The Effect of the IPACK Block on Pain Following Primary TKA: A Double Blinded, Prospective, Randomized Trial

Abstract Introduction The purpose of this this study was to determine if infiltration of local anesthetic between the interspace between the popliteal artery and capsule of knee (IPACK) provides benefit in TKA. Methods Patients were randomized into continuous adductor canal block (ACB) with IPACK block or continuous ACB with sham subcutaneous saline injection. Only the anesthesiologist performing the block was aware of randomization status. Following surgery, a blinded assessor recorded opioid consumption, pain scores, and gait distance. Results There were 35 patients in the IPACK group and 34 in the NO IPACK group. There was no difference demographically between the groups. In the PACU, the average (P=0.0122) and worst (P=0.0168) pain scores at rest were statistically lower in the IPACK group. There was no difference in the pain scores during physical therapy. (P=0.2080) There was no difference in opioid consumption in the PACU (P=0.7928), or at 24 hours (P=0.7456), There was no difference in pain scores on POD 1 in the AM (P=0.4597) or PM (P=0.6273), or in walking distance (P=0.5197). There was also no difference in length of stay in the PACU (P=0.9426) or hospital (P=0.2141). Conclusion The IPACK group had lower pain scores at rest in the PACU, but this is likely not clinically significant. The routine use of the IPACK is not supported by the results of this study. There may indications for the use of the IPACK block as a rescue block or in patients whom have contraindications to our standard multimodal treatment regimen, or in patients with chronic pain or opioid dependence.