Relationship between postrenal transplant osteonecrosis of the femoral head and gene polymorphisms related to the coagulation and fibrinolytic systems in Japanese subjects

Osteonecrosis of the Femoral Head in Patients with Hypercoagulability-From Pathophysiology to Therapeutic Implications

Osteonecrosis of the femoral head (ONFH) is a debilitating disease with major social and economic impacts. It frequently affects relatively young adults and has a predilection for rapid progression to femoral head collapse and end-stage hip arthritis. If not diagnosed and treated properly in the early stages, ONFH has devastating consequences and leads to mandatory total hip arthroplasty. The pathophysiology of non-traumatic ONFH is very complex and not fully understood. While multiple risk factors have been associated with secondary ONFH, there are still many cases in which a clear etiology cannot be established. Recognition of the prothrombotic state as part of the etiopathogeny of primary ONFH provides an opportunity for early medical intervention, with implications for both prophylaxis and therapy aimed at slowing or stopping the progression of the disease. Hereditary thrombophilia and hypofibrinolysis are associated with thrombotic occlusion of bone vessels. Anticoagulant treatment can change the natural course of the disease and improve patients' quality of life. The present work focused on highlighting the association between hereditary thrombophilia/hypofibrinolysis states and ONFH, emphasizing the importance of identifying this condition. We have also provided strong arguments to support the efficiency and safety of anticoagulant treatment in the early stages of the disease, encouraging etiological diagnosis and prompt therapeutic intervention. In the era of direct oral anticoagulants, new therapeutic options have become available, enabling better long-term compliance.

Genetic polymorphism of vitamin D receptors and plasminogen activator inhibitor-1 and osteonecrosis risk in childhood acute lymphoblastic leukemia

BACKGROUND

Osteonecrosis (ON) is one of the major therapy-related complications in childhood acute lymphoblastic leukemia (ALL). The purpose of the current study is to assess the frequency of ON in children with ALL and to detect whether polymorphisms in vitamin D receptor gene (VDR) and plasminogen activator inhibitor-1 (PAI-1) gene can affect the risk of ON.

PATIENTS AND METHODS

Nighty-six ALL children were enrolled. Serum 25-hydroxyvitamin D 25(OH)D levels were performed in addition to the detection of polymorphisms in PAI-1and VDR genes by polymerase chain reaction.

RESULTS

Ten out of 96 patients had ON (four males and six females aged above 10 years) and had an insufficient level of 25(OH)D. Fifty-two percent of patients had PAI-1 GG genotype while 48% had PAI-1 GA genotype. PAI-1 polymorphism was detected in 60% of all ON cases. The frequencies of VDR genotypes were CT (56.3%), CC (39.6%), and TT (4.2%). Osteonecrosis was found in eight patients with CC genotype and in two patients with CT genotype.

CONCLUSION

Osteonecrosis can develop early during the therapy of ALL. Older age and insufficient level of 25(OH)D were considered important risk factor for the development of osteonecrosis. PAT-1 and VDR gene polymorphism may be a genetic risk factor in its pathogenesis.

Japanese Orthopaedic Association 2019 Guidelines for osteonecrosis of the femoral head

PURPOSE

The Clinical Practice Guidelines for Osteonecrosis of the Femoral Head (ONFH) 2019 Edition, written by the working group for ONFH guidelines of the Japanese Investigation Committee (JIC) for ONFH under the auspices of the Japanese Ministry of Health, Labour, and Welfare and endorsed by the Japanese Orthopaedic Association, were published in Japanese in October 2019. The objective of this guideline is to provide a support tool for decision-making between doctors and patients.

METHODS

Procedures for developing this guideline were based on the Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014, which proposed an appropriate method for preparing clinical guidelines in Japan.

RESULTS

This clinical practice guideline consists of 7 chapters: epidemiology; pathology; diagnosis; conservative therapy; surgical treatment: bone transplantation/cell therapy; surgical treatment: osteotomy; and surgical treatment: hip replacement. Twelve background questions and 13 clinical questions were determined to define the basic features of the disease and to be addressed when deciding treatment in daily practice, respectively.

CONCLUSIONS

The clinical practice guidelines for the ONFH 2019 edition will be useful for physicians, investigators, and medical staff in clinical practice, as well as for patients, during the decision-making process when defining how to treat ONFH.

Relationship of Plasminogen Activator Inhibitor 1 4G/5G Gene Polymorphism and Nontraumatic Lunatum Avascular Necrosis

PURPOSE

Plasminogen activator inhibitor 1 (PAI-1) is a critical enzyme that regulates coagulation and fibrinolytic systems. The aim of this study was to determine the role of PAI-1 4G/5G polymorphism in nontraumatic avascular necrosis of the lunate.

METHODS

The study included 45 patients with Kienböck disease and 45 healthy individuals as a control group. In both groups, genomic DNA was extracted from peripheral blood samples to determine the distributions of PAI-1 4G/5G polymorphism using allele-specific polymerase chain reaction and sequencing.

RESULTS

No statistically significant difference was determined in the distribution of the gene polymorphism between the patient and control groups. We found the 5G/5G genotype to be 1.7 times higher in the control group compared with the patient group. A 1.6-fold increase in the 4G homozygote genotype was identified in the patient group. The patient and control groups were also evaluated for 4G/4G plus 4G/5G and 5G/5G in terms of genotype distribution. No statistically significant difference was found.

CONCLUSIONS

The findings suggest that the PAI-1 4G/4G polymorphism is not a genetic risk for Kienböck disease.

CLINICAL RELEVANCE

This study aimed to reveal the genetic etiology of Kienböck disease.

