Femoral nerve block using 0.25% or 0.5% bupivacaine for analgesia after arthroscopic anterior cruciate ligament reconstruction.

Background: Femoral nerve block (FNB) with varying concentrations of bupivacaine is often used for postoperative analgesia after anterior cruciate ligament (ACL) reconstruction.

Objective: To determine whether FNB using 0.25% or 0.