Efficacy of IPACK Block Combined with Intra-articular Steroid Injection in Advanced Knee Osteoarthritis: A Retrospective Cohort Study

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Abstract
Background: Knee osteoarthritis is a major cause of chronic pain and functional limitation, particularly in advanced stages. Intra-articular steroid injections and genicular nerve interventions are commonly used for pain control; however, these methods mainly target the anterior knee and may not sufficiently relieve pain originating from the posterior capsule. The infiltration between the popliteal artery and the capsule of the knee (IPACK) block is a regional anesthesia technique that provides posterior knee analgesia without causing motor weakness. Evidence regarding its effectiveness in chronic, non-surgical knee osteoarthritis is limited. This study aimed to evaluate whether adding an ultrasound-guided IPACK block to intra-articular steroid injection improves pain and functional outcomes in patients with advanced knee osteoarthritis. Methods: This retrospective observational cohort study included 98 patients with Kellgren–Lawrence stage 3–4 knee osteoarthritis who had persistent pain despite conservative treatment. Patients received either intra-articular steroid injection alone (IASI group, n=50) or intra-articular steroid injection combined with an IPACK block (IASI+IPACK group, n=48). Pain severity was assessed using the Numeric Rating Scale (NRS), and functional status was evaluated with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Evaluations were performed at baseline, 1 month, and 6 months after the procedure. Non-parametric tests were used for statistical analysis, and p<0.05 was considered significant. Results: Both groups showed significant improvement in NRS and WOMAC scores at 1 and 6 months compared with baseline (p<0.05). The IASI+IPACK group demonstrated greater pain reduction at 1 month and significantly better WOMAC Function and Total scores at both follow-up visits compared with the IASI group (p<0.05). Although scores increased slightly between 1 and 6 months in both groups, outcomes remained improved compared with baseline. No major complications were observed. Conclusions: Adding an IPACK block to intra-articular steroid injection may provide additional benefit in early pain relief and functional improvement in patients with advanced knee osteoarthritis. This combined approach appears to be a safe and useful option for patients who are not surgical candidates or are awaiting arthroplasty. Trial registration: ClinicalTrials.gov, NCT07269444. Retrospectively registered on 20 November 2025.

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