Perspective: A multi-trait integrative approach to understanding the structural basis of bone fragility for pediatric conditions associated with abnormal bone development.

Bone development is a highly orchestrated process that establishes the structural basis of bone strength during growth and functionality across the lifespan. This developmental process is generally robust in establishing mechanical function, being adaptable to many genetic and environmental factors. However, not all factors can be fully accommodated, leading to abnormal bone development and lower bone strength. This can give rise to early-onset bone fragility that negatively impacts bone strength across the lifespan. Current guidelines for assessing bone strength include measuring bone mineral density, but this does not capture the structural details responsible for whole bone strength in abnormally developing bones that would be needed to inform clinicians on how and when to treat to improve bone strength. The clinical consequence of not operationalizing how altered bone development informs decision making includes under-detection and missed opportunities for early intervention, as well as a false positive diagnosis of fragility with possible resultant clinical actions that may actually harm the growing skeleton. In this Perspective, we emphasize the need for a multi-trait, integrative approach to better understand the structural basis of bone growth for pediatric conditions with abnormal bone development. We provide evidence to showcase how this approach might reveal multiple, unique ways in which bone fragility develops across and within an array of pediatric conditions that are associated with abnormal bone development. This Perspective advocates for the development of new translational research aimed at informing better ways to optimize bone growth, prevent fragility fractures, and monitor and treat bone fragility based on the child's skeletal needs.

Patient-reported prevalence of gastrointestinal issues in the adult skeletal dysplasia population with a concentration on osteogenesis imperfecta.

Patient-reported concerns indicate that gastrointestinal (GI) manifestations affect the skeletal dysplasia population, but quantitative information regarding prevalence and severity of GI issues is limited. We examined the frequency and characteristics of GI symptoms in adults with skeletal dysplasias by reviewing 101 responses to the Gastrointestinal Symptom Rating Scale (GSRS). Participant demographics, medication history, and ambulatory status were collected from medical records. Compared to published GSRS reference data, our cohort scored higher on reflux, diarrhea, and total scores, and lower on abdominal pain and indigestion scores; none of these differences were statistically significant. Although osteogenesis imperfecta respondents had more severe symptoms across all domains, only reflux reached significance (p = 0.009). Scores in patients with achondroplasia were higher for indigestion, constipation, diarrhea, and total scores and lower on abdominal pain and reflux scores than the general population; only the diarrhea score was significant (p = 0.034). There were no statistically significant differences in any of the domain or total GSRS scores across ambulatory status groups. Increased height correlated with worse abdominal pain domain score (p = 0.033). The number of medications positively correlated with total GSRS score (p = 0.013). Future studies should include larger numbers of individuals to allow a more in-depth analysis of patient-reported symptoms and signs within this population.

Orthopedic considerations and surgical outcomes in Ehlers-Danlos syndromes.

The Ehlers-Danlos syndromes (EDS) are a clinically and genetically heterogeneous group of connective tissue disorders with varying physical manifestations. There are no clear guidelines for addressing orthopedic concerns or reporting surgical outcomes in this population. This article reviews the literature, reports on a new study, and offers considerations prior to surgical intervention. The new study seeks to determine the effectiveness of surgical intervention in individuals with EDS. It is a retrospective chart review of 154 individuals clinically diagnosed with EDS who had orthopedic surgery >2 years ago at Hospital for Special Surgery. A total of 120 individuals were included in the study. One hundred eleven females and 9 males underwent a total of 320 orthopedic surgeries, of which 204 surgeries had available post-operative follow-up. The average age at surgery was 38.2 years (range: 7.6-83.3). Multiple post-operative complications (290) were reported in 91% of cases. Common complications were persistent pain/discomfort (45), continued subluxation/dislocation (20), instability (19), pain/discomfort from hardware (17), and infection (16). Our results suggest that surgical outcomes are worse for individuals with EDS compared to the general population, a finding which is similar to other studies. Complications occurred more frequently in the EDS population than the average population, suggesting that surgery should be undertaken by a multidisciplinary team of clinicians with careful pre-operative planning and full knowledge of the risks and benefits. Guidelines for the care of this unique population must be established.

