Microstructural and transcriptomic characterization of trabecular bone in idiopathic osteonecrosis of the femoral head

Association study of hypoxia inducible factor 1α ( HIF1α) with osteonecrosis of femoral head in a Korean population

IntroductionThe most frequent diagnosis in young adults undergoing total hip arthroplasty (THA) is osteonecrosis of the femoral head (ONFH), an evolving and disabling condition with an increasing prevalence worldwide. Treatment of ONFH remains a challenge mainly because of a lack of understanding of the disease's pathophysiological basis. This study investigated the biological processes that could be affected by ONFH by comparing the microstructure, histological characteristics and transcriptomic profile of trabecular bone from the femoral head (FH) and the intertrochanteric region (IT) of patients suffering from this condition.MethodA total of 18 patients with idiopathic ONFH undergoing THA in our institution were included. Trabecular bone explants were taken intraoperatively from the FH and the IT of patients. Bone microstructure was examined by micro-computed tomography (micro-CT). After bone sectioning, histological features were studied by hematoxylin and eosin staining. Differential gene expression was investigated using a microarray platform.ResultMicro-CT imaging showed higher trabecular separation and lower trabecular thickness and bone volume in trabecular bone from the FH than from the IT. Histological staining revealed that the number of osteoblasts on the bone surface and the percentage of empty lacunae were higher in trabecular bone from the FH. Transcriptome analysis identified a differential signature in trabecular bone from the FH compared to the IT. The gene ontology analyses of the genes overexpressed in trabecular bone from the FH revealed a range of enriched biological processes related to cell division and immune response. In contrast, most downregulated transcripts were involved in bone formation.ConclusionThis study identified changes in the microarchitecture, histological features and transcriptomic signature of trabecular bone from the FH of patients with idiopathic ONFH, which might underlie the pathophysiology of this condition. This work was supported by PI22/00939 grant from ISCIII-FEDER-MICINN-AES and Luis Alvarez grant from IdiPAZ.

The pathophysiological basis of alterations in trabecular bone of patients with osteonecrosis of the femoral head (ONFH) remains unclear. ONFH has classically been considered a vascular disease with secondary changes in the subchondral bone. However, there is increasing evidence suggesting that ONFH could be a bone disease, since alterations in the functionality of bone tissue distant from the necrotic lesion have been observed. We comparatively studied the transcriptomic profile of trabecular bone obtained from the intertrochanteric region of patients with ONFH without an obvious aetiological factor, and patients with osteoarthritis (OA) undergoing total hip replacement in our Institution. To explore the biological processes that could be affected by ONFH, we compared the transcriptomic profile of trabecular bone from the intertrochanteric region and the femoral head of patients affected by this condition. Differential gene expression was studied using an Affymetrix microarray platform. Transcriptome analysis showed a differential signature in trabecular bone from the intertrochanteric region between patients with ONFH and those with OA. The gene ontology analyses of the genes overexpressed in bone tissue of patients with ONFH revealed a range of enriched biological processes related to cell adhesion and migration and angiogenesis. In contrast, most downregulated transcripts were involved in cell division. Trabecular bone in the intertrochanteric region and in the femoral head also exhibited a differential expression profile. Among the genes differentially expressed, we highlighted those related with cytokine production and immune response. This study identified a set of differently expressed genes in trabecular bone of patients with idiopathic ONFH, which might underlie the pathophysiology of this condition.Acknowledgements: This work was supported by grants PI18/00643 and PI22/00939 from ISCIII-FEDER, Ministerio de Ciencia, Innovación y Universidades (MICINN)-AES.

