New Pain Treatment for Knee Osteoarthritis Targets Nerves

A relatively new treatment for knee osteoarthritis (OA) appears to reduce pain better than traditional corticosteroid injections, according to a study published recently inInternational Journal of Rheumatic Diseases.

The study, by researchers at Adnan Menderes University in Turkey, compared corticosteroid injections into the joint to a procedure called radiofrequency neurotomy in a group of 73 patients with knee OA. Radiofrequency neurotomy is the use of a heated needle to damage nerves – in this case the genicular (knee) nerves – in order to disrupt pain signals. After receiving treatment, the group that underwent neurotomy reported less pain and greater functional movement than the injection group.

Radiofrequency neurotomy has been used for decades to relieve back and neck pain, but is new to the treatment of knee osteoarthritis. Soo Yeon Kim, MD, an attending physician in the multidisciplinary pain program at Montefiore Health System in New York City, says the location of the back nerves that causeosteoarthritispain is well documented and the procedure has been shown to be safe and effective. But the position of the nerves in the knee is more variable than in the back, she explains. Additionally, major knee arteries run very near the small nerves that need to be heated, creating a slight risk for arterial damage.

It wasn’t until a small 2011 study by Korean researchers that physicians realized neurotomy might be effective for knee OA pain. That study found that more than half of the participants experienced at least 50 percent less pain for up to 12 weeks after the treatment. The study prompted researchers to begin analyzing the structure of the knee.

“Based on that study, it has become en vogue as an alternative treatment for patients with chronic knee pain from osteoarthritis,” says Dawood Sayad, MD, an anesthesiologist and interventional pain specialist at the University of Kansas Hospital in Kansas City.

Who May Benefit

In order to qualify for the more recent study, patients were required to have had pain for longer than three months and to be unable to have knee replacement surgery. Participants also must have unsuccessfully tried conservative treatments, including physical therapy and anti-inflammatory medication.

Those patients are the ideal population for neurotomy, Dr. Kim says. It’s recommended when conservative treatments have failed, for those who can’t have knee surgery, for young people who want to put off surgery for a later time, or for those who have had total knee replacement surgery but continue to have persistent pain.

“I wouldn’t recommend it if the patient hasn’t tried any conservative treatments as the procedure comes with possible risks of complications,” says Dr. Kim.

Reducing Risks

赛义德医生已经进行了大约两年的治疗，他说，医生可以做一些事情来降低手术的风险。图像引导，包括超声波或实时x光，被用来寻找神经。在治疗之前，医生会做感觉测试，刺激神经来确认是哪些神经引起了疼痛。

在土耳其的研究中，无论是注射还是神经切开术，患者都没有任何并发症。虽然两组参与者都比他们自己的基线(开始)测量有所改善，但接受神经切开术的参与者在1个月和3个月后的疼痛缓解明显大于注射组。与注射组相比，他们在两个时间点的僵硬程度都显著降低，而在一个月时(但在三个月时没有)的功能明显增强。赛义德医生告诉他的病人，在三个月到一年的时间里，疼痛会减少50%左右。

Valuable Alternative

Over time, the nerves damaged during a neurotomy regenerate and the pain returns, Dr. Sayed says. At that point, the procedure can be repeated. He has patients who are on their third or fourth treatments – and getting results similar to the first one. In this respect, he says, the procedure may be more promising than injections, which typically wear off after about six months and become less effective with subsequent doses.

The only definitive cure for OA pain in the knee is total replacement, but that isn’t an option for everyone. Dr. Sayed says many of his patients are in their 50s and don’t want the invasive surgery. Instead they end up on opioid pain medications. Neurotomy, he says, may be a valuable alternative to these controversial drugs.

“This study comes at a good time,” he says. “It’s placing this [neurotomy] as something that needs to be considered in the spectrum of care with severe and painful osteoarthritis.”

Author: Tammy Worth for the Arthritis Foundation