TLE4 Is a Critical Mediator of Osteoblast and Runx2-Dependent Bone Development.

Healthy bone homeostasis hinges upon a delicate balance and regulation of multiple processes that contribute to bone development and metabolism. While examining hematopoietic regulation by Tle4, we have uncovered a previously unappreciated role of Tle4 on bone calcification using a novel Tle4 null mouse model. Given the significance of osteoblasts in both hematopoiesis and bone development, this study investigated how loss of Tle4 affects osteoblast function. We used dynamic bone formation parameters and microCT to characterize the adverse effects of Tle4 loss on bone development. We further demonstrated loss of Tle4 impacts expression of several key osteoblastogenic genes, including Runx2, Oc, and Ap, pointing toward a potential novel mechanism for Tle4-dependent regulation of mammalian bone development in collaboration with the RUNX family members.

Quality of life in adults with achondroplasia in the United States.

Studies examining quality of life (QoL) in adults with achondroplasia are limited. We report on QoL and psychiatric illness diagnoses in a modern cohort of adults with achondroplasia. SF-36 Health Survey scores from adults with achondroplasia were compared to general population scores. Demographics, physical measurements, and psychiatric illness diagnoses were recorded from medical records. The achondroplasia population had lower scores than the general population in all categories. Most people with achondroplasia (56%) had a diagnosed psychiatric illness. Those with a diagnosed psychiatric illness had lower scores in physical functioning, role limitations due to physical and emotional health, and mental health. Pain, energy/fatigue, and general health scale scores were roughly equivalent (<2 points difference). Social functioning was >15 points higher in individuals with psychiatric illness diagnoses. Adults with achondroplasia report significantly lower physical and mental well-being and had nearly 3× the rate of psychiatric illness diagnosis than the general population, highlighting the importance of total care for this population. Healthcare providers must understand the physical and mental comorbidities of achondroplasia, beyond short stature and orthopedic issues, so they can proactively improve QoL across the lifespan for patients and families.

Respiratory impairment impacts QOL in osteogenesis imperfecta independent of skeletal abnormalities.

Respiratory insufficiency is the leading cause death in people with osteogenesis imperfecta (OI). Adults with OI reported that respiratory symptoms negatively impacted psychosocial wellbeing and limited daily physical activities, irrespective of OI type, age, stature, or scoliosis. The impact of respiratory status on quality of life in this population warrants further investigation. PURPOSE: Respiratory insufficiency is the leading cause of mortality in osteogenesis imperfecta (OI), a heterogeneous group of heritable connective tissue disorders characterized by fractures, bone fragility, and scoliosis. There is little research on how respiratory health influences daily life in this population. This study explores the relationship between respiratory function and quality of life in adults with OI. METHODS: One hundred fifty-seven adults with OI completed the St. George's Respiratory Questionnaire (SGRQ) and provided demographic and health information through REDCap. SGRQ scores were compared to reference scores for the general population, and comparisons were made between OI type, presence of scoliosis, stature, and other factors such as age or comorbidities. RESULTS: Average age was 45.87 years (range 19-81). Respondents scored worse on average (32 ± 23) than the normative data (6 ± 1). Those with type I OI scored better than those with type IV (p = 0.002) or type III (p = 0.024). Total scores correlated with age, activity level, assistive device use, and presence of pulmonary or cardiac comorbidities but did not correlate with stature or degree of scoliosis. CONCLUSION: Respiratory symptoms negatively impact both psychosocial wellbeing in the OI population and limit daily physical activity. These limitations occur irrespective of their OI type, age, stature, or scoliosis and reflect the dramatic impact of respiratory status on quality of life for people with OI. Future studies should examine the etiology of respiratory insufficiency in this population so guidelines for management can be established.

Cardiopulmonary Status in Adults with Osteogenesis Imperfecta: Intrinsic Lung Disease May Contribute More Than Scoliosis.

