Comparison of genicular nerve block and its combination with IPACK block for analgesia and recovery after total knee arthroplasty: a randomized trial.

backgroundOptimal analgesia is the cornerstone for enhanced recovery following total knee arthroplasty (TKA). The present study was conducted to assess the additive effect of Infiltration between Popliteal Artery and Capsule of Posterior Knee (IPACK) to Genicular Nerve Block (GNB) block compared to GNB alone. The primary outcome was Visual analogue scale (VAS) scores at 8 h with mobility postoperative and secondary outcomes include VAS scores at 2, 4, 6, 12, 18 & 24 h at rest and motion postoperative, duration to first rescue analgesia (morphine) 24 h postoperative, total morphine consumption at 1st 24 h postoperative, functional recovery of knee joint in the 1st 24 h postoperative (number of patients who are capable to hold quadriceps muscle > 5 s in 1st 24 h degree of knee maximum active flexion and extension, 2 min walk test, time up and go (TUG) score) and patients' satisfaction.

methodsSixty-three patients listed for elective TKA in this prospective single-blind, controlled study were randomly assigned into three equal groups. The Control (C) group received standard analgesia (1 g/8hrs paracetamol plus 15 mg/24hrs meloxicam). The GNB group received GNB block with 2.5 ml of 0.5% bupivacaine injected into each target point. The Combination group received GNB block + IPACK block (with 15 ml bupivacaine 0.5% injected). All patients received spinal anesthesia. Rescue analgesia was administered as 3 mg of intravenous morphine to the patient whose visual analogue scale (VAS) score was ≥ 4. The postoperative pain management protocol regimen for all patients in the three groups was administration of intravenous 30 mg ketorolac every 6 h postoperatively not exceeding 120 mg/day.

resultsThe combination group demonstrated significantly the lowest VAS pain scores at 2 h, 4 h, 6 h, 8 h, 18 h and 24 h except at 12 h postoperatively during both rest and mobility compared with other groups. However, the GNB group showed significant lower pain scores at the same measured time points except at 8 h postoperatively compared to control group (p < 0.0001). The time to the first request for rescue analgesia was significantly longer in the combination and GNB groups compared to control group, with the longest duration in the combination group (median 13.5 h, IQR 13-22.7 vs. 8.5 h, IQR 8-9 in GNB, and 3 h, IQR 2-4 h in control; p < 0.0001). Morphine consumption within the first 24 h postoperatively was significantly reduced among groups, being lowest in the combination group (median 3 mg) and highest in the control group (median 9 mg; p < 0.0001). The Combination group demonstrated significantly the best functional rehabilitation of the knee joint at 24hs postoperatively.

conclusionIn patients undergoing Total knee arthroplasty, adding IPACK block to GNB provides the best optimal analgesia and enhancing recovery compared to GNB alone. INSTITUTIONAL REVIEW BOARD APPROVAL: IRB#: 9577/19-9-2022

trial registrationClinicalTrials.gov NCT05672784.