Clinical Outcomes of Transcatheter Arterial Embolisation for Chronic Knee Pain: Mild-to-Moderate Versus Severe Knee Osteoarthritis

Transarterial Embolization for Musculoskeletal Pain Management: AJR Expert Panel Narrative Review

Musculoskeletal embolization has emerged in recent years as a treatment for chronic joint pain, as the inflammatory cascade responsible for such pain has become better understood. Studies have demonstrated a complex interplay between joint inflammation and synovial hypervascularity that causes growth of new unmyelinated nerve fibers responsible for pain. Embolization targets joint hypervascularity, to disrupt the inflammatory cycle and provide pain relief. The standard treatment algorithm for chronic joint pain is well-established and entails escalating therapeutic options that include exercise, self-management programs, analgesic medications, intra-articular injections, and finally surgical replacement or release. Genicular artery embolization (GAE), targeting abnormal vasculature around the knee joint, is the most heavily studied musucloskeletal embolization procedure, reflecting the high worldwide prevalence and increasing incidence of knee osteoarthritis. GAE is now supported by multiple prospective studies, including randomized control trials comparing GAE versus sham treatment. Embolization has also extended outside of the knee joint to include the shoulder (treatment of adhesive capsulitis or secondary stiff shoulder), elbow (medial/lateral epicondylitis), hip (osteoarthritis, great trochanteric pain syndrome), and ankle (plantar fasciitis). This AJR Expert Panel Narrative Review discusses the current status of transarterial embolization for musculoskeletal pain management, focusing on treatment of knee osteoarthritis and chronic shoulder pain.

Minimally invasive interventional procedures for osteoarthritis and inflammatory arthritis: A systematic review and meta-analysis

OBJECTIVE

to summarize the evidence on the efficacy of minimally invasive interventional procedures such as radiofrequency ablation (RFA) and transcatheter arterial embolization (TAE) in patients with osteoarthritis or inflammatory arthritis.

METHODS

a literature search was conducted in PubMed and Web of Science databases. Both randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSI) were included. The results were organized according to the treated anatomical site: knee, hip, foot and ankle, shoulder, hand and wrist, sacroiliac joints. Data about treatment efficacy were extracted. The main outcome was change in pain intensity using the 0-10 visual analog scale (VAS) from baseline to 1 month. Additional timepoints at 3, 6 and 12 months were assessed. Change in functional status was evaluated. Pooled estimates were calculated as the mean difference (MD) and 95 % confidence interval relative to baseline. The meta-analyses of RCTs and NRSI were conducted separately.

RESULTS

of the 4599 retrieved articles, 164 were included in the review and, considering all the established timepoints, 111 (38 RCTs and 73 NRSI) were selected for the meta-analysis. Only one article described patients with inflammatory arthritis. In the meta-analysis of RCTs, one month after the procedure, MD in VAS was -3.98 (-4.41 to -3.55; k = 21) for knee RFA, and -3.18 (-3.96 to -2.39; k = 8) for sacroiliac joints RFA. In the meta-analysis of NRSI, MD in VAS was -4.12 (-4.63 to -3.61; k = 23) for knee RFA, -3.84 (-4.77 to -2.92; k = 7) for knee TAE, -4.34 (-4.96 to -3.71; k = 2) for hip RFA, -3.83 (-4.52 to -3.15; k = 3) for shoulder RFA and -4.93 (-5.58 to -4.28; k = 14) for sacroiliac joints RFA. Significant decrease in pain intensity was found also at 3, 6 and 12 months. Additionally, functional status improved at all the assessed timepoints.

CONCLUSION

minimally invasive interventional procedures can improve pain and functional status of patients affected by OA or chronic sacroiliac pain of degenerative origin. Further research is warranted in the field of inflammatory rheumatic diseases.

Advances in Interventional Radiology Technology for the Treatment of Knee Osteoarthritis

Minimally invasive interventional radiology procedures play an adjunctive role in treating the symptoms of osteoarthritis (OA) with the hopes of delaying total knee arthroplasty (TKA). However, currently available intra-articular injections offer only short-term benefits. This has led to evolution of new techniques such as genicular artery embolization and genicular nerve ablation, which show benefit in pain control and quality of life, especially for mild-to-moderate OA, positioning these techniques as potential alternatives to intra-articular injections to help delay TKA.

Genicular Artery Embolization, Radiofrequency Ablation, and Corticosteroid Therapy for Knee Osteoarthritis: A Cost-Effectiveness Analysis Using Randomized Clinical Trial Data

Background: Many patients with symptomatic knee osteoarthritis (KOA) are refractory to traditional nonsurgical treatments such as intraarticular corticosteroid (CS) injection but are not yet eligible for or decline surgery. Genicular artery embolization (GAE) and radiofrequency ablation (RFA) are emerging adjunctive or alternative minimally invasive treatments. Objective: To perform a cost-effectiveness analysis (CEA) comparing CS, GAE, and RFA, for treatment of symptomatic KOA using a Markov model based on a de novo network meta-analysis (NMA) of randomized control trials. Methods: CEA was conducted to compare GAE and RFA to CS using a Markov cohort state-transition model from a U.S. Medicare payer's perspective over a 4-year time horizon. The model incorporated each treatment's success and attrition rates, costs, and utility benefit. Utility benefit values were derived at short-term (0.5-3 months) and long-term (6-12 months) posttreatment follow-up from NMA of published RCTs using an outcome of improved knee pain and/or function. Analyses were conducted at a willingness-to-pay threshold of $100,000 per quality-adjusted life year (QALY). Sensitivity analyses were performed, including when simulating various cost setting scenarios (i.e., office vs hospital outpatient treatment). Results: RFA demonstrated larger treatment effect than GAE, more pronounced at short-term [standardized mean difference (SMD), -1.6688, 95% CI [-2.7806; -0.5571], p=.003] than long-term (SMD -0.3822, 95% CI [-1.9743; 1.2100], p=.64) follow-up. Across cost setting scenarios, incremental cost-effectiveness ratios relative to CS were $561-1563/QALY for GAE versus $76-429/QALY for RFA (not counting scenarios in which RFA was dominated by CS). GAE demonstrated higher cost-effectiveness probability compared to RFA (41.6-54.8% vs. 18.4-29.2%, respectively). GAE was more cost-effective than RFA when the GAE clinical success rate and post-GAE utility value exceeded 32.1-51.0% and 0.562-0.617, respectively, and when the GAE quarterly attrition rate was less than 8.8-17.4%. RFA was more cost-effective when baseline pre-treatment utility values exceeded 0.695-0.713. Neither GAE costs nor RFA costs were sensitive parameters. Conclusion: Across scenarios, GAE was consistently the most likely cost-effective treatment option compared to RFA and CS, although clinical success rates, attrition rates, and utility values impact its cost-effectiveness. Clinical Impact: GAE is likely to be more cost-effective than RFA or CS for treatment of symptomatic KOA.

Genicular Artery Embolization for Treatment of Symptomatic Knee Osteoarthritis-2-Year Outcomes from a Prospective IDE Trial

PURPOSE

To report the 24-month outcomes and subgroup analysis evaluating the safety and effectiveness of the genicular artery embolization (GAE) for the treatment of symptomatic knee osteoarthritis (OA).

MATERIALS AND METHODS

Forty participants with symptomatic moderate-to-severe knee OA from a single-center, single-arm, prospective investigational device exemption trial of GAE were included in this study. Abnormal genicular artery neovascularity was identified at the subject's focal knee pain with digital subtraction angiography and cone-beam computed tomography (CT). Embolization was performed with 100-μm microspheres. The primary end point was treatment effectiveness as measured by sustained improvement in OA symptoms at 24 months, quantified using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Treatment success was defined as ≥50% decrease in WOMAC relative to baseline. Clinical outcomes were assessed with mean age of 66.0 years (SD ± 8.1) and body mass index of 30.1 kg/m2 (SD ± 6.2).

RESULTS

Of the 40 patients, 2 (5.0%) were lost to follow-up. Overall, 18 of 38 (47.4%) patients demonstrated ≥50% reduction in WOMAC at 24 months. In the subset of patients with initial clinical success at 12 months, 18 of 25 (72.0%) reported sustained clinical success at 24 months. Seven of 25 (28.0%) patients had symptom recurrence between 12 and 24 months and were determined to be clinical failures. All treatment-related adverse events occurred within 12 months after GAE, without additional events after 12 months.

CONCLUSIONS

GAE is effective in achieving sustained symptom relief related to moderate-to-severe knee OA for up to 24 months with an acceptable safety profile.

