Genicular artery embolization (GAE) has moved from experimental concept to a procedure backed by a growing body of randomized, controlled, and prospective clinical evidence. But the field is evolving rapidly, with new trial results published regularly and several important studies still recruiting.
For patients considering GAE—and for physicians evaluating it—this article summarizes the current state of the clinical evidence as of 2026, including what we know, what we’re still learning, and what the next generation of trials will tell us.
The Foundation: Sham-Controlled Randomized Trials
Sham-controlled RCTs are the gold standard of clinical evidence because they control for the placebo effect—the well-documented phenomenon in which patients improve simply because they believe they received treatment. Three sham-controlled RCTs have been published for GAE to date.
Bagla et al. (JVIR, 2022) — The First Sham-Controlled RCT. This multicenter, single-blinded RCT enrolled 21 patients with mild-to-moderate knee OA (KL grade 2–3) and randomized them 2:1 to GAE or sham. At one month, the GAE group showed a dramatic reduction in VAS pain scores compared to sham (−50.8 vs. −0.5). This was the first study to demonstrate that GAE’s pain relief exceeds the placebo effect—a critical milestone for any new treatment. The trial was conducted under an FDA Investigational Device Exemption (NCT03362957).
Bagla et al. (Ann Rheum Dis, 2024) — The GEM-2 Trial. This expanded multicenter sham-controlled trial enrolled additional patients and provided further data on GAE’s efficacy. Early results continued to support GAE’s benefit over sham, with responder analyses showing clinically meaningful improvement in the active treatment group.
Rotterdam RCT (2024). A 58-patient RCT from the Netherlands did not establish a clear clinical benefit of GAE over sham at four months in patients with mild-to-moderate OA. The investigators noted, however, that their embolization protocol evolved during the study—beginning with single-vessel treatment before transitioning to the multi-vessel approach now considered standard. This protocol heterogeneity may have affected outcomes.
The meta-analysis of all three sham-controlled RCTs (138 total patients, published 2025) concluded that GAE demonstrated short-term pain reduction, particularly at one month, but that longer follow-up and larger studies are needed to confirm durability.
What this means: The sham-controlled data confirms that GAE produces real pain relief beyond placebo, particularly at the one-month mark. The question of long-term durability is being addressed by prospective trials with extended follow-up.
Prospective Trials: Longer Follow-Up, Larger Cohorts
NYU Prospective Biomarker Trial (JVIR/ScienceDirect, 2025). This single-arm prospective trial of 25 patients treated with 250-μm permanent microspheres delivered some of the most compelling data to date: 55.4% reduction in VAS pain scores at 12 months (P < .001), 43.7% improvement in WOMAC pain scores, 62% clinical success rate (clinically meaningful WOMAC pain improvement), and statistically significant decreases in serum VEGF and IL-1Ra—providing biological evidence that GAE reduces the molecular drivers of inflammation, not just symptoms.
This biomarker component is scientifically significant. It provides a mechanistic explanation for GAE’s effect: by blocking abnormal blood vessels, the procedure reduces the vascular endothelial growth factor (VEGF) that drives neovascularity and the inflammatory cytokines that drive pain.
UCLA 2-Year IDE Trial (JVIR, 2024). This prospective trial of 40 patients with moderate-to-severe OA examined outcomes through 24 months—the longest prospective follow-up published for GAE. At 12 months, 67.5% achieved clinical success. At 24 months, 72% of initial responders maintained their improvement. No new treatment-related adverse events occurred after the first year, confirming a favorable long-term safety profile.
The GENESIS UK Trial (Cardiovasc Intervent Radiol, 2024). This UK-based trial provided additional long-term data using permanent microspheres, with outcomes consistent with the UCLA results.
Meta-Analysis: The Aggregate Picture
The most comprehensive meta-analysis of GAE (2023) aggregated data from 9 studies covering 270 patients (339 knees). Key findings include statistically significant and clinically meaningful reductions in both VAS and WOMAC scores at every follow-up interval through 12 months, a 99.7% technical success rate, only 5.2% of patients requiring total knee replacement over two years of follow-up, and adverse events that were typically minor and transient—most commonly temporary skin discoloration (11.6%).
Emerging Research: Post-TKA Pain
An exciting frontier for GAE is its application in patients with persistent pain after knee replacement. Two independent studies have shown dramatic pain reduction in post-TKA patients: a 2023 pilot study (n=12) showed VAS improvement from 73 to 38 at six months, and a 2025 cohort (n=15) showed median NRS dropping from 7.0 to 1.0 at one month, sustained through 12 months. Larger trials in this population are anticipated.
What’s Still Being Studied
The GAE evidence base is strong for a procedure at this stage of development, but several important questions remain: Optimal particle size and type. Studies have used 75-μm, 100-μm, and 250-μm microspheres. Head-to-head comparisons are needed to determine the optimal embolic agent. Predictors of response. Not every patient responds equally to GAE. Research is underway to identify imaging, biomarker, and clinical predictors that can better select patients most likely to benefit. Durability beyond 2 years. The UCLA trial provides 24-month data; longer follow-up will be important for understanding the full duration of GAE’s effect and the rate at which patients ultimately progress to knee replacement. Comparison to other bridge treatments. No published RCT directly compares GAE to cortisone injections, PRP, or genicular nerve ablation. Such trials would help position GAE within the broader treatment algorithm.
What This Means for Patients
The clinical trial evidence for GAE has reached a level of maturity that supports informed clinical decision-making. GAE is not experimental—it’s a procedure with multiple published prospective trials, sham-controlled RCTs confirming superiority over placebo, and a consistent safety profile across hundreds of treated patients.
At the same time, the evidence is still evolving. Larger trials are in progress, optimal protocols are being refined, and long-term data continues to accumulate. This is a transparent assessment, not a hedge: GAE works for appropriately selected patients, and the data supporting it is growing stronger with each publication cycle.
Frequently Asked Questions
GAE at SACMD
Dr. Albert Chun performs GAE at Surgical Associates for patients across Maryland, DC, and Northern Virginia. If you’re interested in learning whether your knee pain could benefit from this evidence-based, minimally invasive approach, take our self-assessment checklist or schedule a consultation directly.
Schedule a consultation: Call (240) 427-1630 or visit www.sacmd.com
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Clinical trial results represent group-level data; individual outcomes may vary.
References:
- Bagla S, et al. Multicenter Randomized Sham Controlled Study of GAE. JVIR. 2022;33(1):2-10.
- Taslakian B, et al. Prospective Single-Arm Trial of GAE: Clinical and Biomarker Outcomes. JVIR. 2025.
- Cusumano LR, et al. GAE for Symptomatic Knee OA: 2-Year Outcomes. JVIR. 2024;35(12):1768-1775.
- Little MW, et al. GENESIS Trial: Long-Term Results. Cardiovasc Intervent Radiol. 2024.
- Systematic review and meta-analysis of GAE for knee OA pain. 2023.
- Systematic review of sham-controlled GAE RCTs. 2025.
- Post-TKA GAE pilot study. 2023.
- Post-TKA GAE 12-month cohort. 2025.
