Continuous adductor canal block versus continuous femoral nerve block for analgesia after open reduction and internal fixation of patellar fractures: a randomized controlled trial.

objectiveTo investigate the analgesic efficacy, impact on quadriceps muscle strength, and safety of continuous adductor canal block (CACB) versus continuous femoral nerve block (CFNB) in patients undergoing open reduction and internal fixation (ORIF) of patellar fractures, and to provide evidence for selecting the optimal perioperative analgesic regimen in clinical practice.

methodsA total of 80 patients scheduled for primary unilateral ORIF of patellar fractures at our hospital from August 2018 to May 2019 were enrolled in this randomized controlled trial. Patients were randomly allocated to the CACB group (experimental group) or CFNB group (control group) at a 1:1 ratio using a computer-generated random number table, with 40 patients in each group. Ultrasound-guided nerve block catheterization was performed before anesthesia induction in both groups, with an initial bolus of 20 mL 0.2% ropivacaine. Postoperative patient-controlled analgesia (PCA) with 0.175% ropivacaine was administered in both groups. The primary outcome was quadriceps muscle strength at 2 h, 12 h, 24 h, and 48 h postoperatively. Secondary outcomes included intraoperative sufentanil consumption, Visual Analogue Scale (VAS) pain scores at rest and during 45° active knee flexion at multiple postoperative time points, rate of rescue analgesia, incidence of adverse events, and patient satisfaction with analgesia.

resultsThere were no significant differences in baseline demographic and clinical characteristics between the two groups (all P > 0.05). No significant differences were found in intraoperative sufentanil consumption, VAS scores at rest and during movement at all postoperative time points, or rescue analgesia rate between the two groups (all P > 0.05). Quadriceps muscle strength at 2 h, 12 h, 24 h, and 48 h postoperatively was significantly higher in the CACB group than in the CFNB group (all P < 0.001). The total incidence of adverse events was significantly lower in the CACB group (17.5%) than in the CFNB group (32.5%, P = 0.045), and patient satisfaction with analgesia was significantly higher in the CACB group (P = 0.048).

conclusionUltrasound-guided CACB yields comparable analgesic efficacy compared with CFNB in patients undergoing ORIF of patellar fractures; CACB resulted in significantly less impairment of quadriceps muscle strength than CFNB, with fewer adverse events and higher patient satisfaction. CACB creates favorable conditions for early postoperative functional rehabilitation, aligns with ERAS principles, and is a safe and effective regional analgesic technique worthy of further clinical validation and consideration in appropriate patient populations undergoing patellar fracture surgery.

trial registrationThis trial was registered with ChiCTR (ChiCTR1800017828) on August 16, 2018.