Angioembolization in the management of joint pain: current concepts

Joint pain is a common complaint owing to its origin in inflammatory and degenerative joint diseases. Recent research has helped narrow down inadequate angiogenesis as one of the causes. Angioembolization has emerged as a treatment option for this condition when it is refractory to conservative treatment. This review describes angioembolization by elaborating on the mechanism, safety, efficacy, comparative analysis of treatment and the road ahead, in addition to summarizing the existing data on this treatment. The inferences from this review further consolidate transcatheter arterial embolization as one of the prime options for managing joint pain when it is refractory to conservative treatment and label it as one of the most exciting prospects. A limitation of this review is that most of the data were from open label case series or case reports.

Lipiodol Versus Imipenem/Cilastatin in Genicular Artery Embolization: A Retrospective Study on Safety and Clinical Success

PURPOSE

This study aims to evaluate the safety and effectiveness of genicular artery embolization (GAE) using lipiodol in comparison to imipenem/cilastatin (IPM-CS).

MATERIALS AND METHODS

This retrospective study screened patients who underwent GAE between January 2022 and February 2023 for inclusion. Clinical outcomes were assessed at 1, 3, and 6 months post-procedure using the Visual Analog Scale (VAS) for pain and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for pain, stiffness, functional capacity, and total scores. Technical and clinical success rates, complications, and patient-reported outcomes were assessed.

RESULTS

A total of 42 patients were included in the study, with 13 patients treated with lipiodol and 29 with IPM-CS for GAE. Transient skin discoloration was noted in 23.1% of lipiodol patients and 31% of the IPM-CS group (p = 0.722). One patient (7.6%) in the lipiodol group developed knee edema and erythema due to drug-induced vasculitis (p = 0.309). Clinical success rates in the lipiodol group were 76.9% at 1 month, consistent at 3 months, and 69.2% at 6 months. For the IPM-CS group, success rates were 89.7, 86.2, and 75.9%, respectively, with no significant differences (p = 0.353, p = 0.657, p = 0.713). The median percentage change in WOMAC stiffness scores for the lipiodol group at 1, 3, and 6 months post-GAE were - 25%, - 16.7%, and - 16.7%, respectively, while the IPM-CS group showed decreases of - 40%, - 50%, and - 50%. Significant differences were found between the groups at all time points (p = 0.017, p = 0.009, and p = 0.002, respectively).

CONCLUSION

Lipiodol shows comparable clinical success to IPM-CS in GAE.

Geniculate Artery Embolization for the Treatment of Mild to Moderate Knee Osteoarthritis Improves Pain and Function at Short-Term Follow-Up With Significant Procedural Heterogeneity Described Across the Literature: A Systematic Review

PURPOSE

To evaluate procedural heterogeneity, patient-reported outcomes (PROs), and complications following geniculate artery embolization (GAE) for knee osteoarthritis (OA).

METHODS

A literature search was performed using PubMed, Embase, and Scopus databases from inception to August 2023 according to the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Human clinical studies reporting PROs following GAE for treatment of knee OA were included, and a qualitative comparison across PROs, procedural descriptions, and complications was performed. Study quality was assessed using the Cochrane Collaboration's risk of bias tool and the Methodological Index for Non-Randomized Studies criteria. The primary outcome measures included changes in PROs at 12 months and variances in procedural methodology.

RESULTS

A total of 17 studies, consisting of 533 patients and 620 knees, were identified. The reported mean improvement at 12 months for visual analog scale for pain and Western Ontario and McMaster Universities Arthritis Index scores ranged from 10 to 59 and 35.3 to 47, respectively. At 12 months, median improvements were observed in Knee injury and Osteoarthritis Outcome Score subscales such as Pain (range, 8.3-19.5), Quality of Life (15.49-25.0), Sport (7.5-26.3), and Symptoms (1.8-25.0). Decreasing minimal clinically important difference (MCID) achievement was observed between the 3-month and 6-month follow-up points. Patients with advanced OA and degenerative findings on magnetic resonance imaging exhibited lower rates of MCID achievement. Transient adverse events occurred in up to 80% of patients. Limited evidence from serial magnetic resonance imaging assessments suggests that GAE improves levels of synovitis. Significant heterogeneity exists among the GAE methodology as 4 different definitions of technical success, 4 distinct embolization targets, and use of 5 embolization agents were noted.

CONCLUSIONS

GAE results in short-term improvements in pain and function with decreasing MCID achievement observed after 3 to 6 months. Patients with severe OA also demonstrate lower rates of MCID achievement. A high rate of transient complications is reported, including skin discoloration and access site hematomas. Significant protocol heterogeneity exists, which contributes to variable outcomes.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Comparing technical success and clinical outcomes of macrocatheter versus microcatheter in genicular artery embolization for knee osteoarthritis

PURPOSE

The purpose of this study was to evaluate the comparative effectiveness and safety of using macrocatheters versus microcatheters for genicular artery embolization (GAE) in the management of knee osteoarthritis (OA). The primary outcomes were technical success and adverse events during and immediately after the procedure. The secondary outcome was the clinical outcome over the follow-up period.

MATERIALS AND METHODS

In our retrospective analysis, we included 79 patients undergoing GAE for OA. Patients were categorized based on the catheter type used: microcatheter through macrocatheter or directly through macrocatheter. Key parameters, including technical success, adverse events, procedure duration, radiation exposure, and clinical outcomes (VAS and WOMAC scores), were assessed at 1st, 3rd, and 6th-month intervals.

RESULTS

Technical success stood at 100 % for the microcatheter group, with a slight reduction for the macrocatheter group at 91 % (p = 0.069). Procedure and fluoroscopy durations were significantly shorter in the macrocatheter group (p < 0.001). Additionally, the macrocatheter group demonstrated a marked reduction in radiation dose, with notably decreased air kerma values. Clinical outcomes, including VAS and WOMAC scores at the predefined intervals, revealed no significant disparities between the two cohorts.

CONCLUSION

In GAE procedures utilizing a temporary embolic agent (imipenem/cilastatin), initiating the intervention with a macrocatheter can be deemed cost-effective, safe and advantageous for patients with less complex vascular anatomy, as it significantly reduces procedural and fluoroscopy times, thereby minimizing radiation exposure. Conversely, in patients with intricate vascular pathways, transitioning to a microcatheter enhances technical success.

Society of Interventional Radiology Research Reporting Standards for Genicular Artery Embolization

Genicular artery embolization (GAE) is an emerging, minimally invasive therapy to address the global burden of knee osteoarthritis (OA) and the unmet needs for medically refractory disease. Although total knee arthroplasty has been a standard intervention for severe cases, GAE is developing into a promising alternative, particularly for patients ineligible for or unwilling to undergo surgery. GAE targets the inflammatory cascade underlying OA pathophysiology by arresting neoangiogenesis and preventing pathological neoinnervation, offering potential pain relief. Although early studies have established safety and short-term effectiveness, ensuing studies are needed to validate long-term safety, durability, and comparative effectiveness and to optimize patient selection, embolic agent selection, and administration techniques. Standardized reporting guidelines are therefore essential to enhance transparency and reproducibility across clinical trials, facilitating data aggregation and comparison. This Society of Interventional Radiology (SIR)-endorsed reporting standards consensus document provides a framework to harmonize future research efforts and to improve the interpretation of outcomes.

Transarterial Embolization of Geniculate Arteries Reduces Pain and Improves Physical Function in Knee Osteoarthritis-A Prospective Cohort Study

Knee osteoarthritis (OA) affects millions worldwide, leading to pain and reduced quality of life. Conventional treatments often fail to provide adequate relief, necessitating new therapeutic approaches. This study evaluated the efficacy and safety of genicular artery embolization (GAE) using permanent microspheres in patients with mild-to-moderate knee OA. In this prospective, single-center study, 17 participants underwent GAE. KOOS (Knee injury and Osteoarthritis Outcome Score), WOMAC (The Western Ontario and McMaster Universities Arthritis Index), and IPAQ (International Physical Activity Questionnaire) scores, along with physical performance tests, medication use, and dual-energy X-ray absorptiometry (DEXA) scans, were assessed at baseline and at multiple follow-up points over six months. The primary endpoint, VAS at six months, showed significant improvement (median reduction from 66 mm to 40 mm, p = 0.0004). All pain and function scores, as well as physical performance tests, improved significantly. No clinically relevant changes in medication use or DEXA parameters were observed after six months. Only minor, self-limiting adverse events occurred. This study indicates that GAE is a promising minimally invasive treatment for knee OA, providing significant pain relief and functional improvement. However, further long-term, randomized trials are needed to confirm these findings and establish optimal patient selection criteria.

Value of interventional radiology and their contributions to modern medical systems

Interventional radiology (IR) is a unique specialty that incorporates a diverse set of skills ranging from imaging, procedures, consultation, and patient management. Understanding how IR generates value to the healthcare system is important to review from various perspectives. IR specialists need to understand how to meet demands from various stakeholders to expand their practice improving patient care. Thus, this review discusses the domains of value contributed to medical systems and outlines the parameters of success. IR benefits five distinct parties: patients, practitioners, payers, employers, and innovators. Value to patients and providers is delivered through a wide set of diagnostic and therapeutic interventions. Payers and hospital systems financially benefit from the reduced cost in medical management secondary to fast patient recovery, outpatient procedures, fewer complications, and the prestige of offering diverse expertise for complex patients. Lastly, IR is a field of rapid innovation implementing new procedural technology and techniques. Overall, IR must actively advocate for further growth and influence in the medical field as their value continues to expand in multiple domains. Despite being a nascent specialty, IR has become indispensable to modern medical practice.

