['Although regional anesthesia is the first choice for patients undergoing total knee arthroplasty (TKA), it may not be effective and the risk of complications is greater in patients who are obese or who have spinal deformities. We compared the success of ultrasound-guided femoral and sciatic nerve blocks with sedoanalgesia versus spinal anesthesia in unilateral TKA patients in whom spinal anesthesia was difficult.', 'We enrolled 30 patients; 15 for whom spinal anesthesia was expected to be difficult were classified as the block group, and 15 received spinal anesthesia. Regional anesthesia was achieved with bupivacaine 62.5 mg and prilocaine 250 mg to the sciatic nerve, and bupivacaine 37.5 mg and prilocaine 150 mg to the femoral nerve. Bupivacaine 20 mg was administered to induce spinal anesthesia. Hemodynamic parameters, pain and sedation scores, and surgical and patient satisfaction were compared.', 'A sufficient block could not be obtained in three patients in the block group. The arterial pressure was significantly lower in the spinal group (P < 0.001), and the incidence of nausea was higher (P = 0.017) in this group. Saturation and patient satisfaction were lower in the block group (P < 0.028), while the numerical pain score (P < 0.046) and the Ramsay sedation score were higher (P = 0.007).'] Does ultrasound-guided femoral and sciatic nerve block combined with sedoanalgesia versus spinal anesthesia in total knee arthroplasty?