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

Efficacy of IPACK Block Combined with Intra-articular Steroid Injection in Advanced Knee Osteoarthritis: A Retrospective Cohort Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Efficacy of IPACK Block Combined with Intra-articular Steroid Injection in Advanced Knee Osteoarthritis: A Retrospective Cohort Study Halil Ibrahim Altun, Salim Taner Gözükızıl This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9076754/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version 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. Knee Osteoarthritis Intra-Articular Injections Steroids Nerve Block IPACK Block Ultrasound Guidance Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Knee osteoarthritis (OA) is a multifactorial chronic joint disease that affects not only cartilage but also the meniscus, ligaments, and periarticular muscles. Osteoarthritis (OA) is one of the leading causes of chronic pain and disability worldwide ( 1 ). Symptomatic knee OA affects approximately 10–13% of individuals over the age of 60 and its prevalence continues to increase due to aging populations and rising obesity rates ( 2 ). The main symptoms: pain, stiffness, and dysfunction can significantly impair knee function and reduce quality of life ( 3 ). Beyond the classic clinical symptoms, OA also imposes a substantial economic burden on healthcare systems ( 4 ). Compounding their physical limitations, patients with advanced-stage OA frequently experience higher rates of depression and social isolation compared to those in early stages ( 5 ). The management of knee OA encompasses a wide spectrum of options, ranging from conservative methods like patient education, weight control, and exercise, to intra-articular injections, and finally to surgical treatment (arthroplasty) for patients with resistant pain ( 6 ). However, pain control remains a significant clinical challenge for patients who are unsuitable for surgery, refuse surgery, or are currently on waiting lists. Although intra-articular steroid injections and genicular nerve blocks are frequently preferred in these patients, pain originating from the posterior capsule is a significant component of knee pain that may not be adequately controlled by these approaches ( 7 ). Standard genicular blocks typically target the anterior and lateral aspects of the knee, often neglecting the innervation of the posterior region. This limitation highlights the need for novel methods that can provide more comprehensive and effective analgesia. The infiltration between the popliteal artery and the capsule of the knee (IPACK) block is a relatively novel regional anesthesia technique that can provide analgesic effects on the posterior capsule without inducing motor block ( 8 ). This technique targets the terminal branches of the genicular nerves and popliteal plexus innervating the posterior capsule, while sparing the main trunks of the tibial and common peroneal nerves ( 9 ). Cadaveric studies showed that the injectate spreads not only posteriorly but also anterolaterally and anteromedially, potentially offering a broader field of analgesia ( 10 ). While its efficacy in multimodal analgesia following knee surgery is supported by randomized controlled trials ( 11 ), this method also may be useful as an alternative treatment for patients with advanced knee osteoarthritis. The combined anti-inflammatory effect of the steroid injection and the posterior sensory blockade provided by the IPACK block may create a complementary or possibly synergistic benefit, leading to longer-lasting relief. Although the role of the IPACK block in post-arthroplasty pain management has been extensively studied, data regarding its efficacy in non-surgical chronic pain treatment are limited. The aim of this study was to evaluate whether adding an IPACK block to intra-articular steroid injection improves pain and functional outcomes in patients with advanced knee osteoarthritis. Methods Study Design and Patients This retrospective observational cohort study was conducted between January 2024 and September 2025 at a tertiary hospital in Istanbul, Turkey. The study was designed and reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The study was approved by the Institutional Ethics Committee (385/20.11.2025), and the study was registered in the ClinicalTrials.gov database (NCT07269444). The research was conducted in full compliance with the ethical principles outlined in the 2024 revision of the Declaration of Helsinki. While routine written informed consent for the clinical procedures was obtained from all patients, the requirement for study-specific informed consent was waived by the ethics committee due to the retrospective design of the study. Patients aged 40 years and older diagnosed with Kellgren-Lawrence stage 3 or 4 knee osteoarthritis, who had a Numeric Rating Scale (NRS) score greater than 4 despite prior conservative medical and physical therapy, were screened for eligibility. Exclusion criteria included a history of knee surgery, knee injections within the last six months, psychotic disorders, bleeding diathesis, active malignancy or infection, known allergies to the study medications, and inability to communicate or refusal to undergo the procedure. The diagnosis of knee osteoarthritis was confirmed by clinical examination and radiological imaging, including magnetic resonance (MRI) or plain radiography (X-RAY). Procedures All injections were performed by a single physician experienced in musculoskeletal interventions, using a Toshiba TUS-A300™ (USA) ultrasound device. All procedures were carried out under aseptic conditions, and local anesthesia was applied to the subcutaneous tissue prior to needle insertion. Intra-articular Steroid Injection (IASI): The patient was positioned supine with the knee in slight flexion (approximately 15–30 degrees) and supported. A high-frequency linear ultrasound probe was placed transversely superior to the patella to visualize the suprapatellar recess. Using an in-plane technique, a 22G spinal needle was advanced from the lateral aspect toward the suprapatellar pouch, visualized as the hypoechoic space between the prefemoral fat pad and the quadriceps tendon. Once the needle tip was confirmed to be within the joint space, a mixture of 4 ml of 1% lidocaine and 40 mg of triamcinolone acetonide was injected without resistance. The spread of the injectate within the joint was verified under real-time ultrasound guidance. IPACK Block: With the patient in the supine position, the leg was placed in the "frog-leg" position (knee flexed and hip externally rotated). A low-frequency convex ultrasound probe was placed transversely over the popliteal fossa, approximately 2–3 cm proximal to the femoral condyles. The probe was adjusted proximally and distally to obtain an optimal view of the distal femoral shaft and the popliteal artery. Targeting the space between the femur and the popliteal artery, a 20G block needle was advanced from anteromedial to posterolateral using an in-plane technique. After positioning the needle tip approximately 1–2 cm beyond the lateral border of the popliteal artery, a mixture of 15 ml of 0.25% bupivacaine and 4 mg of dexamethasone was injected during needle withdrawal following negative aspiration (Fig. 1 ). Following the procedure, patients were observed for two hours to monitor for potential complications. One week after the injection, all patients were provided with a simple home exercise booklet for rehabilitation. Patients were advised to use 500 mg of paracetamol (up to a maximum of four tablets per day) as a rescue analgesic only if the pain became intolerable. To ensure the reliability of clinical assessments, they were instructed to refrain from taking analgesics on the days of their follow-up visits. Outcome Measures Baseline demographic data (age, gender, body mass index [BMI], affected side, Kellgren-Lawrence stage) and symptom duration were recorded for all included patients. To monitor treatment efficacy, all clinical assessments were performed at baseline (pre-procedure), and at 1-month and 6-month follow-up visits post-procedure. Primary Outcome Measure: Pain severity was assessed using the Numeric Rating Scale (NRS), an 11-point scale