Genicular Artery Embolization: A New Tool for the Management of Refractory Osteoarthritis-Related Knee Pain

Osteoarthritis (OA) of the knee is a prevalent cause of chronic pain and disability, particularly affecting women. While traditionally attributed to chronic wear and tear, recent evidence highlights multifactorial pathogenesis involving low-grade inflammation and neoangiogenesis. Current therapeutic options include physical therapy, pharmacotherapy, and total knee arthroplasty (TKA). However, a subset of patients remain symptomatic despite conservative measures, necessitating the development of minimally invasive interventions. Genicular artery embolization (GAE) emerges as a promising option, targeting neovascularization and inflammatory processes in OA. This paper reviews the pathophysiological basis, patient selection criteria, procedural details, and outcomes of GAE. Notably, GAE demonstrates efficacy in relieving knee pain and improving function in patients refractory to conventional therapy. While further research is warranted to elucidate its long-term outcomes and compare it with existing modalities, GAE represents a novel approach in the management of symptomatic knee OA, potentially delaying or obviating the need for surgical intervention. Here, we synthesize the relevant literature, technical details of the procedure, and future perspectives. Moreover, the success of GAE prompts the exploration of transarterial embolization in other musculoskeletal conditions, underscoring the evolving role of interventional radiology in personalized pain management strategies.

Identification of Key Factors in Cartilage Tissue During the Progression of Osteoarthritis Using a Non-targeted Metabolomics Strategy

This research was to reveal the key factors in the progression of osteoarthritis (OA) using non-targeted metabolomics and to find targeted therapies for patients with OA. Twenty-two patients with knee OA scheduled for total knee arthroplasty were divided into two groups: Kellgren-Lawrence (KL) grade 3 (n = 16) and grade 4 (n = 6), according to plain X-rays of the knee. After the operation, the cartilages of femur samples were analyzed using non-targeted metabolomics. When compared with grade 3 patients, the levels of choline, 2-propylpiperidine, rhamnose, and monomethyl glutaric acid were higher; while 1-methylhistamine, sphingomyelin (SM) (d18:1/14:0), zeranol, 3- (4-hydroxyphenyl)-1-propanol, 5-aminopentanamide, dihydrouracil, 2-hydroxypyridine, and 3-amino-2-piperidone were lower in grade 4 patients. Furthermore, some metabolic pathways were found to be significantly different in two groups such as the pantothenate and coenzyme A (CoA) biosynthesis pathway, the glycerophospholipid metabolism pathway, histidine metabolism pathway, lysine degradation pathway, glycine, serine and threonine metabolism pathway, fructose and mannose metabolism pathway, the pyrimidine metabolism pathway, and beta-alanine metabolism pathway. This work used non-targeted metabolomics and screened out differential metabolites and metabolic pathways, providing a reliable theoretical basis for further study of specific markers and their specific pathways in the progression of OA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00123-z.

Genicular Artery Embolization: Embolic Material and Imaging Review

Osteoarthritis (OA) of the knee is a degenerative condition impacting numerous individuals globally. Genicular artery embolization (GAE) has emerged as an effective minimally invasive therapy for managing medically refractory OA-related pain in patients who are not eligible for surgery. This intervention works by disrupting the inflammatory and neoangiogenic pathways that contribute to pain. The efficacy of GAE has been demonstrated in various clinical trials, yielding promising results. This review aims to explore recent advancements in the embolic materials used during GAE, examining their properties and potential benefits. Additionally, it will describe the use of pre-, intra-, and postprocedural imaging-particularly magnetic resonance imaging and other modalities-to optimize GAE outcomes.

Selective Genicular Artery Embolization in the Management of Osteoarthritic Knee Pain-A Narrative Review

Many people with pain from osteoarthritis (OA) of the knee are either not ready for surgery or may never be surgical candidates. Genicular artery embolization (GAE) is a new proposed management for those with pain despite maximum medical management. It has historically been used to manage recurrent spontaneous haemarthrosis following total knee replacement, but newer studies are showing a positive effect in managing pre-arthroplasty knee OA. The goal of this review is to summarise current and relevant literature from searches of computerised databases and relevant journals, and analyse their results. Studies included show that GAE has promising outcomes in managing mild to moderate OA knee pain in those who have exhausted at least 3 months of conservative therapy. Most studies show improvements in VAS pain and PROM scores (including KOOS, and/or WOMAC). Minimal adverse effects have been associated in up to two years of follow up, the majority of which are self-resolving. The article précises a concise general procedural technique for performing GAE, as well as comparing and contrasting different embolic agents that may be utilised. GAE shows promising outcomes in management of mild to moderate OA knee pain. In the future, there will need to be higher volume studies to determine effectiveness, suitable candidates, and other potential adverse effects.

Genicular Artery embolisation in Patients with Osteoarthritis of the Knee (GENESIS) Using Permanent Microspheres: Long-Term Results

PURPOSE

To report the 2-year follow-up of patients with mild-to-moderate knee osteoarthritis (OA) treated with genicular artery embolisation (GAE) as part of the GENESIS study.

MATERIALS AND METHODS

Forty-six patients, median age = 60 (45-83) underwent GAE using permanent microspheres (100-300 μm). Technical success was defined as embolisation of the targeted genicular arteries. Knee Injury and Osteoarthritis Outcome Score (KOOS) and Visual Analogue Scale (VAS) (0-100 mm) were recorded at baseline, 6 weeks, 3 months, 1, 2 years. Contrast-enhanced MRI knee scans were acquired at baseline and 1 year, and evaluated with the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Functional MRI brain imaging and psychometric assessments were undertaken to investigate correlation between neuropsychological phenotypes and clinical outcome. Adverse events were recorded prospectively.

RESULTS

Technical success was achieved in forty patients (87%). Mean VAS improved from 58.63 (SD = 20.57, 95% CI 52.7-65.5) at baselines to 37.7 at 2-years (SD = 26.3, 95% CI 27.0-47.5). Whole and subgroup KOOS were significantly improved at each timepoint with associated reductions in analgesia usage. WORMS analysis demonstrated significant reduction in synovitis (p < 0.05) with no cases of osteonecrosis. Self-limiting skin discolouration occurred in four patients. A self-limiting groin haematoma and single case of deep-vein thrombosis due to immobilisation were also recorded. Nine patients subsequently underwent knee arthroplasty with no additional operational complexities identified. Neuropsychometric assessment elucidated a correlation between baseline catastrophising and greater reduction in pain post GAE.

CONCLUSION

GAE is a safe intervention for mild-moderate knee osteoarthritis, with sustained efficacy at 2 years. These results are promising and justify ongoing controlled trials.

Transarterial microembolization for the management of refractory chronic joint pain in osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disease significantly impacting both patient quality of life and socioeconomics. Traditional treatment options, including pharmacological and surgical interventions, are often limited. Advancements in our understanding of the pathological mechanisms behind OA indicate the involvement of pathological angiogenesis. Transarterial microembolization (TAME), a minimally invasive radiological procedure, may present an innovative therapeutic approach. This review aims to consolidate current knowledge and experiences regarding TAME as a therapeutic modality for alleviating chronic joint pain associated with OA. It explores the role of TAME, focusing on its indications, patient selection, clinical outcomes, and future perspectives. Potential complications and associated risks are systematically addressed, alongside proposed strategies for risk mitigation and effective management.The presented patient cases originate from our institution, supplemented by a thorough review of relevant literature retrieved from PubMed.TAME represents a promising therapeutic approach, providing relief from the burden of joint diseases and substantially enhancing patient quality of life. Clinical outcomes emphasize the efficacy and safety of TAME in mitigating pain and improving functional capabilities in patients with chronic joint pain associated with OA. With mounting evidence of its therapeutic benefits and applicability to numerous joint-related pathologies, TAME offers a valuable addition to the arsenal of treatments for these conditions. · TAME is an innovative therapy for treating chronic joint pain related to OA.. · TAME is a technically challenging minimally invasive intervention requiring a high level of expertise.. · Understanding the challenges and complications of TAME can reduce risk and enhance procedural outcomes.. · Wilms LM, Jannusch K, Weiss D et al. Transarterial microembolization for the management of refractory chronic joint pain in osteoarthritis. Fortschr Röntgenstr 2024; DOI 10.1055/a-2288-5743.

