Comparison of Pain Control Outcomes between Direct, Continuous Adductor Canal Block and Ultrasonography Guided, Continuous Femoral Nerve Block after Total Knee Arthroplasty

Background: Purpose of this study was to compare the effects of direct, continuous adductor canal block (ACB) and ultrasonography guided, continuous femoral nerve block (FNB) on postoperative pain control, strength of the knee extensor, walking ability, and related complications after primary total knee arthroplasty. Methods: Between November 2018 and February 2019, 107 patients underwent primary total knee arthroplasty under spinal anesthesia. Forty eight patients received ACB and the other 59 received FNB for postoperative pain control. After the surgery, the patients received adductor canal or femoral nerve block via a catheter. 10 mL of 0.75% ropivacaine was administered initially, followed by continuous injection of 4 mL per hour. ACB was done before capsule repair by orthopedic surgeon and FNB was performed after the surgery. Data were prospectively collected out from these 107 patients. To evaluate postoperative pain control, the numerical rating scale scores at rest and during range of motion were recorded. To evaluate quadriceps strength, motor grade by manual muscle testing was measured. Walking ability was assessed by first weight bearing day and walking distance (steps). We also evaluated analgesic consumption using morphine equivalent and recorded related complications of peripheral nerve block. Results: No significant intergroup difference was observed in the numerical rating scale scores at rest and during range of motion on postoperative days 1, 2, 3, 4, and 5. ACB group had significantly greater quadriceps strength than did the FNB group, as evaluated by manual muscle testing on postoperative days 1. However, there was no significant difference onpostoperative days 2, 3, 4, and 5. These two groups showed no differences in walking ability in terms of first weight bearing day and walking distance. No significant intergroup difference was observed in analgesic consumption. Conclusions: The groups showed no difference in postoperative pain control. ACB showed better motor grade on postoperative day one compared with femoral nerve block, but which was similar in days after postoperative day one.