Can sugar injections really ease knee pain?

A new scientific review shows that sugar injections, or prolotherapy, can help athletes who suffer from knee pain and inflammation.

If you suffer from chronic knee pain, you may have tried anti-inflammatory medicines, physical therapy, or cortisone shots to provide some relief. Now, a new scientific review lends support to a lesser-known remedy that may work when others don’t: prolotherapy, a technique that involves injecting a sugar solution into joints damaged by osteoarthritis or injury.

Italian researchers who conducted the review say there’s only enough evidence to recommend the alternative remedy after traditional treatments haven’t helped. But proponents of prolotherapy say it’s safe, effective, and should be used more often than it currently is.

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The idea behind prolotherapy, says Thomas Bond, MD, president-elect of the American Association of Orthopaedic Medicine (AAOM), is that injecting an irritant near the site of torn or stretched connective tissue will stimulate the body’s immune system and speed up the healing process. That’s why sugar water works well, he adds: It has a higher osmotic pressure than other fluids in the body, so it sucks water out of nearby cells—essentially causing local damage and jump-starting the body’s inflammatory response.

“The first step of all healing, whether your body’s fighting an infection or cancer or a torn ligament, is always inflammation,” says Dr. Bond. “It’s the body’s way of calling 911 so it can get its emergency response team there to address the problem.”

Sugar also has an added benefit of bonding to pain receptors in the body, says Dr. Bond—so at the same time it’s repairing and strengthening ligaments and tendons, it’s also blocking short-term pain signals. Treatment plans usually involve multiple shots over the course of a several months. 

Prolotherapy is used most commonly in the United States for back pain, but it can also be used to treat arthritis, sports injuries, or carpal tunnel syndrome in other joints. But while the AAOM recognizes prolotherapy as safe and effective, other medical groups, such as the American Pain Society, don’t include it in their official treatment guidelines.

The authors of the new review, published in the British Medical Bulletin, are cautious about prolotherapy as well. They looked at 10 previous studies, including a total of 529 patients, that tested injections containing either the sugar dextrose, dextrose plus sodium, or dextrose plus anesthetics such as lidocaine.

Overall, the review found that patients reported improvements in pain, function, and range of motion with prolothreapy, and no dangerous side effects were reported. But the studies were small and weren’t consistent enough that their data could be pooled accurately, say the authors, and several were of poor quality or didn’t report complete results.

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Because of this, senior study author Nicola Maffulli, MD, told Reuters, there’s not enough evidence to recommend prolotherapy as a first-line treatment. Rather, he said, it should be part of a larger plan for pain management that might also include weight loss, activity changes, and physical therapy.

Dr. Bond believes the main reason prolothreapy isn’t more widely known is because insurance companies have been slow to recognize its benefits. (It’s rarely covered, and can cost several hundred dollars a session.) But he hopes this will change in the future.

“In the past few decades, we’ve had professional athletes start to say, ‘We know cortisone shots don’t work long-term and they’re not good for our bones; we want something that actually heals tissue,’” Dr. Bond says. “They’re starting to pay more attention to these regenerative technologies.”

This article was originally published on Health.com.