RESUMO
BACKGROUND:The roles of osteocyte and osteoblast apoptosis in steroid-induced avascular necrosis of the femoral head (ANFH) have arouse much attention,and its pathogenesis has been understood gradually.But there is a lack of knowledge about the mechanisms underlying osteocyte and osteoblast apoptosis.Meanwhile,hormones have been shown to enhance the Dickkopf-1 expression in Wnt signaling pathway.OBJECTIVE:To investigate the roles of Dickkopf-1 and cell apoptosis in steroid-induced ANFH,and to understand their correlations with steroid-induced ANFH.METHODS:Necrotic femoral head samples were removed from 14 patients with steroid-induced ANFH after total hip arthroplasty (experimental group),and normal femoral heads were from 8 patients with femoral neck fracture (control group).The cellular morphology was observed using transmission electron microscope;the number of empty lacunae was counted through hematoxylin-eosin staining;the cell apoptosis was detected by TUNEL assay;the expression level of Dickkopf-1 was detected by immunohistochemistry.Moreover,the correlation between the Dickkopf-1 positive rate and apoptosis index of osteocytes was analyzed by Spearman rank correlation analysis.RESULTS AND CONCLUSION:The number of empty lacunae,expression level of Dickkopf-1,and apoptosis index of osteocytes in the experimental group were significantly higher than those in the control group (P ＜ 0.05).In the experimental group,the Dickkopf-1 positive rate was positively correlated to the apoptosis index of osteocytes (r=0.623).These results indicate that Dickkopf-1 and osteocyte apoptosis both play key roles in steroid-induced ANFH,and increased Dickkopf-1 level may promote the development of ANFH.