Challenges and complications and their management of the transarterial microembolization for chronic musculoskeletal pain

Transarterial microembolization (TAME) is an increasingly well-known novel and minimally invasive treatment option for painful chronic musculoskeletal diseases that is gaining popularity. Although the safety and effectiveness of TAME have been established, limited knowledge of intraarticular and musculocutaneous arterial anatomy may lead to challenges and complications. This article aims to present cases illustrating these challenges and complications, based on multicenter experiences and a comprehensive literature review. Furthermore, the article also provides preventive tips, solutions, and follow-up strategies to reduce the learning curve for interventional radiologists and facilitate familiarity with post-TAME follow-up images for diagnostic radiologists. CLINICAL RELEVANCE STATEMENT: This article illustrates the intra- and post-interventional complications of transarterial microembolization (TAME) through detailed pictorial reviews, including how to distinguish them from normal angiographic findings. It provides strategies for their prevention, management, and follow-up, which can further improve clinical outcomes. KEY POINTS: • Transarterial microembolization for chronic musculoskeletal pain may result in intrainterventional challenges (IIC) and postinterventional complications (PIC), and their importance may be underestimated. • The intrainterventional challenges include microarterial perforation, arterial dissection, and catheter tip fracture, whereas postinterventional complications include tissue ischemia-related complications, puncture site hemorrhage, and arterial injury. • Being familiar with the intrainterventional challenges and postinterventional complications may help minimize the procedure risk and improve outcomes.

Genicular Artery Embolization: A Review of Essential Anatomic Considerations

Genicular artery embolization is increasingly recognized as a safe and effective treatment option for symptomatic knee osteoarthritis and recurrent hemarthrosis after total knee arthroplasty. Genicular arteries are an essential contributor to vascular supply for the knee joint and demonstrate considerable variability. Familiarity with the anatomy and common variations is critical for preprocedural planning, accurate target selection, and minimizing adverse events in transarterial embolization procedures. This review aimed to provide a detailed discussion of the genicular artery anatomy that is relevant to interventional radiologists performing genicular artery embolization.

Genicular artery embolization for knee osteoarthritis: Results of the LipioJoint-1 trial

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of transient genicular artery embolization (GAE) using an ethiodized oil-based emulsion for the treatment of knee osteoarthritis (KOA).

MATERIALS AND METHODS

This prospective, single-arm, open-label, multicenter, first-in-human cohort trial was registered on ClinicalTrials.gov (NCT04733092). The main inclusion criterion was diagnosis of KOA according to a visual analogue scale (VAS) pain score ≥ 40 mm (score range: 0-100 mm), despite conservative treatment for at least three months. Treatment efficacy was assessed using changes in VAS pain score, Mean Western Ontario & McMaster Universities osteoarthritis (WOMAC) function score (normalized to 100; score ranging from 0 to100) and outcome measures in rheumatoid arthritis clinical trials (OMERACT)-Osteoarthritis Research Society (OARSI) set of responder criteria.

RESULTS

Twenty-two consecutive participants (13 women; mean age, 66 ± 9 [standard deviation (SD)]) were included and underwent GAE. Emulsion consisted in a mixture of ioversol and ethiodized oil (ratio 1:3, respectively) prepared extemporaneously. The rate of serious adverse events attributed to GAE within one month was 5% (1/22), corresponding to reversible worsening of renal function. Immediate technical success rate was 100%. Mean VAS pain score dropped from 74.4 ± 16.5 (SD) mm at baseline to 37.2 ± 26.7 (SD) mm at three months (P < 0.001). Mean WOMAC function score (normalized to 100: score ranging from 0 to 100) decreased from 57.3 ± 17.1 (SD) at baseline to 33.5 ± 25.9 (SD) at three months (P < 0.001). At three months, 16 out of 22 participants (73%) were considered responders according to the OMERACT-OARSI set of responder criteria, including high improvement in either pain or WOMAC function, or improvement in both pain and WOMAC function.

CONCLUSION

GAE using an ethiodized oil-based emulsion is safe and improves pain and function in participants with KOA for at least three months.

Safety and Efficacy of Genicular Artery Embolization for the Treatment of Knee Pain Secondary to Osteoarthritis-Initial Indian Experience

Background  Osteoarthritis (OA) is the commonest form of arthritis with pain and disability as hallmark symptoms. Despite various nonpharmacologic, pharmacologic, and surgical approaches, pain control may be hard to achieve. Over the last few years, few studies have been conducted on managing knee OA using novel endovascular genicular artery embolization (GAE) with varied outcomes. No such study has been reported in India yet to the best of our knowledge. Purpose  The main aim of this article was to evaluate the efficacy and safety of transcatheter GAE in relieving knee pain in patients with mild-to-moderate OA. Materials and Methods  Ten patients with radiographic knee OA and moderate-to-severe pain refractory to conservative therapy were enrolled in a prospective observational study. GAE was performed with 100 to 300-μm spherical particles. Patients were assessed with magnetic resonance imaging at the baseline. Visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used to assess pain and disability respectively at the baseline, 1 month, and 3 months. Clinical success was asserted by the downstaging of VAS and WOMAC scores. Adverse events were recorded at all-time points. Descriptive and inferential statistics have been performed using SPSS. A p -Value less than 0.05 was considered statistically significant. Results  Embolization of at least 1 genicular artery was achieved in all the patients (100%). Clinical success was demonstrated in 08 (80%) of the patients. Median VAS reduced from 07 at baseline to 3.5 at 3-month follow-up ( p  < 0.001). Median WOMAC score improved from 53 to 23.50 at 3-month follow-up ( p  < 0.001). Minor complications were seen in two patients in the form of puncture site hematoma and mild petechial spots over the knee. Conclusion  Our pilot study demonstrates GAE as a safe and efficacious procedure to treat knee pain secondary to OA. Further randomized comparative studies with a larger sample size are needed to determine the true treatment effect versus the placebo effect.

Quantifying Change in Perfusion after Genicular Artery Embolization with Parametric Analysis of Intraprocedural Digital Subtraction Angiograms

PURPOSE

To quantify perfusion changes during genicular artery embolization (GAE) with the qualitatively described "pruning" technique using parametric analysis.

MATERIALS AND METHODS

A total of 12 patients underwent unilateral GAE with a total of 36 vessels embolized. Among 34 of the 36 vessels embolized, regions of interest (ROIs) were placed on parent vessels (PVs) and hyperemic target vessels (TVs) before and after GAE. For each ROI, peak intensity (PI), time to arrival (TTA), and area under the curve (AUC) were computed and compared between PV and TV. Volume of embolic administered was correlated with adverse events.

RESULTS

No change was seen in PI, TTA, and AUC in the PV after GAE. Reduction in AUC (1,495.7 ± 521.5 vs 1,667.4 ± 574.0; P << .01) and PI (195.1 ± 43.8 vs 224.3 ± 49.2; P << .01) with increase in TTA (3.42 s ± 1.70 vs 1.92 s ± 1.45; P << .01) within the TV were observed after GAE. Median follow-up time was 89 days (range, 21-254 days). Reduction in clinical symptoms was also noted based on the Western-Ontario and McMaster Universities Arthritis Index total and pain scale at 1 month (total, 42.9% ± 23.0; pain, 54.4% ± 9.8; P << .01) and 3 months (total, 42.5% ± 14.9; pain, 57.8% ± 10.6; P << .01). Eight total mild adverse events (minor/self-limiting) were noted per Society of Interventional Radiology guidelines. A larger volume of embolic was observed in knees with skin changes (3.4 mL ± 0.4 vs 1.7 mL ± 0.4; P << .001). Furthermore, all skin changes were seen with embolic volumes >3.0 mL.

CONCLUSIONS

Quantification of intraprocedural perfusion changes with GAE demonstrated reduced flow to the TV with maintained flow in the PV and acceptable clinical outcomes. A potential relationship between embolic volume and nontarget embolization was also highlighted.

Musculoskeletal Embolotherapy

Painful articular musculoskeletal (MSK) conditions are common, debilitating and sometimes difficult to treat. Transcatheter embolisation may offer an alternative way to manage the pain associated with these conditions, but the field is still in its infancy. To date, the most commonly studied indication is knee osteoarthritis, but the technique has been trailed in multiple other tissue beds, including for adhesive capsulitis and tendinopathies. Whilst early results appear promising, the existing studies are mostly open-labelled and non-randomised; there is a need for high-quality evidence to robustly assess the procedures efficacy. In this review, we set out to evaluate the current evidence underlying the pathophysiology and mechanism of action of embolisation; discuss the technical aspects of the procedure including embolic selection, and appraise the published clinical outcomes and adverse effects. Finally, we discuss the future directions and research priorities in this rapidly developing field.

Evaluating the Safety and Effectiveness of Quick-Soluble Gelatin Sponge Particles for Genicular Artery Embolization for Chronic Knee Pain Associated with Osteoarthritis

PURPOSE

To evaluate the effectiveness and safety of genicular artery embolization (GAE) using quick-soluble gelatin sponge particles (QS-GSPs) to alleviate chronic knee pain associated with osteoarthritis.