AimsTo investigate whether idiopathic osteonecrosis of the femoral head (ONFH) is related to impaired osteoblast activities.MethodsWe cultured osteoblasts isolated from trabecular bone explants taken from the femoral head and the intertrochanteric region of patients with idiopathic ONFH, or from the intertrochanteric region of patients with osteoarthritis (OA), and compared their viability, mineralization capacity, and secretion of paracrine factors.ResultsOsteoblasts from the intertrochanteric region of patients with ONFH showed lower alkaline phosphatase (ALP) activity and mineralization capacity than osteoblasts from the same skeletal site in age-matched patients with OA, as well as lower messenger RNA (mRNA) levels of genes encoding osteocalcin and bone sialoprotein and higher osteopontin expression. In addition, osteoblasts from patients with ONFH secreted lower osteoprotegerin (OPG) levels than those from patients with OA, resulting in a higher receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) ligand (RANKL)-to-OPG ratio. In patients with ONFH, osteoblasts from the femoral head showed reduced viability and mineralized nodule formation compared with osteoblasts from the intertrochanteric region. Notably, the secretion of the pro-resorptive factors interleukin-6 and prostaglandin E2 as well as the RANKL-to-OPG ratio were markedly higher in osteoblast cultures from the femoral head than in those from the intertrochanteric region.ConclusionIdiopathic ONFH is associated with a reduced mineralization capacity of osteoblasts and increased secretion of pro-resorptive factors.Cite this article: Bone Joint Res 2021;10(9):619–628.

There have been few studies investigating the cumulative effect of individual factors related to bone metabolism on the systemic balance between bone formation and resorption in patients with osteonecrosis of the femoral head (ONFH). We investigated bone mineral density (BMD) of lumbar spine and bone turnover markers that reflect systemic bone metabolism. Two-hundred twenty patients with ONFH were matched to 220 healthy subjects according to age, gender, and body mass index. ONFH patients were divided into steroid-induced (18%), alcoholic (21%), and idiopathic ONFH (61%) and subgroup analysis was performed to exclude the effect of steroid and malnutrition on bone metabolism. We compared lumbar spine bone mineral density (BMD) between groups and measured serum bone-specific alkaline phosphatase (BALP) and urinary deoxypyridinoline/creatinine (Dpd/Cr) ratio. Logistic regression analysis revealed low spine BMD was significantly associated with each subgroup of ONFH when compared with that of the control group (odds ratio of 2.27, 4.24, and 1.86 in alcoholic, steroid, and idiopathic ONFH, respectively). The mean value of serum BALP (27.02U/L) was within the normal reference range while average urine Dpd/Cr ratio (6.24nM/mM) increased in ONFH group when compared with respective reference range. Spine BMD decreased and urinary Dpd/Cr ratio increased in patients with non-traumatic ONFH. Further studies will be necessary to identify whether non-traumatic ONFH is merely a regional disease confined to the femoral head or may affect systemic bone metabolism.

Idiopathic osteonecrosis of the femoral head (ONFH) can be correctly diagnosed in accordance with the established criteria. However, some general orthopedic physicians have misdiagnosed patients as having ONFH. The goal of this study was to clarify the radiologic and clinical features of misdiagnosed patients. This study included 50 patients who were referred to the authors' hospital by general physicians with a diagnosis of ONFH. The correct diagnosis was made based on the Japanese Investigation Committee diagnostic criteria for ONFH. Demographic data were compared between patients with and without ONFH. Of the 50 patients, 24 were diagnosed with other diseases: 10 with osteoarthritis, 7 with transient osteoporosis of the femoral head, 4 with rapidly destructive coxopathy, and 3 with subchondral insufficiency fracture. Seventeen patients who did not have ONFH had magnetic resonance imaging findings that showed a bone marrow edema pattern at the femoral head. The mean age of 62.9 years among patients without ONFH was significantly higher than that of 45.2 years among patients with ONFH. There were 18 female patients in the non-ONFH group and 5 female patients in the ONFH group. Bilateral disease was found in 1 patient in the non-ONFH group and 17 patients in the ONFH group. No patients in the non-ONFH group had a history of systemic steroid administration compared with 11 patients in the ONFH group. Clinical features associated with the non-ONFH group were female sex, older age, unilateral disease, and no history of systemic steroid administration. For patients with these features, the diagnosis of ONFH should be made carefully. [Orthopedics. 2017; 40(1):e117-e123.].