ranging from 0 (no pain) to 10 (worst possible pain). NRS scores during activity were recorded for evaluation. Secondary Outcome Measures: Physical functional status and limitations in daily living activities were evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), for which the validity and reliability of the Turkish version have been established ( 12 ). Higher WOMAC scores indicate increased pain and functional impairment, whereas lower scores reflect clinical improvement. Patients were advised to use 500 mg of paracetamol as a rescue analgesic only when pain was intolerable during the post-procedure period. Daily average paracetamol consumption (mg/day) was recorded at follow-up intervals (1 month and 6 months post-procedure). Potential complications such as infection at the injection site, hematoma, neurological deficits, or systemic reactions were also monitored throughout the follow-up period. Statistical Analysis Statistical analyses were performed using SPSS software version 27.0 (IBM Corp., Armonk, NY, USA). Descriptive statistics were presented as mean, standard deviation, and median for continuous variables, and as frequencies and percentages for categorical variables. The normality of data distribution was assessed using the Kolmogorov-Smirnov test. Since the data did not follow a normal distribution, non-parametric tests were utilized for analyses. Comparisons of demographic data and treatment outcomes between the two independent groups were conducted using the Mann-Whitney U test. The homogeneity of categorical variables between groups was analyzed using the Chi-square test. Within-group comparisons of repeated measures (pre-procedure vs. post-procedure) over time were performed using the Wilcoxon Signed-Rank Test. A p-value of < 0.05 was considered statistically significant for all tests. Results Overall, 118 patients were assessed for eligibility. After excluding 7 patients who met the exclusion criteria and 13 patients with incomplete follow-up data, a total of 98 patients were included in the final analysis. Patients were divided into two groups: the Intra-articular Steroid Injection only group (Group IASI; n = 50) and the group receiving Intra-articular Steroid Injection combined with an IPACK block (Group IASI+IPACK; n = 48) (Fig. 2 ). Of the included patients, 65 (66.3%) were female, 56 (57.1%) had Stage 4 osteoarthritis, and 56 (57.1%) presented with symptoms in the right knee (Table 1 ). Baseline demographic and clinical characteristics were similar between the groups. No statistically significant differences were observed in age, gender, BMI, symptom duration or baseline pain/function scores (p > 0.05). Table 1 Demographic and Clinical Characteristics Injection n % IASI IASI+IPACK Total 50 48 98 51,0 49,0 100,0 Sex Woman Man Total 65 33 98 66,3 33,7 100,0 Side Right Left Total 56 42 98 57,1 42,9 100,0 Kellgren-Lawrance 3 4 Total 42 56 98 42,9 57,1 100,0 IASI: Intra Articular Steroid Injection IPACK: Infiltration between Popliteal Artery and Capsule of the Knee Within-Group Changes Both groups demonstrated a significant reduction in NRS scores and WOMAC subscale scores at 1 and 6 months compared with baseline (p < 0.05). Temporally, clinical scores reached their lowest values at one month. While a mild symptomatic rebound was observed by the sixth month, scores in both groups remained significantly lower than pre-procedure baseline values (Table 2 ) (Fig. 3 , 4 ). Table 2 Comparison of NRS and WOMAC score changes between groups NRS IASI (n = 50) IASI+IPACK (n = 48) p T 0 -T 1 3,48 ± 1,31 4,08 ± 1,25 0,015 T 0 -T 2 2,04 ± 0,98 1,97 ± 1,02 0,903 T 1 -T 2 -1,44 ± 0.92 -2.10 ± 0.97 0,001 WOMAC(Pain) T 0 -T 1 5,16 ± 1,81 5,43 ± 1,79 0,436 T 0 -T 2 4,08 ± 2,05 3,83 ± 1,79 0,640 T 1 -T 2 -1,08 ± 1,78 -1,60 ± 1,39 0,260 WOMAC(Stiffness) T 0 -T 1 3,32 ± 1,01 3,58 ± 1,08 0,080 T 0 -T 2 2,62 ± 1,38 2,54 ± 1,23 0,787 T 1 -T 2 -0,7 ± 1,11 -1,04 ± 0,92 0,124 WOMAC(Function) T 0 -T 1 7,52 ± 2,12 11,04 ± 2,19 0,000 T 0 -T 2 3,62 ± 2,18 5,35 ± 2,00 0,000 T 1 -T 2 -3,90 ± 2,44 -5,68 ± 2,61 0,002 WOMAC(Total) T 0 -T 1 16,00 ± 2,94 20,06 ± 3,15 0,000 T 0 -T 2 10,32 ± 3,16 11,72 ± 3,06 0,024 T 1 -T 2 -5,68 ± 3,15 -8,33 ± 3,05 0,000 Data are shown as mean ± SD IASI: Intra Articular Steroid Injection IPACK: Infiltration between Popliteal Artery and Capsule of the Knee T0 = Before the procedure, T1 = 1st month of the procedure, T2 = 6th month of the procedure Between-Group Comparisons The IASI+IPACK cohort exhibited a significantly greater reduction in NRS scores at one month compared to the IASI group (p < 0.05). Although both groups showed improvement at 6 months, the overall change from baseline was similar between them. However, the increase in scores from month 1 to month 6 was more pronounced in the IASI+IPACK group (p < 0.05) (Table 2 ) (Fig. 3 , 4 ). In the WOMAC assessment, no significant differences were found between treatment groups in the changes of Pain and Stiffness subscales. Significant differences were observed in WOMAC Function and WOMAC Total scores. Group IASI+IPACK showed significantly greater improvement than Group IASI in the transition from baseline to both 1 month and 6 months (p < 0.05). Correlation analysis did not show significant relationship between symptom duration and treatment efficacy (changes in NRS and WOMAC scores) at any post-procedure time point in either group (p > 0.05) (Table 2 ) (Fig. 3 , 4 ). Paracetamol consumption decreased significantly in both groups at 1 month and 6 months post-procedure compared to baseline (p < 0.05). Although consumption at 6 months slightly increased compared to 1 month, it remained below baseline levels in both groups. When comparing the two groups, no statistically significant difference was found between the treatment groups regarding the changes in monthly paracetamol usage (p > 0.05). Discussion This retrospective cohort study evaluated the efficacy and safety of adding an IPACK block to intra-articular steroid injection in patients with advanced knee osteoarthritis. We hypothesized that adding an IPACK block to IASI would provide greater improvement in pain and function compared to IASI alone. Our findings suggested that both treatment modalities provided significant improvements in pain and functional scores at 1 and 6 months post-procedure compared to baseline. Although scores increased slightly at 6 months compared with the marked reduction observed at 1 month, they remained significantly lower than baseline values. An important finding of this study was the more pronounced increase (rebound) in scores from the 1st month to the 6th month in the Group IASI+IPACK compared to the control group. Although this might initially appear as a disadvantage, it can be attributed to the more pronounced early improvement provided by the IPACK block. In the IASI+IPACK group, pain and function scores dropped to much lower levels at 1 month compared to the group receiving only steroids. As the pharmacological effects of the steroid and block gradually diminished, symptoms tended to increase again over time. Furthermore, this may be explained by that patients who experienced substantial early pain relief may have gradually increased their physical activity levels, potentially contributing to the relative rise in scores observed toward the sixth month. Despite this, the fact that WOMAC Function and Total scores in the IASI+IPACK group were still significantly better than those in the IASI group at the end of 6 months supports the long-term efficacy of this combined approach. The IPACK block is a relatively novel technique, first described in 2012, which has since gained increasing popularity. It is frequently utilized as part of multimodal analgesia protocols in postoperative pain management. Although its efficacy in this context has been proven by randomized controlled trials ( 11 ), data regarding its use in chronic pain are limited. Edwards et al. reported that an IPACK block with added steroids reduced chronic pain and improved physical function for approximately two months in patients awaiting knee arthroplasty ( 13 ). Consistent with these findings, our study showed the best results at 1 month, followed by an increase in scores toward the 6th month. Previous studies have shown in the literature