120 patients with total knee arthroplasty were randomized to receive dexmedetomidine combined with ropivacaine (n=60) or ropivacaine alone (n=60). The primary outcome of interest was postoperative analgesia, with secondary outcomes including the incidence of postoperative delirium, sleep quality, and the occurrence of postoperative complications. Outcomes were assessed at 6, 12, 24, and 48 hours postoperatively for pain scores, on days 1, 2, and 3 for delirium, before surgery, the night of surgery, and 24 hours for sleep quality. Overall, the results of the study revealed that the combination of dexmedetomidine with ropivacaine resulted in lower pain scores at rest and during exercise at 12, 24, and 48 hours postoperatively compared to ropivacaine alone. Additionally, the incidence of postoperative delirium was lower in the dexmedetomidine combined group on days 1 and 2 postoperatively, and sleep quality scores were better in this group compared to the ropivacaine alone group. There was no significant difference in postoperative adverse reactions between the two groups. The findings suggest that dexmedetomidine combined with ropivacaine improves postoperative analgesia, reduces the incidence of postoperative delirium, and enhances sleep quality without increasing adverse effects in elderly patients undergoing total knee arthroplasty. This combination may offer a beneficial approach to managing postoperative pain and improving recovery outcomes in this patient population.