Knee Pain: Nerve Injections May Help Osteoarthritis

People with knee osteoarthritis experience short-term pain relief from genicular nerve blocks, which are injected anesthetics that block nerves around the knee joint.

That's the conclusion from the results of a new clinical trial published in the journal Arthritis & Rheumatology.

The trial included 59 participants who were randomized to receive either a nerve block or a placebo injection in their knee. Researchers recorded self-reported pain at weeks 2, 4, 8, and 12.

The participants who received the nerve block reported improved or greatly improved pain relief, although there were diminishing effects over time.

About 50% of study participants reported improvement at eight weeks while 30% indicated improvement at 12 weeks.

Success rates varied among participants based on the severity of their disease, prior treatments, and current health.

"At our institution, about 60 percent of patients will benefit significantly for a prolonged duration [while] 20 to 30 percent have moderate relief for shorter durations and 10 percent do not get much benefit at all," Dr. Michael Hunter, an orthopedic surgeon with Hoag Orthopedic Institute in Southern California, told Healthline.

None of the study participants reported any adverse reactions, indicating that the procedure is effective and safe.

"There is always a risk for infection, redness, and bleeding at the injection sites, or an allergic reaction to the medications used," said Dr. Dmitriy Dvoskin, a specialist in pain management and physical medicine and rehabilitation who practices at Pain Management NYC. "Some people might also experience nausea, dizziness, and hot/flushed from the medication."

The genicular nerve block could be an alternative to knee replacement for people who cannot undergo surgery because of age or current health status.

"The goal is to decrease pain, improve mobility and quality of life," Dvoskin told Healthline.

Researchers noted the procedure offers pain relief without pharmacotherapies, such as long-term use of over-the-counter or prescription-strength pain relievers.

At the end of the study, researchers said many participants asked to receive the nerve block again.

"There are three genicular nerves that supply sensations to the knees and transmit pain signals from the joint to the brain," explained Dr. Medhat Mikhael, a pain management specialist and medical director of the non-operative program at the Spine Health Center at MemorialCare Orange Coast Medical Center in California.

"Genicular nerve block is done by advancing needles at the locations of those nerves, guided via fluoroscopy or ultrasound. We block with local anesthetic and possibly mixed with low-dose steroids," Mikhael told Healthline.

Pain relief typically occurs shortly after the procedure, experts say.

"Most patients can expect immediate pain relief," Hunter said. "Some patients do not experience total relief, but many patients will have some degree of pain relief for varying durations."

Early in the course of osteoarthritis, many people find relief from non-drug and non-surgical interventions, according to the Arthritis Foundation.

These include:

Some people find acupuncture or massage helps, too.

If needed, there are over-the-counter and prescription medicines that can help. Acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (Advil, Motrin, Aleve) can lessen the pain temporarily. Steroid injections or lubrication injections help reduce pain for some people.

"The efficacy of a genicular nerve block for a particular patient is oftentimes a useful indicator of one's response toward cryoablation or radiofrequency ablation to those same sensory nerve branches," said Dr. Ilan Danan, a sports neurologist and pain management specialist at the Center for Sports Neurology and Pain Medicine at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles.

"This oftentimes yields longer-lasting pain relief. Alternative treatments may also include viscosupplementation to the arthritic knee or knee replacement surgery," Danan told Healthline.

Radiofrequency ablation is a minimally invasive procedure for pain, according to UCSF Health. A radiofrequency needle is moved alongside the affected nerve to seal the nerves. It is done with the help of X-ray guidance. After a brief period of soreness, there is typically pain relief that lasts from three to 12 months. Cryoablation works the same way but uses cold energy on the nerves instead of radiofrequency.

Viscosupplementation is typically used if other non-surgical methods did not provide relief, according to the American Academy of Orthopedic Surgeons. In this procedure, hyaluronic acid is injected into the knee joint to add lubrication and hopefully reduce pain caused by bones scraping against each other. Some people do report that it helps, but overall, it is not reported to be significantly effective.

Experts say it is essential to talk with your physician about the possible treatment options to determine which one is best for you.

"Each patient has different risk factors for treatments. Surgical management is usually a last resort option," Dvoskin said.