that the addition of steroids to local anesthetics in peripheral nerve blocks prolongs the duration of analgesia through anti-inflammatory effects, suppression of ectopic discharges, and inhibition of C-fiber transmission ( 14 ). Indeed, findings from studies on IPACK blocks suggest that adding steroids may extend efficacy. For instance, one study demonstrated that the combination of IPACK and adductor canal blocks with steroids not only improved postoperative pain management after total knee arthroplasty but also contributed to the reduction of rebound pain and chronic postsurgical pain one year after surgery ( 15 ). Most interventional pain treatments for chronic knee pain target the genicular nerves. While interventions targeting these nerves are often successful, their effects may be limited as they mainly innervate the anterior and lateral aspects of the knee. The IPACK block differs in that it blocks pain originating from the posterior compartment. A cadaveric study reported that the injectate spreads not only posteriorly but also anterolaterally and anteromedially ( 10 ). Although one comparative study found genicular blocks to be more effective than IPACK blocks on postoperative pain ( 16 ), another study reported that adding an IPACK block to a genicular block provided improved analgesia and enhanced recovery compared to the genicular block alone ( 17 ). From a safety perspective, the IPACK block was well tolerated in our cohort. While rare complications such as vascular injury or transient foot drop have been reported in the literature ( 18 – 20 ), the vast majority of studies report no major adverse events ( 21 , 22 ). Consistent with these findings, we observed no major complications associated with the block in our study. Our study has several limitations. The primary limitation is its retrospective nature, which involves a lack of randomization and the associated risk of selection bias. Additionally, the absence of recorded sensory tests to confirm block success in the early post-procedure period, and the assessment of pain using a total score rather than differentiating between anterior and posterior compartments, represent additional limitations. Nevertheless, a significant strength of our study is that it is one of the early studies examining the role of the IPACK block in the non-surgical treatment of chronic knee pain. Future prospective, randomized, placebo-controlled trials are needed to clarify the efficacy of the IPACK block in pain due to chronic knee osteoarthritis. Additional studies comparing this block with other methods, such as genicular nerve block/ablation, would provide valuable contributions to the literature. Conclusion In conclusion, adding an IPACK block to intra-articular steroid injection appears to be a safe and effective option for pain management in advanced knee osteoarthritis. The combined treatment offered more noticeable benefits, especially in physical function and early-term pain control, compared to steroid injection alone. In light of these findings, the IPACK block may be considered a viable alternative for pain management in patients who are awaiting total knee arthroplasty, are at high surgical risk, or unwilling to undergo surgery. Abbreviations BMI Body Mass Index IASI Intra-articular Steroid Injection IPACK Infiltration between the Popliteal Artery and the Capsule of the Knee MRI Magnetic Resonance Imaging NRS Numeric Rating Scale OA Osteoarthritis SPSS Statistical Package for the Social Sciences STROBE Strengthening the Reporting of Observational Studies in Epidemiology WOMAC Western Ontario and McMaster Universities Osteoarthritis Index Declarations Ethics approval and consent to participate: This retrospective study was approved by the Istanbul Prof. Dr. Cemil Taşçıoğlu City Hospital Scientific Research Ethics Committee (Reference Number: 385, Date: 20 November 2025), Istanbul, Türkiye. Due to the retrospective design of the study, the ethics committee waived the requirement for study-specific informed consent. However, routine written informed consent for the procedure had been obtained from all patients prior to the intervention. Consent for publication: Not applicable Availability of data and materials: The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests: The authors declare that they have no competing interests. Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article. Authors' contributions: H.I.A and S.T.G contributed to the study concept and design, defined the intellectual content, and performed the clinical interventions. S.T.G conducted the literature search and was responsible for retrospective data acquisition. H.I.A performed the statistical analysis, data analysis, and interpretation. S.T.G and H.I.A jointly contributed to manuscript preparation, editing, and critical review. All authors read and approved the final manuscript. Acknowledgements: Not applicable References Heidari B. Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I. Caspian J Intern Med. 2011;2:205-12. Zhang Y, Jordan JM. Epidemiology of osteoarthritis. Clin Geriatr Med. 2010;26:355-69. Martel-Pelletier J, Barr AJ, Cicuttini FM, Conaghan PG, Cooper C, Goldring MB, et al. Osteoarthritis. Nat Rev Dis Primers. 2016;2:16072. Peoples BM, Miller RE, Rice SJ, Vincent TL. Knee health is a major determinant of mobility across the healthspan. J Funct Morphol Kinesiol. 2025;10:454. Ozcakir S, Raif P, Sivrioglu K, Kucukcakir N. Relationship between radiological severity and clinical and psychological factors in knee osteoarthritis. Clin Rheumatol. 2011;30:1521-6. Zhu S, Xu X, Zhang S, Zhang Y. Evaluation and management of knee osteoarthritis. J Evid Based Med. 2024;17:675-87. Thobhani S, Horner N, Boden A, Stevens B, Moskop D, Nystrom P, et al. Novel regional techniques for total knee arthroplasty promote reduced hospital length of stay: an analysis of 106 patients. Ochsner J. 2017;17:233-8. Sebastian MP. Saphenous nerve and IPACK block. Reg Anesth Pain Med. 2019. doi:10.1136/rapm-2019-100750. Kandarian BS, Indelli PF, Sinha S, Hunter OO, Mariano ER. Updates on multimodal analgesia and regional anesthesia for total knee arthroplasty patients. Best Pract Res Clin Anaesthesiol. 2019;33:111-23. Tran J, Giron Arango L, Peng P, Sinha SK, Agur A, Chan V. Evaluation of the iPACK block injectate spread: a cadaveric study. Reg Anesth Pain Med. 2019;44:689-94. Wang CG, Song Y, Wang K, Zhang XF. The effect of continuous adductor canal block combined with distal interspace between the popliteal artery and capsule of the posterior knee block for total knee arthroplasty: a randomized, double-blind, controlled trial. BMC Anesthesiol. 2022;22:175. Tüzün EH, Eker L, Aytar A, Daşkapan A, Bayramoğlu M. Acceptability, reliability, validity and responsiveness of the Turkish version of WOMAC osteoarthritis index. Osteoarthritis Cartilage. 2005;13:28-33. Edwards B, Lamacraft G. Does iPACK a punch? A prospective observational study on the efficacy of pain relief and functional improvement of an iPACK block for chronic knee osteoarthritis. Reg Anesth Pain Med. 2024;49:A15-16. Pehora C, Pearson AM, Kaushal A, Crawford MW, Johnston B. Dexamethasone as an adjuvant to peripheral nerve block. Cochrane Database Syst Rev. 2017;11:CD011770. Sreckovic S, Stevanovic K, Simic D, Stevic M. The effect of adding dexamethasone to adductor block and IPACK block on acute postoperative, rebound, and chronic pain following knee arthroplasty-1-year follow-up. Front Med (Lausanne). 2025;12:1570795. Akesen S, Mutlu M, Ersen O, Akesen B. Comparison of efficacy between the genicular nerve block and the popliteal artery and the capsule of the posterior knee (IPACK) block for total knee replacement surgery: a prospective randomized controlled study. Acta Orthop Traumatol Turc. 2021;55:134-40. Fathi HM, Soliman M, El-Sayed M. Comparison of genicular nerve block and its combination with IPACK block for analgesia and recovery after total knee arthroplasty: a randomized trial. BMC Anesthesiol. 2025;25:601. Hadzic A. iPACK block. In: Hadzic A, editor. Hadzic's peripheral nerve blocks and anatomy for ultrasound-guided regional anesthesia. 