339 patients scheduled for lower extremity surgery were randomized to have an ultrasound-guided, combined femoral and sciatic nerve block completed with either 40mL 0.5% ropivacaine, 30mL 0.6% ropivacaine, or 30mL 0.75% ropivacaine. Patients were assessed for time to complete anesthetic onset, intraoperative and postoperative pain score, patient satisfaction, and incidence of adverse events. In comparing different volumes, pain scores were significantly higher among patients treated with 40mL 0.5% ropivacaine compared to 30mL 0.75% ropivacaine at 6 and 12 hours postoperatively. In comparing concentration, no significant differences in pain or patient satisfaction were observed between 30mL 0.6% ropivacaine and 30mL 0.75% ropivacaine.