYPO group. BMD was reduced at both femur and tibia diaphysises; BMD of the metaphysis was significantly reduced in the femur but not in the tibia. An increase in osteoid volume and surfaces was noted in the HYPO group. However, there was no alteration of the mineral phase as the osteoid thickness did not differ from control animals. Bone loss was much more pronounced at the lower femur metaphysis than at the upper metaphysis of the tibia. At the tibia, only microarchitectural changes of trabecular bone could be evidenced. The confined chicken represents a new method for the study of hypodynamia since these animals do not have surgical lesions.

Overrepresentation of multiple birth pregnancies in young infants with four metabolic bone disorders: further evidence that fetal bone loading is a critical determinant of fetal and young infant bone strength

The frequency of multiple birth pregnancies, mostly twin pregnancies, was overrepresented in four different groups of young infants with fractures and bone abnormalities. This finding suggests that fetal bone loading through fetal movement is an important determinant of fetal bone formation and its resultant bone strength.

INTRODUCTION

It has been suggested that intrauterine confinement related to the multiple birth pregnancy (MBP) may lead to an increased risk for fragility fractures in young infants as a result of decreased fetal bone loading.

METHODS

To objectively test this idea, the frequency of MBPs was evaluated in five groups of young infants with bone disorders: (1) infants exposed to prolonged in utero exposure to magnesium, (2) infants with dietary copper deficiency, (3) infants with rickets from vitamin D deficiency, (4) infants with temporary brittle bone disease, and (5) infants with multiple unexplained fractures in which child abuse was the most likely diagnosis.

RESULTS

Compared to a control group and controlled for preterm birth, there was a statistically greater frequency of MBPs in each group.

CONCLUSIONS

The results of this study suggest the following: (a) The overrepresentation of MBPs (95 % twins) in these five groups indicates that fetal bone loading is a critical determinant of fetal bone strength; (b) fetal and young infant bone strength is a multifactorial characteristic; and (c) infants from MBPs are at increased risk for fragility fractures during the first 12 months of life, and thus may be mistakenly diagnosed as victims of child abuse.

Evaluating children with fractures for child physical abuse

Fractures are common injuries caused by child abuse. Although the consequences of failing to diagnose an abusive injury in a child can be grave, incorrectly diagnosing child abuse in a child whose fractures have another etiology can be distressing for a family. The aim of this report is to review recent advances in the understanding of fracture specificity, the mechanism of fractures, and other medical diseases that predispose to fractures in infants and children. This clinical report will aid physicians in developing an evidence-based differential diagnosis and performing the appropriate evaluation when assessing a child with fractures.

Bone mineral density and osteoporosis after preterm birth: the role of early life factors and nutrition

The effects of preterm birth and perinatal events on bone health in later life remain largely unknown. Bone mineral density (BMD) and osteoporosis risk may be programmed by early life factors. We summarise the existing literature relating to the effects of prematurity on adult BMD and the Developmental Origins of Health and Disease hypothesis and programming of bone growth. Metabolic bone disease of prematurity and the influence of epigenetics on bone metabolism are discussed and current evidence regarding the effects of breastfeeding and aluminium exposure on bone metabolism is summarised. This review highlights the need for further research into modifiable early life factors and their effect on long-term bone health after preterm birth.

Longitudinal effects of fat and lean mass on bone accrual in infants

There are conflicting reports on the influence of lean and fat mass on bone accrual during childhood. No infant's studies have been reported that describe the influence of changes in body composition with changes in bone accrual during the first year of life. The objective of this research was to test the hypothesis that greater gains in lean mass will have a positive effect on bone mineral content (BMC) accrual, while greater gains in fat mass will have a negative effect on BMC accrual in infants. Longitudinal data from 3 previous infant studies were used. Linear mixed models, adjusting for age, sex, dietary calcium, and length were used to investigate longitudinal and cross-sectional associations between total body BMC and lean and fat mass in the individual studies and in a combined analysis. In both individual and combined analyses, we found that lean and fat mass were positively associated with whole body BMC accrual (all, P<0.001). The cross-sectional association of BMC and dietary calcium was negative in one study (P<0.05). No differences in BMC change between sexes were observed in three studies. Our results showed positive cross-sectional and longitudinal associations between total body BMC and lean mass in infants. In contradiction to our hypothesis for fat mass, we found a positive cross-sectional and longitudinal association between total body BMC and fat mass in infants.

