Cooled RFA Treats Chronic Pain After Knee Replacement

Cooled radiofrequency ablation treats chronic pain and stiffness in patients who have undergone knee replacement, according to findings from a pilot study presented at the Radiological Society of North America (RSNA) 2021 Annual Meeting this week.

Dr Felix Gonzalez

"It's a very convenient procedure of low risk that offers a lot as an alternative to treat pain after surgical replacement of the knee," study author Felix Gonzalez, MD, an assistant professor in the Department of Radiology at the Emory University School of Medicine in Atlanta, told Medscape Medical News.

Total knee replacement surgery is one of the most common bone surgeries, with more than 600,000 procedures conducted every year in the United States. But while many patients experience improved mobility and quality of life, up to 20% of patients report chronic knee pain after the surgery without underlying hardware complications, said Gonzalez.

"The pain can be so limiting and so excruciating that the patient may actually end up being physically limited to the same degree or even worse than before they had surgery," he said. For this population, pain management is mostly limited to cortical injections or daily pain medication, he added.

But a minimally invasive ablation procedure could offer relief to some of these patients. In a previous study of 23 patients, Gonzalez found that cooled radiofrequency ablation (CRFA) effectively treated hip and shoulder arthritis pain. In the procedure, the physician uses a small needle to deliver low-voltage currents to heat up and damage pain-causing nerves without affecting the surrounding tissue. The procedure is also used as a treatment for patients with knee osteoarthritis.

In this new study, prospective study participants were first given an anesthetic to block the genicular nerve branches. Patients were then asked to rank their pain relief on a scale of 1 to 10, and those who reported at least a 50% reduction in pain were then included in the study. Two to 3 weeks later, the nerves were treated with CRFA in a 45- to 60-minute session. The study included 21 patients with an average age of 70.5 years. Gonzalez and colleagues performed all procedures between April 2019 and January 2020 and recorded follow-up outcomes for up to a year after the procedure.

Patients reported improvement in the Knee injury and Osteoarthritis Outcome Score from a baseline of 36.2 to 61.9 (P < .0001) at an average of 10.2 months after treatment. Patients also reported improvements in the mean pain score from 36.5 before treatment to 72.45 at follow-up (P < .0001) and mean stiffness score from 47 to 68.5 (P < .0001).

Dr Leonardo Kapural

While this procedure has been available for about a decade, the study "confirms again that cooled radiofrequency ablation can successfully be used for patients who underwent previous knee replacement surgery," said Leonardo Kapural, MD, PhD, a pain medicine specialist at the Carolinas Pain Institute in Winston-Salem, North Carolina, in an interview with Medscape. He was not involved with the study. "We've had several case series now — including this one — where we could see improvements not only in pain scores but also functional capacity."

Dr Jonathan Kirschner

"I personally see [the therapy] as the 'gold standard' " for treating chronic pain in patients who underwent knee replacement surgery, added Jonathan Kirschner, MD, RMSK, a physiatrist at the Hospital for Special Surgery in New York City who is also unaffiliated with the work. But more research is necessary to increase awareness about the procedure, he noted.

Kirschner is currently conducting a prospective study looking at how long pain relief lasts after the procedure and which patients respond better to CRFA.

"Historically, the only options we had were drugs and medications to treat the pain," he said. "This is unique and novel way of treating it without drugs."

Kapural consults for Avanos and Medtronic. Gonzalez and Kirschner report no relevant financial relationships.

Radiological Society of North America (RSNA) 2021 Annual Meeting.

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