Preferable Concentration-Volume Combination of Ropivacaine for Femoral Nerve Block in Arthroscopic Meniscoplasty: A...

This study aimed to determine the preferable combination of ropivacaine balancing analgesic efficacy with minimal motor impairment under fixed total dosage for ultrasound-guided femoral nerve block (FNB) in meniscoplasty patients.

In this randomized double-blind trial, 200 patients scheduled for arthroscopic meniscus repair were allocated to four groups receiving ultrasound-guided FNB with equivalent 50 mg ropivacaine doses [R_0.17 : 0.17% (30 mL); R_0.20 : 0.20% (25 mL); R_0.25 : 0.25% (20 mL); R_0.33 : 0.33% (15 mL)]. The primary outcome was area under curve (AUC) of visual analog scale (VAS) pain intensity scores on movement through 24 hours postoperatively.

Statistically significant intergroup differences were observed in the AUC of VAS pain intensity scores on movement through 24 and 48 hours postoperatively (R_0.33 < R_0.20 < R_0.17; R_0.25 ≈ R_0.20 < R_0.17 ). The AUC of VAS scores at rest through 24 hours postoperatively showed: R_0.33 < R_0.25 < R_0.20 < R_0.17 ; and at 48 hours: R_0.33 ≈ R_0.25 < R_0.20 < R_0.17 . The AUC of sensory block scores through 24 and 48 hours postoperatively showed: R_0.33 > R_0.25 ≈ R_0.20 > R_0.17 . In terms of postoperative motor block scores, no significant difference was found between the R_0.17 and R_0.20 groups (P = 0.2233), but both were significantly lower than the R_0.25 and R_0.33 groups (P < 0.05). The AUC of quadriceps muscle strength scores through 24 hours postoperatively showed: R_0.33 < R _0.25 < R _0.20 < R _0.17; and at 48 hours: R _0.33 < R _0.25 < R _0.20 ≈ R _0.17. The number of patients requiring rescue analgesia was significantly higher in the R_0.17 group than in the other three groups (P = 0.0013).

At a dose of 50 mg ropivacaine, 0.20% ropivacaine (25 mL) for FNB provided effective postoperative analgesia for patients undergoing arthroscopic meniscoplasty, while allowing for earlier recovery of muscle strength.