Pericapsular Nerve Group (PENG) Associated with Lateral Femoral Cutaneous Nerve (LFCN) Block Versus Fascia Iliaca Compartment Block (FICB) for Total Hip Replacement Surgery: Double-Blind Randomized Controlled Trial.

Background: Total hip arthroplasty (THA) improves the quality of life by alleviating pain and restoring function. The optimal pain control with minimal muscle weakness is paramount for early rehabilitation and for reducing complications. Although PROSPECT and ICAROS guidelines recommend the Fascia Iliaca Compartment Block (FICB), it is associated with insufficient pain relief and a prolonged quadriceps motor block. The association of the PENG (Pericapsular Nerve Group) with LFCN (lateral femoral cutaneous nerve) blocks may address these limitations, provide improved motor-sparing pain control, and offer a more tailored approach that enhances both an early postoperative recovery and patient satisfaction. Methods: A randomized controlled trial (November 2023-July 2024) compared the PENG + LFCN to the FICB in patients undergoing elective THAs under spinal anesthesia. The primary outcome was quadriceps weakness at 6 h post-block. Secondary outcomes included the degree of hip flexion and pain scores at 6, 24, and 48 h post-block, opioid consumption, and time to ambulation. Results: Fifty-eight patients were randomized (twenty-nine per group). The PENG + LFCN group achieved a significantly greater muscle strength (MRC: 4 [4; 4] vs. 3 [3; 4], p < 0.0001) and better hip flexion at all measured moments (6 h: 45° [37; 60] vs. 30° [25; 43], 24h: 59° [49; 66] vs. 47° [36; 50], 48 h: 62° [55; 70] vs. 50° [40; 55], all p < 0.0001). Resting pain was lower in the PENG + LFCN group (0 [0; 1], 0 [0; 2], and 0 [0; 1] vs. 2 [0; 3], 1 [0; 3], 1 [0; 3]), as was the dynamic pain during movement (1 [0; 2], 2 [2; 4], and 2 [1; 2] vs. 3 [2; 5], 3 [2; 4], and 3 [1; 3]; all p < 0.001), along with a lower total opioid consumption (0 [0; 0] vs. 7.5 [7.5; 22.5] MME, p < 0.001). Conclusions: The PENG + LFCN block outperformed the FICB in muscle strength, hip flexion, pain control, and opioid use, suggesting it may be a more effective option for THAs.