RESUMEN
BACKGROUND: Femoral nerve block (FNB) has been used as part of the multimodal analgesia after total knee arthroplasty (TKA), but leads to weakness in the quadriceps muscles. Recently, adductor canal block (ACB) was reported to provide effective pain relief while sparing the strength of the quadriceps. This simultaneous bilateral randomized study investigated whether patients perceived differences between ACB and the FNB after same-day bilateral TKA. METHODS: We performed a prospective simultaneous bilateral randomized study in 50 patients scheduled to undergo same-day bilateral TKA. One knee was randomly assigned to ACB and the other knee was assigned to FNB. All ACB and FNB were performed using ultrasound-guided single-shot procedures. These 2 groups were compared for pain visual analogue scale, straight leg raising ability and knee extension while sitting, and motor grade. At postoperative week 1, the peak torque for the quadriceps muscle was measured in both knees with an isokinetic dynamometer. RESULTS: There were no differences in pain levels between ACB and FNB during the entire study period. During the first 48 h after TKA, more of the knees that received ACB could perform straight leg raising and knee extension with greater quadriceps strength compared with FNB. However, no group differences in quadriceps functional recovery were found after postoperative 48 h and isometric quadriceps strength at postoperative 1 week. CONCLUSION: This simultaneous bilateral randomized study demonstrates that patients did not perceive differences in pain level, but experienced substantial differences in quadriceps strength recovery between knees during the first 48 h (Identifier: NCT02513082).