Abstract
PURPOSE: 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. PATIENTS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.