Osteogenesis imperfecta

Interlocking Fixation in Fassier-Duval Rods: Performance and Success Factors

INTRODUCTION

Pediatric patients with osteogenesis imperfecta (OI) can be treated with intramedullary Fassier-Duval rod (FDR) systems for limb deformity or recurrent fractures. Single-interlocking pins can improve epiphyseal fixation, but there is a paucity of literature examining incidence of rod migration or pin backout long-term. The purpose of this study is to quantify rates of rod migration and pin backout in OI patients treated with single-interlocking FDRs.

METHODS

A retrospective chart review was performed on pediatric patients treated at a tertiary care center across a 15-year period. Inclusion criteria to select patients was: (1) Pediatric patients (below 18 y of age); (2) Patients with confirmed OI; and (3) Patients with lower extremity fractures or deformity treated with FDRs with distal interlocking pins. Age at time of surgery, rates of obturator migration and pin backout and prominence were collected. We recorded if pin tips were bent by the surgeon during the procedure. Bivariate statistics were used to analyze risk factors for pin backout and prominence.

RESULTS

Twenty-four single-interlocking pin FDRs (21 tibia, 3 femur) were identified. The mean age at index surgery was 5.7±3.4 years, with the mean follow-up time of 7.2±4.7 years. Fourteen (58%) rods underwent revision surgery. Obturator proximal migration was observed in 3/24 rods (13%). No cases of obturator distal migration were observed (0/24, 0%). Mean proximal obturator migration was 2.16±1.8 cm. Revision for pin backout was observed in 10 (42%) rods and pin prominence in 11 (46%) extremities. Bending interlocking pins on at least 1 end was associated with decreased pin backout (P=0.01) and prominence (P=0.04).

CONCLUSIONS

Even with distal interlocking pins, the obturator of FDRs can still migrate over time. Pin backout is a common indication for revision surgery. Bending interlocking pins can decrease rates of pin backout and prominence.

LEVEL OF EVIDENCE

Level III.

Physiological Loading-Induced Interstitial Fluid Dynamics in Osteon of Osteogenesis Imperfecta Bone

Osteogenesis imperfecta (OI), also known as "brittle bone disease," is a genetic bone disorder. OI bones experience frequent fractures. Surgical procedures are usually followed by clinicians in the management of OI. It has been observed physical activity is equally beneficial in reducing OI bone fractures in both children and adults as mechanical stimulation improves bone mass and strength. Loading-induced mechanical strain and interstitial fluid flow stimulate bone remodeling activities. Several studies have characterized strain environment in OI bones, whereas very few studies attempted to characterize the interstitial fluid flow. OI significantly affects bone micro-architecture. Thus, this study anticipates that canalicular fluid flow reduces in OI bone in comparison to the healthy bone in response to physiological loading due to altered poromechanical properties. This work attempts to understand the canalicular fluid distribution in single osteon models of OI and healthy bone. A poromechanical model of osteon is developed to compute pore-pressure and interstitial fluid flow as a function of gait loading pattern reported for OI and healthy subjects. Fluid distribution patterns are compared at different time-points of the stance phase of the gait cycle. It is observed that fluid flow significantly reduces in OI bone. Additionally, flow is more static than dynamic in OI osteon in comparison to healthy subjects. This work attempts to identify the plausible explanation behind the diminished mechanotransduction capability of OI bone. This work may further be extended for designing better biomechanical therapies to enhance the fluid flow in order to improve osteogenic activities in OI bone.

Total Hip Replacements in Patients with Rare Pathologic Conditions Affecting Bone

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As a result of the advances in surgical technique and implant design, total hip arthroplasty (THA) is increasingly offered for the management of osteoarthritis of the hip in patients with fragile or pathologic bone.

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Posttraumatic or congenital deformities associated with fragile or pathologic bone are frequently encountered and necessitate diligent preoperative planning.

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Surgeons should be prepared to evaluate and manage intraoperative iatrogenic fracture.

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While there is limited evidence to date, components made with computer-assisted design can be considered, given the unique and highly variable patient population.

Simultaneous Bilateral Patellar Tendon Rupture in a Patient With Osteogenesis Imperfecta

Simultaneous bilateral patellar tendon rupture is an infrequent and debilitating injury. Although tendon rupture is associated with multiple systemic diseases, there is limited literature regarding its association with osteogenesis imperfecta and successful treatment techniques. We report a case of a 56-year-old man with a history of osteogenesis imperfecta type I who experienced bilateral patellar tendon rupture following a fall from standing height in the absence of other risk factors. Both injuries were effectively treated with primary open repair utilizing Krackow suture technique and transosseous tunnel fixation bilaterally. The patient demonstrated full functional recovery at 14-month follow-up. Osteogenesis imperfecta is a risk factor for the development of bilateral patellar tendon rupture. Open bilateral transosseous suture repair has proven to be successful despite defects in type 1 collagen and underlying tendon weakness.

