RESUMEN
This study was designed to determine the effects of a single-injection femoral nerve block (FNB) using 30 mL of 0.5% bupivacaine with epinephrine 1:200,000, on pain control following total knee arthroplasty (TKA). Forty patients were randomly distributed into 2 groups: Group A received general anesthesia plus a FNB (n = 19), whereas Group B received general anesthesia plus a FNB with 30 mL of preservative-free saline (n = 21). The amount of morphine used, sedation, and average pain perception were measured for the first 24 hours and daily postoperatively. Group A used significantly less morphine (48.1 mg) compared with Group B, which used 76.2 mg during the first 24 hours after surgery (P = 0.003). Group A's sedation scale was significantly less than group B's (2.26 vs 2.67) (P = 0.045). The average pain perception was significantly different (P =.002). Postoperative management of pain following TKA can be improved through a preoperative single-injection FNB with 0.5% bupivacaine plus epinephrine 1:200,000. The cost is minimal, risks appear acceptable, and the procedure is efficacious.