Peripheral Nerve Blocks Improve Analgesia After Total Knee Replacement Surgery

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Abstract
Total knee replacement (TKR) produces severe postop- erative pain. Peripheral nerve blocks can be used as an- algesic adjuncts for TKR, but the efficacy of femoral nerve blocks alone is controversial. The sciatic nerve innervates posterior regions of the knee; thus, perfor- mance of both sciatic and femoral nerve blocks may be necessary to improve analgesia after TKR. We per- formed this study to determine whether peripheral nerve blocks improve analgesia after TKR. In a random- ized, double-blind fashion, 36 patients undergoing TKR received either femoral, sciatic-femoral, or sham nerve blocks after a standardized spinal anesthetic. Fur- ther postoperative analgesia was provided by patient- controlled IV morphine and ketorolac. Pain at rest and with physical therapy, morphine use, nausea, pruritus, sedation, and patient satisfaction were assessed. Patients receiving peripheral nerve blocks reported bet- ter analgesia at rest for at least 8 h after transfer to the hospital ward (P < 0.05). Morphine use was decreased by approximately 50% in the peripheral nerve block groups until the second postoperative day (P < 0.02). Side effect profiles and patient satisfaction were similar between groups. We conclude that femoral nerve blocks improve analgesia and decrease morphine use after TKR. The addition of a sciatic nerve block to the femoral nerve block did not further improve analgesic efficacy. Implications: Performance of femoral nerve blocks improves analgesia and decreases the need for morphine after total knee replacement surgery. The ad- dition of a sciatic nerve block to the femoral nerve block does not provide additional benefits. (Anesth Analg 1998;87:93-7)