Lateral Femoral Cutaneous Nerve Block for Postoperative Pain Control After Total Hip Arthroplasty Using the Direct Anterior Approach: A Single-blinded Randomized Control Trial.

Background: Total hip arthroplasty (THA) employing the direct anterior approach (DAA) is increasingly performed as a less invasive procedure with faster recovery than other approaches. Unlike other approaches, the skin incision is made on the lateral thigh, distal to the inguinal ligament. However, the effectiveness of ultrasound-guided lateral femoral cutaneous nerve (LFCN) block for postoperative analgesia after THA using DAA has not been investigated.We hypothesized that ultrasound-guided LFCN block using DAA would reduce postoperative pain after THA. Methods: A prospective, randomized, observer-blinded controlled trial was conducted. The 92 patients included were divided into two groups: those who received only femoral nerve block (FNB group) and those who received femoral nerve block and LFCN block with 10mL of 0.25% levobupivacaine (FNB + LFCNB group). Both groups received intravenous patient-controlled analgesia (fentanyl) postoperatively. A numerical rating scale was used to quantify pain at 3 and 48 h postoperatively. Results: There was no significant difference in pain at rest and during movement between the FNB and FNB + LFCNB groups (at rest: Z = -1.6814, p=0.0927; during on movement: Z = -0.9677, p=0.9487). There was also no significant difference in pain severity at rest and during movement between the FNB and FNB + LFCNB groups postoperatively. Conclusions: LFCNB did not improve postoperative pain relief in patients undergoing THA with DAA.