BACKGROUND: Osteogenesis imperfecta (OI) is a heterogeneous group of collagen-related disorders characterized by osteopenia, bone fractures, spine deformities, and nonskeletal complications. Cardiopulmonary complications are the major cause of morbidity and mortality in adults with OI. The cause of such problems was often attributed solely to the presence of large scoliosis curves affecting pulmonary function and, indirectly, cardiovascular health. However, recent studies suggest this may not be the case. Therefore, determining the relationships and causative agents of cardiopulmonary problems in patients with OI, specifically pulmonary impairment, is important to improving the overall wellbeing, quality of life, and survival of these patients. QUESTIONS/PURPOSES: (1) Is cardiopulmonary fitness in OI solely related to the presence of scoliosis? (2) What is the prevalence of heart and lung complications in this adult population? (3) Does the presence of pulmonary impairment impact quality of life in adults with OI? METHODS: This is a prospective observational cross-sectional study. Within 1 year, each participant (n = 30) completed pulmonary function testing, echocardiogram, ECG, chest CT, AP spine radiography, and quality-of-life assessments (SF-36, St. George's Respiratory Questionnaire, Functional Outcomes of Sleep Questionnaire, and Pittsburgh Sleep Quality Index). In terms of pulmonary function, we differentiated restrictive and obstructive physiology using the ratio of forced expiratory volume over one second to forced vital capacity (FEV1/FVC), with restrictive lung physiology defined as FEV1/FVC > 0.8 and obstructive lung physiology as FEV1/FVC < 0.7. Spine radiographs were evaluated for scoliosis. Chest CT images were reviewed to qualitatively assess the lungs. The statistical analysis involved a Kruskall-Wallis test with Bonferroni's correction and a bivariate correlation analysis using Spearman's rho correlation coefficient (p < 0.05). RESULTS: Sixteen of 23 participants with restrictive lung physiology had scoliosis; their ages ranged from 19 years to 67 years. There was no correlation between the magnitude of the scoliosis curve and deficient pulmonary function (R = 0.08; p = 0.68). Seven participants had normal pulmonary function. The average scoliosis curve was 44 ± 29°. Thirteen participants had abnormal ECG findings while 10 had abnormal echocardiogram results. All but two individuals with abnormal chest CT results were found to have bronchial wall thickening. There were no differences in pulmonary or cardiac findings between OI types, except for FVC and total lung capacity, which were lower in individuals with Type III OI than in those with other types of OI. FEV1/FVC correlated with St. George's Respiratory Questionnaire (R = 0.429; p = 0.02) but not with Functional Outcomes of Sleep Questionnaire (R = -0.26; p = 0.19) or SF-36 scores (physical component summary: R = -0.037, p = 0.85; mental component summary: R = -0.204, p = 0.29). CONCLUSIONS: The lack of a relationship between decreased pulmonary function and the severity of scoliosis suggests that restrictive lung physiology in this population is likely because of factors intrinsic to OI and not entirely because of thoracic cage deformities. The fact that pulmonary impairment influences self-perceived quality of life exemplifies how detrimental such complications may be to everyday functioning. This also reinforces the importance of determining the underlying cause of cardiopulmonary impairment in this population to set clear clinical guidelines of care. LEVEL OF EVIDENCE: Level II, prognostic study.

Joint Replacements in Individuals With Skeletal Dysplasias: One Institution's Experience and Response to Operative Complications.

