Comparison of the postoperative analgesic effect for infiltration between the popliteal artery and the capsule of the posterior knee and that of periarticular multimodal drug injection in total knee arthroplasty: retrospective study in the immediate postoperative period

BACKGROUND: The aim of this study is to compare the postoperative analgesic effect of infiltration between the popliteal artery and the capsule of the knee (IPACK) and the effect of periarticular multimodal drug injection (PMDI) in addition to adductor canal block (ACB) after total knee arthroplasty. METHODS: Among patients who received total knee arthroplasty from June 2017 to December 2017, 50 who underwent ACB with additional IPACK and 50 who received ACB with additional PMDI were selected for this study. We compared the postoperative pain numerical rating scale (NRS), the number of times patient-controlled analgesia was administered and the amount administered, the total amount of opioids given, and complications associated with the procedure between the two groups. RESULTS: NRS measured at rest and 45° knee flexion at days 1 and 2 after surgery was significantly lower in the IPACK group than in the PMDI group. The resting NRS measured at day 3 after surgery was also significantly lower in the IPACK group than in the PMDI group, and the NRS at 45° knee flexion measured from day 3 to day 5 showed a significant reduction in the IPACK group. No complications relating to the procedure occurred. CONCLUSIONS: IPACK may be a better option than PMDI for controlling acute phase pain in patients undergoing total knee arthroplasty.