3rd ed. New York: McGraw-Hill; 2021. Ruggiero A, Fabio C, Pascarella G. Unexpected foot drop after proximal ipack block. Reg Anesth Pain Med. 2023;48:A306. Biehl M, Wild L, Waldman K. The safety and efficacy of the IPACK block in primary total knee arthroplasty: a retrospective chart review. Can J Anaesth. 2020;67:1271-3. Yin W, Li X, Zhang Y. Effect of adductor canal block combined with infiltration between the popliteal artery and posterior capsular of the knee on chronic pain after total knee arthroplasty: a prospective, randomized, double-blind, placebo-controlled trial. BMC Anesthesiol. 2024;24:320. Patterson ME, Bland KS, Thomas LC, Elliott CE, Soberon JR. The effect of the IPACK block on pain after primary TKA: a double-blinded, prospective, randomized trial. J Arthroplasty. 2020;35(6S):S173-7. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 20 Apr, 2026 Reviews received at journal 19 Apr, 2026 Reviews received at journal 13 Apr, 2026 Reviewers agreed at journal 07 Apr, 2026 Reviewers agreed at journal 07 Apr, 2026 Reviewers invited by journal 26 Mar, 2026 Editor assigned by journal 26 Mar, 2026 Editor invited by journal 16 Mar, 2026 Submission checks completed at journal 11 Mar, 2026 First submitted to journal 11 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Altun","email":"data:image/png;base64,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","orcid":"","institution":"Istanbul Kanuni Sultan Suleyman Training and Research Hospital, Department of Anesthesiology, Division of Pain Medicine","correspondingAuthor":true,"prefix":"","firstName":"Halil","middleName":"Ibrahim","lastName":"Altun","suffix":""},{"id":612658533,"identity":"a58eb6ba-7aab-4ca9-9b54-56da480bcb63","order_by":1,"name":"Salim Taner Gözükızıl","email":"","orcid":"","institution":"Prof. Dr. Cemil Taşçıoğlu City Hospital","correspondingAuthor":false,"prefix":"","firstName":"Salim","middleName":"Taner","lastName":"Gözükızıl","suffix":""}],"badges":[],"createdAt":"2026-03-09 20:39:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9076754/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9076754/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105843837,"identity":"13b449da-cf5a-4283-9a67-6aa4f9d2a212","added_by":"auto","created_at":"2026-03-31 17:28:37","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":253474,"visible":true,"origin":"","legend":"\u003cp\u003eUltrasound-guided IPACK block demonstrating the target area (TA) and surrounding anatomical structures.\u003c/p\u003e\n\u003cp\u003ePA: popliteal artery, PV: popliteal vein, TN: tibial nerve, CPN: common peroneal nerve, VMM: vastus medialis muscle, SM: sartorius muscle, StM: \u0026nbsp;semitendinosus muscle, SmM: semimembranosus muscle, BfM: biceps femoris muscle\u003c/p\u003e","description":"","filename":"figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9076754/v1/5bfa7706c8838c9d14a4a195.jpg"},{"id":105843838,"identity":"fd7aec28-d61a-405d-93d5-4744028c2415","added_by":"auto","created_at":"2026-03-31 17:28:37","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":40306,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of study\u003c/p\u003e\n\u003cp\u003eIASI: Intra Articular Steroid Injection IPACK: Infiltration between the Popliteal Artery and Capsule of the Knee\u003c/p\u003e","description":"","filename":"figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9076754/v1/d8f6d30be83c18d4d7a37fba.jpg"},{"id":105904968,"identity":"7d1b12d7-2f10-48a2-a807-9e057c4a3ad7","added_by":"auto","created_at":"2026-04-01 10:11:15","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":45717,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in Numeric Rating Scale (NRS) scores over time in both groups.\u003c/p\u003e","description":"","filename":"figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9076754/v1/ed36cee96af87bf3365600f1.jpg"},{"id":105843839,"identity":"6cdec6ab-d8e4-4840-8679-522f3698577b","added_by":"auto","created_at":"2026-03-31 17:28:37","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":55718,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Total \u0026nbsp;scores over time in both groups.\u003c/p\u003e","description":"","filename":"figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9076754/v1/918e2f61eddd787df15503ce.jpg"},{"id":105906805,"identity":"a5d6ba00-5076-44f2-a7a6-27d79df387d5","added_by":"auto","created_at":"2026-04-01 10:25:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1000440,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9076754/v1/2fdfe241-9940-430d-8669-8e907dbd0cbf.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Efficacy of IPACK Block Combined with Intra-articular Steroid Injection in Advanced Knee Osteoarthritis: A Retrospective Cohort Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eKnee osteoarthritis (OA) is a multifactorial chronic joint disease that affects not only cartilage but also the meniscus, ligaments, and periarticular muscles. Osteoarthritis (OA) is one of the leading causes of chronic pain and disability worldwide (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Symptomatic knee OA affects approximately 10\u0026ndash;13% of individuals over the age of 60 and its prevalence continues to increase due to aging populations and rising obesity rates (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The main symptoms: pain, stiffness, and dysfunction can significantly impair knee function and reduce quality of life (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Beyond the classic clinical symptoms, OA also imposes a substantial economic burden on healthcare systems (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Compounding their physical limitations, patients with advanced-stage OA frequently experience higher rates of depression and social isolation compared to those in early stages (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe management of knee OA encompasses a wide spectrum of options, ranging from conservative methods like patient education, weight control, and exercise, to intra-articular injections, and finally to surgical treatment (arthroplasty) for patients with resistant pain (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). However, pain control remains a significant clinical challenge for patients who are unsuitable for surgery, refuse surgery, or are currently on waiting lists. Although intra-articular steroid injections and genicular nerve blocks are frequently preferred in these patients, pain originating from the posterior capsule is a significant component of knee pain that may not be adequately controlled by these approaches (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). Standard genicular blocks typically target the anterior and lateral aspects of the knee, often neglecting the innervation of the posterior region. This limitation highlights the need for novel methods that can provide more comprehensive and effective analgesia.\u003c/p\u003e \u003cp\u003eThe infiltration between the popliteal artery and the capsule of the knee (IPACK) block is a relatively novel regional anesthesia technique that can provide analgesic effects on the posterior capsule without inducing motor block (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). This technique targets the terminal branches of the genicular nerves and popliteal plexus innervating the posterior capsule, while sparing the main trunks of the tibial and common peroneal nerves (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Cadaveric studies showed that the injectate spreads not only posteriorly but also anterolaterally and anteromedially, potentially offering a broader field of analgesia (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). While its efficacy in multimodal analgesia following knee surgery is supported by randomized controlled trials (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), this method also may be useful as an alternative treatment for patients with advanced knee osteoarthritis. The combined anti-inflammatory effect of the steroid injection and the posterior sensory blockade provided by the IPACK block may create a complementary or possibly synergistic benefit, leading to longer-lasting relief. Although the role of the IPACK block in post-arthroplasty pain management has been extensively studied, data regarding its efficacy in non-surgical chronic pain treatment are limited. The aim of this study was to evaluate whether adding an IPACK block to intra-articular steroid injection improves pain and functional outcomes in patients with advanced knee osteoarthritis.