BACKGROUND: Skeletal dysplasias are a heterogeneous group of >400 genetic disorders characterized by abnormal bone growth. Many individuals experience joint pain and limitation, coming to require joint replacement much earlier than the average-statured population. In addition, prosthesis survival rate is less in the dysplastic population. The purpose of this study is to identify risk factors for surgery and provide recommendations to improve surgical outcomes. METHODS: This a retrospective review of 29 individuals with a skeletal dysplasia who had 64 joint replacements between April 1985 and January 2019 at a single institution. We collected demographics, physical examination, medical history, imaging studies, surgical indication, and complications. RESULTS: Spondyloepiphyseal dysplasia was the most common skeletal dysplasia (7), followed by pseudoachondroplasia (4) and multiple epiphyseal dysplasia (4). Average age of the cohort was 40.6 years (range 14-64). Hip arthroplasty (34) was the most commonly performed surgery. The majority of arthroplasties (75%) required custom components. Complication rate was 37.3%, most commonly pulmonary embolism (3) and pneumonia (3). Most complications (81.8%) occurred in individuals with either a pre-existing cardiopulmonary comorbidity or lumbar/sacral deformity. Body mass index did not correlate with complication severity (R = -0.042, P = .752) or rate (R = 0.006, P = .963). CONCLUSION: Surgical complications are highest in patients with pre-existing cardiopulmonary conditions. Body mass index does not predict complications in this cohort. Preoperative evaluations for individuals with skeletal dysplasias should include comprehensive work-up of spine issues and extraskeletal systems that present an operative risk. Intraoperative protocol should include special consideration for placement on the table, airway maintenance, and spinal cord monitoring in select cases.

Acetabular Protrusio in Patients With Osteogenesis Imperfecta: Risk Factors and Progression.

BACKGROUND: Osteogenesis imperfecta (OI) is a genetic disorder commonly associated with osteopenia, osteoporosis, bone fractures, bone deformities, and other clinical features. A frequent radiologic finding with OI is acetabular protrusio (AP). We hypothesized that AP develops in patients with OI over time. In addition, we hypothesized that AP also develops in patients with OI without radiographic evidence of AP on initial examination. METHODS: Medical records and radiographs of 55 patients (109 hips) diagnosed with OI evaluated at our institution were retrospectively reviewed. Previously established radiographic criteria using the center-edge (CE) angle of Wiberg, position of the acetabulum relative to the iliopectineal line, crossing of the acetabulum across the ilioischial (Kohler) line, and position of the teardrop figure relative to the ilioischial (Kohler) line were utilized to assess AP severity. In addition, pharmacological treatments and patient factors including body mass index (BMI) were recorded. Radiographs of patients with OI that were taken ≥2 years apart were analyzed utilizing AP radiographic criteria to assess for changes. The changes in AP-related measurements were standardized by distance or degree per year. In addition, patient factors were evaluated for associations with AP development. RESULTS: In this series of 109 hips (55 patients), incidence of AP in earliest radiographs was 45% (49/109). Patients with OI type I and III demonstrated the highest incidence of AP (65%). Among the hips that did not meet the criteria for AP in their early radiographs, 24 (40%) were positive for AP by their latest radiograph. In the hips that initially presented with AP, 42% showed increased CE angles on later radiographs. Twenty-six hips (24%) showed either no observable changes or reduced CE angles. Risk factors that were significantly associated with greater odds of developing AP included (1) an age under 12; (2) a BMI>25; (3) presence of AP of the contralateral hip; and (4) female sex. Bisphosphonates, vitamin D, physical therapy, and other drugs related to treatment of OI reduced the risk of developing AP but did not achieve statistical significance. CONCLUSIONS: AP is a common finding in OI patients (54%). Among hips of OI patients that met criteria for AP in early radiographs, 42% (20/48) demonstrated greater CE angles in their latest radiographs. Similar changes were observed in OI patients who did not initially meet criteria for diagnosis for AP. However, CE angle measurements between the 2 groups did not significantly differ (P=0.71). In terms of Kohler line crossing, patients that met criteria for AP in early radiographs had significantly greater change per year than those that did not have AP criteria (P<0.05). The findings suggest AP may develop over time in patients with OI and may be influenced by patient factors such as age, sex, and BMI. In addition, unilateral AP may have a significant impact on the development of AP of the contralateral hip. LEVEL OF EVIDENCE: Level IV-retrospective case series.

