Everyday Health, "What to Know About Injections for Knee Osteoarthritis"

Published March 9, 2017

If your knee osteoarthritis treatment isn’t working, you may need to consider corticosteroid injections or hyaluronic acid injections. Here’s why.

When osteoarthritis first begins causing pain, you might find relief with conservative methods — weight loss, physical therapy, and modifying your activities to put less stress on your knees, for instance. Oral and topical pain relievers may also help.

But osteoarthritis is a type of joint disease that gets worse over time. When the initial strategies for managing pain and stiffness stop working, it might be time to consider injections for osteoarthritis treatment.

Corticosteroid Injections for Osteoarthritis of the Knee

Corticosteroid injections are the most common type of injections for osteoarthritis. The drug works like the natural hormone cortisol in your body to change your immune response and lower inflammation, according to the Arthritis Foundation.

People who have painful, swollen knees are candidates for the treatment, says Scott C. Faucett, MD, an orthopedic surgeon at the Centers for Advanced Orthopaedic Center in Washington, D.C.

During the procedure, a surgeon pairs cortisone with an anesthetic and injects it directly into the joint. “You’ll get an immediate response from the anesthetic,” Dr. Faucett says. The anesthetic wears off in 12 to 24 hours, and the cortisone begins working within 24 to 72 hours. The effects of the shots typically last about two to three months.

However, results vary from person to person. In a study published in BMC Musculoskeletal Disorders in January 2017, 61 percent of the people who received corticosteroid injections for knee osteoarthritis reported less pain three weeks after the injection, and 46 percent continued to experience pain relief at nine weeks.

“I liken it to a fire,” Faucett says. “If you have a small trash can fire, you can use a fire extinguisher and it won’t come back. If it's a large house fire, [the extinguisher] won’t keep it out for long.” In the case of osteoarthritis, you may need to have a shot every three to four months to keep inflammation at bay.

For many people, the shots are safe, but there are possible side effects, according to the Arthritis Foundation. These include:

  • Nerve damage
  • Bone thinning
  • Short-term joint irritation
  • Infection

There's been debate about whether frequent injections actually accelerate osteoarthritis, notes William J. Bryan, MD, an orthopedic surgeon at Houston Methodist Hospital in Texas. On the other hand, he says, you could argue that since corticosteroids lower inflammation, this may slow the progression of osteoarthritis rather than hasten it.

Hyaluronic Acid Injections

Hyaluronic acid injections are another option when conservative treatment no longer offers pain relief. Hyaluronic acid is a component of synovial fluid, which is found naturally in your joints and acts as a lubricant and cushion. It’s injected directly into the knee and can reduce inflammation, Faucett says.

Effects typically last longer than cortisone — about six months, Faucett says, but studies on their effectiveness have been mixed. “That being said, there’s certainly a lot of experience among doctors that they’re helpful in some patients,” he adds.

A review of overlapping meta-analyses published in September 2016 in Scientific Reports found that injecting hyaluronic acid in people with knee osteoarthritis was an effective treatment.

One caveat: These injections don’t work as quickly as cortisone shots. They typically take one or two weeks before you start to notice the effects, Faucett says, but they can be paired with cortisone for a more immediate benefit.

Cost is also a consideration. Hyaluronic acid is expensive compared with cortisone, Dr. Bryan adds.

The Future of Osteoarthritis Injections

Another therapy still being evaluated — and not currently covered by insurance — is platelet-rich plasma. Some studies have shown knee improvement for at least a year, says Faucett.

The therapy is done by drawing a patient's own blood in the doctor's office and separating out the platelets through centrifugation. Platelets, which are growth factors that doctors think may decrease inflammation, are then injected into the knee.

In one clinical trial, researchers compared platelet-rich plasma to hyaluronic acid treatment in people with mild to moderate osteoarthritis. They found that the plasma was an effective treatment and that combining both therapies had even greater results, according to the findings, published in November 2016 in the Journal of Stem Cells & Regenerative Medicine.

Because it’s not covered by insurance, however, this therapy can be quite expensive, says Stephen J. Nicholas, MD, a clinical assistant professor at Pace University and director of the Nicholas Institute of Sports Medicine and Athletic Trauma at Lenox Hill Hospital, both in New York City. Injections may cost about $500 to $1,000 each, and they’re typically given as a series of three shots.

When it comes to osteoarthritis treatment, it’s smart to know your options and discuss them with your doctor when initial therapies no longer cut it. This will help you decide the next best step for pain relief.

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