Interventional Procedures For Knee Pain

We offer interventional treatments for knee pain. Here is some research on the benefits of minimally invasive treatments.

A Joint Resolution

By Keith Loria

Radiology Today

Vol. 23 No. 2 P. 14

New Interventional Procedures Improve Quality of Life in Patients Suffering From Knee Arthritis

Knee arthritis is a considerable problem. Patients who suffer from it often progress to a severe form of the condition and experience intense pain and lack of mobility. Thankfully, there have been some noteworthy knee treatments in IR of late; these can help alleviate the pain and improve mobility.

“Interventional radiology is a specialty that has always pushed the boundaries and methods for minimally invasive techniques, including the treatment of chronic pain,” says David Hahn, MD, head of medical affairs, interventional solutions for Varian, a Siemens Healthineers Company. “This has been an important area of focus due to the World Health Organization’s recommendation for minimally invasive techniques for chronic pain in response to the opioid epidemic.”

Recently, interventional radiologists have been treating patients with chronic pain from symptomatic knee osteoarthritis (OA).

“OA is the most common form of arthritis, affecting more than 30 million people in the United States alone, and is a condition characterized by inflammation of the synovium, or the capsule surrounding the knee joint, caused by the breakdown of cartilage,” Hahn says. “This cyclic chronic condition worsens over time, causing pain that decreases mobility, impacting a patient’s activities of daily living as well as their overall health status and quality of life.”

In addition, according to the Centers for Disease Control and Prevention, total national arthritis-attributable lost wages in 2013 alone were $164 billion, so this condition impacts the livelihood of a huge number of patients.

Genicular Artery Embolization

“There is a sudden interest in treating people with chronic musculoskeletal conditions such as arthritis, because we have found new therapies,” says Siddharth A. Padia, MD, FSIR, a professor of radiology at UCLA Health. “This field had not had any new treatments available in several years. As of 2021, however, we’ve seen a significant interest toward knee arthritis via a new procedure called genicular artery embolization [GAE].”

Padia notes that GAE reduces inflammation in the knee to improve function and quality of life for people with moderate to severe knee pain. GAE is “a minimally invasive procedure consisting of an angiogram with embolization of one or more genicular arteries in the knee,” Padia says. “The concept is to reduce the synovial inflammation in the knee joint, which thereby reduces people’s pain.”

It’s an outpatient procedure, he says, with improvement that typically takes about a month.

Padia and his colleagues recently ran a GAE clinical study looking at a nonsurgical treatment for arthritis in the knee; it provided immediate and long-term pain relief.

In the study, which was published in the open access Journal of Bone and Joint Surgery, he found that at 12 months after the procedure, 68% of subjects continued to have marked improvement in their pain.

For instance, his first patient on the clinical trial was a woman who couldn’t walk half a mile without experiencing severe pain and had difficulty walking down a flight of stairs. She had taken oral medications with minimal benefit and then undergone joint injections with steroids; this, too, was no longer helping.

“She was actively working and couldn’t take the time off for the surgery and recuperation of a total arthroplasty,” Padia says. After getting the GAE—which was completely painless—the patient reported that after three months, she was able to walk six miles per day without pain or medications.

GAE has been a hot IR topic in peer-reviewed literature since Yuji Okuno, MD, PhD, and his colleagues at Edogawa Hospital in Tokyo first reported on the technique in 2015. Since these initial data were published, investigators around the world have been working to lay the foundation for regulatory authorization for this novel therapy, including focusing on patient selection and correct techniques.

In October 2021, Varian received FDA Breakthrough Device Designation for its Embozene microspheres for GAE for symptomatic knee OA.

“While the Breakthrough designation does not mean that Embozene is authorized to be used for OA, it does mean that, for a Breakthrough device, FDA will expedite the traditional review and assessment process to help accelerate the development, assessment, and review of the device for possible marketing authorization,” says Kate Pietrovito, senior director of medical affairs for Varian. “Varian also will be pursuing a clinical study to further demonstrate the use of GAE in OA of the knee and support marketing authorization in jurisdictions where clinical studies may be needed.”

Hahn notes that interventional radiologists have been performing GAE for hemarthrosis post–total knee arthroscopy, with the first case report published in 2003.

“While the cause of the debilitating symptoms of knee hemarthroses and knee OA are different, the treatment of embolizing the genicular arteries is the same, as they both require identifying the genicular artery causing the bleeding or inflammation,” Hahn says. “Several studies have found GAE to be successful for OA with the proper training on device selection and endpoint, with most complications considered mild and self-limiting.”