Histopathology of osteogenesis imperfecta bone. Supramolecular assessment of cells and matrices in the context of woven and lamellar bone formation using light, polarization and ultrastructural microscopy

Diaphyseal long bone cortical tissue from 30 patients with lethal perinatal Sillence II and progressively deforming Sillence III osteogenesis imperfecta (OI) has been studied at multiple levels of structural resolution. Interpretation in the context of woven to lamellar bone formation by mesenchymal osteoblasts (MOBLs) and surface osteoblasts (SOBLs) respectively demonstrates lamellar on woven bone synthesis as an obligate self-assembly mechanism and bone synthesis following the normal developmental pattern but showing variable delay in maturation caused by structurally abnormal or insufficient amounts of collagen matrix. The more severe the variant of OI is, the greater the persistence of woven bone and the more immature the structural pattern; the pattern shifts to a structurally stronger lamellar arrangement once a threshold accumulation for an adequate scaffold of woven bone has been reached. Woven bone alone characterizes lethal perinatal variants; variable amounts of woven and lamellar bone occur in progressively deforming variants; and lamellar bone increasingly forms rudimentary and then partially compacted osteons not reaching full compaction. At differing levels of microscopic resolution: lamellar bone is characterized by short, obliquely oriented lamellae with a mosaic appearance in progressively deforming forms; polarization defines tissue conformations and localizes initiation of lamellar formation; ultrastructure of bone forming cells shows markedly dilated rough endoplasmic reticulum (RER) and prominent Golgi bodies with disorganized cisternae and swollen dispersed tubules and vesicles, structural indications of storage disorder/stress responses and mitochondrial swelling in cells with massively dilated RER indicating apoptosis; ultrastructural matrix assessments in woven bone show randomly oriented individual fibrils but also short pericellular bundles of parallel oriented fibrils positioned obliquely and oriented randomly to one another and in lamellar bone show unidirectional fibrils that deviate at slight angles to adjacent bundles and obliquely oriented fibril groups consistent with twisted plywood fibril organization. Histomorphometric indices, designed specifically to document woven and lamellar conformations in normal and OI bone, establish ratios for: i) cell area/total area X 100 indicating the percentage of an area occupied by cells (cellularity index) and ii) total area/number of cells (pericellular matrix domains). Woven bone is more cellular than lamellar bone and OI bone is more cellular than normal bone, but these findings occur in a highly specific fashion with values (high to low) encompassing OI woven, normal woven, OI lamellar and normal lamellar conformations. Conversely, for the total area/number of cells ratio, pericellular matrix accumulations in OI woven are smallest and normal lamellar largest. Since genotype-phenotype correlation is not definitive, interposing histologic/structural analysis allowing for a genotype-histopathologic-phenotype correlation will greatly enhance understanding and clinical management of OI.

Osteogenesis imperfecta: an update on clinical features and therapies

Osteogenesis imperfecta (OI) is an inherited skeletal dysplasia characterized by bone fragility and skeletal deformities. While the majority of cases are associated with pathogenic variants in COL1A1 and COL1A2, the genes encoding type I collagen, up to 25% of cases are associated with other genes that function within the collagen biosynthesis pathway or are involved in osteoblast differentiation and bone mineralization. Clinically, OI is heterogeneous in features and variable in severity. In addition to the skeletal findings, it can affect multiple systems including dental and craniofacial abnormalities, muscle weakness, hearing loss, respiratory and cardiovascular complications. A multi-disciplinary approach to care is recommended to address not only the fractures, reduced mobility, growth and bone pain but also other extra-skeletal manifestations. While bisphosphonates remain the mainstay of treatment in OI, new strategies are being explored, such as sclerostin inhibitory antibodies and TGF beta inhibition, to address not only the low bone mineral density but also the inherent bone fragility. Studies in animal models have expanded the understanding of pathomechanisms of OI and, along with ongoing clinical trials, will allow to develop better therapeutic approaches for these patients.

Evaluation of Fracture and Osteotomy Union in the Setting of Osteogenesis Imperfecta: Reliability of the Modified Radiographic Union Score for Tibial Fractures (RUST)

BACKGROUND

Evaluation of the union of osteotomies and fractures in patients with osteogenesis imperfecta (OI) is a critical component of patient care. Studies of the OI patient population have so far used varied criteria to evaluate bony union. The radiographic union score for tibial fractures (RUST), which was subsequently revised to the modified RUST, is an objective standardized method of evaluating fracture healing. We sought to evaluate the reliability of the modified RUST in the setting of the tibias of patients with OI.

METHODS

Tibial radiographs of 30 patients with OI fractures, or osteotomies were scored by 3 observers on 2 separate occasions. Each of the 4 cortices was given a score (1=no callus, 2=callus present, 3=bridging callus, and 4=remodeled, fracture not visible) and the modified RUST is the sum of these scores (range, 4 to 16). The interobserver and intraobserver reliabilities were evaluated using intraclass coefficients (ICC) with 95% confidence intervals.

RESULTS

The ICC representing the interobserver reliability for the first iteration of scores was 0.926 (0.864 to 0.962) and for the second series was 0.915 (0.845 to 0.957). The ICCs representing the intraobserver reliability for each of the 3 reviewers for the measurements in series 1 and 2 were 0.860 (0.707 to 0.934), 0.994 (0.986 to 0.997), and 0.974 (0.946 to 0.988).

CONCLUSIONS

The modified RUST has excellent interobserver and intraobserver reliability in the setting of OI despite challenges related to the poor quality of the bone and its dysplastic nature. The application and routine use of the modified RUST in the OI population will help standardize our evaluation of osteotomy and fracture healing.

LEVEL OF EVIDENCE

Level III-retrospective study of nonconsecutive patients.

Treatment of Femur Neck Fracture in Children with Osteogenesis Imperfecta: Two Case Reports

CASE

We present 2 cases of femoral neck fracture (FNF) in patients with osteogenesis imperfecta (OI) with a previously placed intramedullary nail (IMN). Case 1: A 12-year-old girl who sustained a right FNF after spine surgery. Case 2: An 18-year-old boy who sustained a right FNF after IMN of the left side. Both patients underwent our modified surgical technique as described below. Both patients recovered well overall.

