Figure 6.

A proposed scheme for enhanced oxidative stress and hyperactive osteoclasts following the use of steroids. A decline in the expression of antioxidant enzymes correlates with the administration of steroids, which may, in turn, contribute to elevated ROS levels and subsequent osteoclast numbers/activity observed during the pathogenesis and progression of ONFH. HO1: heme oxygenase 1; ROS: reactive oxygen species; RANKL: receptor activator of NF-κB ligand; TRAP: tartrate-resistant acid phosphatase; γ-GCSc: γ-glutamylcysteine synthetase.