Oral Corticosteroids Reduce Pain After Total Knee Arthroplasty: A Higher Dose of Dexamethasone Effectively Controlled Pain During Motion

Background: Intravenous corticosteroids have been used to manage pain following total knee arthroplasty (TKA). Oral dexamethasone has good bioavailability and is suitable for ambulatory TKA. This study investigated the efficacy and dose-response relationship of oral dexamethasone in pain control after TKA. Methods: In this randomized controlled trial, 120 Thai patients (mean, 68 ± 8 years; 86% female) undergoing primary TKA were allocated to 1 of 3 groups: 16 mg of oral dexamethasone (DEX-16), 8 mg of oral dexamethasone (DEX-8), or placebo. Dexamethasone or placebo was administered once daily, in the morning before surgery and the morning of the first 4 postoperative days. The primary outcome was pain at rest and during motion, measured over time. Linear mixed-effects modeling was used to compare outcomes between groups. Results: Both DEX-8 and DEX-16 significantly reduced pain at rest within 48 hours postoperatively compared with placebo (p < 0.05). However, only DEX-16 significantly reduced pain during motion (p < 0.05). At 48 hours postoperatively, the DEX-16 group showed approximately 50% reductions in pain at rest (p < 0.001) and during motion (p = 0.006) relative to placebo. Conclusions: Oral dexamethasone was effective in reducing pain after TKA, with a 16-mg dose providing superior pain relief during motion, compared with an 8-mg dose, within the first 48 hours. These findings support the use of oral dexamethasone as part of multimodal pain management, particularly in an ambulatory TKA setting. Level of Evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.