CONCLUSIONS

FNF in patients with OI poses a significant challenge especially in the presence of an IMN. Here, we describe a surgical technique that provides stable fixation with a less stress riser effect by bypassing the screws and a previously placed nail.

Surgical Treatment of Bilateral Tibia Deformity in a 9-Year-Old Child Suffering from Osteogenesis Imperfecta Type III: A Case Report

Patient: Male, 9

Final Diagnosis: Osteogenesis imperfecta type III

Symptoms: Walking difficulties

Medication: —

Clinical Procedure: Osteotomies and realignment of bone deformity

Specialty: Orthopedics and Traumatology

Management of Catastrophic Proximal Junctional Failure Following Spinal Deformity Correction in an Adult with Osteogenesis Imperfecta: Case Report and Technical Note

BACKGROUND

Proximal junctional failure (PJF) is a major and sometimes devastating problem following adult spinal deformity (ASD) correction surgery. Common consensus still lags on guidelines for preventing and managing these complications. Surgical treatment of scoliosis in the presence of osteogenesis imperfecta (OI) in the pediatric population is well described. The complication rates are unusually higher in this special subset of patients owing to poor quality of bone. There is a paucity of literature focusing on surgical techniques, strategies, and problems involved in the management of ASD associated with OI.

CASE DESCRIPTION

We report a 59-year-old female with type 1 OI and adult scoliosis who underwent T10-to-pelvis fusion for ASD according to the principles of adult deformity correction. At a 1-year follow-up, she presented with asymptomatic proximal junctional kyphosis of 45° and 2 weeks later had PJF along with spinal cord injury after a fall. On computed tomography scan, kyphosis was increased to 60° at T9-T10. She underwent decompression and revision deformity correction using quadruple rods, with extension of instrumentation to T2 with soft landing using rib bands. At a 4-year follow-up, she had a good functional outcome after revision surgery.

CONCLUSIONS

This is the first report of successful management of PJF following ASD correction in the presence of OI using this technique. Suboptimal hold of implants due to poor bone quality must be at the focus of any surgical planning for these patients. All possible strategies to prevent PJF must be considered when planning the deformity correction in adults with OI.

COL1A1/2 Pathogenic Variants and Phenotype Characteristics in Ukrainian Osteogenesis Imperfecta Patients

Osteogenesis imperfecta (OI) is a hereditary bone disorder caused by defects of type I collagen. Although up to 90% of patients harbor pathogenic variants in the COL1A1/2 gene, which codes for collagen α1/2 chains, the spectrum of OI genotypes may differ between populations, and there is academic controversy around OI genotype-phenotype correlations. In the current study, 94 Ukrainian OI families were interviewed. Clinical and genealogical information was collected from patients in spoken form, and their phenotypes were described. To identify the spectrum of collagen I pathogenic variants, COL1A1/2 mutational analysis with Sanger sequencing was performed on the youngest affected individual of every family. Of the 143 patients investigated, 67 (46.85%) had type I OI, 24 (16.78%) had type III, 49 (34.27%) had type IV, and III (2.10%) had type V. The mean number of fractures suffered per patient per year was 1.32 ± 2.88 (type I 0.50 ± 0.43; type III 3.51 ± 6.18; type IV 1.44 ± 1.77; and type 5 0.77 ± 0.23). 87.23% of patients had skeletal deformations of different severity. Blue sclera, dentinogenesis imperfecta, and hearing loss were present in 87%, 55%, and 22% of patients, respectively. COL1A1/2 pathogenic variants were harbored by 60 patients (63.83%). 27 pathogenic variants are described herein for the first time. The majority of the pathogenic variants were located in the COL1A1 gene (76.19%). Half (49.21%) of the pathogenic variants were represented by structural variants. OI phenotype severity was highly correlated with type of collagen I defect. The current article presents an analysis of the clinical manifestations and COL1A1/2 mutational spectrum of 94 Ukrainian OI families with 27 novel COL1A1/2 pathogenic variants. It is hoped that this data and its analysis will contribute toward the increased understanding of the phenotype development and genetics of the disorder.

Osteogenesis Imperfecta: A Pediatric Orthopedic Perspective

Osteogenesis imperfecta is a genetically and phenotypically heterogeneous disorder related to a defect or deficiency in the production of type I collagen. It is characterized by brittle bones, fractures, spine and extremity deformity, and a host of extraskeletal manifestations. Type I collagen is present in bone, tendons, ligaments, skin, dentin, and the sclera of the eye and other connective tissues. Osteogenesis imperfecta includes a multitude of disease manifestations that may be present at birth or develop over time and vary depending on the severity of the disease. This article describes the disease presentation and management considerations from a pediatric orthopedic perspective.

Results of Rodding and Impact on Ambulation and Refracture in Osteogenesis Imperfecta: Study of 21 Children

INTRODUCTION

Delay in presentation and surgical intervention is quite usual in osteogenesis imperfecta (OI) because of various local and cultural beliefs. The purpose of this study is to review the results of 21 children who had intramedullary rodding and its effect on ambulation and refracture.

