Steroid-associated osteonecrosis: Epidemiology, pathophysiology, animal model, prevention, and potential treatments (an overview)

Xie, Xin-Hui; Wang, Xin-Luan; Yang, Hui-Lin; Zhao, De-Wei; Qin, Ling

During the development of SAON, the destructive repair at necrotic lesions was characterised by predominant resorption of necrotic bone exceeding bone formation accompanied by decreased angiogenesis. Vascular endothelial growth factor (VEGF) is an important factor to act on the endothelial cells and induce neovascularisation during bone healing. Decreased VEGF expression after treatment with dexamethasone was both dose-and time-dependent. Clinical and animal experiments showed decreased VEGF expression at the early stage of SAON and increased VEGF in the reactive nitric oxide lesion at the late stage [Association Research Circulation Osseus (ARCO): stage IV] of the femoral head [29] . As well as the decreased VEGF expression at the early stage of ON found by others, we also found increased VEGF expression 2 weeks after ON induction, which was maintained at Week 6 during the destructive repair in SAON rabbits, whereas VEGF expression in reconstructive repair decreased from Week 2 to Week 6 [9] .