Efficacy of adductor canal block combined with posterior branch of obturator nerve block for postoperative analgesia in elderly patients undergoing total knee arthroplasty

Objective To evaluate the efficacy of adductor canal block combined with posterior branch of obturator nerve block for postoperative analgesia in the elderly patients undergoing total knee arthroplasty. Methods Sixty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 65-75 yr, weighing 55-80 kg, scheduled for elective unilateral total knee arthroplasty, were divided into 2 groups(n=30 each)using a random number table: adductor canal block group(group A)and blockade of adductor canal and posterior branch of obturator nerve group(group AO). At the end of anesthesia induction, adductor canal block was performed under ultrasound guidance, and 0.5% ropivacaine 20 ml was injected in A and AO groups, and in addition posterior branch of obturator nerve block was then performed under ultrasound guidance, and 0.5% ropivacaine 10 ml was injected in group AO.When postoperative visual analog scale score≥3, patient-controlled intravenous analgesia was performed with morphine 0.05 mg/kg at a 10-min interval.When postoperative visual analog scale score was still≥3, morphine 0.025 mg/kg was intravenously injected as rescue analgesic.The duration of first requirement for analgesic, consumption of morphine within 24 and 48 h after operation, patient′s satisfaction with analgesia at 48 h after operation and development of nerve block-related complications and adverse reactions such as nausea, vomiting and itching were recorded. Results Compared with group A, the duration of first requirement for analgesic was significantly prolonged, and the consumption of morphine within 24 h after operation was reduced in group AO(P 0.05). Nerve block-related complications were not found in two groups. Conclusion Adductor canal block combined with posterior branch of obturator nerve block produces better efficacy than either alone when used for postoperative analgesia in the elderly patients undergoing total knee arthroplasty. Key words: Arthroplasty, replacemnt, knee; Nerve black; Adductor canal; obturator nerve; Analgesia