METHODS

We reviewed 21 children with a clinical diagnosis of OI. The mean age of children at presentation was 8.74 years (3-21 years). All children had recurrent fractures of long bones. Twenty eight femurs and 21 tibiae were stabilized with intramedullary rodding. Ambulatory status was assessed by the Hoffers and Bullock's (H and B) grading, and muscle power was recorded using the Medical Research Council, U. K., grade. Ten children had received intravenous bisphosphonates preoperatively. Postoperatively, the children were assessed for ambulatory status, pain, and ability for independent self-care.

RESULTS

The mean followup period was 34 months (24-48 months). Rush rods were used in 20 femurs, the Fassier-Duval (FD) rods in 6 femurs, and in two cases, with narrow intramedullary canals, Kirshner (K) wires were used. For the tibiae, 15 children received rush rods and in 6 cases, an FD rod was used. The mean time to fracture union was 8 weeks (6-12 weeks). Before surgery, 13 children were in H and B Grade 4 (wheel-chair independent or carried by parents usually in a developing country), four were able to ambulate with a walking aid (H and B Grade 3b), and four children were able to walk about in the house without aids (H & B Grade 2). After the rodding procedure, the ambulatoty status improved in 11 (50%) children. Seven children (33%) became household physiologic walkers (H & B Grade 3b), three achieved independent ambulation with orthosis (H & B Grade 1b), and one child with mild OI could walk unaided (H & B Grade 1a). No child had deterioration in ambulatory status. Only two children had refractures at the distal end of the rod due to continual growth of bones.

CONCLUSIONS

Intramedullary rodding treatment for recurrent fractures in children with OI improves their mobility potential. It also and prevents repeated cast application, disuse wasting, and osteopenia which can lead to deterioration in the quality of the long bones.

Hip Dysplasia in Children With Osteogenesis Imperfecta: Association With Collagen Type I C-Propeptide Mutations

BACKGROUND

Osteogenesis imperfecta (OI) is a heritable skeletal disorder characterized by bone fragility and short stature that is usually due to mutations in 1 of the 2 genes that code for collagen type I α-chains. The association between hip dysplasia and OI has not been systematically investigated. In this single-center study, we retrospectively reviewed all cases of OI associated with hip dysplasia to describe clinical characteristics and the effect of therapy.

METHODS

We reviewed the charts of 687 patients with OI who were seen at the Shriners Hospital for Children in Montreal between 1999 and 2013 to identify patients with a diagnosis of hip dysplasia. Clinical characteristics and the course after therapeutic interventions were extracted from the charts.

RESULTS

Hip dysplasia was diagnosed in 8 hips of 5 patients (4 boys, 1 girl; age at diagnosis ranged between 3 wk and 27 mo old). The prevalence of hip dysplasia and OI was therefore 0.87% (per patient). In 4 of the 5 patients (80%), OI was caused by mutations affecting the C-propeptide of collagen type I, which is otherwise rare in OI. Among the 26 patients with C-propeptide mutations followed at our institution, 4 (15%) had hip dysplasia. Pavlik harness treatment was attempted in 2 patients (3 hips) but was not effective in either case and resulted in avascular necrosis of 1 hip. Femoral varus derotational shortening osteotomies using a telescopic rod were performed in all 8 hips along with a closed reduction in 4 hips and an open reduction in 4 hips. Concomitant pelvic osteotomies were performed in 2 hips (1 patient). Surgery resulted in redislocation of 1 hip; all other surgically treated hips remained reduced.

CONCLUSIONS

Clinical screening for hip dysplasia is difficult in OI owing to the bowing of the proximal femur and the risk of causing fractures. OI patients with positive C-propeptide mutation should therefore be screened for hip dysplasia by use of ultrasound. Presence of a C-propeptide mutation appears to be a risk factor for hip dysplasia (80%). It appears that Pavlik harness treatment is not useful in children with OI. The usual treatment of children with OI who pull to stand or started walking with femoral deformity is femoral osteotomy and rodding. In case of associated hip dysplasia with a dislocation, open reduction of the hip and a possible concomitant pelvic osteotomy appears to be a valid management option.

LEVEL OF EVIDENCE

Level IV.

The Spine in Patients With Osteogenesis Imperfecta

Osteogenesis imperfecta is a genetic disorder of type I collagen. Although multiple genotypes and phenotypes are associated with osteogenesis imperfecta, approximately 90% of the mutations are in the COL1A1 and COL1A2 genes. Osteogenesis imperfecta is characterized by bone fragility. Patients typically have multiple fractures or limb deformity; however, the spine can also be affected. Spinal manifestations include scoliosis, kyphosis, craniocervical junction abnormalities, and lumbosacral pathology. The incidence of lumbosacral spondylolysis and spondylolisthesis is higher in patients with osteogenesis imperfecta than in the general population. Use of diphosphonates has been found to decrease the rate of progression of scoliosis in patients with osteogenesis imperfecta. A lateral cervical radiograph is recommended in patients with this condition before age 6 years for surveillance of craniocervical junction abnormalities, such as basilar impression. Intraoperative and anesthetic considerations in patients with osteogenesis imperfecta include challenges related to fracture risk, airway management, pulmonary function, and blood loss.

Multiple Spontaneous Intracranial-Extracranial Arterial Dissections in a Patient with Osteogenesis Imperfecta

A 40-year-old male with osteogenesis imperfecta (OI) was admitted to the hospital with an acute right monoparesis. Diffusion-weighted MRI showed infarction in the territory of the left anterior cerebral artery (ACA) and in the left posterior cerebral artery (PCA). In his vascular imaging, occlusion of the left vertebral artery (VA) starting from V2 segment was consistent with dissection and pseudoaneurysm in the right ACA. We presented this case because of the presence of spontaneous and simultaneous occurrence of both intracranial and extracranial arterial dissections in OI.