Biophysical stimuli induced by passive movements compensate for lack of skeletal muscle during embryonic skeletogenesis

In genetically modified mice with abnormal skeletal muscle development, bones and joints are differentially affected by the lack of skeletal muscle. We hypothesise that unequal levels of biophysical stimuli in the developing humerus and femur can explain the differential effects on these rudiments when muscle is absent. We find that the expression patterns of four mechanosensitive genes important for endochondral ossification are differentially affected in muscleless limb mutants, with more extreme changes in the expression in the humerus than in the femur. Using finite element analysis, we show that the biophysical stimuli induced by muscle forces are similar in the humerus and femur, implying that the removal of muscle contractile forces should, in theory, affect the rudiments equally. However, simulations in which a displacement was applied to the end of the limb, such as could be caused in muscleless mice by movements of the mother or normal littermates, predicted higher biophysical stimuli in the femur than in the humerus. Stimuli induced by limb movement were much higher than those induced by the direct application of muscle forces, and we propose that movements of limbs caused by muscle contractions, rather than the direct application of muscle forces, provide the main mechanical stimuli for normal skeletal development. In muscleless mice, passive movement induces unequal biophysical stimuli in the humerus and femur, providing an explanation for the differential effects seen in these mice. The significance of these results is that forces originating external to the embryo may contribute to the initiation and progression of skeletal development when muscle development is abnormal.

Temporary brittle bone disease: relationship between clinical findings and judicial outcome

There is a wide differential diagnosis for the child with unexplained fractures including non-accidental injury, osteogenesis imperfecta and vitamin D deficiency rickets. Over the last 20 years we and others have described a self-limiting syndrome characterised by fractures in the first year of life. This has been given the provisional name temporary brittle bone disease. This work had proved controversial mostly because the fractures, including rib fractures and metaphyseal fractures, were those previously regarded as typical or even diagnostic of non-accidental injury. Some have asserted that the condition does not exist. Over the years 1985 to 2000 we investigated 87 such cases with fractures with a view to determining the future care of the children. In 85 of these the judiciary was involved. We examined the clinical and radiological findings in the 33 cases in which there was a judicial finding of abuse, the 24 cases in which the parents were exonerated and the 28 cases in which no formal judicial finding was made. The three groups of patients were similar in terms of demographics, age at fracturing and details of the fractures. The clinical similarities between the three groups of patients contrast with the very different results of the judicial process.

The radiographic approach to child abuse

BACKGROUND

Osseous injuries are a major facet of child abuse and in most patients radiographic imaging plays a major role in diagnosis. While some injuries are typically produced as a result of excessive and inappropriate force other injuries are nonspecific in terms of their causation, but become suspicious when the history provided by the caretakers is inconsistent with the type of injury produced.

QUESTIONS/PURPOSES

I detail the radiographic imaging of the more characteristic of the highly specific injuries, discuss the major issues that relate to some moderate- or low-specificity injuries, and describe several diseases that mimic abuse.

METHODS

A review of the current and recent literature focused on the radiographic imaging of child abuse was performed by searching the National Library of Medicine database at pubmed.gov. Keywords used included: radiology, fracture, child abuse, and/or nonaccidental trauma.

RESULTS

Injuries that are highly specific for the diagnosis of abuse include metaphyseal corner fractures, posteromedial rib fractures, and sternal, scapular, and spinous process fractures. Lesions of moderate specificity include, among other injuries, multiple fractures of various ages and epiphyseal separations. Long-bone fractures and clavicular fractures, while common, are of low specificity. In addition to the appropriate accurate diagnosis of these injuries, several diseases and syndromes may mimic abuse due to the similarity in the radiographic picture.

CONCLUSIONS

Stratification of fractures sustained in child abuse according to specificity and an understanding of the several diseases that mimic abuse are helpful in the accurate diagnosis of child abuse.

