Adductor Canal Block versus Femoral Nerve Block in Total Knee Arthroplasty: Network Meta-Analysis

Objectives: The quality of postoperative analgesia in total knee arthroplasty is crucial for patient recovery, rehabilitation and hospital stay duration. In line with the above, а single-shot adductor canal block has been considered as surpassing method over continuous femoral nerve block. However, continuous adductor canal block and single-shot femoral nerve block 'kept overboard' the discussion. This study aims to compare the effectiveness of various types of adductor and femoral nerve blocks on clinically relevant outcomes in patients following total knee arthroplasty.

Methods: A systematic review and network meta-analysis were conducted following 'PRISMA-NMA' and Cochrane Handbook guidelines. Eligibility criteria included randomized trials and, where these were lacking for a comparison, non-randomized studies involving adults undergoing primary total knee arthroplasty, comparing single-shot adductor canal block, continuous adductor canal block, single-shot femoral nerve block, and continuous femoral nerve block.

Results: A total of 36 studies involving 3308 patients were included. Single-shot adductor canal block showed higher pain scores and opioid consumption but better functional recovery at 24-h compared to continuous femoral nerve block. However, this trend vanishes by the 48-h assessment post-surgery. Continuous adductor canal block had higher opioid consumption but better functional recovery and shorter hospital stay compared to continuous femoral nerve block. Single-shot adductor canal block showed higher pain scores but comparable opioid consumption and functional recovery to continuous adductor canal block.

Discussion: The shift from continuous femoral nerve block to single-shot adductor canal block as the preferred method for pain relief after total knee arthroplasty may be premature. While the latter improves mobility, it falls short in pain control and doesn't shorten hospital stays. Continuous adductor canal block shows promise but is currently underappreciated, and single-shot femoral nerve block is often overshadowed by other techniques in regional anesthesia. Further high-quality, multicenter randomized controlled trials are needed to validate these findings.