Clinical Outcomes of Ultrasound-Guided IPACK Block for Posterior Knee Pain in Advanced Osteoarthritis: A Multicenter Prospective Single-Arm Study

Background/Objectives: Posterior knee pain is a common but often overlooked component of knee osteoarthritis (KOA), especially in advanced stages. Conventional nerve blocks targeting anterior innervation may provide insufficient relief. The IPACK block selectively targets posterior capsular innervation; however, evidence for its effectiveness in chronic KOA-related posterior pain remains limited. Methods: In this multicenter, prospective, single-arm, nonrandomized interventional study, patients aged 50–90 years with Kellgren–Lawrence grade III-IV KOA and predominant posterior knee pain unresponsive to conservative treatment received an ultrasound-guided IPACK block. Pain (NRS), function (WOMAC), and quality of life (SF-12) were assessed at baseline, 1 month, and 3 months. Results: Eighty-four patients (84 knees) were included. Mean NRS decreased from 7.8 ± 1.3 to 3.5 ± 1.5 at 1 month and 6.7 ± 1.3 at 3 months (p < 0.001). WOMAC improved from 71.5 ± 11.0 to 37.3 ± 10.4 and 60.2 ± 10.5 at 1 and 3 months, respectively (p < 0.001). SF-12 physical and mental scores also improved significantly (p < 0.001). Conclusions: Improvements in pain, physical function, and health-related quality-of-life measures were observed during the three-month period following the IPACK block. No serious procedure-related adverse events were recorded during the three-month follow-up period.