Effect of single shot femoral nerve block combined with intrathecal morphine versus patient - controlled analgesia for postoperative analgesia following total knee arthroplasty : A Randomized Controlled Trial

Abstract

Background and Objective : Pain after total knee arthroplasty (TKA) is severe. Adequate pain control improve TKA outcome and patient satisfaction and prevent of complication. Limitation of patient-controlled analgesia device (PCA) is high cost and its side effect. Intrathecal morphine (ITM) provides good postoperative analgesia for TKA, but high dose ITM may increase side effect. Femoral nerve block (FNB) is simple, high efficacy and low side effect. The aim of this study was to compare the efficacy and side effect of single shot femoral nerve block (SSFNB) combined with ITM and PCA morphine.

Methods : 40 patients undergoing elective TKA in Nakornping hospital were randomized into 2 groups. First group (SSFNB with ITM, n=20) was assigned to spinal anesthesia with 2.8ml of 0.5% hyperbaric bupivacaine and 0.15mg of morphine combined with SSFNB (0.5% bupivacaine 35ml). In first 24 hour, patients receive additional intravenous tramadol and intravenous morphine after 24 hour. Second group (PCA group, n=20) was assigned to spinal anesthesia with 2.8ml of 0.5% hyperbaric bupivacaine and control post operative pain with PCA morphine. Numerical rating scale (NRS) and side effects were recorded at 0, 1, 6, 12, 24, 36 and 48 hour postoperative. Patient satisfaction was evaluated at 48 hour postoperative visit.

Results : NRS was significant lower in SSFNB with ITM group than PCA group at 0 hour (0.35 vs 2.40, respectively; P-value = 0.000) and 1 hour (0.60 vs 3.75, respectively; P-value = 0.001) postoperative. Most side effects were not statistically different between both group except pruritus in SSFNB with ITM group significantly more than PCA group. Patient satisfaction was rated out standing 70% in SSFNB with ITM group compare to 40% in PCA group.

Conclusion : our results show that SSFNB combined with ITM may be efficient and increase patient satisfaction than PCA morphine for postoperative analgesia after TKA.