A Multicenter Observational Cohort Study to Evaluate the Effects of Bisphosphonate Exposure on Bone Mineral Density and Other Health Outcomes in Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is characterized by low bone mass and bone fragility. Using data from a large cohort of individuals with OI from the Osteogenesis Imperfecta Foundation's linked clinical research centers, we examined the association between exposure to bisphosphonate (BPN) treatment (past or present) and lumbar spine (LS) areal bone mineral density (aBMD), fractures, scoliosis, and mobility. From 466 individuals, we obtained 1394 participant-age LS aBMD data points. Though all OI subtypes were examined, primary analyses were restricted to type I OI (OI-1). Using linear regression, we constructed expected OI-1 LS aBMD-for-age curves from the data from individuals who had never received BPN. LS aBMD in those who had been exposed to BPN was then compared with the computed expected aBMD. BPN exposure in preadolescent years (age <14 years) was associated with a LS aBMD that was 9% more than the expected computed values in BPN-naïve individuals (p < 0.01); however, such association was not observed across all ages. Exposure to i.v. BPN and treatment duration >2 years correlated with LS aBMD in preadolescent individuals. BPN exposure also had a significant association with non-aBMD clinical outcome variables. Logistic regression modeling predicted that with BPN exposure, a 1-year increase in age would be associated with an 8.2% decrease in fracture probability for preadolescent individuals with OI-1, compared with no decrease in individuals who had never received any BPN (p < 0.05). In preadolescent individuals with OI-1, a 0.1 g/cm2 increase in LS aBMD was associated with a 10.6% decrease in scoliosis probability, compared with a 46.8% increase in the BPN-naïve group (p < 0.01). For the same changes in age and LS aBMD in preadolescent individuals, BPN exposure was also associated with higher mobility scores (p < 0.01), demonstrating that BPN treatment may be associated with daily function. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

TBX6-associated congenital scoliosis (TACS) as a clinically distinguishable subtype of congenital scoliosis: further evidence supporting the compound inheritance and TBX6 gene dosage model.

PURPOSE: To characterize clinically measurable endophenotypes, implicating the TBX6 compound inheritance model. METHODS: Patients with congenital scoliosis (CS) from China(N = 345, cohort 1), Japan (N = 142, cohort 2), and the United States (N = 10, cohort 3) were studied. Clinically measurable endophenotypes were compared according to the TBX6 genotypes. A mouse model for Tbx6 compound inheritance (N = 52) was investigated by micro computed tomography (micro-CT). A clinical diagnostic algorithm (TACScore) was developed to assist in clinical recognition of TBX6-associated CS (TACS). RESULTS: In cohort 1, TACS patients (N = 33) were significantly younger at onset than the remaining CS patients (P = 0.02), presented with one or more hemivertebrae/butterfly vertebrae (P = 4.9 × 10‒8), and exhibited vertebral malformations involving the lower part of the spine (T8-S5, P = 4.4 × 10‒3); observations were confirmed in two replication cohorts. Simple rib anomalies were prevalent in TACS patients (P = 3.1 × 10‒7), while intraspinal anomalies were uncommon (P = 7.0 × 10‒7). A clinically usable TACScore was developed with an area under the curve (AUC) of 0.9 (P = 1.6 × 10‒15). A Tbx6-/mh (mild-hypomorphic) mouse model supported that a gene dosage effect underlies the TACS phenotype. CONCLUSION: TACS is a clinically distinguishable entity with consistent clinically measurable endophenotypes. The type and distribution of vertebral column abnormalities in TBX6/Tbx6 compound inheritance implicate subtle perturbations in gene dosage as a cause of spine developmental birth defects responsible for about 10% of CS.

Multiparametric Classification of Skin from Osteogenesis Imperfecta Patients and Controls by Quantitative Magnetic Resonance Microimaging.

The purpose of this study is to evaluate the ability of quantitative magnetic resonance imaging (MRI) to discriminate between skin biopsies from individuals with osteogenesis imperfecta (OI) and skin biopsies from individuals without OI. Skin biopsies from nine controls (unaffected) and nine OI patients were imaged to generate maps of five separate MR parameters, T1, T2, km, MTR and ADC. Parameter values were calculated over the dermal region and used for univariate and multiparametric classification analysis. A substantial degree of overlap of individual MR parameters was observed between control and OI groups, which limited the sensitivity and specificity of univariate classification. Classification accuracies ranging between 39% and 67% were found depending on the variable of investigation, with T2 yielding the best accuracy of 67%. When several MR parameters were considered simultaneously in a multivariate analysis, the classification accuracies improved up to 89% for specific combinations, including the combination of T2 and km. These results indicate that multiparametric classification by quantitative MRI is able to detect differences between the skin of OI patients and of unaffected individuals, which motivates further study of quantitative MRI for the clinical diagnosis of OI.