MATERIALS AND METHODS

This retrospective study included 71 patients (97 procedures, including 26 patients for both knees) who underwent GAE to treat osteoarthritic knee pain between August 2019 and January 2022. QS-GSPs were used for all the procedures. Technical success was defined as the embolization of at least 1 feeding artery. Clinical outcomes were evaluated using a 10-point visual analog scale (VAS). Clinical success was defined as a decrease in the VAS score of >50%.

RESULTS

The technical success rate was 100% (97 of 97). The mean VAS scores at baseline, immediately after TAE, and at 1 day, 1 week, 1 month, 3 months, and 6 months after TAE were 6.3, 4.3, 5.0, 3.0, 2.9, 2.9, and 2.8, respectively. The clinical success rate was 72% (70 of 97 patients) at 6 months. No major adverse events were reported, and temporary skin color change (50.5%, 49 of 97) and hematoma at the puncture site (10.3%, 10 of 97) were observed.

CONCLUSIONS

GAE using QS-GSPs had a high technical success rate and was considered safe. Clinical outcomes using QS-GSPs were comparable with those of existing materials.

Transcatheter arterial embolisation for the relief of shoulder and elbow chronic joint pain refractory to conventional treatment: Systematic review

Angiogenesis and accompanying nerve fibres might cause unsettling joint pain. Studies have suggested that transcatheter arterial embolisation (TAE) of these abnormal neovessels could relieve pain and symptoms in patients with upper limb joint pain refractory to conventional treatment. This study aims to investigate the efficacy and safety of TAE in treating chronic pain of shoulder and elbow joints that have been resistant to other treatments. Using six databases, a systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The primary outcome involved changes in the visual analogue scale (VAS) after TAE; while secondary outcomes involved comparing other parameters where relevant. Average VAS decreased from baseline, then at 1 day, 1 week, 1 month, 3 months, 4 months, 6 months, 1 year, 2 years and 44 months (7.5 at baseline vs. 4.7, 4.3, 3.4, 2.1, 2.5, 1.2, 0.7, 1.1 and 0.1, respectively). Average Quick-DASH scores decreased from baseline, then at 1, 3 and 6 months (61.3 at baseline vs. 30.6, 19.3 and 6.9, respectively). Minor adverse events were reported in 27/143 (18.9%) patients, where they resolved spontaneously or with oral analgesia. TAE is a possible treatment option for refractory shoulder and elbow joint pain; however, randomised controlled trials are still required.

Intra-Arterial Injection of Temporary Embolic Material Through a Needle Inserted into the Radial or Ulnar Artery for Distal and Proximal Interphalangeal Joint Osteoarthritis: A Retrospective Study of 92 Patients

PURPOSE

To assess the efficacy and safety of intra-arterial injection of imipenem/cilastatin sodium (IPM/CS) via a needle placed into the radial artery or ulnar artery (RA/UA) for distal interphalangeal and proximal interphalangeal joint osteoarthritis (DIP/PIP-OA).

MATERIALS AND METHODS

This is a retrospective single-arm cohort study. Ninety-two patients [92% women, mean (SD) age 55(8.3) years] with a primary DIP/PIP-OA meet the American College of Rheumatology criteria for hand osteoarthritis with pain ≥ 4 on the 0-10 numeric rating scale (NRS) were enrolled. All procedures were performed by injecting IPM/CS through a 24-gauge needle percutaneously inserted into the RA/UA. Two procedures were planned; the second procedure was scheduled 1-2 months after the first. NRS, Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score, Patient Global Impression of Change (PGIC) scale, and procedure-related adverse events were evaluated.

RESULTS

Technical success, defined as injection of IPM/CS into the RA/UA, was achieved in all patients. Clinical success, defined as a reduction of 2 points or more in the NRS at 12 months, was 77% (95% confidence interval 68-85%). The NRS improved from the baseline to 3, 6, and 12 months (7.8 ± 1.6 vs. 3.8 ± 2.6, 3.9 ± 2.7, and 4.0 ± 2.8, respectively, all p < 0.001). The QuickDASH score improved from the baseline to 12 months (27 ± 15 vs. 19 ± 17, p < 0.001) respectively. No major adverse events were observed.

CONCLUSIONS

Intra-arterial injection of IPM/CS is a feasible treatment option for DIP/PIP-OA.

Outcomes after Genicular Artery Embolization Vary According to the Radiographic Severity of Osteoarthritis: Results from a Prospective Single-Center Study

This prospective single-center study compared outcomes after genicular artery embolization (GAE) in people with mild radiographic knee osteoarthritis (OA) (n = 11) versus moderate to severe radiographic knee OA (n = 22). The mild OA group was older and had experienced symptoms for less time (P < .05). All participants underwent complete embolization of neovessels from genicular arteries. The primary outcome was the proportion of responders at 6 months according to predetermined improvements in pain, function, and/or global change. Results indicated that a higher proportion of participants (n = 9, 81.8%) with mild OA fulfilled responder criteria after treatment compared with people with moderate to severe OA (n = 8, 36.4%) (P = .014). Secondary outcomes for pain, quality of life, and global change were also better in the mild OA group (P < .05). No serious adverse events occurred, including the absence of osteonecrosis on magnetic resonance imaging. The study demonstrated that outcomes after GAE varied according to the severity of baseline radiographic OA.

Genicular Artery Embolisation in Patients with Osteoarthritis of the Knee (GENESIS 2): Protocol for a Double-Blind Randomised Sham-Controlled Trial

Knee osteoarthritis is a leading cause of chronic disability and economic burden. In many patients who are not surgical candidates, existing treatment options are insufficient. Clinical evidence for a new treatment approach, genicular artery embolisation (GAE), is currently limited to single arm cohort, or small population randomised studies. This trial will investigate the use of a permanent embolic agent for embolisation of abnormal genicular arterial vasculature to reduce pain in patients with mild to moderate knee osteoarthritis. Up to 110 participants, 45 years or older, with knee pain for ≥ 3 months resistant to conservative treatment will be randomised (1:1) to GAE or a sham procedure. The treatment group will receive embolisation using 100-micron Embozene™ microspheres (Varian, a Siemens Healthineers Company) (investigational use for this indication in the UK), and the sham group will receive 0.9% saline in an otherwise identical procedure. Patients will be followed for 24 months. At 6 months, sham participants will be offered crossover to GAE. The primary endpoint is change of 4 Knee Injury and OA Outcome Score subscales (KOOS4) at 6 months post-randomisation. The study will also evaluate quality of life, health economics, imaging findings, and psychosocial pain outcomes. The primary manuscript will be submitted for publication after all participants complete 6 months of follow-up. The trial is expected to run for 3.5 years. Trial Registration: ClinicalTrials.gov, Identifier: NCT05423587.

Transcatheter embolisation in chronic musculoskeletal disorders

Chronic musculoskeletal conditions affect millions of patients worldwide resulting in disability, reduced quality of life, and have a profound economic impact on the individual and society. Current treatment strategies fail patients who have not responded to conservative management but are not surgical candidates. Over the last decade, transcatheter embolisation has emerged as a potential treatment for these difficult to treat patients. By exploiting pathological neovascularisation within conditions such as knee osteoarthritis, adhesive capsulitis, and tendinopathy, embolisation has been used to improve patients' pain and function. This review explores the rationale for musculoskeletal transcatheter embolisation, illustrating the technique, and latest evidence for the most common procedures.

Genicular Artery Embolization for Knee Osteoarthritis: A Comprehensive Review

» Genicular artery embolization (GAE) is a promising treatment option for patients with knee osteoarthritis who are unresponsive to nonsurgical treatments and not yet candidates for surgery.» Current evidence supports the effectiveness of GAE in reducing pain and synovitis, with few reported major adverse events.» The cost-effectiveness and long-term results of GAE compared with other treatment options require further investigation.» Limitations of existing studies include small sample sizes, single-center trials, and lack of comparison between embolic agents and other treatments.» Future research should focus on larger, multicenter trials with longer follow-up periods and head-to-head comparisons with alternative treatment modalities to establish the role of GAE in the management of knee osteoarthritis.

Short-Term Effects of Genicular Artery Embolization on Symptoms and Bone Marrow Abnormalities in Patients with Refractory Knee Osteoarthritis

PURPOSE

To evaluate the short-term outcomes of genicular artery embolization (GAE) for knee osteoarthritis (OA) with and without bone marrow lesion (BML) and/or subchondral insufficiency fracture of the knee (SIFK).

