Harvard Health Ad Watch: A new treatment for knee arthritis

The TV ad promises pain relief for knee osteoarthritis, the source of most of the 600,000 knee replacement surgeries performed in the US each year. A man in a bowling alley winces with pain. He nearly falls as he rolls a ball into the gutter. (Did I mention the arrow sticking out of his knee?)

"Knee acting up again?" asks his buddy, clearly concerned. When pain pills don't seem to help, his buddy suggests a procedure called Coolief for knee osteoarthritis.

"I had it done six months ago," says the bowling buddy. "And the best part is that it lasts up to one year."

What is Coolief?

Coolief is a procedure, not a pill. A doctor inserts electrodes through the skin, placing them near nerves in several locations around the knee. Electric current applied through the electrodes delivers heat to the nerve. This impairs its ability to send pain signals to the brain.

Standard nerve blocks use a similar method to block pain signals. But Coolief doesn't just heat up the electrodes, it cools them down – a technique called "cooled radiofrequency ablation." The idea is to deliver more energy where it's supposed to go with less collateral damage.

The procedure is considered minimally invasive. However, it requires several injections and x-ray guidance to be sure of the proper location. By comparison, a cortisone shot in the knee to relieve pain is usually only one injection, and x-ray guidance is rarely needed.

Does Coolief work?

A number of studies have tried to answer this question, but the evidence is iffy. According to a recent review of previous research, the evidence supporting cooled radiofrequency ablation as a reliable and long-lasting way to relieve pain from knee osteoarthritis is quite limited. Many studies included only a few patients and did not assess response after more than a few weeks.

Here's a quick rundown of some of the largest and most recent studies:

• A 2015 study of nine people with osteoarthritis receiving cooled radiofrequency ablation reported improvement in measures of pain and function "beyond one year," but specific details, including how many people improved, were not provided.
• A 2017 study of 33 people found a success rate of only 35% six or more months after treatment.
• A 2018 study of 151 people compared cooled radiofrequency ablation to having a single cortisone shot. After six months, 74% of people who had the procedure reported a reduction in pain by at least half. A similar improvement was reported by only 16% of those receiving a cortisone injection.

What else should you consider?

Most studies found few or no side effects associated with the Coolief procedure. Even so, the manufacturer warns of potential risks that include infection, nerve damage, increased pain — even paralysis and death. In part, this may be based on reports of cooled radiofrequency ablation in other areas of the body.

One downside that's worth emphasizing is cost: according to an NBC News story about this treatment, it can cost $2,000 to $4,000, and may not be covered by health insurance.

Are the ads accurate?

Based on the 30-second TV commercial described above and a six-page online brochure, some of the claims seem exaggerated, misleading, or incomplete. For example:

• A major marketing point of Coolief is that it lasts up to a year. Yet, evidence showing such long-lasting improvement in pain, function, and quality of life is quite limited. I could find only one published report (the 2015 study mentioned above) that monitored treated individuals for a year. It followed only nine patients, three of whom had already had knee replacement surgery. No details were provided on how long improvements lasted for individual patients. Also, the study cited by the online ad as evidence for the one-year claim actually monitored patients for only 12 weeks. Another study of long-term results is "available upon request" from the company marketing Coolief.
• Some evidence cited to support using Coolief for osteoarthritis of the knee comes from treatment of hip and spine pain. One study cited as proof of long-term benefit did not even use cooled radiofrequency ablation — it used a standard nerve block. And lasted only 12 weeks.
• The online ad repeatedly reminds the reader that Coolief is not an opiate, and that we need non-opiate options to treat pain given the risks and side effects of opiates. That's true. But other statements aren't true. Opioid prescriptions are not given to patients as a first-line treatment for chronic pain. Nor has relief from osteoarthritis knee pain relied on a daily regimen of prescription opioid medication. In fact, because osteoarthritis of the knee tends to affect older adults who are prone to medication side effects, and because opiates come with a host of risks and side effects, physicians tend to avoid opiates in these patients.
• The online ad describes the Coolief procedure as "minimally invasive" and cortisone injections as "invasive." In fact, they are both minimally invasive.

Finally, learning that Coolief was "cleared" by the FDA might lead you to assume the FDA evaluated the evidence and concluded this procedure is safe and effective. In fact, Coolief did not require specific FDA approval because the FDA concluded it was similar enough to other "legally marketed" devices.

The bottom line

Coolief might be helpful for some people with osteoarthritis of the knee. Or it might not. Before I recommend this expensive procedure, I'd like to see more and better studies. The ads are dramatic and eye-grabbing, just as they're intended to be (see my blog on direct-to-consumer ads). Unfortunately, the evidence supporting the benefits of this product is not nearly so impressive.

If you have osteoarthritis of the knee, talk to your doctor about all the options, including cooled radiofrequency ablation. And if you see an arrow sticking out of your knee, stop bowling and seek immediate medical attention.