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Functional and Analgesic Effects of iPACK Blocks Added to Continuous Adductor Canal Blocks for ACL Reconstruction
Carey L Brewbaker1, Thomas E Moran2, Christopher D Wolla1
1Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.
Background:
An adjunctive infiltration between popliteal artery and capsule of the posterior knee (iPACK) block-an infiltration between the popliteal artery and posterior knee capsule-has been used in knee surgery to address posterior knee pain, complementing the anterior and medial sensory coverage of an adductor canal block (ACB). Its benefit in all-inside anterior cruciate ligament reconstruction (ACL-R) using quadriceps tendon (QT) autograft remains uncertain.
Purpose:
To compare acute postoperative pain, opioid consumption, and 6-week knee range of motion between patients receiving continuous ACB alone and continuous ACB plus a single-shot iPACK block.
Study Design:
Randomized controlled trial; Level of evidence, 2.
Methods:
Patients undergoing primary all-inside ACL-R with QT autograft were randomized to either continuous ACB with placebo skin wheal (ACB group) or continuous ACB with iPACK (ACB-iPACK group). Demographic and surgical data were collected prospectively. The primary outcome was visual analog scale (VAS) pain scores during the first 72 postoperative hours. Secondary outcomes included opioid use (morphine milligram equivalents), achievement of full knee extension, and difference in maximal flexion between the surgical and nonsurgical limb at 6 weeks.
Results:
A total of 71 patients were analyzed (ACB, n = 33; ACB-iPACK, n = 38), with no significant group differences in baseline characteristics. Median VAS scores at discharge were significantly lower in the ACB-iPACK group (20 mm) versus the ACB group (32.5 mm) (P = .049). No further differences occurred between 12 and 72 hours postoperatively. Perioperative and postoperative opioid consumption did not differ between groups (perioperative, P = .52; postoperative, P = .47 to ≥.99). Rates of achieving full extension were similar. At 6 weeks, the difference in knee flexion between limbs was significantly smaller in the ACB-iPACK group (37.7°) compared with the ACB group (47.6°) (mean difference, 9.9°; P = .02). No perioperative regional anesthesia complications occurred.
Conclusion:
Adding an iPACK block to continuous ACB for all-inside ACL-R with QT autograft provided a slight reduction in pain at discharge (VAS difference, 12.5 mm) and improved knee flexion at 6 weeks. However, pain scores and opioid use beyond the immediate postoperative period were not significantly different between groups. These findings may help guide patient counseling regarding the expected benefits of incorporating an iPACK block in this surgical setting.
Registration:
NCT05498870 (ClinicalTrials.gov identifier).