Association between MTHFR C677T polymorphism and non-traumatic osteonecrosis of the femoral head: An update meta-analysis

Objective To investigate the correlation between MTHFR C677T polymorphism and non-traumatic osteonecrosis of the femoral head.

Methods Open published studies relevant to MTHFR C677T polymorphism and non-traumatic osteonecrosis of the femoral head were electronic systematic searched in the databases of cochrane central register of controlled trials, EMBSE and CNKI. The correlation between MTHFR C677T polymorphism and non-traumatic osteonecrosis of the femoral head was calculated by odds ratio (OR) and corresponding 95% confidence interval (95%CI). The publication bias for the included studies were assessed by Begg’s funnel plot and Egger’s line regression text.

Results After systematic searching the electronic databases, 11 original studies were finally included the present work. The I2 test indicated significant statistical heterogeneity (I2=53.5%, P=0.018) across the included 11 publications. The polled results indicated that subjects of Caucasians with CC genotype had decreased risk of developing non-traumatic osteonecrosis of the femoral head (OR=0.65,95%CI: 0.44-0.96, P=0.031). However, there was no correlations between MTHFR C677T polymorphism and non-traumatic osteonecrosis of the femoral head in American Jewish and East Asian races(p>0.05). Sensitivity analysis indicated the pooled ORs were not sensitive to any included single study. The Begg’s funnel plot was generally left and right symmetrical which indicated no obviously publications. The Egger’s line regression test also demonstrated no statistical publication bias (t=1.57, P=0.15).

Conclusion According to the present evidence, MTHFR C677T polymorphism was correlated with non-traumatic osteonecrosis of the femoral head especially for Caucasians race. Subjects of Caucasians race with CC genotype had decreased risk of developing non-traumatic osteonecrosis of the femoral head.

Association between genetic polymorphisms and osteonecrosis in steroid treatment populations: a detailed stratified and dose-response meta-analysis

Steroid treatment has become recognized as an important risk factor for avascular osteonecrosis of the femoral head. However, not all patients who receive long-term, high-dose steroids develop osteonecrosis, indicating that there are individual differences in occurrence.We explored the relationship between polymorphisms and steroid-induced osteonecrosis of the femoral head (SONFH) incidence with variables. We used a multilevel mixed-effects logistic regression model, which is an expansion of logistic regression, for each type of steroid, primary disease, drug dose, applied duration, and single-nucleotide polymorphism (SNP). We also conducted a dose-response meta-analysis to analyze the cumulative dosage and SONFH risk in mutation carriers. There were significant correlations between the ABCB1 rs1045642 mutant and SONFH in the prednisone-use and methylprednisolone/prednisone-use populations. The ABCB1 rs2032582 mutant homozygote had a protective effect in the methylprednisolone/prednisolone renal transplant population. For ApoB rs693, mutation increased the incidence of SONFH in prednisone-use and methylprednisolone/prednisolone-use populations and renal transplant patients. For ApoB rs1042031, mutation increased the risk of SONFH in the prednisone-use population. The PAI-1 rs1799768 mutation had a protective effect on the SONFH risk prednisone-use and renal transplant populations. ABCB1 rs1045642 mutations have a protective effect against SONFH, and ApoB rs693 and rs1042031 increase the SONFH risk. Cumulative dosage and treatment duration had little effect on the results. In addition, there was a dose-effect correlation in ABCB1 rs1045642 and rs2032582 mutation carriers.

Lipid Transporter Activity-Related Genetic Polymorphisms Are Associated With Steroid-Induced Osteonecrosis of the Femoral Head: An Updated Meta-Analysis Based on the GRADE Guidelines

Aims: The purpose of this study was to assess the relationship between genetic variants and steroid-induced osteonecrosis of the femoral head (SONFH) in steroid use populations. Methods: We searched the public databases up to April 15, 2018. This study analyzed only the single-nucleotide polymorphisms (SNPs) that have appeared in more than three studies and assessed the level of evidence by classifying the outcomes according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Results: The ABCB1 rs1045642 C>T mutation had a protective effect against SONFH in the allelic model (I ² = 50.2%; OR: 0.74; 95% CI: 0.55-1.00; p = 0.046). The rs2032582 mutation in the ABCB1 gene showed no relationship to SONFH (allelic model: I ² = 63.4%; OR: 0.85; 95% CI: 0.58-1.23; p = 0.382). In ApoB rs693, four models showed that mutations can increase SONFH risk, but the allelic model did not. The ApoB rs1042031 mutation increased SONFH risk in the dominant model (I ² = 50.3%; OR: 2.90; 95% CI: 1.49-5.66; p = 0.002). Conclusion: An allelic model of ABCB1 rs1045642 showed that mutations have a protective effect against SONFH at a very low level of evidence. The mutations in ApoB rs693 and rs1042031 increase the SONFH risk with moderate levels of evidence.

Role of coagulopathy in glucocorticoid-induced osteonecrosis of the femoral head

The two major theories of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) are apoptosis and ischaemia. The traditional theory implicates ischaemia as the main aetiological factor because the final common pathway of ONFH is interruption of blood supply to the bone. The most common causes of interruption of blood supply include fat embolism and coagulation disorders. GCs can directly or indirectly lead to coagulation disorders, producing a hypercoagulable state, followed by poor blood flow, ischaemia, and eventually ONFH. This review summarizes the existing knowledge on coagulation disorders in the context of GC-induced ONFH, including hypofibrinolysis and thrombophilia, endothelial cell dysfunction and damage, endothelial cell apoptosis, lipid metabolism, platelet activation, and the effect of anticoagulant treatment.

