A total of 165 patients undergoing total knee arthroplasty (TKA) were randomized to receive either sublingual sufentanil tablet system (SSTS) (n=84) or a single-shot peri-nervous injection of ropivacaine (n=81). The primary outcome was performance on the Timed Up and Go (TUG) test on the third postoperative day. Secondary outcomes included hospital length of stay, numeric rating scale (NRS) for pain, joint mobility, frequency of rescue analgesic use, side effects, and patient satisfaction. Outcomes were assessed during the hospital stay, typically up to three days postoperatively. Overall, the results revealed that SSTS significantly outperformed ropivacaine in pain control, joint mobility, and recovery metrics, with fewer treatment discontinuations due to uncontrolled pain. These findings suggest that SSTS may provide superior pain management and enable faster recovery in TKA patients.