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Patients\u003c/h2\u003e \u003cp\u003eThis retrospective observational cohort study was conducted between January 2024 and September 2025 at a tertiary hospital in Istanbul, Turkey. The study was designed and reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The study was approved by the Institutional Ethics Committee (385/20.11.2025), and the study was registered in the ClinicalTrials.gov database (NCT07269444). The research was conducted in full compliance with the ethical principles outlined in the 2024 revision of the Declaration of Helsinki. While routine written informed consent for the clinical procedures was obtained from all patients, the requirement for study-specific informed consent was waived by the ethics committee due to the retrospective design of the study.\u003c/p\u003e \u003cp\u003ePatients aged 40 years and older diagnosed with Kellgren-Lawrence stage 3 or 4 knee osteoarthritis, who had a Numeric Rating Scale (NRS) score greater than 4 despite prior conservative medical and physical therapy, were screened for eligibility. Exclusion criteria included a history of knee surgery, knee injections within the last six months, psychotic disorders, bleeding diathesis, active malignancy or infection, known allergies to the study medications, and inability to communicate or refusal to undergo the procedure. The diagnosis of knee osteoarthritis was confirmed by clinical examination and radiological imaging, including magnetic resonance (MRI) or plain radiography (X-RAY).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eProcedures\u003c/h3\u003e\n\u003cp\u003eAll injections were performed by a single physician experienced in musculoskeletal interventions, using a Toshiba TUS-A300\u0026trade; (USA) ultrasound device. All procedures were carried out under aseptic conditions, and local anesthesia was applied to the subcutaneous tissue prior to needle insertion.\u003c/p\u003e \u003cp\u003eIntra-articular Steroid Injection (IASI):\u003c/p\u003e \u003cp\u003eThe patient was positioned supine with the knee in slight flexion (approximately 15\u0026ndash;30 degrees) and supported. A high-frequency linear ultrasound probe was placed transversely superior to the patella to visualize the suprapatellar recess. Using an in-plane technique, a 22G spinal needle was advanced from the lateral aspect toward the suprapatellar pouch, visualized as the hypoechoic space between the prefemoral fat pad and the quadriceps tendon. Once the needle tip was confirmed to be within the joint space, a mixture of 4 ml of 1% lidocaine and 40 mg of triamcinolone acetonide was injected without resistance. The spread of the injectate within the joint was verified under real-time ultrasound guidance.\u003c/p\u003e \u003cp\u003eIPACK Block:\u003c/p\u003e \u003cp\u003eWith the patient in the supine position, the leg was placed in the \"frog-leg\" position (knee flexed and hip externally rotated). A low-frequency convex ultrasound probe was placed transversely over the popliteal fossa, approximately 2\u0026ndash;3 cm proximal to the femoral condyles. The probe was adjusted proximally and distally to obtain an optimal view of the distal femoral shaft and the popliteal artery. Targeting the space between the femur and the popliteal artery, a 20G block needle was advanced from anteromedial to posterolateral using an in-plane technique. After positioning the needle tip approximately 1\u0026ndash;2 cm beyond the lateral border of the popliteal artery, a mixture of 15 ml of 0.25% bupivacaine and 4 mg of dexamethasone was injected during needle withdrawal following negative aspiration (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFollowing the procedure, patients were observed for two hours to monitor for potential complications. One week after the injection, all patients were provided with a simple home exercise booklet for rehabilitation. Patients were advised to use 500 mg of paracetamol (up to a maximum of four tablets per day) as a rescue analgesic only if the pain became intolerable. To ensure the reliability of clinical assessments, they were instructed to refrain from taking analgesics on the days of their follow-up visits.\u003c/p\u003e\n\u003ch3\u003eOutcome Measures\u003c/h3\u003e\n\u003cp\u003eBaseline demographic data (age, gender, body mass index [BMI], affected side, Kellgren-Lawrence stage) and symptom duration were recorded for all included patients. To monitor treatment efficacy, all clinical assessments were performed at baseline (pre-procedure), and at 1-month and 6-month follow-up visits post-procedure.\u003c/p\u003e \u003cp\u003ePrimary Outcome Measure:\u003c/p\u003e \u003cp\u003ePain severity was assessed using the Numeric Rating Scale (NRS), an 11-point scale ranging from 0 (no pain) to 10 (worst possible pain). NRS scores during activity were recorded for evaluation.\u003c/p\u003e \u003cp\u003eSecondary Outcome Measures:\u003c/p\u003e \u003cp\u003ePhysical functional status and limitations in daily living activities were evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), for which the validity and reliability of the Turkish version have been established (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). Higher WOMAC scores indicate increased pain and functional impairment, whereas lower scores reflect clinical improvement.\u003c/p\u003e \u003cp\u003ePatients were advised to use 500 mg of paracetamol as a rescue analgesic only when pain was intolerable during the post-procedure period. Daily average paracetamol consumption (mg/day) was recorded at follow-up intervals (1 month and 6 months post-procedure). Potential complications such as infection at the injection site, hematoma, neurological deficits, or systemic reactions were also monitored throughout the follow-up period.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using SPSS software version 27.0 (IBM Corp., Armonk, NY, USA). Descriptive statistics were presented as mean, standard deviation, and median for continuous variables, and as frequencies and percentages for categorical variables. The normality of data distribution was assessed using the Kolmogorov-Smirnov test. Since the data did not follow a normal distribution, non-parametric tests were utilized for analyses.\u003c/p\u003e \u003cp\u003eComparisons of demographic data and treatment outcomes between the two independent groups were conducted using the Mann-Whitney U test. The homogeneity of categorical variables between groups was analyzed using the Chi-square test. Within-group comparisons of repeated measures (pre-procedure vs. post-procedure) over time were performed using the Wilcoxon Signed-Rank Test. A p-value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant for all tests.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eOverall, 118 patients were assessed for eligibility. After excluding 7 patients who met the exclusion criteria and 13 patients with incomplete follow-up data, a total of 98 patients were included in the final analysis. Patients were divided into two groups: the Intra-articular Steroid Injection only group (Group IASI; n\u0026thinsp;=\u0026thinsp;50) and the group receiving Intra-articular Steroid Injection combined with an IPACK block (Group IASI+IPACK; n\u0026thinsp;=\u0026thinsp;48) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOf the included patients, 65 (66.3%) were female, 56 (57.1%) had Stage 4 osteoarthritis, and 56 (57.1%) presented with symptoms in the right knee (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Baseline demographic and clinical characteristics were similar between the groups. No statistically significant differences were observed in age, gender, BMI, symptom duration or baseline pain/function scores (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic and Clinical Characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInjection\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIASI\u003c/p\u003e \u003cp\u003eIASI+IPACK\u003c/p\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50\u003c/p\u003e \u003cp\u003e48\u003c/p\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51,0\u003c/p\u003e \u003cp\u003e49,0\u003c/p\u003e \u003cp\u003e100,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWoman\u003c/p\u003e \u003cp\u003eMan\u003c/p\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65\u003c/p\u003e \u003cp\u003e33\u003c/p\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66,3\u003c/p\u003e \u003cp\u003e33,7\u003c/p\u003e \u003cp\u003e100,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSide\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003cp\u003eLeft\u003c/p\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e56\u003c/p\u003e \u003cp\u003e42\u003c/p\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57,1\u003c/p\u003e \u003cp\u003e42,9\u003c/p\u003e \u003cp\u003e100,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eKellgren-Lawrance\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003cp\u003e4\u003c/p\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e42\u003c/p\u003e \u003cp\u003e56\u003c/p\u003e \u003cp\u003e98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42,9\u003c/p\u003e \u003cp\u003e57,1\u003c/p\u003e \u003cp\u003e100,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eIASI: Intra Articular Steroid Injection\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eIPACK: Infiltration between Popliteal Artery and Capsule of the Knee\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eWithin-Group Changes\u003c/h2\u003e \u003cp\u003eBoth groups demonstrated a significant reduction in NRS scores and WOMAC subscale scores at 1 and 6 months compared with baseline (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Temporally, clinical scores reached their lowest values at one month. While a mild symptomatic rebound was observed by the sixth month, scores in both groups remained significantly lower than pre-procedure baseline values (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e,\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of NRS and WOMAC score changes between groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNRS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIASI\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;50)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIASI+IPACK\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;48)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,48\u0026thinsp;\u0026plusmn;\u0026thinsp;1,31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4,08\u0026thinsp;\u0026plusmn;\u0026thinsp;1,25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,015\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2,04\u0026thinsp;\u0026plusmn;\u0026thinsp;0,98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,97\u0026thinsp;\u0026plusmn;\u0026thinsp;1,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,903\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1,44\u0026thinsp;\u0026plusmn;\u0026thinsp;0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-2.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWOMAC(Pain)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5,16\u0026thinsp;\u0026plusmn;\u0026thinsp;1,81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5,43\u0026thinsp;\u0026plusmn;\u0026thinsp;1,79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,436\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4,08\u0026thinsp;\u0026plusmn;\u0026thinsp;2,05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,83\u0026thinsp;\u0026plusmn;\u0026thinsp;1,79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,640\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1,08\u0026thinsp;\u0026plusmn;\u0026thinsp;1,78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1,60\u0026thinsp;\u0026plusmn;\u0026thinsp;1,39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,260\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWOMAC(Stiffness)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,32\u0026thinsp;\u0026plusmn;\u0026thinsp;1,01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3,58\u0026thinsp;\u0026plusmn;\u0026thinsp;1,08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,080\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2,62\u0026thinsp;\u0026plusmn;\u0026thinsp;1,38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2,54\u0026thinsp;\u0026plusmn;\u0026thinsp;1,23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,787\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0,7\u0026thinsp;\u0026plusmn;\u0026thinsp;1,11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1,04\u0026thinsp;\u0026plusmn;\u0026thinsp;0,92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,124\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWOMAC(Function)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7,52\u0026thinsp;\u0026plusmn;\u0026thinsp;2,12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11,04\u0026thinsp;\u0026plusmn;\u0026thinsp;2,19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3,62\u0026thinsp;\u0026plusmn;\u0026thinsp;2,18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5,35\u0026thinsp;\u0026plusmn;\u0026thinsp;2,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-3,90\u0026thinsp;\u0026plusmn;\u0026thinsp;2,44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-5,68\u0026thinsp;\u0026plusmn;\u0026thinsp;2,61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWOMAC(Total)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16,00\u0026thinsp;\u0026plusmn;\u0026thinsp;2,94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20,06\u0026thinsp;\u0026plusmn;\u0026thinsp;3,15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e0\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10,32\u0026thinsp;\u0026plusmn;\u0026thinsp;3,16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11,72\u0026thinsp;\u0026plusmn;\u0026thinsp;3,06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,024\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\u003csub\u003e1\u003c/sub\u003e-T\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-5,68\u0026thinsp;\u0026plusmn;\u0026thinsp;3,15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-8,33\u0026thinsp;\u0026plusmn;\u0026thinsp;3,05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0,000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eData are shown as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003cp\u003eIASI: Intra Articular Steroid Injection IPACK: Infiltration between Popliteal Artery and Capsule of the Knee\u003c/p\u003e \u003cp\u003eT0\u0026thinsp;=\u0026thinsp;Before the procedure, T1\u0026thinsp;=\u0026thinsp;1st month of the procedure, T2\u0026thinsp;=\u0026thinsp;6th month of the procedure\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eBetween-Group Comparisons\u003c/h3\u003e\n\u003cp\u003eThe IASI+IPACK cohort exhibited a significantly greater reduction in NRS scores at one month compared to the IASI group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Although both groups showed improvement at 6 months, the overall change from baseline was similar between them. However, the increase in scores from month 1 to month 6 was more pronounced in the IASI+IPACK group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e,\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the WOMAC assessment, no significant differences were found between treatment groups in the changes of Pain and Stiffness subscales. Significant differences were observed in WOMAC Function and WOMAC Total scores. Group IASI+IPACK showed significantly greater improvement than Group IASI in the transition from baseline to both 1 month and 6 months (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Correlation analysis did not show significant relationship between symptom duration and treatment efficacy (changes in NRS and WOMAC scores) at any post-procedure time point in either group (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e,\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eParacetamol consumption decreased significantly in both groups at 1 month and 6 months post-procedure compared to baseline (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Although consumption at 6 months slightly increased compared to 1 month, it remained below baseline levels in both groups. When comparing the two groups, no statistically significant difference was found between the treatment groups regarding the changes in monthly paracetamol usage (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis retrospective cohort study evaluated the efficacy and safety of adding an IPACK block to intra-articular steroid injection in patients with advanced knee osteoarthritis. We hypothesized that adding an IPACK block to IASI would provide greater improvement in pain and function compared to IASI alone. Our findings suggested that both treatment modalities provided significant improvements in pain and functional scores at 1 and 6 months post-procedure compared to baseline. Although scores increased slightly at 6 months compared with the marked reduction observed at 1 month, they remained significantly lower than baseline values.