MicroRNA expression profile of dexamethasone-induced human bone marrow-derived mesenchymal stem cells during osteogenic differentiation

MiRNAs have been identified in various plants and animals where they function in post-transcriptional regulation. Although studies revealed that dexamethasone play a pivotal role in the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs), the identification of specific miRNAs and their regulatory roles in this process remain poorly defined. In this study, microarrays were used to analyze the miRNA expression profile of dexamethasone-induced hBMSCs derived from three donors, and RT-PCRs were used to confirm the microarray results. Nine upregulated miRNAs and seven downregulated miRNAs were identified. The putative target genes of these miRNAs were predicted using bioinformatics analysis. Subsequently, we focused our attention on the functional analysis of an upregulated miRNA, miR-23a. Overexpression of miR-23a inhibited osteogenic differentiation of hBMSCs at the cellular, mRNA, and protein levels. The results of our study provide an experimental basis for further research on miRNAs functions during osteogenic differentiation of dexamethasone-induced hBMSCs.

Genetic association between methylenetetrahydrofolate reductase gene polymorphism and risk of osteonecrosis of the femoral head

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) SNP rs1801133 has been frequently investigated in recent years. Relevant candidate gene association studies with this SNP and osteonecrosis of the femoral head (ONFH) reported conflicting results. Meta-analysis provides a method to combine these data and to determine the association in a larger sample size.

METHOD

We conducted a systematic search to identify possible studies. Four pooled ORs (odds ratios, T versus C, TT versus CC, TT/CT versus CC, and TT versus CT/CC), along with 95% confidence interval (CI), were calculated to evaluate the association between SNP rs1801133 and ONFH susceptibility. Both fixed effects model and random effects model were used.

FINDINGS

We eventually included twelve studies in this analysis, with results showing no overall association between ONFH susceptibility and SNP rs1801133 (T versus C: OR=1.15, 95% CI=0.97-1.38; TT versus CC: OR=1.15, 95% CI=0.91-1.46; TT/CT versus CC: OR=1.09, 95% CI=0.95-1.25; and TT versus

CT/CC

OR=1.16, 95% CI=0.93-1.45). When stratified based on ethnicity, the results were still not significant.

CONCLUSION

Our findings are generally supportive of no association between MTHFR SNP rs1801133 and the etiology of ONFH.

Genetic polymorphisms in plasminogen activator inhibitor-1 predict susceptibility to steroid-induced osteonecrosis of the femoral head in Chinese population

Background

Steroid usage has been considered as a leading cause of non-traumatic osteonecrosis of the femoral head (ONFH), which is involved in hypo-fibrinolysis and blood supply interruption. Genetic polymorphisms in plasminogen activator inhibitor-1 (PAI-1) have been demonstrated to be associated with ONFH risk in several populations. However, this relationship has not been established in Chinese population. The aim of this study was to investigate the association of PAI-1 gene polymorphisms with steroid-induced ONFH in a large cohort of Chinese population.

Methods

A case–control study was conducted, which included 94 and 106 unrelated patients after steroid administration recruited from 14 provinces in China, respectively. Two SNPs (rs11178 and rs2227631) within PAI-1 were genotyped using Sequenom MassARRAY system.

Results

rs2227631 SNP was significantly associated with steroid-induced ONFH group in codominant (P = 0.04) and recessive (P = 0.02) models. However, there were no differences found in genotype frequencies of rs11178 SNP between controls and patients with steroid-induced ONFH (all P > 0.05).

Conclusions

Our data offer the convincing evidence for the first time that rs2227631 SNP of PAI-1 may be associated with the risk of steroid-induced ONFH, suggesting that the genetic variations of this gene may play an important role in the disease development.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1569909986109783.

Prevalence of genetic risk factors related with thrombophilia and hypofibrinolysis in patients with osteonecrosis of the femoral head in Poland

Background

The etiology of osteonecrosis of femoral head (ONFH) has not been fully elucidated. Increased intravascular coagulation and/or hypofibrinolysis have been proposed as pathogenic mechanisms. Previous reports demonstrated significant association between incidence of ONFH and polymorphisms of genes related with thrombophilia especially in Caucasian subjects. The aim of our study was to evaluate the relationship between genetic mutations leading to coagulation disorders and ONFH in Polish patients.

Methods

We have investigated the frequencies of four markers among 68 unrelated individuals with clinically and radiographically documented ONFH and among 100 healthy unrelated blood donors in Eastern part of Poland. The three genes were involved in thrombophilia: factor V Leiden (G1691A), prothrombin (G20210A), Methylenetetrahydrofolate Reductase (MTHFR C677T) and one in hypofibrinolysis: Tissue Plasminogen Activator (PLAT TPA25 I/D). The samples were genotyped with polymerase chain reaction followed by restriction enzyme analysis for the restriction fragment length polymorphisms. The allele and genotype frequencies were analyzed in the relation to ONFH etiology (idiopathic and secondary), gender, age (patients younger or older than 50 years) and the number of affected joints (unilateral or bilateral ONFH).

