Knee OA Next Market for Interventional Radiologists?

A new study highlighted at the March 20-26, 2021 Annual Scientific Meeting of the Society of Interventional Radiology may mark the entry of Interventional Radiologists into the massive knee OA treatment market. A new outpatient, minimally invasive procedure, genicular artery embolization (GAE), was tested in a small, 40-patient study and, it appears, has the potential to compete effectively with current standard of care treatments for patients with moderate to severe knee OA.

The study (“Genicular Artery Embolization for the Treatment of Knee Osteoarthritis: Final Results from a Prospective Investigational Device Exemption Trial”), the largest to date in the U.S. to evaluate the safety and efficacy of genicular artery embolization for the treatment of knee OA, was performed at the University of California, Los Angeles (UCLA) and led by UCLA radiology professor, Siddharth A. Padia, M.D., F.S.I.R.

OA has traditionally been thought of as a “wear and tear” disease and a common result of the aging process. Looking deeper into the biology of OA, numerous researchers have described OA in terms of a low-grade inflammatory disease of the synovial joints.

If the blood supply to the nerves that cause knee pain was somehow occluded, could pain be safely and effectively reduced?

Using Boston Scientific’s product Embozene, which has been used to treat hypervascular tumors and arteriovenous malformations by occluding blood flow with thousands of microscopic spheres, a team of interventional radiologists decided to test it as a treatment for moderate to severe knee osteoarthritis.

Like most interventional radiology procedures, genicular artery embolization is an outpatient procedure and takes about two hours. Using an angiogram to assess level of blood flow to the knee and, presumably, the level of inflammation in the knee, the interventional radiologist sedates the entry site with a numbing anesthetic given at the fold of the leg. The radiologist then insert a catheter and maneuvers via the genicular artery (1-2mm diameter) to a particular spot near the knee joint where inflammation appears to be most prominent. Under angiogram visualization, the radiologist then injects Embozene particles to slow blood flow to the inflamed and/or painful area.

Did it work? How safe was it?

Dr. Padia and his team enrolled 40 patients (treated over 9 months), all of whom had failed conservative treatment but were NOT considered candidates for total knee replacement. Following genicular artery embolism, the investigators reported patient pain scores had decreased and within the first week—from 8 out of 10 before treatment to 3 out of 10 post-treatment.

At one year follow-up, seven in 10 patients reported more than 50% reduction in pain scores. Ten patients experienced minor adverse events, such as transient skin discoloration and small bone infarct, that resolved without treatment within days.

“Prior to treatment, patients’ knee pain had taken over their whole life,” said Dr. Padia, lead researcher of the study. “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.”

OTW asked Dr. Padia to explain what makes the genicular artery embolism so apparently effective, Dr. Padia explained, “The key advantage of GAE and what separates it from other procedures, is that it is minimally invasive, patients can resume their normal activities immediately, and it has minimal side effects.”

“When it does work, the pain reduction and functional improvement is significant. The results after a single procedure are effective for at least 1-2 years (and possibly longer). In addition, undergoing GAE does not prevent future treatment (such as knee replacement).

As for what Dr. Padia envisions over the next 12 months, he told OTW, “We will continue to refine the technique and learn about which patients benefit most from this procedure. Randomized trials will likely begin in the U.S. (here at UCLA) and the UK in late 2021.”