Systematic data-querying of large pediatric biorepository identifies novel Ehlers-Danlos Syndrome variant

BACKGROUND

Ehlers Danlos Syndrome is a rare form of inherited connective tissue disorder, which primarily affects skin, joints, muscle, and blood cells. The current study aimed at finding the mutation that causing EDS type VII C also known as "Dermatosparaxis" in this family.

METHODS

Through systematic data querying of the electronic medical records (EMRs) of over 80,000 individuals, we recently identified an EDS family that indicate an autosomal dominant inheritance. The family was consented for genomic analysis of their de-identified data. After a negative screen for known mutations, we performed whole genome sequencing on the male proband, his affected father, and unaffected mother. We filtered the list of non-synonymous variants that are common between the affected individuals.

RESULTS

The analysis of non-synonymous variants lead to identifying a novel mutation in the ADAMTSL2 (p. Gly421Ser) gene in the affected individuals. Sanger sequencing confirmed the mutation.

CONCLUSION

Our work is significant not only because it sheds new light on the pathophysiology of EDS for the affected family and the field at large, but also because it demonstrates the utility of unbiased large-scale clinical recruitment in deciphering the genetic etiology of rare mendelian diseases. With unbiased large-scale clinical recruitment we strive to sequence as many rare mendelian diseases as possible, and this work in EDS serves as a successful proof of concept to that effect.

Mutations in COL1A1 Gene Change Dentin Nanostructure

Although many studies have attempted to associate specific gene mutations with dentin phenotypic severity, it remains unknown how the mutations in COL1A1 gene influence the mechanical behavior of dentin collagen and matrix. Here, we reported one osteogenesis imperfecta (OI) pedigree caused by two new inserting mutations in exon 5 of COL1A1 (NM_000088.3:c.440_441insT;c.441_442insA), which resulted in the unstable expression of COL1A1 mRNA and half quantity of procollagen production. We investigated the morphological and mechanical features of proband's dentin using atomic force microscope (AFM), scanning electron microscope, and transmission electron microscope. Increased D-periodic spacing, variably enlarged collagen fibrils coating with fewer minerals were found in the mutated collagen. AFM analysis demonstrated rougher dentin surface and sparsely decreased Young's modulus in proband's dentin. We believe that our findings provide new insights into the genetic-/nano- mechanisms of dentin diseases, and may well explain OI dentin features with reduced mechanical strength and a lower crosslinked density.

Severe osteogenesis imperfecta Type-III and its challenging treatment in newborn and preschool children. A systematic review

Osteogenesis imperfecta (OI) is a group of genetic disorders, of which Type III is the most severe among survivors. The disease is characterised in particular by bone fragility, decreased bone mass and increased incidence of fractures. Other usual findings are muscle hypotonia, joint hypermobility and short stature. Fractures and weak bones may consequently cause limb and spinal deformity and chronic physical disability. Bisphosphonates have revolutionised the treatment of newborn children with severe OI type III. Surgery is still needed in most patients due to high frequency of the fractures. In this systematic review we describe the present state-of-art in treating the most severe type of OI in newborn and preschool children with their bone fractures.

Orthodontic and orthognathic management of a patient with osteogenesis imperfecta and dentinogenesis imperfecta: a case report

This case report describes a patient's severe Class III malocclusion, managed with a combination of orthodontic and orthognathic treatment. The medical history was complicated by osteogenesis imperfecta and dentinogenesis imperfecta. In addition the patient was a Jehovah's Witness. Patients with osteogenesis imperfecta carry an increased risk of perioperative haemorrhage, and this led to bimaxillary surgery being carried out as two discrete surgical episodes for the patient described. In addition, the risk of enamel fracture led to orthodontic bands being cemented on all teeth. In spite of the increased risks a successful outcome was achieved.

Intravitreal bevacizumab for treatment of choroidal neovascularization associated with osteogenesis imperfecta

A 12-year-old girl, diagnosed of osteogenesis imperfecta, presented with sudden visual loss in the left eye. Investigations revealed an active choroidal neovascular membrane. She underwent treatment with intravitreal Bevacizumab (1.25 mg/0.05 ml). Follow-up at 1 month revealed the development of lacquer crack running through the macula, underlying the fovea. The patient received two re-treatments at 1-month intervals, following which the choroidal neovascularization (CNV) regressed completely. However, further progression of lacquer cracks was noted. At the last follow-up, 6 months following the last injection, the fundus remained stable and vision was maintained at 20/200. Considering the natural history of the disease and the increased risk of rupture of the Bruch's membrane in such eyes, the possible complication of a lacquer crack developing must be borne in mind, before initiating treatment.

Congenital and metabolic disorders leading to fracture

While fractures in children are usually due to trauma only, there are a number of congenital and metabolic conditions which will predispose a child to fractures and lower the threshold of a bone to breaking. These conditions can also influence the pattern of the fracture and the process of bone healing.

There are a number of conditions which lead to specific pathological and clinical changes and also several relatively common conditions which must be considered when assessing any child with recurrent fractures.

We present a review of congenital and metabolic causes of fractures, focusing largely on the details of osteogenesis imperfecta and congenital pseudoarthrosis of the tibia.

