Effect of ultrasound-guided continuous femoral nerve analgesia for total knee arthroplasty

Objective To investigate the effect of ultrasound-guided continuous femoral nerve block (CFNB) with ropivacaine on postoperative pain after unilateral total knee arthroplasty (TKA).Methods Forty ASA Ⅰ or Ⅱ patients undergoing unilateral TKA surgery were randomly divided into group PCIA (n=20) and group PCNA (n=20). The patients in group PCIA received continuous intravenous fentanyl and the patients in group PCNA received ultrasound-guided CFNB with ropivacaine for two days. Visual analogue score (VAS) during rest and continuous passive movement (CPM), the angle of initiative flections, muscle strength grades, Ramsay sedation scores and side effects were recorded. Results VAS during rest and movement 8 h, 12 h, 24 h, and 48 h postoperatively in group PCNA were significantly lower than those in group PCIA(P0.05 or P0.01). The angle of initiative flections 24 h and 48 h after surgery in group PCNA were significantly bigger than those in group PCIA.There was no statistical difference in muscle strength grades between groups. Compared with group PCIA, group PCNA had a significantly lower incidence of side effects.Conclusion Ultrasound-guided CFNB is an ideal analgesic method for TKA surgery with better analgesic effect, lower negative effect on muscle strength and lower side effects.