Pain management In Total Knee Arthroplasty: Which helps in better post-operative outcomes?

Abstract

Background: Individuals exhibit variations in pain perception and pain threshold, and these differences exist between the right and left limbs, resulting in biases related to inter-cerebral pain variability and inter-patient pain variability. Currently, there is limited available data comparing adductor canal block (ACB) with femoral nerve block (FNB) in individuals who have undergone bilateral total knee arthroplasty (TKA). Methods: We conducted a prospective, non-randomized, controlled study involving patients scheduled for bilateral total knee arthroplasty (TKA) under central neuraxial anesthesia. Following surgery, patients received intermittent 12-hourly boluses of 15 mL ropivacaine 0.5% through two distinct peripheral nerve blocks (adductor canal block - ACB and femoral nerve block - FNB) in either of the lower limbs. The primary objective was to evaluate the postoperative Visual Analog Scale (VAS) score, while the secondary outcomes included the assessment of quadriceps muscle strength and the degree of flexion at the knee joint. Results: Out of the 70 patients evaluated for eligibility, 63 were enrolled, and 60 were included in the final analysis. Visual Analog Scale (VAS) scores after both blocks during periods of rest at 30 minutes, 6 hours, 12 hours, and 48 hours post-operatively did not exhibit any significant differences. However, VAS scores during rest at 24 hours and during exercise at 24 hours and 48 hours demonstrated a notable disparity. Furthermore, there was a significant difference in favour of adductor canal block (ACB) over femoral nerve block (FNB) regarding quadriceps muscle strength and the degree of knee flexion at 24 hours and 48 hours post-operatively. Conclusions: Adductor canal block (ACB) delivers comparable pain relief to femoral nerve block (FNB) both at rest and during passive exercise for up to 48 hours after surgery. ACB notably maintains the motor strength of quadriceps muscles when contrasted with FNB, and this preservation comes without introducing any additional complications.