Analgesic efficacy of ultrasound guided anterior femoral cutaneous nerve block (AFCNB) plus femoral triangle block (FTB) vs. adductor canal block (ACB) in total knee arthroplasty

Background& objective: Femoral Triangle Block (FTB) offers an efficient pain relief in total knee arthroplasty (TKA), except the anteromedial cutaneous region which may not be completely anesthetized by solely utilizing FTB. Therefore, adding the Anterior Femoral Cutaneous Nerve Block (AFCNB) to the FTB could provide complete pain relief. Adductor Canal Block (ACB) is a common technique to provide analgesia after total knee arthroplasty. In the current study, we assessed and contrasted the effectiveness of ultrasound (US) guided AFCNB plus FTB versus ACB regarding analgesia and early mobilization after TKA. Methodology: Sixty patients who had total knee arthroplasty were randomly assigned into two equivalent groups; Group A which obtained AFCNB in Combination with FTB or Group B which received ACB before the beginning of the surgery. After completion of the desired block, spinal anesthesia was given under complete aseptic conditions. The primary outcome was comparison of the time to first request of the post-operative rescue pethidine in the case of visual analogue scale (VAS) score above 3. Secondary outcomes were the total amount of rescue pethidine used, VAS scores and time to ambulation. Immediate postoperative complications of the given nerve blocks and the adverse effects of the used drugs were recorded and managed accordingly. Results: Sixty participants successfully finished the study. No significant statistical differences between both groups were noted at the time of request of the first post-operative rescue pethidine (P = 0.159). Additionally, there was no statistical difference concerning postoperative VAS between the two groups except at 8 hours and 20 hours where Group A showed a statistically significant lower VAS than Group B (P = 0.039 and 0.005 respectively). However, Group A consumed a statistically significant smaller total amount of pethidine than Group B (P = 0.030). Conversely, Group B showed a shorter duration than Group A regarding ‘Timed Up and Go’ test (TUG) at 12 hours and 24 hours post operatively with a high statistically significant difference between them (P< 0.001 in both). Incidence of complications and adverse effects of the used drugs was comparable between the two groups without significant difference. Conclusion: We concluded that AFCNB in combination with FTB provided better analgesic and pethidine-sparing effects compared to ACB after TKA. However, ACB provided better preservation of motor function and provided early ambulation. Abbreviations: ACB: Adductor canal block, AFCNB: Anterior Femoral Cutaneous Nerve Block, FTB: Femoral Triangle Block, TKA: Total knee arthroplasty, VAS: visual analogue pain scale Keywords: Anterior Femoral Cutaneous Nerve Block; Femoral Triangle Block; Adductor Canal Block; Anesthesia; Total Knee Arthroplasty Citation: Mohamed ElRazzaz MHS, Kamel Youssif GF, Wahba SS, Mohamed SA, Mohamed AM. Analgesic efficacy of ultrasound guided anterior femoral cutaneous nerve block (AFCNB) plus femoral triangle block (FTB) vs. adductor canal block (ACB) in total knee arthroplasty. Anaesth. pain intensive care 2025;29(2):232-241. DOI: 10.35975/apic.v29i2.2709 Received: May 09, 2024; Reviewed: October 26, 2024; Accepted: January 01, 2025