Analgesic efficacy and quadriceps strength of adductor canal block versus femoral nerve block following total knee arthroplasty

Femoral nerve blocks (FNBs) provide effective analgesia after total knee arthroplasty, but have been associated with quadriceps weakness. Adductor canal block (ACB) is a promising alternative option that delivers a primarily sensory blockade. The aim of this study was to determine whether ACB provides superior quadriceps strength and similar pain control than FNB. A systematic search of PubMed, the Cochrane Library, EMBASE and Web of Science was conducted without publication data or language restriction. Comparative studies comparing ACB with FNB were included. Two authors independently assessed data extraction and quality of the studies. Nine studies with 639 patients were identified. Results of meta-analysis showed that compared with FNB, ACB preserved quadriceps muscle strength better than FNB [MD24h = 1.14, 95 % CI (0.38, 1.91), p < 0.01; MD48h = 0.40, 95 % CI (0.16, 0.64), p < 0.01], while there were no significant differences in pain score during rest at 24 h [SMD = - 0.04, 95 % CI (-0.17, 0.26); n.s] or 48 h [SMD = - 0.10, 95 % CI (-0.27, 0.08); n.s], pain score during activity at 24 h [SMD = 0.13, 95 % CI (-0.36, 0.62); n.s] or 48 h [SMD = - 0.13, 95 % CI (-0.37, 0.12); n.s], opioid consumption at 24 h [SMD = - 0.01, 95 % CI (-1.68, 1.66); n.s] or 48 h [SMD = - 0.92, 95 % CI (-6.86, 5.01); n.s], length of hospital stay [MD = 0.05, 95 % CI (-0.91, 1.00); n.s] and nausea or vomiting [RR = 1.17, 95 % CI (0.62, 2.20); n.s] between ACB and FNB. ACB preserved the strength of quadriceps more than FNB and achieves similar analgesic effects in post-operative pain. Level III.