Hahn explains that one of the main contributors to chronic OA pain lies in the chronic inflammation and formation of new blood vessels within the synovium of the knee. This process contributes to the ongoing cycle of destruction of bone and cartilage around the knee.

“GAE is a minimally invasive technique in which a tiny catheter is advanced into the genicular arteries, which are the tiny blood vessels that supply the knee joint,” he says. “Once in place, small spherical particles known as embolic microspheres are injected through the catheter to reduce the blood supply to the areas of greatest inflammation. This quickly reduces the swelling of the joint capsule and alleviates pain.”

The entire procedure is performed in a few hours, without general anesthesia in most cases.

“Like most treatments, the properly selected patient will benefit most,” Pietrovito says. “The most recent guidelines on treating OA from the American Academy of Orthopedic Surgeons recommend first-line therapy consisting of low-impact exercise and limb strengthening, weight loss, and the use of NSAIDs or tramadol to help reduce inflammation and pain. However, when these conservative measures fail and the patient is either high risk for surgery or wishes to avoid it, GAE may be a viable alternative.”

In general, the most common candidates are adults older than 40 with moderate to severe OA pain, who have both failed conservative therapy (ie, medications and joint injections) and are either considered high risk for surgery or have refused surgery.

Padia adds that those who are not candidates for total knee replacement surgery, or who don’t wish to undergo such a procedure, are also good candidates for GAE.

Cooled Radiofrequency Ablation

Felix M. Gonzalez, MD, clinical site director of the musculoskeletal division at Georgia’s Emory University Hospital, notes when looking specifically at knee arthritis, a treatment with the prospect to become a frontline treatment modality is cooled radiofrequency ablation (c-RFA).

In this procedure, a probe is guided through the introducers and the tip of the probe imparts a low-voltage current (radiofrequency) to the deep sensory nerves around the knee.

“This technology imparts a low-voltage current into the genicular nerves—the main sensory nerves around the knee—slowing down the transmission of pain signals through them,” Gonzalez says.

Water circulating through the system allows for a greater dissipation of heat from the tip of the probe.

“c-RFA provides a mechanism to perform a minimally invasive procedure without a long period of postprocedural recovery, allowing the patient to experience pain relief improving their quality of life,” Gonzalez says.

Gonzalez presented a study on the attributes of c-RFA at 2021’s RSNA conference. In his presentation, Gonzalez noted that 15% to 30% of people who get a knee replacement continue to experience pain and stiffness in the knee, and while they can opt for another surgery, there is no guarantee that the pain will not return.

“A lot of patients don’t achieve any resolution of pain,” he says. “It’s a big problem, and up until now, there weren’t any other options.”

In previous studies, Gonzalez’s team revealed that c-RFA provides lasting pain relief for people with knee, shoulder, and hip arthritis.

His new study, focusing exclusively on the knee, looked at 21 patients experiencing persistent chronic pain after total knee replacement, without underlying hardware complications. All 21 had previously failed conservative care. They filled out clinically validated questionnaires to assess pain severity, stiffness, functional activities of daily living, and use of pain medication before and after the procedure. Follow-up outcome scores were collected up to one year after the c-RFA procedure.

“Our results showed that the patients experienced, on average, a statistically significant improvement in quality of life,” Gonzalez says. “Both pain and stiffness scores improved dramatically. No major complications were encountered, and no patients required repeat treatment, surgical revision, or other intervention.”

Patients with moderate to severe arthritis who have failed conservative measures such as anesthetic-corticosteroid injections, physical therapy, and weight loss and are still experiencing knee pain are the best candidates for this procedure. As it’s minimally invasive, the procedure can be repeated and can also reduce or eliminate the use of opioid pain relievers, which carry significant risks associated with dependency. Gonzalez notes that this procedure is a way to offer pain relief to those patients that continue having pain after their surgeries.

“Our study showed that the patients experienced significant reduction of pain and stiffness and dramatic improvement in quality of life,” he says. “The hope is that in that period of time, the patient can become more mobile and increase their activity. Even if pain comes back, we predict that it won’t come back with the same intensity as before.”

Looking Ahead

Studies continue and there’s great optimism that solutions such as this will help millions of people in the years to come.

“As an organization, we believe that new, innovative treatment options that support patients in their activities of daily living can have tremendous overall impact on patient lives,” Hahn says. “We are proud to support further clinical investigations in this area; we are excited about addressing the important scientific questions on the role of GAE in treating knee OA and expanding the availability of this treatment for patients by securing regulatory marketing authorizations.”

— Keith Loria is a freelance writer based in Oakton, Virginia. He is a regular contributor to Radiology Today.

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