Characterization of skin abnormalities in a mouse model of osteogenesis imperfecta using high resolution magnetic resonance imaging and Fourier transform infrared imaging spectroscopy

Evaluation of the skin phenotype in osteogenesis imperfecta (OI) typically involves biochemical measurements, such as histologic or biochemical assessment of the collagen produced from biopsy-derived dermal fibroblasts. As an alternative, the current study utilized non-invasive magnetic resonance imaging (MRI) microscopy and optical spectroscopy to define biophysical characteristics of skin in an animal model of OI. MRI of skin harvested from control, homozygous oim/oim and heterozygous oim/+ mice demonstrated several differences in anatomic and biophysical properties. Fourier transform infrared imaging spectroscopy (FT-IRIS) was used to interpret observed MRI signal characteristics in terms of chemical composition. Differences between wild-type and OI mouse skin included the appearance of a collagen-depleted lower dermal layer containing prominent hair follicles in the oim/oim mice, accounting for 55% of skin thickness in these. The MRI magnetization transfer rate was lower by 50% in this layer as compared to the upper dermis, consistent with lower collagen content. The MRI transverse relaxation time, T2, was greater by 30% in the dermis of the oim/oim mice compared to controls, consistent with a more highly hydrated collagen network. Similarly, an FT-IRIS-defined measure of collagen integrity was 30% lower in the oim/oim mice. We conclude that characterization of phenotypic differences between the skin of OI and wild-type mice by MRI and FT-IRIS is feasible, and that these techniques provide powerful complementary approaches for the analysis of the skin phenotype in animal models of disease.

Osteogenesis imperfecta misdiagnosed as child abuse

The differential diagnosis of child abuse includes osteogenesis imperfecta (OI). Mild phenotypes of OI may be misdiagnosed as child abuse. The purpose of this study was to review the experience of families in which OI was misdiagnosed as child abuse. Sixty-one potential cases of misdiagnosis were identified from a lay support organization. Upon review of the medical records, 33 cases were identified with a confirmed diagnosis of OI (skin biopsy or DNA blood test). Questionnaires were given to families to describe their condition and experiences. There were 19 male and 14 female children. Mean age at presentation was 7.1 months (range: 1-23 months). All patients had fractures and the presenting symptoms included pain (n=14), swelling (n=7), decreased limb movement (n=5), or unusual limb position (n=2). Abnormal radiograph findings consistent with OI were found in 19 of 33 patients (58%), clinical findings of OI were present in 23 of 33 patients (70%), and a family history that could be supportive of OI was present in 18 of 33 families (55%). Children were removed from the family in 70% of cases and older siblings were removed from the family in 62% of cases. The mean age at the time of diagnosis of OI was 10.5 months (range: 3-35 months). The consequences of misdiagnosis of OI as child abuse are devastating to the family. OI should be considered in all cases of suspected child abuse. In children with any clinical, radiographic, or family history features of OI, early involvement of a bone specialist and performance of laboratory testing should be considered to establish a timely and accurate diagnosis.

Sutureless 25-gauge vitrectomy for retinal detachment repair in a patient with osteogenesis imperfecta

PURPOSE

The purpose of this study was to report the successful repair of retinal detachment in a patient with osteogenesis imperfecta with sutureless 25-gauge vitrectomy.

METHODS

This was a single case report.

RESULTS

A patient with osteogenesis imperfecta and a retinal detachment was successfully repaired without complication using 25-gauge vitrectomy with a final visual acuity of 20/20.

CONCLUSION

In light of abnormal and thin sclera in patients with osteogenesis imperfecta, small-gauge sutureless vitrectomy should be considered for the repair of retinal detachment in this subset of patients.

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.

Oxygen tension differentially influences osteogenic differentiation of human adipose stem cells in 2D and 3D cultures

Skeletal defects commonly suffer from poor oxygen microenvironments resulting from compromised vascularization associated with injury or disease. Adipose stem cells (ASCs) represent a promising cell population for stimulating skeletal repair by differentiating toward the osteogenic lineage or by secreting trophic factors. However, the osteogenic or trophic response of ASCs to reduced oxygen microenvironments is poorly understood. Moreover, a direct comparison between 2D and 3D response of ASCs to hypoxia is lacking. Thus, we characterized the osteogenic and angiogenic potential of human ASCs under hypoxic (1%), normoxic (5%), and atmospheric (21%) oxygen tensions in both 2D and 3D over 4 weeks in culture. We detected greatest alkaline phosphatase activity and extracellular calcium deposition in cells cultured in both 2D and 3D under 21% oxygen, and reductions in enzyme activity corresponded to reductions in oxygen tension. ASCs cultured in 1% oxygen secreted more vascular endothelial growth factor (VEGF) over the 4-week period than cells cultured in other conditions, with cells cultured in 2D secreting VEGF in a more sustained manner than those in 3D. Expression of osteogenic markers revealed temporal changes under different oxygen conditions with peak expression occurring earlier in 3D. In addition, the increase of most osteogenic markers was significantly higher in 2D compared to 3D cultures at 1% and 5% oxygen. These results suggest that oxygen, in conjunction with dimensionality, affects the timing of the differentiation program in ASCs. These findings offer new insights for the use of ASCs in bone repair while emphasizing the importance of the culture microenvironment.