MATERIALS AND METHODS

This single-institution prospective observational pilot study analyzed 24 knees in 22 patients with mild to moderate knee OA, including 8 knees without BML, 13 knees with BML, and 3 knees with both BML and SIFK. The area and volume of BMLs on magnetic resonance images were measured before and after GAE. Baseline and postoperative pain and physical function were assessed using the visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

RESULTS

GAE significantly reduced the BML area and volume 3 months after embolization in the knees with BML (both P < .0005). GAE significantly decreased the VAS scores at 3 and 6 months after embolization in patients without BML (both P = .04) and those with BML (both P = .01). GAE also lowered the WOMAC scores 3 months after embolization in patients without and with BML (P = .02 and P = .0002, respectively). However, GAE did not significantly alter the BML area and volume (both P = .25), VAS scores (P = 1.00), and WOMAC scores (P = .08) in patients with BML and SIFK at 3 months after GAE.

CONCLUSIONS

This observational pilot study suggested that GAE effectively reduces the BML area and volume and improves pain and physical function in patients with knee OA accompanied by BML but is inefficacious in those with both BML and SIFK.

The short-to-midterm outcomes of geniculate artery embolization for mild-to-moderate osteoarthritis of the knee: a systematic review

Background

Geniculate Artery Embolization (GAE) is a novel, minimally-invasive treatment for mild to moderate Osteoarthritis (OA) associated with musculoskeletal pain.

Purpose

To investigate the outcomes of GAE in patients with mild to moderate OA of the knee using a Quantitative-analysis of the available literature.

Methods

The PubMed, EMBASE and Cochrane databases were searched for GAE-related studies. Qualitative and quantitative analyses were performed following PRISMA-guidelines. Quantitative-analysis was performed using windows based 'MedCalc-Statistical-Software version 19.6.1 (2020). Statistical analysis was performed in Stata-IC-13.1(Stata corp-USA). Quantitative-analysis was done using the random-effects model, and the Standardized-Mean-Differences (SMD) were calculated.

Results

After a full-text review, 13 studies with 399 knees (345-patients) were included in the qualitative synthesis, 10 were included in the quantitative synthesis. The total WOMAC score improved by a [SMD (95% CI)] of 3.46 points (1.27, 5.65), 3.50 (1.28, 5.71), 3.77 (0.58, 6.96), 5.46 (1.59, 9.33), 2.96 (-0.93, 6.85) compared to baseline at 1, 3, 6, 12, 24 months respectively. The VAS score improved by 2.06 (1.35, 2.76), 2.13 (1.39, 2.87), 2.36 (1.85, 2.90), 2.09 (0.91, 3.28) compared to baseline at 1, 3, 6, 12 months respectively. The Pain WOMAC score improved by SMD 2.97 (0.51, 5.43), 3.77 (0.58, 6.96), 2.27 (0.31, 4.22), 2.27 (0.31, 4.22) compared to baseline at 1, 3, 12, 24 months, respectively.

Conclusion

There was a statistically significant change from baseline in all outcome measures after GAE. GAE is a safe and effective method for pain control in mild to moderate OA-associated knee pain in the short and medium term.

Genicular Artery Embolization as a Treatment for Osteoarthritis Related Knee Pain: A Systematic Review and Meta-analysis

OBJECTIVE

Genicular artery embolization (GAE) is a minimally invasive therapy for symptomatic osteoarthritis (OA) in patients with knee pain refractory to conservative management. The purpose of this study was to evaluate evidence on the effectiveness of GAE for OA related knee pain as part of a systematic review and meta-analysis.

MATERIALS AND METHODS

Using Embase, PubMed, and Web of Science, a systematic review was performed to identify studies evaluating treatment of knee OA with GAE. The primary outcome measure was change in pain scale score at 6 months. A Hedge's g was computed as a measure of effect size, selecting Visual Analog Scale (VAS) first if available and Knee Injury and Osteoarthritis Outcome Score and Western Ontario and McMaster Universities Osteoarthritis Index if VAS was not available.

RESULTS

After screening titles, abstracts, and the full text, 10 studies met inclusion criteria. A total of 351 treated knees were included. Patients who underwent GAE demonstrated declines in VAS pain scores at 1 month {- 34 points [95% CI (- 43.8, - 24.6)], 3 months {- 30 points [95% CI (- 41.7, - 19.2)], 6 months {- 41 points [95% CI (- 54.0, - 27.2)], and 12 months {- 37 points [95% CI (- 55.0, - 18.1)]. Hedges' g from baseline to 1, 3, 6, and 12 months, was {- 1.3 [95% CI (- 1.6, - 0.97)]}, {- 1.2 [95% CI (- 1.54, - 0.84)]}, {- 1.4 [95% CI (- 2.1, - 0.8)]}, and {- 1.25 [95% CI (- 2.0, - 0.6)]}, respectively.

CONCLUSION

GAE provides durable reductions in pain scores for patients suffering with mild, moderate, and severe OA.

Classification of Genicular Artery Anatomic Variants Using Intraoperative Cone-Beam Computed Tomography

PURPOSE

Genicular artery embolization (GAE) is a new treatment option for symptomatic knee osteoarthritis. Genicular arterial anatomy is complex with limited published reports. This study describes the genicular artery anatomy utilizing intraprocedural cone-beam computed tomography (CBCT) during GAE.

MATERIALS AND METHODS

This retrospective single-center study was approved by the institutional review board. All patients who underwent GAE between May 2018 and April 2022 were reviewed. Patients with a technically adequate CBCT were included in the analysis. CBCTs were analyzed to determine the presence, course, and branching patterns of the genicular arteries.

RESULTS

A total of 222 patients underwent GAE and 205 (92%) were included for analysis. The descending genicular artery was present in 197 (96%) CBCTs with two branches in 152 (77%). The superior medial genicular artery (SMGA) was present in 186 (91%), superior lateral genicular artery (SLGA) in 203 (99%), inferior medial genicular artery (IMGA) in 195 (95%), inferior lateral genicular artery (ILGA) in 196 (95%), and median genicular artery (MGA) in 200 (97%). Four unique branching patterns were identified: common origin of SLGA and MGA (115, 56%), unique origins (45, 22%), trifurcation of SLGA, SMGA, and MGA (32, 15.5%), and common origin of SMGA and MGA (12, 6%). The recurrent ascending tibial was identified in 156 (76%) CBCTs and superior patellar artery in 175 (85%) CBCTs.

CONCLUSION

Genicular artery anatomy is complex with numerous common variants. CBCT is a powerful adjunct in GAE to rapidly identify target vessels for embolization and potentially decrease the risk of nontarget embolization.

Genicular Artery Embolization Technique

Genicular artery embolization (GAE) is a safe and effective treatment for knee pain related to osteoarthritis, however there are several aspects of the procedure technique which may be unique. Familiarity with procedural steps, arterial anatomy, embolic endpoints, technical challenges, and potential complications is imperative for good clinical practice and outcomes. The success of GAE depends on correctly interpreting angiographic findings and variable anatomy, navigating small and acutely angled arteries, recognizing collateral supply, and avoiding non-target embolization. The procedure can potentially be performed for a wide range of patients with knee osteoarthritis. When effective, pain relief can be durable for many years. When done meticulously, adverse events from GAE are uncommon.

Genicular Artery Embolization Data Review

Osteoarthritis of the knee poses an ever-expanding healthcare challenge worldwide. Current treatments include conservative methods such as weight loss, pharmacological treatments including NSAIDs, and surgical techniques including total knee arthroplasty. Although frequently successful, contraindications and failure of pharmacological agents leave many, especially with mild-moderate disease, without effective treatment. Genicular artery embolization is an interventional radiology technique being developed to fill this treatment gap. For this procedure to become established, the literature must provide evidence of its underlying scientific principles, safety, efficacy and economic viability. Pathological investigation of osteoarthritis reveals that low-level inflammation plays a crucial role in disease development. Joint inflammation stimulates neoangiogenesis and accompanying neuronal growth, with the degree of microvascular invasion being correlated with more severe pain in animal models. These neovessels provide a target for embolization however, the microscopic effects of this intervention are yet to be elucidated. The side effects of GAE have been extensively investigated with no severe adverse events being recorded. Skin discoloration and puncture site hematoma are the most common, occurring in 10%-65% and 0%-17% of patients respectively. The literature also discusses ways to minimize these events. Phase one studies provide promising evidence of efficacy, demonstrating an 80% improvement in Visual Analogue Scale (VAS) and a mean difference of 36.8 in Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores at 24-months. These positive signals are also supported by a single randomized control trial. A single study has been completed regarding the cost of GAE, however further work is needed. The GAE literature demonstrates a safe procedure with promising initial evidence of efficacy. Future work should further elucidate the pathology of osteoarthritis and ways in which embolization modifies this process, alongside providing further randomized control evidence that aligns with the recommendations from the National Institute for Health and Care Excellence. The future of GAE is exciting!

