When you have pain, stiffness, or other problems because of knee osteoarthritis (OA), and other treatments haven't helped, your doctor may suggest injections to ease your symptoms.
Shots in your knee joint are an option if you don’t get relief from a pain reliever like acetaminophen or ibuprofen, says Jemima Albayda, MD, a rheumatologist at Johns Hopkins University. Your doctor may also suggest injections if you can't take those drugs because of side effects.
Knee Injection Basics
The shot may be a little uncomfortable, but it shouldn't be very painful. To lessen the chance of infection, your doctor will clean your knee before giving you the shot.
If you have fluid in your knee, your doctor may drain it first. She may give you a numbing injection or spray before the shot of medicine.
There are several different kinds of injections, Albayda says, but the two main types for osteoarthritis are:
- Viscosupplements with hyaluronic acid
Cortisone-type shots help ease joint inflammation.
Fast relief. You may feel better as soon as you get the shot because you are numbed first, says Craig Bennett, MD, an orthopaedic surgeon at the University of Maryland Rehabilitation & Orthopaedic Institute. But when that wears off, you should feel relief of symptoms within a couple of days. Relief from these injections can last for several weeks to several months.
You can't use them very often. "Corticosteroids generally work more powerfully and better the first time in," Bennett says. Each time after that, you may get a little less relief. In most cases, Albayda suggests that people with OA get the shot no more than every 3 months.
Complications from injections are rare but can happen. Talk to your doctor to know your risks. You can also have a flare right after you get the shot. Getting corticosteroid injections can also affect blood sugar temporarily, so this may be a concern for several days if you have diabetes.
Hyaluronic acid is the fluid inside your knee. It keeps the bones in the joints moving smoothly against each other. When you have OA, the fluid changes and contributes to inflammation. These injections provide a man-made version of that fluid. This treatment is often offered to people who get no relief from pain relievers.
"I tell my patients it's like an oil job," Bennett says. "It's going to give your joint the same concentration and the same type of fluid that a healthy non-arthritic joint should have."
You may need more than one shot. Some hyaluronic acid injections provide relief with just one injection, but others come in a series of injections.
Relief takes time. Because these injections aren't usually given with a numbing drug, there's no immediate pain relief like you get with a steroid shot. It typically takes about a week or more before you start to feel better, Bennett says. The effect may last longer than cortisone shots -- up to 6 months or more.
They're expensive. These treatments are also typically more expensive than cortisone shots, says Joseph Bosco, MD, an orthopaedic surgeon at NYU Langone Medical Center’s Hospital for Joint Diseases. "With all these injections, be sure to ask your doctor if insurance will cover it and how much will it cost."
A Third Option: Platelet-Rich Plasma
Some doctors are using this type of knee injection to treat knee OA symptoms. Doctors take your blood and collect the platelets, the part of blood that forms clots. They increase the number of platelets and inject them into your knee. Natural chemicals in platelets help heal injuries and lower inflammation.
Experts are still researching how well it works for osteoarthritis. It's very expensive and still in early stages of research, Albayda says, so it's not a mainstream form of OA treatment.