Epidural infusion or combined femoral and sciatic nerve blocks as perioperative analgesia for knee arthroplasty

Background. Peripheral neural blockade appears to provide effective analgesia with potentially less morbidity than central neuraxial techniques. We compared the relative benefits of combined femoral (3-in-1) and sciatic nerve block with epidural blockade for postoperative knee arthroplasty analgesia. Methods. Sixty patients, ASA I-III, undergoing unilateral knee replacement were prospectively randomized to receive either a lumbar epidural infusion or combined single-shot femoral (3-in-1) and sciatic blocks (combined blocks). All patients received standard general anaesthesia. Visual analogue pain scores and rescue opioid requirements were recorded at four time points postoperatively. Patient satisfaction, morbidity, block insertion time, perioperative blood loss and rehabilitation indices were also assessed. Results. In both groups, pain on movement was well controlled at discharge from recovery and 6 h postoperatively but increased at 24 and 48 h. Median (95% CI) analogue scale scores were 0 (0-0), 15 (0-30), 55 (38-75) and 54 (30-67) mm for epidural block and 0.5 (0-22), 21.5 (10-28), 40 (20-50) and 34.5 (21-55) mm for combined block. VAS pain scores with the combined blocks were significantly lower at 24 h (P=0.004). Total morphine usage was low in both groups: median epidural group 17 mg (8-32) versus combined blocks 13 mg (7.8-27.5). Patient satisfaction was high in both groups with median (95% CI) scores of 100 (85-100), 83 (70-100) and 82 (57-90) mm for epidural and 90 (73-100), 100 (77-100) and 97 (80-100) mm for combined blocks (not significant). Perioperative blood loss and rehabilitation indices were also similar. Conclusions. Combined femoral (3-in-1) and sciatic blocks offer a practical alternative to epidural analgesia for unilateral knee replacements.