Results

No significant difference in allele frequencies between patients and control groups were observed in genes involved in thrombophilia. We have found a statistically significant increased frequency of D allele of PLAT TPA 25 I/D polymorphism between the entire group of patients with ONFH and controls (p=0,026, OR=1,54, CI 0,99-2,4). D allele frequency was also significantly increased in patients with primary ONFH (p=0,009, OR=1,81 CI 1,1-3,01), in males (p= 0,013; OR 1,74; 95% CIs 1,08-2,78), patients older than 50 years (p= 0,018, OR= 2,04; 95% CIs 1,09-3,82) and in cases with bilateral ONFH (p= 0,01; OR= 1,92; 95% CIs 1,13-3,27) (Table 9). The differences in DD homozygous genotype frequency were statistically significant for patients with idiopathic ONFH compared with control group (p=0,023, OR=2,75, CI 0,99-7,9) and in cases of bilateral ONFH (p=0,034; OR 3,12; 95% CIs 1,06-9,18) (Table 10). The frequencies of ID heterozygous genotype were statistically significantly higher in entire group of patients with ONFH (p=0,004 OR 2,71; 95% CIs 1,32-5,57), idiopathic ONFH (p= 0,01; OR 2,91; 95% CIs 1,24-6,87), males (p=0,0007; OR 3,75; 95% CIs 1,67-8,42), patients older than 50 years (p=0,001; OR 6,89; 95% CIs 1,87-25,84) and in cases with bilateral ONFH (p=0,009; OR 3,19; 95% CIs 1,26-8,03).

Conclusion

The results suggest that inherited hypofibrinolysis is a risk factor of idiopathic ONFH in Polish population.

Relationship between post-SARS osteonecrosis and PAI-1 4G/5G gene polymorphisms

OBJECTIVE

To explore the correlation between post-severe acute respiratory symptom (SARS) patients with osteonecrosis, investigate the etiology of post-SARS osteonecrosis and select the sensitive molecular symbols for early diagnosis and distinguish the high-risk population.

METHODS

The studied subjects were divided into two groups. Sixty-two post-SARS patients with osteonecrosis were one group, and 52 age- and sex-matched healthy people were as normal controlled group. Empty stomach blood samples from cubital veins were collected from both groups. Plasminogen activator inhibitor (PAI) by means of enzyme-linked immunosorbent assay and PAI-1 4G/5G polymorphism was detected by polymerase chain reaction and solid phase oligonucleotide assay.

RESULTS

The blood agents of post-SARS patients changed obviously with 15.64 ± 13.85 U/ml while the control group 7.96 ± 4.27 U/ml; 4G/4G genotype for the PAI-1 polymorphism detected in post-SARS group was more than that of the control group, but had no statistical significance. The plasma PAI activity was related to homozygote 4G/4G genotype. This reveals that homozygote 4G/4G genotype may be a susceptible gene mark to Chinese osteonecrosis patients.

CONCLUSION

Plasminogen activator inhibitor-1 is sensitive blood symbol for screening high-risk susceptible population; 4G/4G PAI-1 genotype may be an etiological factor in osteonecrosis.

Genetic risk factors for glucocorticoid-induced osteonecrosis: a meta-analysis

Glucocorticoid-induced osteonecrosis is a common and severe adverse event. We conducted a meta-analysis to investigate whether polymorphisms in target genes were associated with the risk of corticosteroid-induced osteonecrosis. Published literature from PubMed and EMBASE were searched for eligible publications. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using a fixed- or random-effects model. There were 23 articles with 35 genes described the relationship between polymorphisms and glucocorticoid-induced osteonecrosis. Meta-analyses were carried out for those SNPs with three or more eligible studies, which included four SNPs located in three genes (PAI-1, MTHFR, ABCB1). The meta-analysis revealed that the PAI-1 4G allele was associated with an increased risk of osteonecrosis compared with the 5G allele (combined studies: OR=1.932, 95% CI=1.145-3.261). The OR for the 4G/4G vs. 5G/5G genotype of PAI-1 was 3.217 (95% CI 1.667-6.209 with combined studies), The relative risk of osteonecrosis was increased in the 4G allele vs. 5G/5G and 4G/4G genotype vs. 5G allele, with odds ratios of 2.304 (95% CI=1.235-4.299) and 2.307 (95% CI=1.527-3.485) in combined studies, respectively. The ABCB1 C3435T genotype distributions available confirmed that the C allele increased osteonecrosis risk compared with the T allele (OR 1.668, 95% CI=1.214-2.293) and TT genotype (OR 2.946, 95% CI=1.422-6.101). There was no evidence for significant association between MTHFR C677T and ABCB1 G2677T/A polymorphisms and risk of osteonecrosis. Results of this meta-analysis indicate that the PAI-1 4G/5G and ABCB1 C3435T polymorphisms may be risk factors for osteonecrosis.

Current concepts on the pathogenesis and natural history of steroid-induced osteonecrosis

The pathophysiology of non-traumatic osteonecrosis is more complex than that of traumatic osteonecrosis, and corticosteroid-induced osteonecrosis presents the greatest challenge because of the multiple effects of corticosteroids on multi-system pathways; these pathways include the effects of corticosteroids on osteoblast differentiation, osteoblast and osteoclast apoptosis, lipid metabolism, coagulation pathways, and calcium metabolism. These pathways are frequently interrelated with each other, which makes the pathogenesis even more difficult to understand. Host factors and underlying disease have been shown to play a significant role in the risk of developing osteonecrosis, and our understanding of the pathogenesis must be able to explain why some patients are at greater risk than others. Identification of genetic variants that convey additional risk will also help to personalize the way we deliver care, both in the prevention and treatment of osteonecrosis. Further understanding of the intricate immunologic and genetic pathways contributing to osteonecrosis is at the forefront of research and may soon lead to viable and less invasive non-surgical therapeutic strategies.

Avascular osteonecrosis and accompanying anemia, leucocytosis, and decreased bone mineral density in renal transplant recipients

BACKGROUND

Avascular osteonecrosis (AVN) is a complication of renal transplantation. In this study, we present 12 cases of AVN associated with renal transplantation.