LEVEL OF EVIDENCE

Level V, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Assisted exercise improves bone strength in very low birthweight infants by bone quantitative ultrasound

AIM

To evaluate whether assisted exercise could prevent the development of osteopenia of prematurity, we performed assisted exercise in the study group of very low birthweight (VLBW) premature infants.

METHODS

Sixteen premature infants with birthweight below 1500 g were enrolled in this study and randomly assigned into the exercise (n = 8) and control (n = 8) groups. Assisted exercise involved full extension and flexion range of motion of the upper and lower extremities by a trained nurse with a schedule of 5 days a week for a total of 4 weeks. Bone strength was determined by quantitative ultrasound measurement of tibial bone speed of sound every 2 weeks during the study period.

RESULTS

No difference in gender, birthweight, and gestation age between the exercise and control groups was noted. There was statistically significant less tibial bone speed of sound decrease in the exercise group on the sixth and eighth week of life. During the study period, there were no statistically significant differences in blood biochemistry data, including calcium, phosphorus, magnesium, alkaline phosphatase, osteocalcin and osteoprotegerin, between the two groups.

CONCLUSIONS

This study revealed that early assisted exercise could improve bone strength in very low birthweight infants. The biochemical markers of bone metabolism, osteocalcin and osteoprotegerin, could not be the indicators for early diagnosis of osteopenia of prematurity.

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.

Mechanobiology of embryonic skeletal development: Insights from animal models

A range of clinical conditions in which fetal movement is reduced or prevented can have a severe effect on skeletal development. Animal models have been instrumental to our understanding of the interplay between mechanical forces and skeletal development, particularly the mouse and the chick model systems. In the chick, the most commonly used means of altering the mechanical environment is by pharmaceutical agents which induce paralysis, whereas genetically modified mice with nonfunctional or absent skeletal muscle offer a valuable tool for examining the interplay between muscle forces and skeletogenesis in mammals. This article reviews the body of research on animal models of bone or joint formation in vivo in the presence of an altered or abnormal mechanical environment. In both immobilized chicks and "muscleless limb" mice, a range of effects are seen, such as shorter rudiments with less bone formation, changes in rudiment and joint shape, and abnormal joint cavitation. However, although all bones and synovial joints are affected in immobilized chicks, some rudiments and joints are unaffected in muscleless mice. We propose that extrinsic mechanical forces from movements of the mother or littermates impact on skeletogenesis in mammals, whereas the chick embryo is reliant on intrinsic movement for mechanical stimulation. The insights gained from animal models into the mechanobiology of embryonic skeletal development could provide valuable cues to prospective tissue engineers of cartilage and bone and contribute to new or improved treatments to minimize the impact on skeletal development of reduced movement in utero.

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.

Evaluating infants and young children with multiple fractures

Infants and toddlers with multiple unexplained fractures are often victims of inflicted injury. However, several medical conditions can also cause multiple fractures in children in this age group. In this report, the differential diagnosis of multiple fractures is presented, and diagnostic testing available to the clinician is discussed. The hypothetical entity "temporary brittle-bone disease" is examined also. Although frequently offered in court cases as a cause of multiple infant fractures, there is no evidence that this condition actually exists.

Hypothesis: fetal movement influences fetal and infant bone strength

Infants who present with multiple unexplained fractures in which there is no prior trauma, no radiographic evidence of metabolic bone disease, and no biochemical evidence of metabolic bone disease are almost always diagnosed as victims of child abuse, even though parents and caregivers deny wrongdoing. Such a diagnosis has far reaching implications for the infant and family. This article describes the clinical features of 65 such infants with multiple unexplained fractures in which the parents and caregivers deny wrongdoing and in which child abuse was diagnosed. These infants have the phenotype of temporary brittle bone disease that was described by Paterson. A striking observation in these young infants is the pregnancy history of decreased fetal movement. A hypothesis is suggested as an alternative explanation for the mechanism of these fractures in these infants--namely temporary brittle bone disease from fetal immobilization. This hypothesis states that fetal bone loading through fetal movement is essential for the formation of bones of normal strength. This hypothesis is an application of Frost's mechanostat/bone-loading model of bone physiology to the prenatal period of bone formation. This hypothesis explains many of the other observations about temporary brittle bone disease including the early onset of the fractures in the first several months of life, the lack of bruising, the lack of other internal organ injury, and the low risk profile of many of the parents for committing child abuse.

