Effect of Proximal End versus Middle Continuous Adductor Canal Block after Total Knee Arthroplasty
Description
Study Objective: In this study, we localized the proximal end of the abbductor canal (AC) at which the medial borders of the sartorius and adductor longus muscles align (visualized with ultrasound guidance) to evaluate the analgesic effect of proximal end versus middle continuous adductor canal blocks (ACBs). Design: Prospective, randomized, double-blind, controlled study. Setting: The study was performed in the procedure room, operating room, and the inpatient ward at the Peking Union Medical College Hospital (Beijing, China). Patients: Patients between the ages of 18 and 70 years with an American Society of Anesthesiologists score of I-III who were scheduled for a unilateral total knee anthroplasty (TKA) were included. Sixty patients completed the study, including 30 in each treatment group. Interventions: Patients undergoing a unilateral TKA were randomized to receive continuous ACB (loading dose of 10 ml of 0.2% ropivacaine, followed by 6 ml/h of 0.2% ropivacaine until 48 h after the surgery) at the proximal end or middle of the canal. All patients received patient-controlled intravenous analgesia with sulfentanil after the surgery. Measurements: The primary outcome measure was the cumulative sulfentanil consumption within 24 h after surgery, which was analyzed using Mann-Whitney U tests. P-values <0.05 (two-sided) were considered statistically significant. Main Results: The 24 h sulfentanil consumption was 0.22 µg/kg (interquartile range: 0.15–0.40 µg/kg) in the proximal end group and 0.39 µg/kg (interquartile range: 0.23–0.52 µg/kg) in the middle group (P = 0.026). Conclusions: For patients undergoing TKA, the opioid-sparing effect of continuous ACB is improved with a catheter inserted at the level of the proximal end of the canal, which was identified as the intersection of the medial borders of satorious and adductor longus muscles in the ultrasound image, compared with at the middle of the canal