METHODS

Renal transplant recipients (RTRs) with AVN (group I [GI]) were evaluated by using magnetic resonance imaging and blood urea nitrogen, creatinine, glucose, calcium, phosphorus, magnesium, alkaline phosphatase, parathyroid hormone, and urine analysis. We evaluated bone mineral density (BMD) of the femoral neck and lumbar vertebrae. All patients were treated with steroids, cyclosporine, or tacrolimus plus mycophenolate mofetil. Twenty-six RTRs (GII) without AVN were randomly selected as control subjects.

RESULTS

The mean ages of GI and GII, were 33.81 ± 6.72 and 34.00 ± 7.65 years respectively (P > .05). The mean interval between transplantation and development of AVN was 12.08 ± 6.48 months. Although levels of blood urea nitrogen, creatinine, calcium, magnesium, and parathyroidhormone, as well as glucocorticoid doses in the first 12 months were similar in GI and GII, there were significant differences in serum alkaline phosphatase, hemoglobin levels, and white blood cell count between GI and GII (P < .05 for each). BMD T score <-1.5 was observed in 8/9 GI and 15/26 patients in GII. All of the patients with AVN except 1, were followed with conservative measures including calcium, magnesium, and vitamin D replacement therapies, bisphosphonate, and reduced or ceased glucocorticoid treatment. Although T scores of the femoral head were similar in GI and GII, the lumbar vertebral T score was significantly lower in GI than in GII (P < .052).

CONCLUSION

AVN developed within the first year after transplantation. Decreased lumbar vertebral BMD, which can be an indicator of glucocorticoid effect, accompanied AVN in nearly all patients. Despite the absence of renal dysfunction, increased bone destruction, anemia, and leucocytosis were coincidental or accompanying findings in our patients with AVN.

Significant associations of PAI-1 genetic polymorphisms with osteonecrosis of the femoral head

BACKGROUND

The pathogenesis of osteonecrosis of the femoral head (ONFH) has been implicated in hypofibrinolysis and blood supply interruption. Previous studies have demonstrated that decreased fibrinolytic activity due to elevated plasminogen activator inhibitor-1 (PAI-1) levels correlates with ONFH pathogenesis. The -675 4G/5G single nucleotide polymorphism (SNP rs1799889) in the PAI-1 gene promoter is associated with PAI-1 plasma level. We investigated whether rs1799889 and two other SNPs of the PAI-1 gene (rs2227631, -844 G/A in the promoter; rs11178, +10700 C/T in the 3'UTR) are associated with increased ONFH risk.

METHODS

Three SNPs in PAI-1 were genotyped in 206 ONFH patients and 251 control subjects, using direct sequencing and a TaqMan® 5' allelic discrimination assay. We performed association analysis for genotyped SNPs and haplotypes with ONFH.

RESULTS

The 4G allele of rs1799889, A allele of rs2227631, and C allele of rs11178 were significantly associated with increased ONFH risk (p = 0.03, p = 0.003, and p = 0.002, respectively). When we divided the population according to gender, an association between the three SNPs and increased risk of ONFH was found only in men. In another subgroup analysis based on the etiology of ONFH, rs2227631 (A allele) and rs11178 (C allele) in the idiopathic subgroup (p = 0.007 and p = 0.021) and rs1799889 (4G allele) and rs11178 (C allele) in the alcohol-induced subgroup (p = 0.042 and p = 0.015) were associated with increased risk of ONFH. In addition, a certain haplotype (A-4G-C) of PAI-1 was also significantly associated with ONFH (p < 0.001).

CONCLUSION

Our findings demonstrated that three SNPs (rs1799889, rs2227631, and rs11178) of the PAI-1 gene were associated with ONFH risk. This study also suggests that PAI-1 SNPs may play an important role in ONFH.

Idiopathic and secondary osteonecrosis of the femoral head show different thrombophilic changes and normal or higher levels of platelet growth factors

BACKGROUND AND PURPOSE

Thrombophilia represents a risk factor both for idiopathic and secondary osteonecrosis (ON). We evaluated whether clotting changes in idiopathic ON were different from corticosteroid-associated ON. As platelet-rich plasma has been proposed as an adjuvant in surgery, we also assessed whether platelet and serum growth factors were similar to those in healthy subjects.

METHODS

18 patients with idiopathic ON and 18 with corticosteroid-associated ON were compared with 44 controls for acquired and inherited thrombophilia. Platelet factor 4 (PF4), transforming growth factor-β1, platelet-derived growth factor-BB (PDGF-BB), and vascular endothelial growth factor were assayed in the supernatants of thrombin-activated platelets, in platelet lysates, and in serum from 14 ON patients and 10 controls.

RESULTS

Idiopathic ON patients had higher plasminogen levels (median 118%) than controls (101%) (p = 0.02). Those with corticosteroid-associated ON had significantly higher D-dimer (333 ng/mL) and lower protein C levels (129%) than controls (164 ng/mL, p = 0.004; 160%, p = 0.02). The frequency of inherited thrombophilia was not different from the controls. No statistically significant differences were found between idiopathic and corticosteroid-associated ON. 20 of the 36 ON patients were smokers. (The controls were selected from smokers because nicotine favors hypercoagulability). ON patients had significantly higher serum PF4 levels (7,383 IU/mL) and PDGF-BB levels (3.1 ng/mL) than controls (4,697 IU/mL, p = 0.005; 2.2 ng/mL, p = 0.02).

INTERPRETATION

Acquired hypercoagulability was common in both ON types, but the specific changes varied. The release of GF from platelets was not affected, providing a biological basis for platelet-rich plasma being used as an adjuvant in surgical treatment.

