Comparison of efficacy between the genicular nerve block and the popliteal artery and the capsule of the posterior knee (IPACK) block for total knee replacement surgery: A prospective randomized controlled study

Objective: The aim of this study was to compare the efficacy of popliteal artery and the capsule of the posterior knee (IPACK) block and genicular nerve block on postoperative pain scores, the need for rescue analgesics, range of motion (ROM), walking distance, and perioperative monitorization variables in patients undergoing total knee replacement (TKR) surgery. Methods: Sixty American Society of Anesthesiologists (ASA) physical status I-III patients were enrolled in this study and then were randomly assigned into three groups: the IPACK block group (17 female, 3 male; mean age=67.5 +/- 1.4 years), genicular nerve block (16 female, 4 male; mean age=68 +/- 1.76 years), and the control group (13 female, 7 male; mean age=63 +/- 1.67years). All the patients underwent TKR under spinal anesthesia. The visual analog scale (VAS) score, mobility, pre- and intra-operative monitorization of systolic and diastolic holding area, non-invasive blood pressure, heart rate, and SPO 2 were compared between the groups. Results: Patients in the IPACK and genicular block groups had a significantly lower visual analogous scale (VAS) at postoperative 4 hours (p<0.01), 8h (p<0.01), 12h (p<0.01), and 24h (p<0.05). VAS score was significantly lower in the genicular block group at the postoperative 4h (5.5 +/- 0.55) and 8h (5.0 +/- 0.53) in the mobile state compared to the IPACK (8.0 +/- 0.47 and 8.0 +/- 0.43, respectively) and the control group (9.5 +/- 0.20; 10 +/- 0.28, respectively) (p<0.01). The use of patient-controlled-analgesia (PCA) devices and button push count for analgesics demand were significantly lower in the genicular block group on the immediate postoperative period (p<0.01 at the postoperative 0 to 4 h). The total consumption of morphine equivalents on the postoperative day 0 was significantly lower in the genicular block group (p<0.01, and p<0.001 for IPACK and control groups, respectively). The degree of flexion was significantly higher in the genicular block group at the postoperative 12h compared to the IPACK and the control group (p<0.001). The length of hospital stay was significantly lower in the genicular block group compared to the IPACK and the control group (p<0.05 for both variables). Conclusion: IPACK and genicular blocks both are effective in improving patient comfort during and after TKR surgery and reducing the potential need for systemic analgesic and opioids. The genicular block seems to be a promising technique that can offer improved pain management in the immediate and early postoperative period without adverse effects on systemic and motor variables.