Midterm Clinical Outcomes and MR Imaging Changes after Transcatheter Arterial Embolization as a Treatment for Mild to Moderate Radiographic Knee Osteoarthritis Resistant to Conservative Treatment
Osteoarthritis (OA) is a common and debilitating condition that leads to decreased functional status and quality of life in the affected population. Low grade inflammation with associated angiogenesis is now recognized as part of the etiopathophysiology of OA symptoms. Okuno et al. present a prospective, single-center observational study on outcomes following transcatheter arterial embolization for mild-to-moderate knee osteoarthritis. 95 knees in 72 patients with symptoms resistant to conservative therapy, of median duration 30 months, were included. All patients with osteonecrosis, local infection, malignancy, rheumatoid arthritis, and previous knee surgery were excluded. The embolization procedures were performed using antegrade femoral artery access, with a 3-French catheter to select the popliteal artery. Additional selective arteriography was performed with a 1.7-French catheter if needed. Abnormal vessels were identified from a mean of 3.2 arteries per knee. Embolization was performed with imipenem and cilastatin sodium in the majority of patients and 75 um Embozene in the minority of patients with hypersensitivity to the antibiotics. Embolization endpoint was suppression or reduction of filling of the abnormal popliteal vasculature and reduction in local tenderness by palpation. The authors state that patients described pain, itching, or heat sensation at the site of symptoms when the culprit vessel was embolized. All cases were technically successful. The most common adverse events were puncture site bleeding in 12 patients and transient cutaneous color changes in 4/7 patients treated with Embozene, with no major adverse events. At all follow-up time points, there were significant reductions in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores compared to baseline (mean 12.1 at baseline versus 6.2, 4.4, 3.7, 3.0, and 2.6 at 1, 4, 6, 12, and 24 months, respectively; all P< .001). There was no difference in clinical outcomes between embolization with imipenem and cilastatin sodium and Embozene. Magnetic resonance imaging follow-up in 35 knees of 29 patients at 2 years showed decrease in synovitis, with no osteonecrosis or other evidence of aggressive progression in degenerative OA changes.
Figure. Angiographic findings before and after transcatheter arterial microembolization in a 69-year-old patient treated with imipenem and cilastatin. (a) Selective arteriography from the descending genicular artery before embolization showing abnormal neovessels (arrow) adjacent to the medial condyle (MC). (LC ¼ lateral condyle.) (b) Post-embolization arteriography demonstrating elimination of hypervascularity.
Although joint replacement is an effective management of severe OA, conservative treatment is used for most patients with mild-to-moderate OA. Many of these patients struggle with symptom control and new therapies could have an impactful role in improving quality of life and functional mobility. The recognition that synovitis and associated neovascularity underlie OA symptoms has raised interest of transcatheter embolization for symptomatic OA. At this nascent stage in investigation of this therapy, this study from Okuno et al. provides an important groundwork by delineating the technical approach, confirming a favorable safety profile, and demonstrating promising midterm clinical and imaging follow-up results. No patients in this study had any ischemic complications, including osteonecrosis, and did not have significant progression of OA from the decreased pain and increased mobility and joint loading. The authors also used a small volume of embolic material to reduce the risk of embolization-associated inflammation which could theoretically contribute to short-term worsening of joint inflammation. This study was limited by the lack of a control group and blinding and additional studies are certainly needed to validate efficacy and safety. Nonetheless, this work provides a promising foundation for subsequent studies into transcatheter embolization as a novel treatment approach for symptomatic OA.
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Jeffrey Forris Beecham Chick, MD, MPH, DABR
Assistant Professor of Vascular and Interventional Radiology
Vice Quality Assurance and Safety Officer
Venous Health Program Faculty
University of Michigan Health System
James X. Chen, MD
Resident in Radiology
Hospital of the University of Pennsylvania