title: Association between VEGF -634G/C polymorphism and osteonecrosis of the femoral head susceptibility: a meta analysis.
abstract: BACKGROUND
  VEGF plays an important role in bone formation and repair. However, the effects of VEGF -634G/C polymorphisms on the pathogenesis of osteonecrosis of the femoral head (ONFH) were not conclusive. Our research was aimed to further analyze the association of VEGF -634G/C polymorphism with ONFH risk.
  
  
  METHODS
  The relevant articles were searched in PubMed, Elsevier, EMBASE, Web of Science and Chinese National Knowledge Infrastructure (CNKI) database. And a total of 692 cases and 875 controls were included. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the correlation of VEGF -634G/C polymorphism and ONFH susceptibility. Chi-square based Q-statistic test was used to evaluate heterogeneity among the studies. The random-effects model or fixed-effects model was used depending on heterogeneity.
  
  
  RESULTS
  The sensitivity analysis and publication bias test indicated that our results were stable and credible. And the results suggested that VEGF -634G/C polymorphism was significantly related with increased risk for ONFH in Asian population (CC versus GG: OR=1.34, 95% CI=1.02-1.76).
  
  
  CONCLUSIONS
  The results indicated that VEGF -634G/C polymorphism might serve as genetic-susceptibility factor for ONFH.
authors.affiliation: Department of Orthopedics, 307 Hospital of PLA Beijing, People's Republic of China.
authors.forename: Yaosheng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: PLA Institute of Orthopedics, Beijing military general hospital Beijing, People's Republic of China.
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, 307 Hospital of PLA Beijing, People's Republic of China.
authors.forename: Shubin
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Orthopedics, 307 Hospital of PLA Beijing, People's Republic of China.
authors.forename: Xiuyun
authors.initials: X
authors.lastname: Su
authors.affiliation: Statistics Room, Capital Medical University Affiliated Beijing Friendship Hospital Beijing, People's Republic of China.
authors.forename: Shiguo
authors.initials: S
authors.lastname: Zhou
keywords: VEGF; osteonecrosis of the femoral head; polymorphism