Differences in the microarchitectural features of the lateral collapsed lesion between osteonecrosis and subchondral insufficiency fracture of the femoral head.

BackgroundThis study examined whether use of a specific questionnaire sheet for nontraumatic osteonecrosis of the femoral head (ONFH) could affect the subclassification of ONFH compared with a conventional medical interview.Material/MethodsStudy participants consisted of 400 patients with ONFH who visited our hospital between February 2011 and March 2015. Data on history of systemic steroid therapy and habitual alcohol intake were obtained during a conventional medical interview at the first visit and were re-evaluated using a specific questionnaire sheet at another visit. Patients were subclassified into 4 groups: steroid-associated, alcohol-associated, steroid/alcohol-associated, or idiopathic ONFH.ResultsUse of the specific questionnaire sheet resulted in a 4.0% increase in the proportion of patients with a history of systemic steroid therapy, from 57.3% (n=229) to 61.3% (n=245), and a 14.3% increase for history of habitual alcohol intake, from 35.0% (n=140) to 49.3% (n=197). The proportion of patients with steroid/alcohol-associated ONFH increased from 2.5% (n=10) to 17.8% (n=71), while the proportion in the other 3 groups decreased: steroid-associated ONFH from 54.8% (n=219) to 43.5% (n=174); alcohol-associated ONFH from 32.5% (n=130) to 31.5% (n=126); and idiopathic ONFH from 10.2% (n=41) to 7.2% (n=29). Ninety-six patients (24.0%) were classified into a different subgroup based on the specific questionnaire sheet.ConclusionsThe use of a specific questionnaire sheet can change the distribution of ONFH subclassifications compared with use of a conventional medical history interview. Use of a specific questionnaire sheet can allow for more detailed self-reporting regarding potential causative factors for nontraumatic ONFH, especially habitual alcohol intake.

Osteonecrosis of the femoral head (ONFH) is a multifactorial disease and is associated with genetic predisposition, and exposure to certain risk factors. In particular, idiopathic ONFH in twins and the clustering of cases in families have indicated that genetic factors are involved. However, the majority of cases of ONFH are sporadic and various studies have demonstrated that differences in the study design and/or the ethnic groups analyzed leads to different results. The present study performed one of the first genome-wide association studies to identify genetic loci that may increase the risk of idiopathic ONFH. In total, 217 patients with idiopathic ONFH and 217 control samples, without ONFH, were genotyped using Axiom™ chips. Following quality control, 509,886 single-nucleotide polymorphisms (SNPs) were included in the association analysis to identify genetic variants that may influence susceptibility to idiopathic ONFH. The lowest P-value identified by the current study was for an association with rs220324 (P=3.57×10-7), an SNP that is located near to the uromodulin-like 1 gene region on chromosome 21q22.3, although none of the SNPs reached the traditional genome-wide significance level of 5×10–8. However, the DnaJ heat shock protein family (Hsp40) member C6 (DNAJC6) locus, a region between 65.37 and 65.67 Mb located on chromosome 1p31.3, harbored a cluster of SNPs that were associated with idiopathic ONFH at a significance level of P<1×10–5. Four variants, rs10493374, rs12032616, rs17127529 and rs6679032, with marginal associations were located in and around the DNAJC6 locus and were in strong linkage disequilibrium with each other. In conclusion, the current study did not identify any SNPs that were associated with idiopathic ONFH at a genome-wide significance level, however, the results suggest that future studies should investigate the effects of SNPs in the DNAJC6 gene on the idiopathic ONFH risk.

