Dexamethasone AUC was associated with severe osteonecrosis. (A) Dexamethasone AUC (nM × h) at week 8 in patients with grade 0 or 1, grade 2, and grade 3 or 4 osteonecrosis (ON). Statistical significance was determined after adjustment for age and treatment arm. (B) Representative plasma concentration versus time curves in patients with low, medium, and higher dexamethasone exposure.