New insights into the pathogenesis of glucocorticoid-induced avascular necrosis: microarray analysis of gene expression in a rat model

Introduction

Avascular necrosis of the femoral head (ANFH) occurs variably after exposure to corticosteroids. Microvascular thrombosis is a common pathological finding. Since systemic thrombophilia is only weakly linked with ANFH, we propose that microvascular vessel pathology may be more related to local endothelial dysfunction and femoral head apoptosis. Corticosteroid effects on the endothelium and resultant apoptosis have been reported. We hypothesize that corticosteroids contribute to a differential gene expression in the femoral head in rats with early ANFH.

Methods

Besides bone marrow necrosis, which is a common sign in ANFH and reported in the early stages, we include the presence of apoptosis in this study as a criterion for diagnosing early disease. Forty Wistar Kyoto (WKY) rats were randomized to either a corticosteroid-treated group or an age-matched control group for six months. After sacrifice, the femoral heads were examined for ANFH. Total mRNA was extracted from femoral heads. Affymetrix exon array (Santa Clara, CA, USA) was performed on 15 selected RNA samples. Validation methods included RT-PCR and immunohistochemistry (IHC).

Results

Although rat exon array demonstrated a significant upregulation of 51 genes (corticosteroid(+)/ANFH(+) VS control), alpha-2-macroglobulin (A2M) gene was particularly over-expressed. Results were validated by RT-PCR and IHC. Importantly, A2M is known to share vascular, osteogenic and cartilage functions relevant for ANFH.

Conclusions

The findings suggest that corticosteroid-induced ANFH in rats might be mediated by A2M. Investigation of A2M as a potential marker, and a treatment target, for early ANFH should be carried out.

Lack of association of MTHFR gene polymorphisms with the risk of osteonecrosis of the femoral head in a Korean population

Some studies have suggested that coagulation disorders may be implicated in osteonecrosis of the femoral head (ONFH). The C677T polymorphism of the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene has been postulated to be a genetic risk factor for venous thromboembolism and osteonecrosis in Caucasians, but this relationship has not been established in other populations. In this study, we conducted case-control analysis of whether MTHFR polymorphisms are associated with ONFH in Korean patients. Fifteen single nucleotide polymorphisms (SNPs) were selected and genotyped in 443 ONFH patients and 273 control subjects using the TaqMan 5' allelic discrimination assay. Comparison of ONFH and control subjects using logistic regression models revealed no statistically significant differences in the frequencies of the MTHFR polymorphisms and haplotypes. Further analysis stratified by etiology also showed no association. These results suggest that MTHFR polymorphisms play no significant role in susceptibility to ONFH in the Korean population.

Glucocorticoids in osteonecrosis of the femoral head: a new understanding of the mechanisms of action

Glucocorticoid (GC) usage is the most common non-traumatic cause of osteonecrosis of the femoral head (ON). Despite the strong association of GC with ON, the underlying mechanisms have been unclear. Investigators have proposed both direct and indirect effects of GC on cells. Indirect and direct mechanisms remain intimately related and often result in positive feedback loops to potentiate the disease processes. However, the direct effects, in particular apoptosis, have recently been shown to be increasingly important. Suppression of osteoblast and osteoclast precursor production, increased apoptosis of osteoblasts and osteocytes, prolongation of the lifespan of osteoclasts and apoptosis of endothelial cells (EC) are all direct effects of GC usage. Elevated blood pressure through several pathways may raise the risk of clot formation. High-dose GC also decreases tissue plasminogen activator activity (t-PA) and increases plasma plasminogen activator inhibitor-1 (PAI-1) antigen levels increasing the procoagulant potential of GC. Inhibited angiogenesis, altered bone repair and nitric oxide metabolism can also result. Also, GC treatment modulates other vasoactive mediators such as endothelin-1, noradrenalin and bradykinin. Thus, GCs act as a regulator of local blood flow by modulating vascular responsiveness to vasoactive substances. Vasoconstriction induced in intraosseous femoral head arteries causes femoral head ischemia. GCs also cause ischemia through increased intraosseous pressure, which subsequently decreases the blood flow to the femoral head by apoptosis of ECs as well as elevating the level of adipogenesis and fat hypertrophy in the bone marrow. It is difficult to predict which patients receiving a specific dose of GC will develop ON, indicating individual differences in steroid sensitivity and the potential of additional mechanisms. The textbook model of ON is a multiple hit theory in which, with a greater number of risk factors, the risk of ON increases. While more effort is needed to better comprehend the role of GC in ON, newer data on GC action upon the endothelial cell and the regional endothelial bed dysfunction theory sheds new light on particular GC mechanisms. Better understanding of GC pathomechanisms can lead to better treatment options.

Promoter polymorphisms of the vascular endothelial growth factor gene is associated with an osteonecrosis of the femoral head in the Korean population

OBJECTIVE

Disruption of the vascular supply to the bone and subsequent hypoxia has been implicated in the pathogenesis of osteonecrosis of the femoral head (ONFH). Vascular endothelial growth factor (VEGF), a major inducer of angiogenesis, has been correlated with several pathological conditions, from inflammation to ischemic processes. A number of polymorphisms in the VEGF gene have been described as being associated with several diseases, such as diabetic retinopathy, prostate cancer and breast cancer. The aim of this study was to evaluate the association of VEGF gene polymorphisms with ONFH in a case--control study.

