Effectiveness and safety of continuous ultrasound-guided femoral nerve block versus epidural analgesia after total knee arthroplasty

Total knee arthroplasty is associated with severe postoperative pain. The aim of this study was to compare continuous ultrasound-guided femoral nerve block with continuous epidural analgesia, both with low concentrations of local anaesthetic after total knee arthroplasty. A prospective, randomised, unblinded study of 60 patients undergoing total knee replacement, randomised into two groups. A total of 30 patients received continuous epidural block, while the other 30 received continuous ultrasound-guided femoral nerve block, as well as using 0.125% levobupivacaine infusion in both groups. Differences in pain control, undesirable effects, and complications between the two techniques were assessed, as well as the need for opioid rescue and the level of satisfaction with the treatment received during the first 48hours after surgery. No differences were found in demographic and surgical variables. The quality of analgesia was similar in both groups, although in the first six hours after surgery, patients in the epidural group had less pain both at rest and with movement (P=.007 and P=.011). This difference was not observed at 24hours (P=.084 and P=.942). Pain control at rest in the femoral block group was better at 48hours after surgery than in the epidural group (P=.009). The mean consumption of morphine and level of satisfaction were similar. Epidural analgesia showed the highest rate of side effects (P=.003). Continuous ultrasound-guided femoral nerve block provides analgesia and morphine consumption similar to epidural analgesia, with the same level of satisfaction, but with a lower rate of side effects after total knee arthroplasty.