Bone morphogenetic protein (BMP)-2 and ibandronate (IB) decrease the femoral head deformity following ischemic osteonecrosis of the femoral head (ONFH). The purpose of this study was to determine the effects of BMP-2 and IB on the mineral content and nanoindentation properties of the bone following ONFH. ONFH was surgically induced in the femoral head of piglets. There were five groups: normal control, untreated, IB, BMP, and BMP + IB (n = 5/group). Backscattered electron imaging, Raman spectroscopy, and nanoindentation testing were performed. Both BMP and BMP + IB groups showed calcium content in the trabecular bone similar to the normal group, while the IB and no-treatment groups showed a significant increase in the calcium content compared to the normal group. The carbonate content relative to phosphate was significantly increased in the IB and BMP + IB groups (p < 0.01) compared to the normal group. No significant difference was found between the BMP and the normal group. The nanoindentation modulus of the bone in the IB group was significantly increased compared to the normal group (p < 0.05). No significant differences were observed between the BMP and BMP + IB groups compared to the normal group. The nanoindentation hardness measurements in the IB group were also significantly increased compared to the BMP and BMP + IB groups (p < 0.05). In summary, trabecular bone treated with BMP or BMP + IB had material properties comparable to normal bone whereas the bone in the IB group retained the increased mineral content and the nanoindentation hardness found in the necrotic bone. Hence, BMP or BMP + IB better restores the normal mineral content and nanomechanical properties after ONFH than IB treatment alone. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1453-1460, 2017.

PurposeNitric oxide (NO) synthesised by endothelial NO synthase (eNOS) is a potent regulator of internal haemodynamics. A polymorphism in intron 4 of the eNOS is associated with different vascular disorders. We investigated the potential involvement of this polymorphism in idiopathic and secondary osteonecrosis of the femoral head (ONFH) in Polish patients.MethodsWe performed a study involving 68 patients with ONFH (45 idiopathic and 23 secondary) and 100 healthy controls. All subjects were genotyped for the eNOS4 polymorphism by the polymerase chain reaction followed by agarose gel electrophoresis.ResultsThe analysis revealed that the frequencies of eNOS4 genotypes were significantly different in ONFH patients (both idiopathic and secondary) than in controls. The frequencies of the 4a allele were significantly higher in the total group of patients versus controls [22.79 vs 9 %, p = 0.00039, odds ratio (OR) 2.98]. In subgroup analysis the 4a allele increased significantly in both idiopathic (20 vs 9 %, p = 0.0074, OR = 2.52) and secondary (28.26 vs 9 %, p = 0.00047, OR = 3.98) ONFH patients compared to control subjects. The frequency of the 4a/b genotype in the total group of patients (36.76 vs 16 %, p = 0.0011, OR = 3.24) as well as patients with idiopathic (35.56 vs 16 %, p = 0.0069, OR = 2.96) and secondary (39.13 vs 16 %, p = 0.0073, OR = 3.89) ONFH was higher than in the control group.ConclusionsThere was a significantly higher frequency of eNOS 4a allele carriers among the total group of patients as well as in idiopathic and secondary ONFH. This suggests that the eNOS gene polymorphism may be associated with increased risk of ONFH.

BackgroundIn this retrospective case investigation, we analysed the data of patients with osteonecrosis of the femoral head (ONFH) to reveal demographic and clinical diagnostic features of ONFH in three northeastern provinces of China and provide a reference for its prevention, diagnosis, and treatment.MethodsWe collected data from patients in Beijing Orthopaedic Hospital of Liaoning, focusing on the aetiology and diagnosis of ONFH. Medical records and self-designed questionnaires were used to collect information for statistical analysis, including age, aetiology, reason for glucocorticoid use, hospital level at first visit, and diagnosis.ResultsIn total, 906 patients with complete medical records were included in the analysis. The mean patient age was 47.65 ± 12.12 years. The peak age distribution was in the 40s for men and the 50s for women. Among the total cohort, 72 patients (7.95%; 40 men and 32 women) had traumatic ONFH, 198 (21.85%; 131 men and 67 women) had steroid-induced ONFH, 230 (25.39%; 121 men and 109 women) had idiopathic ONFH, and 406 (44.81%; 397 men and 9 women) had alcohol-induced ONFH. Six hundred and twenty patients were diagnosed with ONFH at the first visit, while 286 patients were misdiagnosed, with a diagnosis rate of 68.43%. The diagnosis rate at the first visit in tertiary hospitals was 76.14%. The diagnosis rate at the first visit in second-class hospitals was 52.07%.ONFH was most likely to be misdiagnosed as lumbar disc herniation.ConclusionsMost patients with ONFH in three northeastern provinces of China were middle-aged, male, and had alcohol-induced ONFH. The misdiagnosis rate of ONFH at the first visit was very high, especially for misdiagnosis of lumbar disc herniation, indicating that the diagnosis of ONFH requires further improvement.