METHODS

Three polymorphisms (-2578C>A, -634G>C and +936C>T) in VEGF were genotyped in 317 ONFH patients and 497 control subjects, using the TaqMan 5' allelic discrimination assay. We performed the association analysis of genotyped single nucleotide polymorphisms (SNPs) and haplotypes with ONFH.

RESULTS

The -634G>C genotype was significantly associated with an increased risk for ONFH in dominant model with odds ratio (OR) of 1.47, 95% confidence intervals (CIs) 1.08-2.01 with P value 0.015. Further analysis stratified by sex showed that the -634G>C genotype was also significantly associated with a high risk for male patients considering the dominant model with OR of 1.60, 95% CI 1.13-2.26 with P value 0.008. Haplotype association analysis did not provide a further delineation of the risk allele.

CONCLUSION

Our study is, to our knowledge, the first report that shows the -634G>C polymorphism in the VEGF promoter was associated with an increased susceptibility of ONFH in the Korean population.

A PAI-1 (SERPINE1) polymorphism predicts osteonecrosis in children with acute lymphoblastic leukemia: a report from the Children's Oncology Group

As glucocorticoid use increased in acute lymphoblastic leukemia, osteonecrosis became an increasingly frequent complication. Besides increased age, host risk factors are poorly defined. We tested whether 12 polymorphisms were associated with osteonecrosis among patients 10 years and older treated on the CCG1882 protocol. Candidate genes (TYMS, MTHFR, ABCB1, BGLAP, ACP5, LRP5, ESR1, PAI-1, VDR, PTH, and PTHR) were chosen based on putative mechanisms underlying osteonecrosis risk. All children received dexamethasone, with doses varying by treatment arm. A PAI-1 polymorphism (rs6092) was associated with risk of osteonecrosis in univariate (P = .002; odds ratio = 2.79) and multivariate (P = .002; odds ratio = 2.89) analyses (adjusting for gender, age, and treatment arm). Overall, 21 of 78 (26.9%) children with PAI-1 GA/AA genotypes, versus 25 of 214 (11.7%) children with GG genotype, developed osteonecrosis. PAI-1 polymorphisms and PAI-1 serum levels have previously been associated with thrombosis. We conclude that PAI-1 genetic variation may contribute to risk of osteonecrosis.

Osteogenic abilities of bone marrow stromal cells are not defective in patients with osteonecrosis

We investigated whether the proliferation activities and osteogenic capacities of bone marrow stromal cells (BMSCs) are depressed in patients with osteonecrosis of the femoral head (ONFH). BMSCs were isolated from fresh bone marrow of the iliac crests of 54 donors and were differentiated into osteogenic lineage in vitro. The results of 27 consecutive patients with ONFH (16 idiopathic and 11 alcohol-induced) were compared with those of 27 patients with a nonnecrotic hip disorder. The proliferative activities of BMSCs in patients with ONFH were not found to be reduced and their osteogenic capacities (alkaline phosphatase activity and calcium deposition amount) were unaltered during in vitro differentiation. Results from patients with idiopathic or alcohol-induced ONFH were similar to those of matched patients with nonnecrotic disorder. These findings suggest that the osteogenic potentials of BMSCs are not defective in patients with ONFH.

Therapy Insight: orthopedic complications after solid organ transplantation in childhood

Several factors, such as immobilization, metabolic bone disease and immunosuppressive drugs, can compromise the quality of bone in children who have undergone solid organ transplantation. In contrast to adults, decreased bone mineral density has been reported in only a small proportion of pediatric transplant patients, and the relationship between low bone mineral density and fracture risk has not been established in children. Nevertheless, fractures, scoliosis, and joint and spinal degeneration are common in patients who received solid organ grafts as children. Avascular bone necrosis occurs infrequently in this patient population. Future studies should evaluate the effects of the underlying disease, transplantation and immunosuppression on the metabolism of bone and cartilage. On the basis of our own clinical experience and literature review, the growing spine of children who have received transplants should be continuously evaluated, and follow-up of bone mineral density is indicated. By contrast, routine MRI of the joints seems unnecessary.

Endothelial nitric oxide synthase gene polymorphisms in patients with nontraumatic femoral head osteonecrosis

As endothelial nitric oxide synthase (eNOS) has beneficial effects on skeletal, vascular, and thrombotic systems, the association between nontraumatic femoral head osteonecrosis (FHON) and eNOS gene polymorphisms was investigated in Korean patients with FHON. Genomic DNA from 103 patients with nontraumatic FHON (idiopathic in 50, steroid-induced in 29, and alcohol abuse in 24) and 103 control subjects matched for gender and age (3-year range) was analyzed for the 27-bp repeat polymorphism in intron 4 and Glu298Asp polymorphism in exon 7. The frequencies of alleles and genotypes were compared between patients and control subjects. The frequency of 4a allele was significantly higher in total patients than control subjects [6.8% vs. 2.4%, p = 0.0345, odds ratio (OR) 2.931]. In subgroup analysis, the 4a allele significantly increased in patients with idiopathic FHON versus control subjects (9.0% vs. 2.4%, p = 0.0297, OR 3.976). The frequency of the 4a/b genotype in total patients (13.6% vs. 4.9%, p = 0.0302, OR 3.083) as well as patients with idiopathic FHON (18.0% vs. 4.9%, p = 0.0246, OR 4.302) was higher than control subjects. The distribution of Glu298Asp polymorphisms was not significantly different between patients and control subjects. Microstellate polymorphism in intron 4 of eNOS polymorphism was significantly associated with idiopathic FHON in Korean patients. Because 4a allele is associated with lower synthesis of eNOS, these results suggest that carrier state of 4a allele in intron 4 might be a genetic risk factor of FHON and could provide insight into the protective role of nitric oxide in the pathogenesis of FHON.

