FEMORAL VERSUS COMBINED FEMORAL AND SCIATIC NERVE BLOCK IN TOTAL KNEE REPLACEMENT: A PROSPECTIVE COMPARATIVE STUDY

Abstract

Background and objectives: Total knee replacement (TKR) produces severe postoperative pain. Peripheral nerve blocks can be used as analgesic adjuncts after TKR. The use of peripheral nerve block has certainly reduced the use of opiates by 50%; however adding the sciatic nerve block to the femoral nerve block is controversial. The aim of this study was to compare femoral and femoral plus sciatic nerve blocks in postoperative pain management of patients undergoing TKR.

Materials and Methods: Total of 42 patients were studied. Twenty patients with an average of 75yrs (51–86yrs) received femoral nerve block alone. Twenty-two patients with an average age of 69yrs (53–83yrs) received femoral plus sciatic nerve block. 0.5% Chirocaine was used for nerve blocks. There was no significant difference between two groups in terms of pre-operative pain, pre-operative deformity, ROM and patella replaced. The primary outcome measures used were visual analogue scale (VAS) pain scores at 24 hours, 48 hours and 72 hours after the surgery. The amount of opiate consumption and PCA (patient controlled analgesia) used were also recorded. The secondary outcomes were postoperative nausea and vomiting, straight leg raise, neurological deficit, knee flexion, independent mobility and discharge from the hospital.

Results: The results showed significant decrease in the amount of pain in the femoral nerve block group than the combined nerve block patients. Patients who had combined nerve block complained of heaviness in the legs and were slow to mobilise. There was no significant difference in consumption of opiates, use of PCA, nausea and vomiting, independent mobility and the time of discharge from the hospital between the two groups.

Conclusion: The addition of sciatic nerve block to the femoral nerve block does not provide any additional benefits in TKR.