Femoral nerve block with bupivacaine 0.25 per cent for postoperative analgesia after open knee surgery.

An assessment was made, in a randomised double-blind fashion, of the pain relief afforded by femoral nerve block (FNB) performed at the end of ligament reconstruction of the knee, using 0.25 per cent bupivacaine in ten patients, and normal saline in ten patients. All patients commenced "continuous passive motion" (CPM) of the operated knee after arrival in the Recovery Room. The postoperative analgesic requirement, both for intravenous fentanyl in the Recovery Room, and intramuscular and oral analgesia on the ward, was then studied. The time interval between FNB and first dose of analgesia was significantly longer in the bupivacaine group than in the control group. The bupivacaine group also required significantly less intravenous fentanyl in the Recovery Room. On the ward, there was no difference between the two groups in the total dose of intramuscular meperidine given in the first 12 hours postoperatively. We conclude that femoral nerve block is a useful adjunct in pain management after ligament reconstruction of the knee, especially in the early postoperative period, but does not decrease the total intramuscular dose of analgesia in the first 12 postoperative hours.