[Effect of continuous femoral nerve catheter length on blockade of femoral nerve, lateral femoral cutaneous nerve and obturator nerve].

OBJECTIVE: To assess the effects of length of continuous femoral catheter on blockade of femoral nerve, lateral femoral cutaneous nerve and obturator nerve. METHODS: In the study, 70 patients with American Association of Anesthesiologist grades I-II undergoing total knee arthroplasty were randomly divided into three groups, femoral nerve catheters were inserted 5 cm, 10 cm or 20 cm with assistance of a nerve stimulator, patient-controlled analgesia pumps were connected after load of 30 mL 0.3% ropivacaine via the catheters. Sensory blockade of the femoral nerve, lateral femoral cutaneous nerve and obturator nerve were recorded at 24 h postoperatively. Visual analog scale (VAS) pain scores during rest and motion were recorded at 24 h and 48 h postoperatively. RESULTS: The blockade effect of lateral femoral nerve in the 20 cm group was the best. There was no significant difference in sensory blockade between the 5 cm group and the 10 cm group. There was no significant difference in VAS score among the three groups. CONCLUSION: When continuous femoral nerve block is used for postoperative analgesia after total knee arthroplasty surgery, the catheters that are inserted 5 cm, 10 cm or 20 cm could provide similar and satisfying analgesia effect.