Role of geniculate artery embolization in the treatment of knee pain secondary to osteoarthritis

Background

Osteoarthritis (OA) is a leading cause of chronic knee pain and disability with a reported prevalence of 25–30% of the population. Knee OA has traditionally been thought as a degenerative disease only related to chronic repetitive injury “wear and tear” mechanism, yet it is now considered as a much more complex disease of inflammatory nature induced by cytokines and inflammatory mediators through abnormal neo-vascularization (angiogenesis). The rational of geniculate artery embolization (GAE) is based on the hypothesis that suggesting a direct relationship between the abnormal angiogenesis and the chronic knee pain. As a novel treatment option based on occlusion of these abnormal neo-vessels via geniculate artery embolization, we postulated that such a mechanism will relieve pain and improve the quality of life. GAE has been previously approved as a safe and effective treatment in cases of post-knee arthroplasty hemarthrosis.

Purpose

To evaluate the feasibility, safety, and efficacy of geniculate artery embolization for OA-related knee pain.

Materials and methods

Sixteen patients with knee pain secondary to chronic OA refractory to conservative therapies for at least 6 months and not yet fit for total knee replacement were enrolled in a prospective single arm interventional study. GAE was performed using 150–300 μm microspheres. Patients were assessed and followed up using the visual analogue scale (VAS) for pain and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for the overall knee function at baseline and at 1 week, 1, 3, and 6 months post-embolization.

Results

A total 16 patients presented by knee pain secondary to chronic OA were enrolled. All of them showed a remarkable improvement in the VAS and WOMAC scores, with better clinical outcome after GAE. Pre- versus post-embolization ± MDs in VAS score from 8.38 ± 0.81 (baseline) to 2.88 ± 1.54 after 6 months (post-embolization) equivalent to 66.66% improvement. There was also a satisfactory improvement in the WOMAC scores, with ± MDs drop from 77.94 ± 10.62 (baseline) to 49.69 ± 15.43 (post-embolization) equivalent to 37.41% improvement. No severe or life-threatening complications were reported.

Conclusions

GAE holds promise as an effective minimally invasive procedure for the treatment of knee pain secondary to OA and could be introduced as a safe technique with no serious complications.

Genicular artery embolization for treatment of knee osteoarthritis pain: Systematic review and meta-analysis

Objective

Genicular artery embolization (GAE) is a novel, minimally invasive procedure for treatment of knee osteoarthritis (OA). This meta-analysis investigated the safety and effectiveness of this procedure.

Design

Outcomes of this systematic review with meta-analysis were technical success, knee pain visual analog scale (VAS; 0-100 scale), WOMAC Total Score (0-100 scale), retreatment rate, and adverse events. Continuous outcomes were calculated as the weighted mean difference (WMD) versus baseline. Minimal clinically important difference (MCID) and substantial clinical benefit (SCB) rates were estimated in Monte Carlo simulations. Rates of total knee replacement and repeat GAE were calculated using life-table methods.

Results

In 10 groups (9 studies; 270 patients; 339 knees), GAE technical success was 99.7%. Over 12 months, the WMD ranged from -34 to -39 at each follow-up for VAS score and -28 to -34 for WOMAC Total score (all p ​< ​0.001). At 12 months, 78% met the MCID for VAS score; 92% met the MCID for WOMAC Total score, and 78% met the SCB for WOMAC Total score. Higher baseline knee pain severity was associated with greater improvements in knee pain. Over 2 years, 5.2% of patients underwent total knee replacement and 8.3% received repeat GAE. Adverse events were minor, with transient skin discoloration as the most common (11.6%).

Conclusions

Limited evidence suggests that GAE is a safe procedure that confers improvement in knee OA symptoms at established MCID thresholds. Patients with greater knee pain severity may be more responsive to GAE.

Two-year outcomes comparing Embosphere® microspheres versus Imipenem Cilastatin for genicular artery embolization in patients with moderate to severe knee osteoarthritis

BACKGROUND

Genicular artery embolization (GAE) is a novel technique and has the potential to provide midterm relief of pain for patients with mild-to-moderate knee osteoarthritis resistant to conservative management. This study compares the efficacy and safety of trisacryl gelatin microspheres to Imipenem/Cilastatin particles for GAE with 2 years of clinical follow-up.

METHODS

In this retrospective study, eight patients with knee osteoarthritis (11 knees) who underwent GAE with 100-300 μm trisacryl gelatin microspheres particles were compared with six patients (nine knees) who underwent GAE with Imipenem/Cilastatin particles. Clinical outcomes were evaluated at 3-month and 24-month follow-ups and compared to baseline using the WOMAC questionnaire.

RESULTS

The median follow-up was 796 days (range: 736-808). There were no significant differences in clinical outcome measures at the 3-month or 24-month follow-up. Both embolic materials resulted in a decrease in Pain WOMAC and Total WOMAC scores at 3 months (p < 0.05), and the effect of treatment on Pain WOMAC and Total WOMAC score reduction was sustained until the 24-month follow-up (p < 0.05). Minor events (Clavien-Dindo classification grade I) included transient cutaneous color change (n = 3) and transient leg numbness (n = 1) after embolization with trisacryl gelatin microspheres particles (p = 0.08). All minor adverse events resolved spontaneously. There were no major adverse events.

CONCLUSION

One hundred to three hundred μm trisacryl gelatin microspheres particles can be considered for genicular artery embolization and is comparable to Imipenem/Cilastatin particles in pain reduction of moderate to severe knee osteoarthritis. A sustained effect is observed for up to 2 years of follow-up.

Mechanism of action of genicular artery embolization in a rabbit model of knee osteoarthritis

OBJECTIVES

To establish a rabbit osteoarthritis model for genicular artery embolization (GAE) experiments and to investigate the cellular mechanism of action of this novel procedure for interventional radiologists.

METHODS

Rabbit knee osteoarthritis was surgically modeled by anterior cruciate ligament transection and medial partial meniscectomy of the bilateral hindlimbs followed by 10 weeks of incubation. Rabbits exhibiting synovitis on magnetic resonance imaging were randomly divided into two groups: the bilateral GAE group and the control (sham procedure) group. Four weeks later, the rabbits' mobility (moving time, sec/10 min) and the histopathological features of each knee were assessed, and inter-group differences were evaluated using Student's t-test and ordinal/linear logistic models with generalized estimating equations.

RESULTS

Osteoarthritis modeling and endovascular procedures were successful in 15 of 20 rabbits (8 and 7 in the GAE and control groups, respectively). There was no significant difference in moving times between the two groups (p = .958). The degree of structural cartilage damage was similar in both groups (p = .780). However, the synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) scores were significantly lower in the GAE group than in the control group. The CD3+ cell density (p = .018) and CD3 + cell-infiltrated area (p = .019) were also significantly lower in the GAE group than in the control group.

CONCLUSION

GAE can limit inflammatory processes in the synovium of osteoarthritis-affected knees.

KEY POINTS

Surgical transection of the anterior cruciate ligament and medial partial meniscectomy of rabbit knees provides a useful animal model for research of genicular artery embolization. Osteoarthritic knees treated by genicular artery embolization showed milder synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) than the untreated knees. Osteoarthritic knees treated by genicular artery embolization presented lower CD3+ cell density (p = .018) and CD3+ cell-infiltrated area (p = .019) in the synovium than the untreated knees.

Clinical Outcomes of Transarterial Embolization for Chronic Achilles Tendinopathy Refractory to Conservative Treatment: A Pilot Study

PURPOSE

To evaluate the effectiveness and safety of transarterial embolization (TAE) for chronic Achilles tendinopathy (AT) refractory to conservative treatment.

MATERIALS AND METHODS

This retrospective study included 20 patients (12 men and 8 women; mean age, 30.3 years) who received TAE using imipenem/cilastatin sodium for refractory chronic AT from May 2019 to April 2021. Nine patients had bilateral involvement. A total of 29 procedures were performed (8 for nonathletes and 21 for athletes). If feasible, embolization was performed superselectively of the arterial branch demonstrating hypervascularity, early venous drainage, and/or supplying the pain site noted using a radiopaque marker. The visual analog scale (VAS, 0-10) score was used to assess pain symptoms at baseline and during the follow-up period (1 day; 1 week; 1, 3, and 6 months; and open period). Clinical success was defined as a decrease of >50% in the VAS score at 6 months when compared with baseline.

RESULTS

In 25 (86.2%) of 29 procedures, clinical success was achieved. Significant decreases in the VAS scores were noted at 1 day, 1 week, 1 month, 3 months, and 6 months (6.86 at the baseline vs 3.48, 3.41, 3.10, 2.55, and 1.62, respectively; all P < .01). For patients available for the 12- and 24-month follow-ups (n = 19 and 6, respectively), the mean VAS scores significantly decreased (6.84 vs 2.00 and 7.33 vs 1.17, respectively; all P < .01). No serious adverse events were observed during follow-up.

CONCLUSIONS

TAE may alleviate pain for patients with chronic AT refractory to the conservative treatment with a low risk of adverse events.

