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

Histopathologically, the ON lesion is characterised by the diffuse presence of empty lacunae or pyknotic nuclei of osteocytes in bone trabeculae, accompanied by surrounding necrotic bone marrow [8e10]. Decreased trabecular width and increased number of apoptotic osteoblasts and osteocytes were also identified in patients with glucocorticoid administration. There were two repair types in ON lesions in SAON found by others and us. Appositional bone formation with osteoblast-like cells around the necrotic lesion is classified as reparative osteogenesis, whereas granulation tissue creep linked to necrotic bone resorption is classified as destructive repair [9, 11, 12] . In terms of destructive repair, the necrotic bone will subsequently induce an inadequate repair process, i.e., the predominant resorption of necrotic bone exceeds bone formation that frequently leads to subchondral collapse. In terms of reconstructive repair in the femoral head, reparative bone formation starts from subchondral fractures and/or the reactive interface, that finally reduces the size of the necrotic lesion.