Femoral and tibial fractures in a child with myelomeningocele

Femoral and tibial fractures can occur from accidents, child abuse or pathological causes. It is often very difficult to distinguish the cause among those cases. Radiological diagnosis may be needed for clinicians and medical examiners in order to assist determining the reason of fractures. In this report, we submit a case with femoral and tibial fractures associated with myelomeningocele. This patient was diagnosed as child abuse by clinicians. On review it was decided that her fractures were not because of non-accidental injury. The values of bone mineral density of the upper limb were low and illness caused her fractures.

The lesson of temporary brittle bone disease: all bones are not created equal

Temporary brittle bone disease (TBBD) is a recently described phenotype of multiple, unexplained fractures in the first year of life and predominantly in the first 6 months of life. There is usually no other injury such as bruising, subdural hematomas, retinal hemorrhages, or other internal organ injury. The susceptibility to fracture is transient, and there are no other radiographic or biochemical abnormalities noted in the standard evaluation that might suggest an underlying cause. The child abuse and pediatric radiology communities have, for the most part, been unwilling to accept this as a real condition, for they believe it is a ruse for child abuse. This review describes the experience of the author in evaluating infants with multiple unexplained fractures and the hypothesis that has emerged for explaining TBBD. The hypothesis is a prenatal application of the mechanostat/bone loading theory of bone formation and states that TBBD is caused by fetal immobilization which leads to fetal bone unloading and transient, relative osteopenia. Such susceptible infants can fracture with routine handling and present with a pattern of fractures that is similar to that which has been thought to be highly specific for child abuse. The review presents: (a) the evidence that indicates that normal fetal movement is important for normal fetal bone strength, (b) a critique of the radiologic approach in the diagnosis of child abuse in infants with multiple unexplained fractures, (c) observations that would indicate that child abuse is unlikely in infants with TBBD, and (d) new approaches to the infant with multiple unexplained fractures that would assist in accurate diagnosis.

The bone disease of preterm birth: a biomechanical perspective

The bone disease of preterm birth has traditionally been explained by a decrease in bone formation from insufficient availability of calcium and phosphorus. However, there is emerging evidence that there is increased bone resorption in the bone disease of preterm birth, an observation that indicates some other explanation for this condition. The biomechanical model of postnatal bone formation states that, through a regulatory feedback system in the bone called the mechanostat, bone is able to respond to increased bone loading by increasing bone strength and to decreased bone loading by decreasing bone strength. It is suggested that this increased bone resorption in the markedly preterm infant compared with the term infant is secondary to decreased bone loading. Application of this model to the fetus and preterm infant suggests that intrauterine bone loading of the fetus from movement and kicking against the uterus is critical for normal fetal bone formation. The associated muscle growth from this activity also contributes to bone loading. The markedly preterm infant is deprived of much of this critical time period of intrauterine bone accretion, and bone formation occurs in the less favorable extrauterine environment, where there is significantly less bone loading.

Imaging of child abuse

Skeletal imaging plays a critical role in the diagnosis of abuse. High-detail radiographs of the entire skeleton, at times supplemented with nuclear imaging, CT, US, and MR imaging, elucidate the variety of findings with this entity. The radiologist's role includes careful analysis of clinical history, familiarity with typical osseous findings in abuse, and awareness of potential normal variants and pitfalls. An accurate diagnosis of abuse can then lead to appropriate measures to protect all family members at risk of serious injury.

Osteogenesis imperfecta: perspectives and opportunities

The last 2 years have seen additions proposed to the very limited armamentarium of treatments for osteogenesis imperfecta. These include the use of bisphosphonates to decrease bone resorption, growth hormone to augment growth and collagen production, and bone marrow transplantation to create chimeras at the level of the collagen production unit in bone. Although there are optimistic proponents for each strategy, the lack of well-controlled studies and the absence of clearly defined objectives for therapy hinder clear assessment.

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.

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.