Effects of single femoral nerve block and continuous femoral nerve block on perioperative analgesia and muscle strength in elderly patients undergoing total knee arthroplasty, a randomized clinical trial

Yan Tao¹Nan Cai¹Juxia Zhang¹Pengfei Liu^2*Yan Zhou^1*

• ¹Beijing Jishuitan Hospital, Capital Medical University, Beijing, China
• ²Beijing Shijitan Hospital, Capital Medical University, Beijing, China

Objective: To investigate the effect of single femoral nerve block (SFNB) with 0.2% ropivacaine 50 ml on postoperative pain and muscle strength in elderly patients undergoing knee replacement.Methods: Ninety-four patients scheduled for primary total knee arthroplasty (TKA) were randomized into two groups. The patients in the SFNB group received SFNB with 50 ml 0.2% ropivacaine (n = 48), while the patients in the continuous femoral nerve block (CFNB) group (n = 46) received CFNB with an initial load of 20 ml 0.5% ropivacaine and a continuous injection of 0.2% ropivacaine at a rate of 5 ml/h. After the surgery, all patients were administered patient-controlled intravenous analgesia.The primary outcome was the visual analogue scale (VAS) score at 24 hours postoperatively. The secondary outcomes included: a. Pain scores at 2h, 6h, 12h, 48h, and 72h after surgery, and the total dosage of celecoxib; b. Muscle strength of the quadriceps at 2h, 6h, 12h, 24h, 48h, and 72h postoperatively; c. Range of motion (ROM) at 24h, 72h, and 1 week after surgery; d. American Knee Society knee score (AKS) at 1 week postoperatively; e. Related complications (e.g., nausea and vomiting), and length of hospitalization; f. General Comfort Questionnaire (GCQ) score at 72h postoperatively.Results: a. There were no statistically significant differences in VAS scores (p > 0.05) or the total dosage of celecoxib (p > 0.05) between the two groups at various time points; b. The muscle strength scores in the SFNB group were higher than those in the CFNB group (p < 0.05) at 6h, 12h, and 24h postoperatively; c. Knee ROM in the SFNB group was better than in the CFNB group (p < 0.05); d. There were no significant differences in adverse events between the two groups (p > 0.05); e. The physiological and psychological scores on the GCQ in the SFNB group were higher than those in the CFNB group (p < 0.05).SFNB, with 0.2% ropivacaine 50 ml provides effective pain relief, and improves patient comfort after surgery, without increasing adverse effects. SFNB is a safe and convenient option for postoperative pain management following knee surgery.