Effect of HIP/ribosomal protein L29 deficiency on mineral properties of murine bones and teeth

Mice lacking HIP/RPL29, a component of the ribosomal machinery, display increased bone fragility. To understand the effect of sub-efficient protein synthetic rates on mineralized tissue quality, we performed dynamic and static histomorphometry and examined the mineral properties of both bones and teeth in HIP/RPL29 knock-out mice using Fourier transform infrared imaging (FTIRI). While loss of HIP/RPL29 consistently reduced total bone size, decreased mineral apposition rates were not significant, indicating that short stature is not primarily due to impaired osteoblast function. Interestingly, our microspectroscopic studies showed that a significant decrease in collagen crosslinking during maturation of HIP/RPL29-null bone precedes an overall enhancement in the relative extent of mineralization of both trabecular and cortical adult bones. This report provides strong genetic evidence that ribosomal insufficiency induces subtle organic matrix deficiencies which elevates calcification. Consistent with the HIP/RPL29-null bone phenotype, HIP/RPL29-deficient teeth also showed reduced geometric properties accompanied with relative increased mineral densities of both dentin and enamel. Increased mineralization associated with enhanced tissue fragility related to imperfection in organic phase microstructure evokes defects seen in matrix protein-related bone and tooth diseases. Thus, HIP/RPL29 mice constitute a new genetic model for studying the contribution of global protein synthesis in the establishment of organic and inorganic phases in mineral tissues.

[Bilateral spontaneous carotid artery dissection in osteogenesis imperfecta (type I)]

We report on a 36-year-old patient with an acute cerebral infarction due to a spontaneous dissection of both internal carotid arteries in conjunction with type I osteogenesis imperfecta. Spontaneous dissections of cerebral arteries (DCA) represent a common cause of cerebral infarctions in younger patients. Our case shows that a hereditary connective tissue disorder should be considered in all patients with "spontaneous" DCA. The identification of an - initially unknown - hereditary connective tissue disorder may con-tribute to primary and secondary prophylaxis of cerebral ischemia.

Osteogenesis imperfecta: diagnosis and treatment

Osteogenesis imperfecta is a heritable disorder characterized by extremely fragile bones, blue sclerae, dentinogenesis imperfecta, hearing loss, and scoliosis. In 1979, Sillence classified the condition into four types based on genetic and clinical criteria. Three more classifications have subsequently been added. Diagnosis of osteogenesis imperfecta may be done prenatally (in severe cases), clinically, radiographically, or via biochemical or genetic examination. Medical treatment consists of bisphosphonate use, even in patients younger than age 2 years. Surgical treatment consists of internal splinting of long bones. Research is currently being done on the use of smart intramedullary rods (ie, composed of nitinol shape-memory alloy) for correction of bone deformity and on the use of bone marrow transplantation to increase osteoblast density, thereby reducing fracture frequency.

Osteogenesis imperfecta: determining the demographics and the predictors of death from an inpatient population

Osteogenesis imperfecta is a heritable disease that may result in bone fragility, increased joint laxity, decreased muscle tone, thinning of the skin, a bluish appearance of the sclerae, and scoliosis in as many as 60% of cases. The purpose of this study was to examine the impact of patient and hospital characteristics on mortality rate during inpatient stays. Data was collected retrospectively from the Healthcare Cost and Utilization Project Kids' Inpatient Database, a resource designed to analyze pediatric hospital usage. Data were collected from 1793 patients in the 27 states. Overall, 3% of this population died during hospitalization. Self-pay patients, patients in hospitals with small bed sizes, patients in non pediatric hospitals, and younger patients all had higher mortality rates than did their counterparts. In addition, black patients were 3.7 times more likely to die than did patients of any other race, and women were more likely to die than did men, although more than half of the number of patients were classified as white and 52% were men. Although these trends suggest that the mortality of younger patients may be reduced by admittance to children's hospitals, the children who are hospitalized younger tend to have more severe forms of the disease and are therefore more deformed and more difficult to treat. Overall, the results of this study indicate that children with osteogenesis imperfecta who need hospitalization may benefit from being referred to a large children's hospital, and that there is further research needed into the significant differences in the mortality of black patients and female patients.

Dentofacial rehabilitation by osteodistraction, augmentation and implantation despite osteogenesis imperfecta

Osteogenesis imperfecta-- a heritable systemic disorder characterized by enhanced bone fragility-- is frequently associated with a Class III malocclusion and distinct dental disorders. This patient, suffering from a late form of osteogenesis imperfecta, displayed early loss of teeth and severe maxillary hypoplasia. Bone grafting of the alveolar ridge was assumed not to guarantee a neutral basal relation before dental implantation. Due to the risk of atypical fractures conventional orthognathic surgery was excluded in the atrophic maxilla. In contrast to a conventional Le Fort I osteotomy, osteodistraction of the maxilla can be performed omitting the precarious down-fracture procedure. Despite a lack of reports on this technique in patients with osteogenesis imperfecta, dysgnathia was corrected by osteodistraction of the upper jaw. The loss of teeth was treated by augmentation of the alveolar crest using autogenous bone from the iliac crest followed by placement of dental implants. Stable normocclusion of the implant-supported overdentures was achieved without any detectable relapse over 4 years. For the first time it has been demonstrated that advanced surgical techniques like osteodistraction, alveolar crest augmentation and dental implantation can successfully be combined for dentofacial rehabilitation even in patients suffering from osteogenesis imperfecta.