\u003c/p\u003e \u003cp\u003eAn important finding of this study was the more pronounced increase (rebound) in scores from the 1st month to the 6th month in the Group IASI+IPACK compared to the control group. Although this might initially appear as a disadvantage, it can be attributed to the more pronounced early improvement provided by the IPACK block. In the IASI+IPACK group, pain and function scores dropped to much lower levels at 1 month compared to the group receiving only steroids. As the pharmacological effects of the steroid and block gradually diminished, symptoms tended to increase again over time. Furthermore, this may be explained by that patients who experienced substantial early pain relief may have gradually increased their physical activity levels, potentially contributing to the relative rise in scores observed toward the sixth month. Despite this, the fact that WOMAC Function and Total scores in the IASI+IPACK group were still significantly better than those in the IASI group at the end of 6 months supports the long-term efficacy of this combined approach.\u003c/p\u003e \u003cp\u003eThe IPACK block is a relatively novel technique, first described in 2012, which has since gained increasing popularity. It is frequently utilized as part of multimodal analgesia protocols in postoperative pain management. Although its efficacy in this context has been proven by randomized controlled trials (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e), data regarding its use in chronic pain are limited. Edwards et al. reported that an IPACK block with added steroids reduced chronic pain and improved physical function for approximately two months in patients awaiting knee arthroplasty (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Consistent with these findings, our study showed the best results at 1 month, followed by an increase in scores toward the 6th month. Previous studies have shown in the literature that the addition of steroids to local anesthetics in peripheral nerve blocks prolongs the duration of analgesia through anti-inflammatory effects, suppression of ectopic discharges, and inhibition of C-fiber transmission (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). Indeed, findings from studies on IPACK blocks suggest that adding steroids may extend efficacy. For instance, one study demonstrated that the combination of IPACK and adductor canal blocks with steroids not only improved postoperative pain management after total knee arthroplasty but also contributed to the reduction of rebound pain and chronic postsurgical pain one year after surgery (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eMost interventional pain treatments for chronic knee pain target the genicular nerves. While interventions targeting these nerves are often successful, their effects may be limited as they mainly innervate the anterior and lateral aspects of the knee. The IPACK block differs in that it blocks pain originating from the posterior compartment. A cadaveric study reported that the injectate spreads not only posteriorly but also anterolaterally and anteromedially (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e). Although one comparative study found genicular blocks to be more effective than IPACK blocks on postoperative pain (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e), another study reported that adding an IPACK block to a genicular block provided improved analgesia and enhanced recovery compared to the genicular block alone (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFrom a safety perspective, the IPACK block was well tolerated in our cohort. While rare complications such as vascular injury or transient foot drop have been reported in the literature (\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e), the vast majority of studies report no major adverse events (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Consistent with these findings, we observed no major complications associated with the block in our study.\u003c/p\u003e \u003cp\u003eOur study has several limitations. The primary limitation is its retrospective nature, which involves a lack of randomization and the associated risk of selection bias. Additionally, the absence of recorded sensory tests to confirm block success in the early post-procedure period, and the assessment of pain using a total score rather than differentiating between anterior and posterior compartments, represent additional limitations. Nevertheless, a significant strength of our study is that it is one of the early studies examining the role of the IPACK block in the non-surgical treatment of chronic knee pain. Future prospective, randomized, placebo-controlled trials are needed to clarify the efficacy of the IPACK block in pain due to chronic knee osteoarthritis. Additional studies comparing this block with other methods, such as genicular nerve block/ablation, would provide valuable contributions to the literature.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, adding an IPACK block to intra-articular steroid injection appears to be a safe and effective option for pain management in advanced knee osteoarthritis. The combined treatment offered more noticeable benefits, especially in physical function and early-term pain control, compared to steroid injection alone. In light of these findings, the IPACK block may be considered a viable alternative for pain management in patients who are awaiting total knee arthroplasty, are at high surgical risk, or unwilling to undergo surgery.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBMI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBody Mass Index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIASI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eIntra-articular Steroid Injection\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIPACK\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInfiltration between the Popliteal Artery and the Capsule of the Knee\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMRI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMagnetic Resonance Imaging\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNRS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNumeric Rating Scale\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eOA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOsteoarthritis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSPSS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStatistical Package for the Social Sciences\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSTROBE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStrengthening the Reporting of Observational Studies in Epidemiology\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eWOMAC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eWestern Ontario and McMaster Universities Osteoarthritis Index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eThis retrospective study was approved by the Istanbul Prof. Dr. Cemil Taşçıoğlu City Hospital Scientific Research Ethics Committee (Reference Number: 385, Date: 20 November 2025), Istanbul, Türkiye. Due to the retrospective design of the study, the ethics committee waived the requirement for study-specific informed consent. However, routine written informed consent for the procedure had been obtained from all patients prior to the intervention.