Are Changes in Composition in Response to Treatment of a Mouse Model of Osteogenesis Imperfecta Sex-dependent?

BACKGROUND: Osteogenesis imperfecta (OI) is a genetic disease characterized by skeletal fragility and deformity. There is extensive debate regarding treatment options in adults with OI. Antiresorptive treatment reduces the number of fractures in growing oim/oim mice, an animal model that reproducibly mimics the moderate-to-severe form of OI in humans. Effects of long-term treatments with antiresorptive agents, considered for treatment of older patients with OI with similar presentation (moderate-to-severe OI) are, to date, unknown. QUESTIONS/PURPOSES: Fourier transform infrared (FTIR) imaging, which produces a map of the spatial variation in chemical composition in thin sections of bone, was used to address the following questions: (1) do oim/oim mice show a sex dependence in compositional properties at 6.5 months of age; (2) is there a sex-dependent response to treatment with antiresorptive agents used in the treatment of OI in humans; and (3) are any compositional parameters in oim/oim mice corrected to wild-type (WT) values after treatment? METHODS: FTIR imaging data were collected from femurs from four to five mice per sex per genotype per treatment. Treatments were 24 weeks of saline, alendronate, or RANK-Fc; and 12 weeks of saline+12 weeks RANK-Fc and 12 weeks of alendronate+RANK-Fc. FTIR imaging compositional parameters measured in cortical and cancellous bones were mineral-to-matrix ratio, carbonate-to-mineral ratio, crystal size/perfection, acid phosphate substitution, collagen maturity, and their respective distributions (heterogeneities). Because of the small sample size, nonparametric statistics (Mann-Whitney U- and Kruskal-Wallis tests with Bonferroni correction) were used to compare saline-treated male and female mice of different genotypes and treatment effects by sex and genotype, respectively. Statistical significance was defined as p<0.05. RESULTS: At 6.5 months, saline-treated male cortical oim/oim bone had increased mineral-to-matrix ratio (p=0.016), increased acid phosphate substitution (p=0.032), and decreased carbonate-to-mineral ratio (p=0.016) relative to WT. Cancellous bone in male oim/oim also had increased mineral-to-matrix ratio (p=0.016) relative to male WT. Female oim/oim mouse bone composition for all cortical and cancellous bone parameters was comparable to WT (p>0.05). Only the female WT mice showed a response of mean compositional properties to treatment, increasing mineral-to-matrix after RANK-Fc treatment in cancellous bone (p=0.036) compared with saline-treated mice. Male oim/oim increased mineral-to-matrix cortical and cancellous bone heterogeneity in response to all long-term treatments except for saline+RANK-Fc (p<0.04); female oim/oim cortical mineral-to-matrix bone heterogeneity increased with ALN+RANK-Fc and all treatments increased cancellous female oim/oim bone acid phosphate substitution heterogeneity (p<0.04). CONCLUSIONS: Both oim/oim and WT mice, which demonstrate sex-dependent differences in composition with saline treatment, showed few responses to long-term treatment with antiresorptive agents. Female WT mice appeared to be more responsive; male oim/oim mice showed more changes in compositional heterogeneity. Changes in bone composition caused by these agents may contribute to improved bone quality in oim/oim mice, because the treatments are known to reduce fracture incidence. CLINICAL RELEVANCE: The optimal drug therapy for long-term treatment of patients with moderate-to-severe OI is unknown. Based on bone compositional changes in mice, antiresorptive treatments are useful for continued treatment in OI. There is a reported sexual dimorphism in fracture incidence in adults with OI, but to date, no one has reported differences in response to pharmaceutical intervention. This study suggests that such an investigation is warranted.

Acetabular Protrusio and Proximal Femur Fractures in Patients With Osteogenesis Imperfecta.