Ruptured Cerebral Artery Aneurysm and Bacterial Meningitis in a Man With Osteogenesis Imperfecta

This report describes a 38-year-old man with osteogenesis imperfecta who died of a ruptured cerebral artery aneurysm and bacterial meningitis. He had multiple long bone fractures in the past, and approximately 4 months before death, he had surgery to relieve symptoms of basilar impression. The surgery was complicated by a postoperative wound infection. For the next 4 months, he had intermittent headaches and vomiting. He was found dead in his bed at home. At autopsy, he had a ruptured anterior communicating artery aneurysm and bacterial meningitis. Cerebrospinal fluid and blood cultures had growth of Staphylococcus aureus. Osteogenesis imperfecta is a disorder of type I collagen. Type I collagen is present in many tissues, including blood vessels. The etiology of cerebral artery aneurysm formation is multifactorial. Some patients with cerebral artery aneurysms have been shown to have abnormalities in type III collagen. There has not been a reported relationship made between abnormalities in type I collagen and aneurysms. Meningitis can also result in cerebral artery aneurysms, but they are usually due to Aspergillus or Mycobacterium species. The case we report is unique; cerebral artery aneurysm formation may have been due to osteogenesis imperfecta and/or bacterial meningitis.

Spontaneous and simultaneous bilateral rupture of the quadriceps tendon in a patient with osteogenesis imperfecta: a case report

Bilateral rupture of the quadriceps tendon is an uncommon and serious injury that usually occurs in middle aged to elderly patients. It is frequently associated with chronic metabolic disorders like diabetes, hyperparathyroidism, gout, chronic renal failure or the chronic use of steroids. We report a case of spontaneous bilateral rupture of the quadriceps tendon in a patient with osteogenesis imperfecta.

Surgical management of severe cervical kyphosis with myelopathy in osteogenesis imperfecta: a case report

STUDY DESIGN

A case of a 9-year-old child with Osteogenesis Imperfecta and severe cervical kyphosis associated with wedged vertebrae and progressive neurological deterioration is presented.

OBJECTIVE

To highlight the difficulties in surgical management of this condition and to discuss the appropriate surgical approach.

SUMMARY OF BACKGROUND DATA

This case demonstrates an unusual case of Osteogenesis Imperfecta with associated wedged vertebrae causing a quadriparesis. Surgical decompression and stabilization can be performed with resolution of symptoms even in this age group with the appropriate approach and implants.

METHODS

A 9-year-old girl presented with progressive cervical kyphosis and quadriparesis. At the age of 3 years, she underwent posterior cervical fusion (C1-C6) for instability. Radiological and laboratory investigations confirmed the diagnosis of Osteogenesis Imperfecta, and radiographs of the cervical spine revealed a kyphotic deformity of 120 degrees . Magnetic resonance imaging and computerized tomography scans showed anterior cord compression attributable to wedged vertebrae at C3 and C4. Magnetic resonance imaging-angiography was performed before surgery to identify the anatomic position of the vertebral arteries. A modified anterolateral approach to the upper cervical spine was performed, and anterior C3 and C4 corpectomies with interbody cage and plate fixation were carried out.

RESULTS

After surgery the patient made a full neurological recovery, and significant correction of the deformity was achieved and maintained at follow-up.

CONCLUSIONS

Cervical kyphotic deformity in Osteogenesis Imperfecta is uncommon. Association of this condition with wedged vertebrae is rare. Surgical decompression of the upper cervical spine is a challenging problem in the presence of this deformity. Which surgical approach to use is controversial. There are difficulties exposing wedged vertebrae by a standard anterior approach, and hence we have used a modified anterolateral approach to address this surgical problem, because a posterolateral approach was impossible with the intervening vertebral arteries. Spinal stabilization in children with Osteogenesis Imperfecta and poor bone stock is a challenge. We have used a small diameter MOSS cage ("Harms mesh cage") with maxillofacial plate and screws to achieve stabilization and fusion.

Arthroscopic-assisted revision of telescopic rods in osteogenesis imperfecta

Bailey-Dubow extensible nails are intramedullary stabilization devices designed to prevent deformities and recurrent long bone fractures in patients with osteogenesis imperfecta. The rods consist of a hollow outer sleeve and a solid inner obturator, allowing for telescoping of the rods and expansion of the device with longitudinal growth of the bone. Migration of the nail into the joint is a known complication of this procedure, which can lead to pain and loss of motion. This is a case report of the use of an arthroscopic approach to manipulate femoral and tibial Bailey-Dubow rods that migrated into the knee joint.

Cloning, expression and characterization of the murine Efemp1, a gene mutated in Doyne-Honeycomb retinal dystrophy

Development of the bone and cartilage structures is one of the best-studied systems for epithelial-mesenchymal interaction as well as proliferation and differentiation. In a screen for genes differentially expressed in mice deficient for transcription factor AP-2alpha, we have identified a gene which, based on its homology to the human EFEMP-1 gene was designated Efemp1. It encodes for six repeats similar to the domain of the epidermal growth factor. Sequence comparison with EFEMP1 genes of human and rat revealed that the three proteins share a high amino acid identity (92%), suggesting a conserved function during vertebrate development. However, there is no EFEMP1ortholog annotated in sequence databases of other non-mammalian species indicating that it might have evolved in higher vertebrates only. Analysis of the murine genomic locus revealed that the gene is encoded by 11 exons, which are spread over 80 kb of distance on murine chromosome 11A4. The multidomain protein structure may indicate that Efemp1 protein interacts with extracellular matrix components and serves to connect and integrate the function of multiple partner molecules. The gene is expressed in the embryo proper starting from day 9.5 to day 18.5 of murine development. In situ analyses showed that Efemp1 is found in condensing mesenchyme, giving rise to bone and cartilage as well as in developing bone structures of the cranial and the axial skeleton. These results will help in further defining the role of Efemp1 during murine embryogenesis.