The purpose of this article is to relate intramedullary perfusion of the proximal femur to severity of osteonecrosis of the femoral head by using dynamic contrast-enhanced MRI (DCE-MRI). Twelve patients (14 symptomatic hips) who underwent DCE-MRI and had subsequent core decompression of the femoral head were examined. Hips were graded for severity according to MRI findings and were assigned scores of 0 (negative findings), 1 (focal marrow abnormalities), and 2 (subchondral collapse). Thirteen asymptomatic hips acted as controls. The DCE-MRI data were analyzed by use of a pharmacokinetic two-compartment model. Compared with control hips, there was significantly greater peak enhancement in the femoral head in hips of all grades (p < 0.001) and in the femoral neck (p = 0.001) and intertrochanteric area (p = 0.001) in grade 2 hips. The time to peak was significantly delayed in the femoral head in grade 0 hips (p = 0.02) and in the intertrochanteric area in grade 2 hips (p = 0.003) compared with the controls. As evaluated by DCE-MRI, intramedullary peak enhancement in the femoral head increased with progression of idiopathic osteonecrosis of the femoral head, whereas there was delayed peak enhancement in the femoral head in hips with negative findings and intertrochanteric stasis in advanced osteonecrosis of the femoral head. Such perfusion changes as shown on MRI can occur with early osteonecrosis in the absence of other MRI abnormalities.

Mesenchymal stem cells (MSCs) with multipotential differentiation capacity can differentiate into bone cells under specific conditions and can be used to treat osteonecrosis (ON) of the femoral head (ONFH) through cell transplantation. The current study aims to explore the role of bone marrow (BM) MSCs (BMSCs)-derived exosomes carrying microRNA-122-5p (miR-122-5p) in ONFH rabbit models.First, rabbit models with ONFH were established. ONFH-related miRNAs were screened using the Gene Expression Omnibus (GEO) database. A gain-of-function study was performed to investigate the effect of miR-122-5p on osteoblasts and BMSCs and effects of exosomes carrying miR-122-5p on ONFH. Co-culture experiments for osteoblasts and BMSCs were performed to examine the role of exosomal miR-122-5p in osteoblast proliferation and osteogenesis. The target relationship between miR-122-5p and Sprouty2 (SPRY2) was tested.MiR-122, significantly decreased in ONFH in the GSE89587 expression profile, was screened. MiR-122-5p negatively regulated SPRY2 and elevated the activity of receptor tyrosine kinase (RTK), thereby promoting the proliferation and differentiation of osteoblasts. In vivo experiments indicated that bone mineral density (BMD), trabecular bone volume (TBV), and mean trabecular plate thickness (MTPT) of femoral head were increased after over-expressing miR-122-5p in exosomes. Significant healing of necrotic femoral head was also observed.Exosomes carrying over-expressed miR-122-5p attenuated ONFH development by down-regulating SPRY2 via the RTK/Ras/mitogen-activated protein kinase (MAPK) signaling pathway. Findings in the present study may provide miR-122-5p as a novel biomarker for ONFH treatment.

76 BASIC FIBROBLAST GROWTH FACTOR INDUCES OSTEOGENESIS AND SUPPRESSES THE PROGRESSION OF SECONDARY OA IN A RABBIT MODEL OF OSTEONECROSIS OF THE FEMORAL HEAD