Adductor Canal Block Combined with Interspace between the Popliteal Artery and Capsule of the Knee (iPACK) versus Periarticular Injection for Total Knee Arthroplasty

BACKGROUND: The combination of the adductor canal block (ACB) and the infiltration of anesthetic solution into the interspace between the popliteal artery and capsule of the knee (iPACK) has become increasingly used to augment rapid recovery protocols in total knee arthroplasty (TKA). However, its efficacy in comparison with periarticular anesthetic injection (PAI) alone has yet to be evaluated. Hence, we conducted a retrospective study to compare PAI and ACB + iPACK for controlling pain after TKA. METHODS: Propensity scores, incorporating American Society of Anesthesiologists scores, body mass index, age, and sex, were used to match the ACB + iPACK group with the PAI group. All patients received the identical surgical technique and postoperative care. Outcome measures were visual analog scale (VAS) for pain, morphine consumption, knee flexion angle, straight leg raising (SLR), postoperative nausea vomiting (PONV), and length of stay (LOS) after the surgery. RESULTS: After matching by propensity score, there were 49 patients with comparable demographic data in each group. The VAS and morphine requirements of the PAI and ACB + iPACK groups were not different during the first 48 hours after TKA. At 72 hours postoperatively, the VAS of the ACB + iPACK was 0.97 higher than that of the PAI group (p = 0.020). Knee flexion angle, SLR, PONV, and LOS were not significantly different between groups. No procedure-related complications were identified in either group. CONCLUSIONS: The anesthesiologist-administered ACB + iPACK was as effective as surgeon-administered PAI in controlling pain in the first 48 hours after TKA. However, the ACB + iPACK group had higher intensity of pain than did the PAI group at 72 hours after TKA.