Severity of inflammation in the different treatment groups. (A) Joint swelling displayed as delta (Δ) between ipsilateral (inflamed) and contralateral (noninflamed) knee joints during the observation period of 21 days. *Differences between saline and dexamethasone. +Differences between morphine and dexamethasone. (B) Histopathological scores of joint inflammation. (C) Histopathological scores of cartilage and bone destruction. Data are presented as means ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001. AIA: antigen-induced arthritis.