Effect of femoral nerve catheter location on postoperative pain relief after total knee arthroplasty

Abstract

We enrolled 60 patients with American Association of Anesthesiologists grade Ⅰ - Ⅱ undergoing unilateral total knee arthroplasty. All patients received combined epidural and spinal anesthesia,and a nerve stimulator was used to guide placement of a femoral nerve catheter. Patients were divided into three groups according to the catheter location on X-ray : psoas muscle group ( n = 18 ), iliacus muscle group (n = 19) and local group (n =23). Visual analog scale (VAS) pain scores were recorded at rest and with movement at 4, 24 and 48 h postoperatively and sensory blockade of the femoral, obturator and lateral femoral cutaneous nerves was recorded at 24 h. There were no significant differences in femoral nerve blockade among the three groups. Obturator nerve blockade was significantly better in the psoas muscle group than in the iliacus muscle and local groups, and was also better in the local group than in the iliacus muscle group. There was no significant difference in lateral femoral cutaneous nerve blockade between the psoas muscle and iliacus muscle groups, but there was better blockade in both these groups than in the local group. At 4 h postoperatively, VAS pain scores at rest were significantly lower in the psoas muscle group than in the iliacus muscle and local groups, but there were no significant differences in VAS pain scores with movement among the three groups. At 24 and 48 h postoperatively, VAS scores at rest and with movement were significantly lower in the psoas muscle group than in the iliacus muscle and local groups. Key words: Anesthesia and analgesia; Arthroplasty, replacement, knee