If you have osteoarthritis in the knee, doctors may offer several treatments to relieve your symptoms. One option is to inject medication into your knee.
There are several types of injections, and they are an important part of knee osteoarthritis treatment for many people, says Roy Altman, MD, an osteoarthritis expert at UCLA. Injections may be especially helpful for people who have not gotten relief from NSAIDs such as ibuprofen, or for people who cannot take these medications because of side effects.
Osteoarthritis (OA) is a common form of arthritis that often affects the knees. It occurs when the cartilage – the smooth covering that protects the bones in the joint – breaks down. The surface of the bones becomes damaged, causing pain, swelling, stiffness and disability.
How knee injections work
First, your doctor will give you an injection of anesthetic to numb your knee.
Then your doctor may use a needle to aspirate any extra fluid from your knee.
You will then receive the pain-relieving injection, usually just below your kneecap. The shot shouldn’t hurt, and the medicine will work through the entire joint, says John Richmond, MD, an orthopedic surgeon at New England Baptist Hospital in Boston.
Various treatments have side effects that you should discuss with your doctor in advance. The two most common types of knee injections for osteoarthritis are corticosteroids and hyaluronic acid.
Reduce inflammation with steroids
Corticosteroid injections are useful for treating flare-ups of osteoarthritis pain and swelling with fluid buildup in the knee, says Richmond.
These injections help relieve symptoms by reducing inflammation in the joint. But they are not a perfect solution in all cases. If you are considering this treatment, keep the following in mind:
They work quickly. These injections provide “very quick” relief, usually within 24 to 48 hours, Richmond says.
The benefit is short-lived. On average, pain relief lasts six to 12 weeks, Richmond says. Often that’s long enough to get you through a flare-up of osteoarthritis until your symptoms go away.
You should not use them often. A corticosteroid injection often works best the first time, says Altman. After that they usually provide less relief.
In most cases, Richmond tells his patients they can use these injections two to three times a year. Using them too often can damage the cells in the knee that make cartilage.
Hyaluronic acid
Most of the fluid in a healthy knee is hyaluronic acid, says Altman. But if you have knee osteoarthritis, the hyaluronic acid in your knee becomes thinner. Your doctor may inject more hyaluronic acid into your knee to stimulate its supply.
Studies have shown that hyaluronic acid injections may help more than painkillers for some people with osteoarthritis. Other studies have shown that they can improve symptoms, just as corticosteroid injections do. If you are considering hyaluronic acid injections, keep the following in mind:
It is often not the first approach. Your doctor may suggest hyaluronic acid if:
- Your symptoms are not improved by pain-relieving medications or non-drug treatments such as heat or ice.
- You cannot take pain relievers such as Advil or Motrin (ibuprofen), Aleve (naproxen sodium), or Tylenol (acetaminophen).
- A steroid injection doesn’t help enough, or you or your doctor are concerned about the side effects.
It can work in different ways. After an injection, hyaluronic acid helps soften and lubricate the moving parts in your knee, says Altman. This effect is quite short-lived. But the treatment also appears to provide long-term benefits by relieving pain and inflammation.
You may need more than one injection. There are five versions of hyaluronic acid injections available in the US. Some types require only one injection. Others require up to five injections, usually within a five-week period. If necessary, you can get another injection after six months, says Altman.
Platelet-rich plasma: can it help OA?
Another treatment receiving attention is platelet-rich plasma (PRP). This requires taking a sample of your blood and processing it to create a fluid that contains a higher-than-normal amount of platelets, small discs that help the blood to clot. The doctor then injects the fluid back into your injured area.
The platelets in your blood contain natural chemicals that help heal injuries. Doctors have been treating other problems, such as tendon damage, with PRP for more than a decade.
However, experts still know little about whether it works for knee osteoarthritis.