Purpose: This study aimed to develop and evaluate a patient-tailored educational intervention for postoperative nausea and vomiting to improve pain management behaviors and clinical outcomes in patients undergoing total knee arthroplasty (TKA). Methods: A randomized controlled trial powered to detect a large effect size (Cohen’s d=0.80) was conducted with 59 patients undergoing TKA, assigned to an experimental (n=29) or control group (n=30). The intervention group received tailored postoperative nausea and vomiting video education based on the Apfel risk scores, whereas the control group received standard care. The key outcomes (postoperative nausea and vomiting, analgesic use, pain, satisfaction, range of motion, and ambulation) were assessed for 7 days. Results: Although postoperative nausea and vomiting incidence was similar between groups (φ=.02, p=.895), the intervention group showed significantly better pain management: higher patient-controlled analgesia consumption (Cohen’s d=0.61, p=.027), no patient-controlled analgesia discontinuations (φ=.33, p=.011), and greater rescue analgesic use (φ=.38, p=.005). This resulted in less pain, higher satisfaction, superior range of motion, and faster ambulation (all p<.001). Conclusion This study challenges the clinical notion that elderly patients are unable to manage complex medical information. By translating complex Apfel risk scores into tailored, actionable video education, the intervention empowered patients to become active agents in their own recovery rather than passive recipients of care. This demonstrates that a well-designed, patient-centered approach is crucial not only for improving functional outcomes but also for reinforcing the core value of viewing patients as leaders in their own healthcare journey.