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u0026nbsp;\u003c/strong\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u0026nbsp;\u003c/strong\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003eThe author(s) received no financial support for the research, authorship, and/or publication of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' contributions:\u0026nbsp;\u003c/strong\u003eH.I.A and S.T.G contributed to the study concept and design, defined the intellectual content, and performed the clinical interventions.\u003c/p\u003e\n\u003cp\u003eS.T.G conducted the literature search and was responsible for retrospective data acquisition.\u003c/p\u003e\n\u003cp\u003eH.I.A \u0026nbsp;performed the statistical analysis, data analysis, and interpretation.\u003c/p\u003e\n\u003cp\u003eS.T.G and H.I.A \u0026nbsp;jointly contributed to manuscript preparation, editing, and critical review.\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eHeidari B. Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I. Caspian J Intern Med. 2011;2:205-12.\u003c/li\u003e\n \u003cli\u003eZhang Y, Jordan JM. Epidemiology of osteoarthritis. Clin Geriatr Med. 2010;26:355-69.\u003c/li\u003e\n \u003cli\u003eMartel-Pelletier J, Barr AJ, Cicuttini FM, Conaghan PG, Cooper C, Goldring MB, et al. Osteoarthritis. Nat Rev Dis Primers. 2016;2:16072.\u003c/li\u003e\n \u003cli\u003ePeoples BM, Miller RE, Rice SJ, Vincent TL. Knee health is a major determinant of mobility across the healthspan. J Funct Morphol Kinesiol. 2025;10:454.\u003c/li\u003e\n \u003cli\u003eOzcakir S, Raif P, Sivrioglu K, Kucukcakir N. Relationship between radiological severity and clinical and psychological factors in knee osteoarthritis. Clin Rheumatol. 2011;30:1521-6.\u003c/li\u003e\n \u003cli\u003eZhu S, Xu X, Zhang S, Zhang Y. Evaluation and management of knee osteoarthritis. J Evid Based Med. 2024;17:675-87.\u003c/li\u003e\n \u003cli\u003eThobhani S, Horner N, Boden A, Stevens B, Moskop D, Nystrom P, et al. Novel regional techniques for total knee arthroplasty promote reduced hospital length of stay: an analysis of 106 patients. Ochsner J. 2017;17:233-8.\u003c/li\u003e\n \u003cli\u003eSebastian MP. Saphenous nerve and IPACK block. Reg Anesth Pain Med. 2019. doi:10.1136/rapm-2019-100750.\u003c/li\u003e\n \u003cli\u003eKandarian BS, Indelli PF, Sinha S, Hunter OO, Mariano ER. Updates on multimodal analgesia and regional anesthesia for total knee arthroplasty patients. Best Pract Res Clin Anaesthesiol. 2019;33:111-23.\u003c/li\u003e\n \u003cli\u003eTran J, Giron Arango L, Peng P, Sinha SK, Agur A, Chan V. Evaluation of the iPACK block injectate spread: a cadaveric study. Reg Anesth Pain Med. 2019;44:689-94.\u003c/li\u003e\n \u003cli\u003eWang CG, Song Y, Wang K, Zhang XF. The effect of continuous adductor canal block combined with distal interspace between the popliteal artery and capsule of the posterior knee block for total knee arthroplasty: a randomized, double-blind, controlled trial. BMC Anesthesiol. 2022;22:175.\u003c/li\u003e\n \u003cli\u003eT\u0026uuml;z\u0026uuml;n EH, Eker L, Aytar A, Daşkapan A, Bayramoğlu M. Acceptability, reliability, validity and responsiveness of the Turkish version of WOMAC osteoarthritis index. Osteoarthritis Cartilage. 2005;13:28-33.\u003c/li\u003e\n \u003cli\u003eEdwards B, Lamacraft G. Does iPACK a punch? A prospective observational study on the efficacy of pain relief and functional improvement of an iPACK block for chronic knee osteoarthritis. Reg Anesth Pain Med. 2024;49:A15-16.\u003c/li\u003e\n \u003cli\u003ePehora C, Pearson AM, Kaushal A, Crawford MW, Johnston B. Dexamethasone as an adjuvant to peripheral nerve block. Cochrane Database Syst Rev. 2017;11:CD011770.\u003c/li\u003e\n \u003cli\u003eSreckovic S, Stevanovic K, Simic D, Stevic M. The effect of adding dexamethasone to adductor block and IPACK block on acute postoperative, rebound, and chronic pain following knee arthroplasty-1-year follow-up. Front Med (Lausanne). 2025;12:1570795.\u003c/li\u003e\n \u003cli\u003eAkesen S, Mutlu M, Ersen O, Akesen B. Comparison of efficacy between the genicular nerve block and the popliteal artery and the capsule of the posterior knee (IPACK) block for total knee replacement surgery: a prospective randomized controlled study. Acta Orthop Traumatol Turc. 2021;55:134-40.\u003c/li\u003e\n \u003cli\u003eFathi HM, Soliman M, El-Sayed M. Comparison of genicular nerve block and its combination with IPACK block for analgesia and recovery after total knee arthroplasty: a randomized trial. BMC Anesthesiol. 2025;25:601.\u003c/li\u003e\n \u003cli\u003eHadzic A. iPACK block. In: Hadzic A, editor. Hadzic\u0026apos;s peripheral nerve blocks and anatomy for ultrasound-guided regional anesthesia. 3rd ed. New York: McGraw-Hill; 2021.\u003c/li\u003e\n \u003cli\u003eRuggiero A, Fabio C, Pascarella G. Unexpected foot drop after proximal ipack block. Reg Anesth Pain Med. 2023;48:A306.\u003c/li\u003e\n \u003cli\u003eBiehl M, Wild L, Waldman K. The safety and efficacy of the IPACK block in primary total knee arthroplasty: a retrospective chart review. Can J Anaesth. 2020;67:1271-3.\u003c/li\u003e\n \u003cli\u003eYin W, Li X, Zhang Y. Effect of adductor canal block combined with infiltration between the popliteal artery and posterior capsular of the knee on chronic pain after total knee arthroplasty: a prospective, randomized, double-blind, placebo-controlled trial. BMC Anesthesiol. 2024;24:320.\u003c/li\u003e\n \u003cli\u003ePatterson ME, Bland KS, Thomas LC, Elliott CE, Soberon JR. The effect of the IPACK block on pain after primary TKA: a double-blinded, prospective, randomized trial. J Arthroplasty. 2020;35(6S):S173-7.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Knee Osteoarthritis, Intra-Articular Injections, Steroids, Nerve Block, IPACK Block, Ultrasound Guidance","lastPublishedDoi":"10.21203/rs.3.rs-9076754/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9076754/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003cbr\u003e\n\u003c/strong\u003eKnee 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.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods:\u003cbr\u003e\n\u003c/strong\u003eThis 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\u0026lt;0.05 was considered significant.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003cbr\u003e\n\u003c/strong\u003eBoth groups showed significant improvement in NRS and WOMAC scores at 1 and 6 months compared with baseline (p\u0026lt;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\u0026lt;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.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003cbr\u003e\n\u003c/strong\u003eAdding 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.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinicalTrials.gov, NCT07269444. Retrospectively registered on 20 November 2025.\u003c/p\u003e","manuscriptTitle":"Efficacy of IPACK Block Combined with Intra-articular Steroid Injection in Advanced Knee Osteoarthritis: A Retrospective Cohort Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-31 17:28:32","doi":"10.21203/rs.3.rs-9076754/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-20T11:33:25+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-19T15:35:04+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-13T11:58:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"294281981803767154310385184528197034687","date":"2026-04-07T14:36:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"216353518226630306351757370367014241538","date":"2026-04-07T11:20:22+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-26T12:15:37+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-26T11:54:29+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-16T18:48:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-12T02:58:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2026-03-11T19:32:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"1832d2ae-8bfe-4f9a-bd7c-4021cacea63f","owner":[],"postedDate":"March 31st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-05T09:10:28+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-31 17:28:32","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9076754","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9076754","identity":"rs-9076754","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}