Adductor Canal Block Versus Femoral Nerve Block For Analgesia After Arthroscopic Anterior Cruciate Ligament Reconstruction

BACKGROUND AND OBJECTIVE: Severe pain after arthroscopic anterior cruciate ligament(ACL)reconstruction challenges postoperative pain treatment.Femoral nerve block(FNB)has been traditionally used for analgesia after procedures on the knee,while in recent years,some researches have pointed out that FNB may increase the risk of falling because of quadriceps weakness.In contrast,adductor canal block(ACB)is predominantly a sensory blockade.We hypothesized that ACB can provide adequate analgesia and preserves quadriceps muscle strengths as compared with FNB.METHODS: We enrolled 40 patients scheduled for arthroscopic ACL reconstruction with general anesthesia into our study.The patients were randomized to receive either a continuous ACB or an FNB via a catheter after the operation.Both groups received postoperatively IV patient controlled analgesia(PCA)with morphine beside the continuous nerve block.Patients were visited at 6h?24h and 48 h postoperatively.Quadriceps strength was assessed with a five-grade scale.VAS at rest time?VAS during knee flexion?morphine consumption?morphine-related complications were also recorded.RESULTS: Number of patients who could reach grade 3(against gravity)was significantly higher in the ACB group compared with the FNB group at 6h?24h?48h postoperatively(P<0.05).There was no difference between the groups regarding pain at rest as well as pain during knee flexion(P>0.05).Morphine consumption and morphine-related adverse effects were also similar(P > 0.05).CONCLUSION: Adductor canal block is superior to femoral nerve block in preserving quadriceps muscl strength,without a significant difference in analgesic effect.