BACKGROUND: Osteogenesis imperfect (OI) is a genetic disorder characterized by increased bone fragility, frequent fractures, and extremity deformities among other clinical findings. A frequent radiographic finding in OI patients is acetabular protrusio (AP). We hypothesized that AP incidence would be significant in OI patients and highest among type III OI patients, who have a more severe disease phenotype. In addition, we hypothesized that there would be a correlation between AP and proximal femur fracture incidence. METHODS: We retrospectively reviewed radiographs and medical records of 49 patients with OI evaluated at our institution. Demographic information and modified Sillence classification were recorded. AP was diagnosed using previously published radiographic criteria using the center-edge angle of Wiberg, acetabulum relative to the iliopectineal line, teardrop figure relative to the ilioischial (Kohler) line, and acetabulum relative to the ilioischial (Kohler) line. Medical record and radiographs were reviewed for evidence of proximal femur or acetabulum fracture. Associations between OI type, AP, and fracture incidence were examined with χ or Fisher exact tests. RESULTS: In this series of 49 OI patients, the overall incidence of AP was 55.1% (27/49) with the highest incidence among patients with type III OI (70.6%). There was an increased incidence of proximal femur, and particularly femoral neck, fractures among patients with AP compared with patients with normal hip anatomy. Overall, patients with AP had a 30% increased risk for proximal femur and acetabulum fractures (P=0.03). CONCLUSIONS: AP is a common deformity in OI patients (55.1%) and particularly type III OI (70.6%). Patients with AP have an increased risk for proximal femur fractures and particularly femoral neck fractures. This novel finding adds to the growing body of literature on clinical implications of AP in OI patients. LEVEL OF EVIDENCE: Level IV-Retrospective case series.

Risedronate in children with osteogenesis imperfecta: a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Children with osteogenesis imperfecta are often treated with intravenous bisphosphonates. We aimed to assess the safety and efficacy of risedronate, an orally administered third-generation bisphosphonate, in children with the disease. METHODS: In this multicentre, randomised, parallel, double-blind, placebo-controlled trial, children aged 4-15 years with osteogenesis imperfecta and increased fracture risk were randomly assigned by telephone randomisation system in a 2:1 ratio to receive either daily risedronate (2·5 or 5 mg) or placebo for 1 year. Study treatment was masked from patients, investigators, and study centre personnel. Thereafter, all children received risedronate for 2 additional years in an open-label extension. The primary efficacy endpoint was percentage change in lumbar spine areal bone mineral density (BMD) at 1 year. The primary efficacy analysis was done by ANCOVA, with treatment, age group, and pooled centre as fixed effects, and baseline as covariate. Analyses were based on the intention-to-treat population, which included all patients who were randomly assigned and took at least one dose of assigned study treatment. The trial is registered with ClinicalTrials.gov, number NCT00106028. FINDINGS: Of 147 patients, 97 were randomly assigned to the risedronate group and 50 to the placebo group. Three patients from the risedronate group and one from the placebo group did not receive study treatment, leaving 94 and 49 in the intention-to-treat population, respectively. The mean increase in lumbar spine areal BMD after 1 year was 16·3% in the risedronate group and 7·6% in the placebo group (difference 8·7%, 95% CI 5·7-11·7; p<0·0001). After 1 year, clinical fractures had occurred in 29 (31%) of 94 patients in the risedronate group and 24 (49%) of 49 patients in the placebo group (p=0·0446). During years 2 and 3 (open-label phase), clinical fractures were reported in 46 (53%) of 87 patients in the group that had received risedronate since the start of the study, and 32 (65%) of 49 patients in the group that had been given placebo during the first year. Adverse event profiles were otherwise similar between the two groups, including frequencies of reported upper-gastrointestinal and selected musculoskeletal adverse events. INTERPRETATION: Oral risedronate increased areal BMD and reduced the risk of first and recurrent clinical fractures in children with osteogenesis imperfecta, and the drug was generally well tolerated. Risedronate should be regarded as a treatment option for children with osteogenesis imperfecta. FUNDING: Alliance for Better Bone Health (Warner Chilcott and Sanofi).

