But because knee osteoarthritis worsens over time, it’s important to be aware of your symptoms and set up a treatment plan sooner rather than later. “There are no curative strategies for knee osteoarthritis,” says Scott C. Faucett, MD, an orthopedic surgeon at the Centers for Advanced Orthopaedics in Washington, DC. “For now, there are only management strategies.” If you’re not ready to consider knee replacement surgery, but the pain, swelling, and stiffness are slowing you down, you might want to consider having injections into the osteoarthritic knee, Dr. Faucett says. There are three types of injections that are currently supported by good quality studies, he says: cortisone shots, injection of hyaluronic acid (HA) supplements, and injection of platelet-rich plasma (PRP). Here is what to know about each type of injection.
Cortisone Injections for Knee Osteoarthritis
Cortisone (also called corticosteroid, or steroid) injections are the most common type of injections for the treatment of knee osteoarthritis. According to the Arthritis Foundation, the drug works like the natural hormone cortisol to change the body’s immune response and lower inflammation levels. The injection, which is given directly into your knee joint, will work quickly to give you relief. “You’ll get an immediate response from the anesthetic,” says Faucett. The anesthetic wears off in 12 to 24 hours, and the cortisone begins working within 24 to 72 hours. “If there’s a lot of swelling and pain, and a seemingly active inflammatory process, I tend to recommend cortisone because that will act relatively quickly for swelling,” Faucett says. The effects of the shots typically last about two months, says the Arthritis Foundation, and people may need a cortisone shot every three to four months to keep inflammation at bay. However, knee injections may not work for everyone. In a study published in the January 2017 issue of BMC Musculoskeletal Disorders, 61 percent of the people who received cortisone injections for knee osteoarthritis reported feeling less pain three weeks after the injection, and 46 percent continued to experience pain relief at nine weeks. Plus, there are possible side effects from these shots, according to the Arthritis Foundation, including:
Nerve damageBone thinningShort-term joint irritationInfection
The Arthritis Foundation also cautions that repeated cortisone injections may actually add to the breakdown of cartilage in the knee, accelerating the osteoarthritis process. Because of this risk, your doctor may limit the number of injections you should get. William J. Bryan, MD, an orthopedic surgeon at Houston Methodist Hospital in Houston, says that frequent cortisone injections could accelerate osteoarthritis, but they also may slow down the progression of the condition by lowering inflammation in the joint. Authors of a major review of studies published by the Cochrane Database of Systematic Reviews in October 2015 reported that, based on their analysis of 27 clinical trials comparing the effect of cortisone injections with fake (sham) injections or no intervention at all, steroid injections seem to offer a moderate improvement in pain and a small improvement in physical function for up to six weeks after the injection. “I liken a cortisone shot for your osteoarthritic knee to a how you handle a fire,” Faucett says. “If you have a small trash-can fire, you can use a fire extinguisher and it won’t come back. But if it’s a large house fire, [the extinguisher] won’t keep it out for long.” If you’ve already tried cortisone injections for a stiff or painful knee, or are in an arthritic phase with a very swollen knee, another option for you may be a procedure called joint aspiration. Faucett says that he often offers joint aspiration (which involves removing excess fluid) to, for example, people with “effusions,” some of which have grown to the size of a grapefruit.
Hyaluronic Acid Injections for Knee Osteoarthritis
If cortisone injections haven’t worked for you, you may want to consider having an injection of hyaluronic acid. In healthy joints, hyaluronic acid works like a lubricant and cushion, or shock absorber, says the Arthritis Foundation, and people with osteoarthritis may have experienced some breakdown of this fluid. HA injections aim to add a natural fluid back into the joint. Typically, HA injections are given weekly for three to five weeks. Doctors first take out a little joint fluid to make space for the injection. Once injected directly into the knee, this component of synovial fluid can reduce inflammation, Faucett says. While the injections don’t work as quickly as cortisone shots (it typically takes one or two weeks before you start to notice the effects, Faucett says), they can be paired with cortisone injections for a more immediate benefit. What’s more, the effects typically last longer than a cortisone shot — about six months, Faucett says. A review of overlapping meta-analyses published in September 2016 in Scientific Reports found that HA was both safe and effective at easing the symptoms of knee osteoarthritis and led to few side effects or unwanted reactions.
Platelet-Rich Plasma (PRP) Injections for Knee Osteoarthritis
Another option to consider is a PRP injection. Here’s how it works: A doctor will draw your blood in their office and separate your blood platelets, which are growth factors that may decrease inflammation. These platelets are then injected into the knee to help supplement the fluid there. In addition to calming inflammation, they may also help lubricate and cushion the joint. Side effects of the treatment may include passing dizziness, headaches, and nausea, according to a February 2017 article published in the journal EFORT Open Review. Plus, PRP injections aren’t currently covered by insurance and therefore are more expensive than other options. This cost may be an issue for some people, says Stephen J. Nicholas, MD, director of the Nicholas Institute of Sports Medicine and Athletic Trauma at Lenox Hill Hospital in New York City. Each injection may cost about $500 to $1,000 or more, and they’re typically given as a series of three shots. “There’s not enough head-to-head evidence to support [opting for PRP injections over HA injections or vice-versa],” says Faucett. The choice comes down to other factors specific to you, so it’s important to talk things through with your doctor. Both are relatively expensive compared with cortisone shots, Dr. Bryan adds, but some people choose PRP because its effects tend to last a little longer and they’re attracted to the idea of using their own healing proteins to get relief.
What’s Next for Treating Knee Osteoarthritis?
“As of now, these are the options we have for managing the inflammation and pain of knee osteoarthritis,” Faucett says. In the future, “there hopefully will be some new types of biologic treatments — and there are some Food and Drug Administration studies on stem cell injections for this condition.” For now, read up on your options and discuss them with your doctor — especially if your current therapy is no longer working for you.