Association of corticosteroids and factor V, prothrombin, and MTHFR gene mutations with avascular osteonecrosis in renal allograft recipients

The mechanism of posttransplantation avascular osteonecrosis (AVN) is controversial. Besides an increased bone marrow pressure due to reduced blood supply, enhanced coagulation has been considered. We investigated the associations of factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations as well as cumulative corticosteroid doses with AVN in renal allograft recipients. The records of 39 volunteer patients and 11 patients in whom osteonecrosis was previously identified were reviewed for cumulative corticosteroid dosages during the first year. All patients were screened for factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations by direct sequencing of genomic DNA. The cumulative corticosteroid dosages at 3, 6, and 12 months in the osteonecrotic group (5033.5 +/- 1565.3, 7164.9 +/- 2063.1, 8835.1 +/- 2216.8 mg) were significantly higher than in the control group (3629 +/- 1504.1, 4784.5 +/- 1568.7, 6322.4 +/- 1686.6 mg; P = .013, P = .001, P = .001, respectively). No significant difference in factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations was observed between the osteonecrotic and control groups (P > .05). In conclusion, an association between the first year (3, 6, and 12 month) cumulative corticosteroid dosages and AVN was demonstrated in renal transplant recipients. However, no correlation was determined between factor V Leiden, prothrombin G20210A, and MTHFR C677T mutations and osteonecrosis.

Avascular Bone Necrosis of the Hip Joint after Solid Organ Transplantation in Childhood: A Clinical and MRI Analysis

BACKGROUND

Aseptic osteonecrosis is a well-known complication after solid organ transplantation in adults. The occurrence of osteonecrosis in growing age has been studied after kidney transplantation, but no systematic evaluation of the joints has been reported after heart or liver transplantation in childhood.

METHODS

A total of 196 children--93% of patients surviving kidney, liver and heart transplantation in Finland--participated in a cross-sectional survey. All children underwent a detailed clinical examination and filled out a questionnaire on musculoskeletal symptoms. Radiographs were taken in case of joint pain or abnormal clinical findings. In addition, magnetic resonance imaging (MRI) from the hips was taken on a random basis from 34 adult patients transplanted as a child. The mean follow-up time of all patients after transplantation was 9.2 years (range, 2.4 to 20.5 years).

RESULTS

Twenty-eight (14%) patients reported prolonged joint or limb pain without previous trauma. Specific etiology for the limb pain was not found in 10 (5.1%) patients. Osteonecrosis seen in radiographs or MRI was noted in seven (3.6%) patients, of which three had received kidney, three liver, and one heart graft. Femoral head was affected in five patients, as well as talus bilaterally in one patient and lateral femoral condyle in one patient. All patients were older than 12 years at the time of diagnosis of the osteonecrosis. MRI of the hips of 34 randomly selected patients showed only one asymptomatic necrosis of the femoral head.

CONCLUSIONS

Symptomatic osteonecrosis of the hip is uncommon after solid organ transplantation in childhood using the current immunosuppressive medications.

Nontraumatic osteonecrosis of the femoral head: ten years later

The etiology of osteonecrosis of the hip may have a genetic basis. The interaction between certain risk factors and a genetic predisposition may determine whether this disease will develop in a particular individual. The rationale for use of joint-sparing procedures in the treatment of this disease is based on radiographic measurements and findings with other imaging modalities. Early diagnosis and intervention prior to collapse of the femoral head is key to a successful outcome of joint-preserving procedures. The results of joint-preserving procedures are less satisfactory than the results of total hip arthroplasty for femoral heads that have already collapsed. New pharmacological measures as well as the use of growth and differentiation factors for the prevention and treatment of this disease may eventually alter our treatment approach, but it is necessary to await results of clinical research with long-term follow-up of these patients.

Maintenance immunosuppression use and the associated risk of avascular necrosis after kidney transplantation in the United States

BACKGROUND

Avascular necrosis (AVN) after renal transplantation has been largely attributed to the use of corticosteroids. However, other risk factors such as microvascular thrombosis and hyperlipidemia have been well described and may be of increased importance in the era of early steroid cessation and avoidance. We hypothesized that maintenance immunosuppressive medications known to be associated with these risk factors for AVN would also be associated with a higher risk of AVN.

METHODS

By using the U.S. Renal Data System database, we studied 27,772 primary patients on Medicare who received a solitary kidney transplant between January 1, 1996, and July 31, 2000. Cox proportional hazards regression models were used to calculate adjusted hazard ratios (AHRs) for patient- and transplant-related factors (including allograft rejection) with Medicare claims for AVN. The intensity and duration of corticosteroid use could not be assessed.

RESULTS

Among patients who were prescribed sirolimus at discharge, 3.5% of patients who received the combination of sirolimus-cyclosporine A (CsA) demonstrated AVN, compared with 1.4% of patients who received the combination of sirolimus-tacrolimus (P=0.06 by chi). In Cox regression, CsA use (vs. tacrolimus) (AHR 1.36, 95% confidence interval, 1.09-1.71) was independently associated with an increased risk of AVN. Sirolimus use showed a trend toward significance (AHR 1.59, 95% confidence interval, 0.99-2.56), with no significant interaction with CsA.

CONCLUSIONS

Compared with other maintenance immunosuppression, AVN was significantly more common after use of CsA prescribed at the time of discharge for renal transplantation. Whether this increased risk of AVN was directly attributable to hyperlipidemia, microvascular thrombosis, or differences in corticosteroid dosing could not be determined.