Analgesic efficacy of adding the IPACK block to a multimodal analgesia protocol for primary total knee arthroplasty

Background and objectives Peripheral nerve blocks have been integrated into most multimodal analgesia protocols for total knee arthroplasty (TKA). The adductor canal block (ACB) has gained popularity because of its quadriceps muscle sparing. Similarly, local anesthetic injection between the popliteal artery and the posterior capsule of the knee, IPACK block, has been described to provide analgesia to the posterior capsule of the knee with motor-sparing qualities. This prospective randomized controlled trial aimed to assess the analgesic efficacy of adding the IPACK block to our current multimodal analgesic regimen, including the ACB, in patients undergoing primary TKA. Methods 119 patients were randomized to receive either an IPACK or a sham block in addition to multimodal analgesia and an ACB. We were set to assess pain in the back of the knee 6 hours after surgery. Other end points included quality of recovery after surgery, pain scores, opioid requirements, and functional measures. Results Patients who received the IPACK block had less pain in the back of the knee 6 hours after surgery when compared with the sham block: 21.7% vs 45.8%, p<0.01. There was marginal improvement in other pain measures in the first 24 hours after surgery. However, opioid requirements, quality of recovery and functional measures were similar between the two groups. Conclusion The IPACK block reduced the incidence of posterior knee pain 6 hours postoperatively.