Injections of Tiny Particles Reduce Osteoarthritis Knee Pain
/By Pat Anson, PNN Editor
A minimally invasive procedure significantly reduces pain and inflammation caused by knee osteoarthritis, according to preliminary research being presented this week at the annual meeting of the Society of Interventional Radiology.
Geniculate artery embolization (GAE) is a relatively new procedure in which thousands of microscopic particles are injected into arthritic knees. The particles reduce inflammation by disrupting the abnormal flow of blood caused by osteoarthritis (OA), a joint disorder that causes thinning of cartilage and progressive joint damage. As the cartilage breaks down, it releases enzymes that cause inflammation and pain.
GAE takes about one to two hours, and many patients with knee OA report significant improvement in pain and physical function that can last up to a year.
"Prior to treatment, patients' knee pain had taken over their whole life," said lead researcher Siddharth Padia, MD, a professor of radiology at UCLA Health. "But after treatment, patients who initially could walk only three or four blocks were walking three miles. Some were able to do away with walking aids, such as canes, while others reported being in a better mood now that they were living without pain."
For their Phase 2 study, Padia and his colleagues enrolled 40 patients with knee OA who were not candidates for total knee replacement, and who failed to benefit from pain relievers, joint injections and physical therapy.
Catheters were inserted into arteries leading to the knees through pinhole incisions in the patients’ hips. The microscopic particles — called Embozene microspheres — were then slowly injected through the catheter into the knees. Each patient was evaluated for pain and adverse events at one week; one, three and six months; and one year after the treatment.
Researchers say patients saw benefits as soon as three days after the procedure. Average pain levels decreased from 8 out of 10 before GAE to 3 out of 10 within the first week. Most patients reported more than 50% reduction in their pain levels at the one-year follow up.
Adverse events, such as skin ulceration and small bone infarction – the death of bone tissue due to reduced blood supply -- were reported by 9 patients, but resolved without treatment.
Embozene microspheres are made by Boston Scientific and are currently used in the treatment of vascular tumors, uterine fibroids and arterial malformations. They must be carefully injected into affected tissue to prevent them from circulating in the blood and reaching healthy tissue and organs.
“This prospective trial demonstrates that GAE is highly effective and durable in reducing symptoms due to moderate to severe knee OA that is refractory to other conservative therapy, and has an acceptably low toxicity profile,” researchers concluded.
The UCLA researchers plan to conduct a larger, randomized trial to determine which patients may benefit most from GAE and the impact it has on slowing the progression of arthritis.
Results from other studies on the use of GAE are also being presented at the meeting of the Society of Interventional Radiology. One review found that GAE can be effective for patients who don't respond well to conservative treatments for knee OA, but cautioned that “definitive conclusions can't be made on the true efficacy of GAE until studies are done with longer follow up and larger patient numbers.”