Analysis of maternal risk factors associated with congenital vertebral malformations.

STUDY DESIGN: A retrospective medical record review of cases with congenital vertebral malformations (CVMs) and controls with normal spine morphology. OBJECTIVE: To determine the relative contribution of maternal environmental factors (MEFs) during pregnancy to CVM development. SUMMARY OF BACKGROUND DATA: CVMs represent defects in formation and segmentation of somites occurring with an estimated incidence of between 0.13 and 0.50 per 1000 live births. CVMs may be associated with various phenotypes and represent significant morbidity due to pain and cosmetic disfigurement. METHODS: A multicenter retrospective medical record review of 229 cases with CVM and 267 controls with normal spine morphology between the ages of 1 and 50 years was performed to obtain the odds ratio (OR) of MEF related to CVM among cases versus controls. An imputation-based analysis was performed in which subjects with no documentation of MEF history were treated as "no maternal exposure." Univariate and multivariate analyses were conducted to calculate the OR. RESULTS: Of the 229 total cases, 104 cases had single or multiple CVMs without additional congenital malformations (group 1) and 125 cases had single or multiple CVMs and additional congenital malformations (group 2). Nineteen percent of total cases had an identified MEF. The OR for MEF history for group 1 was 6.0 (95% confidence interval, 2.4-15.1; P < 0.001) in the univariate analysis. The OR for MEF history in group 2 was 9.1 (95% confidence interval, 3.8-21.6, P < 0.001) in the univariate analysis. The results were confirmed in the multivariate analysis after adjusting for age, sex, and institution. CONCLUSIONS: These results support a hypothesis for an association between these MEFs during pregnancy and CVM and have implications for development of prevention strategies. Further prospective studies are needed to quantify association between CVMs and specific MEF. LEVEL OF EVIDENCE: 4.

Lack of cyclophilin B in osteogenesis imperfecta with normal collagen folding.

Osteogenesis imperfecta is a heritable disorder that causes bone fragility. Mutations in type I collagen result in autosomal dominant osteogenesis imperfecta, whereas mutations in either of two components of the collagen prolyl 3-hydroxylation complex (cartilage-associated protein [CRTAP] and prolyl 3-hydroxylase 1 [P3H1]) cause autosomal recessive osteogenesis imperfecta with rhizomelia (shortening of proximal segments of upper and lower limbs) and delayed collagen folding. We identified two siblings who had recessive osteogenesis imperfecta without rhizomelia. They had a homozygous start-codon mutation in the peptidyl-prolyl isomerase B gene (PPIB), which results in a lack of cyclophilin B (CyPB), the third component of the complex. The proband's collagen had normal collagen folding and normal prolyl 3-hydroxylation, suggesting that CyPB is not the exclusive peptidyl-prolyl cis-trans isomerase that catalyzes the rate-limiting step in collagen folding, as is currently thought.

A novel locus for adolescent idiopathic scoliosis on chromosome 12p.

Adolescent idiopathic scoliosis (AIS) is a common disorder with strong evidence for genetic predisposition. Quantitative trait loci (QTLs) for AIS susceptibility have been identified on chromosomes. We performed a genome-wide genetic linkage scan in seven multiplex families using 400 marker loci with a mean spacing of 8.6 cM. We used Genehunter Plus to generate linkage statistics, expressed as homogeneity (HLOD) scores, under dominant and recessive genetic models. We found a significant linkage signal on chromosome 12p, whose support interval extends from near 12 pter, spanning approximately 10 million bases or 31 cM. Fine mapping within the region using 20 additional markers reveals maximum HLOD = 3.7 at 5 cM under a dominant inheritance model, and a split peak maximum HLOD = 3.2 at 8 and 18 cM under a recessive inheritance model. The linkage support interval contains 95 known genes. We found evidence suggestive of linkage on chromosomes 1, 6, 7, 8, and 14. This study is the first to find evidence of an AIS susceptibility locus on chromosome 12. Detection of AIS susceptibility QTLs on multiple chromosomes in this and other studies demonstrate that the condition is genetically heterogeneous.