[Comparing the analgesic efficacy of continuous femoral nerve blockade and continuous intravenous analgesia after total knee arthroplasty].

Objective: To compare the analgesic efficacy of continuous femoral nerve blockade (CFNB) and continuous intravenous analgesia (CIA) after total knee arthroplasty (TKA).

Methods: 126 patients undergoing TKA under combined epidural-spinal anesthesia were randomized to receive either a femoral infusion of ropivacaine 0.2% (median infusion rate 5 ml/h) (n = 63) or an intravenous infusion of fentanyl 30 µg/kg (2 ml/h) (n = 63). Adjuvant analgesics were oral celebrex or IM pethidine. In the CFNB group, CFNB was established before combined epidural-spinal anesthesia and 20 ml 0.5%ropivacaine was infused through the catheter placed near femoral nerve. Visual analogue scale (VAS) scores were assessed at rest and on passive mobilization by acute pain service blinded to analgesic treatment. Nausea and vomiting, dizziness, satisfaction and other side-effects were assessed postoperatively.

Results: There was significantly less VAS scores in the CFNB group comparing the CIA group at rest 4, 8, 12, 16, 24, 36, 48 h after surgery (P < 0.01). A significant difference in VAS scores was found in CFNB group vs CIA group on passive mobilization 24, 36, 48 h after operation (P < 0.01). There was significantly less dizziness, nausea and vomiting in the CFNB group (P < 0.01). Patient satisfaction was higher in the CFNB group (92.1%) than the CIA group (20.6%) (P < 0.01).

Conclusion: CFNA with ropivacaine 0.2% is more effective in controlling postoperative pain than CIA and CFNB is an effective regional component of a multimodal analgesic strategy after TKA.