Transcatheter Arterial Embolization for Alleviating Chronic Musculoskeletal Pain and Improving Physical Function: A Narrative Review

Chronic musculoskeletal pain imposes immense suffering and diminishes the quality of life for millions of patients worldwide; the pain persists despite the use of standard conservative treatments. Increases in our understanding of the pathophysiological mechanisms underlying musculoskeletal disorders indicate the involvement of inappropriate angiogenesis. Accordingly, the resulting neovessels are the target of emerging treatments for chronic musculoskeletal pain, including transarterial embolization. The use of this noninvasive procedure to treat pain refractory to standard therapy in a variety of musculoskeletal conditions is the focus of numerous recent investigations. Here, we describe the pathophysiological indications for the use of transarterial embolization and summarize the findings of studies investigating its use in a variety of histopathological conditions and anatomical sites.

Embolization of genicular arteries in patients with knee osteoarthritis as an alternative for refractory pain treatment: A systematic review

BACKGROUND

Genicular artery embolization emerges as an innovative technique described for the treatment of refractory pain in patients with knee osteoarthritis. This review summarizes the available data on the efficacy of genicular artery embolization in patients with knee osteoarthritis (OA) and refractory pain as an alternative treatment or associated with pharmacological treatment.

METHODS

Review according to PRISMA® standards on genicular artery embolization and knee osteoarthritis.

RESULTS

Thirteen publications out of a total of 63 studies reporting data from 914 patients were analyzed according to inclusion criteria. The indication of embolization was performed in patients with severe chronic pain refractory to conservative treatment and moderate-to-severe knee OA. Only minor complications have been reported.

CONCLUSION

Genicular artery embolization is a possible and potentially very effective alternative in the treatment of chronic refractory pain in patients with knee OA, without serious complications. All studies conclude in favor of embolization of the genicular arteries in the treatment of chronic refractory pain in patients with knee OA.

Interventional Therapies for Osteoarthritis: An Update

Osteoarthritis (OA) is one of the most common diseases worldwide and is expected to increase in incidence as the age of the general population rises. Both oral medications, such as NSAIDs, and surgical treatments used for OA management have limitations. Demand is rising for minimally invasive techniques such as intraarticular injections and percutaneous interventions for use in place of or in conjunction with oral medications and surgical therapies, and the past 2 decades have seen a rapid expanse in both pharmacologic and nonpharmacologic minimally invasive OA treatments. Image guidance with fluoroscopy, CT, or ultrasound is often used in conjunction with these procedures to achieve precise treatment localization to achieve maximal therapeutic effect. The choice of modality used for image guidance is often influenced by clinician experience, patient characteristics, and equipment availability. This article reviews the mechanisms of action, contraindications, complications, and efficacy of conventional and developing minimally invasive OA treatments. The minimally invasive treatment options described in this Review include therapeutic injections such as antiinflammatory agents, viscosupplements, and biologics, as well as nonpharmacologic treatments of subchondroplasty, nerve ablation, genicular artery embolization, intraarticular pulsed radiofrequency therapy, and MRI-guided focused ultrasound therapy.

Anatomical description and short-term follow up clinical results for ultrasound-guided injection of medial collateral ligament bursa: New conservative treatment option for symptomatic degenerative medial meniscus tear

BACKGROUND

In this study, we investigated newly developed ultrasound (US)-guided medial collateral ligament (MCL) bursa injection as a conservative therapy for symptomatic degenerative medial meniscal (MM) tears. We aimed to describe the anatomical target and precise technique of this injection, confirm its accuracy using fresh cadaveric knees, and then evaluate preliminary clinical outcomes.

METHODS

Anatomical studies were performed on three fresh cadavers. For the clinical study, 50 patients with medial knee joint pain without knee osteoarthritis were treated with US-guided MCL bursa injection. Severity of pain was assessed pre-injection, and 1 week and 4 weeks post-injection using a 0-10 numerical rating scale (NRS). Clinical success was defined as a full return to daily activities. All patients underwent magnetic resonance imaging (MRI) within 1 week of the first injection. Patients who underwent surgery within 12 months of the first injection were investigated as clinically unsuccessful cases, and MRI and arthroscopic findings were examined.

RESULTS

Compared with pre-injection (6.8 ± 1.2), the average NRS score was significantly lower at 1 week (1.8 ± 2.0) and at 4 weeks (1.5 ± 1.7) post-injection (both P < 0.01). The primary clinical success rate was 76.0%, and injection-related adverse events were not observed. Nine patients underwent surgery (arthroscopic surgery for degenerative flap tear (n = 7) and high tibial osteotomy for medial meniscus posterior root tear and proximal tibial malalignment (n = 2)).

CONCLUSIONS

US-guided MCL bursa injection is safe, reproducible, and effective for symptomatic MM degenerative tears. However, US-guided injections of the MCL bursa may be ineffective for flap tears and posterior root tears.

The efficacy of transcatheter arterial embolization for knee pain on patients with knee osteoarthritis: A case series

BACKGROUND

Knee osteoarthritis (OA) is accompanied by inflammation and angiogenesis. Modifying angiogenesis through transcatheter arterial embolization (TAE) can be a potential treatment for knee OA.

OBJECTIVE

We subjected five OA knees in three patients to TAE and report the results of our post-treatment observations.

CASE DESCRIPTION

Three patients that had experienced knee pain for a minimum of one year prior to the study, and whose pain had persisted despite conservative treatment, were included in this study. Patients more often chose conservative treatment over surgical treatment. Pain and functional scales were evaluated before, immediately, and 1 month after TAE using the Numeric Rating Scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). TAE was performed by an experienced interventional radiologist. The average values of NRS evaluated before and after 5 TAEs were 5.2 before TAE, 3 immediately after TAE, and 3.6 after 1 month of TAE, and the average values of WOMAC were 52, 38.4, and 36.4, respectively. There were no major adverse effects.

CONCLUSION

The examined cases support the conclusion that TAE is an effective treatment for patients with knee OA. Substantial pain relief and WOMAC improvement were observed both immediately and one month after TAE.

Emerging Targets for the Treatment of Osteoarthritis: New Investigational Methods to Identify Neo-Vessels as Possible Targets for Embolization

Osteoarthritis (OA) is the major cause of disability, affecting over 30 million US adults. Continued research into the role of neovascularization and inflammation related to osteoarthritis in large-animal models and human clinical trials is paramount. Recent literature on the pathogenetic model of OA has refocused on low-level inflammation, resulting in joint remodeling. As a result, this has redirected osteoarthritis research toward limiting or treating joint changes associated with persistent synovitis. The overall goal of this review is to better understand the cellular and tissue-specific mechanisms of inflammation in relation to a novel OA treatment modality, Genicular Artery Embolization (GAE). This article also assesses the utility and mechanism of periarticular neovascular embolization for the treatment of OA with a particular emphasis on the balance between pro-angiogenic and anti-angiogenic cytokines, inflammatory biomarkers, and imaging changes.

Assessing the Effects of Geniculate Artery Embolization in a Non-Surgical Animal Model of Osteoarthritis

PURPOSE

To create a non-surgical animal model of osteoarthritis (OA) to evaluate effects of embolotherapy during geniculate artery embolization.

MATERIALS AND METHODS

Fluoroscopy-guided injections of 700mg Sodium-Monoiodoacetate were made into the left stifle in 6 rams. Kinematic data were collected pre/post-induction. 10-weeks post-induction, subjects 1, 4-6 underwent MRI with dynamic contrast enhancement (DCE-MRI), and angiography (subjects 1, 3, 4-6) with angiographic scoring to identify regions with greatest disease severity for superselective embolization (75-250μm microspheres, subjects 1, 3, 4, and 6). Target vessel size was measured. 24-weeks after angiography, DCE-MRI, angiography, and euthanasia were performed and bilateral stifles harvested. Medial/lateral tibial and femoral condyles, patella and synovium samples were cut, preserved, decalcified, and scored with OARSI criteria. Stifle and synovium WORMS and MOST scores were obtained. Ktrans and extracellular volume fraction (ve) were calculated from DCE-MRI along lateral synovial regions of interest.

RESULTS

Mean gross/microscopic pathological scores were elevated at 38/61. Mean synovitis score was elevated at 9.2. Mean pre/post-embolization angiographic scores were 5/3.8, respectively. Mean Superior/Transverse/Inferior Geniculate artery diameters(mm) were 3.1±1.21, 2.0±0.50, and 1.6±0.41. Mean Pre/post-embolization cartilage/synovitis scores were elevated at 35.13/73.3 and 5.5/9.2, respectively. Subjects 4-6 K_trans/v_e values were elevated at 0.049/0.38, 0.074/0.53, and 0.065/0.51. Altered gait of the hind limb was observed in all subjects post-induction, with reduced joint mobility. No skin or osteonecrosis were observed.

CONCLUSION

A non-surgical ovine animal knee OA model was created which allowed the collection of angiographic, histopathological, MRI and kinematic data were obtained to study the effects of geniculate artery embolization.