One hundred ten patients with high-pain-response after primary TKA were randomized to receive oral dexamethasone 24 mg on postoperative day 1 (n=55) or placebo (n=55). The primary outcome was the proportion with moderate–to–severe walking pain (VAS>30) at 48 h. Secondary outcomes included pain over days 2–3 and 2–7 (walking, rest, night), rescue opioid use (morphine-milligram equivalents), sleep quality, symptoms (lethargy, dizziness, nausea), satisfaction, length of stay, and 30-day readmissions. Outcomes were assessed through day 7, with follow-ups at days 8 and 30. Overall, the results showed no significant reduction in the primary outcome with dexamethasone vs placebo, and mean 48-h walking VAS was borderline lower. Exploratory time-point analyses found mixed, small differences at 60–96 h that did not change overall conclusions. These findings suggest adding a repeat dose after a pre-operative 1 mg/kg dexamethasone does not meaningfully prevent pain relapse in this high-risk cohort.