Osteoarthritis (OA) of the knee begins when the cartilage breaks down in your knee and eventually results in bone and joint damage. Movement as simple as standing can trigger pain.

Lifestyle changes and over-the-counter (OTC) treatment can help relieve mild symptoms.

In time, however, these may cease to be effective, and your doctor may prescribe stronger medications, including occasional steroid injections.

Injections aren’t a cure, but they can be effective in relieving pain and decreasing inflammation, possibly for several months or sometimes even longer.

Read on to learn how knee injections work.

There are several types of knee injection for treating OA, but experts do not recommend them all.

Corticosteroids

Corticosteroids, also referred to as glucocorticoids, are similar to cortisol, a hormone that the body produces naturally.

Hydrocortisone is an example. A hydrocortisone injection into the knee joint can help reduce inflammation and relieve pain.

Steroids that treat pain and inflammation are different from anabolic steroids, which bodybuilders may use. Oral corticosteroids are also available, but they’re not used for treating OA.

Fluid aspiration (arthrocentesis)

There’s normally a few cubic centimeters (cc) of synovial fluid within a joint, which lubricates it for ease of movement through its range of motion.

However, inflammation can cause fluid to collect within the knee joint. Arthrocentesis takes the extra fluid out of the knee, which can provide immediate relief from pain and swelling.

Aspirating the joint fluid is also important if your doctor suspects you may have a joint infection. A sample of your joint fluid is taken and sent to a lab for a cell count, culture, and antimicrobial sensitivity.

Occasionally, a crystal analysis is performed.

Other injections: Hyaluronic acid, botox, and more

Some people have used other types of injections for OA of the knee.

However, experts from the American College of Rheumatology and the Arthritis Foundation (ACR/AF) don’t currently recommend using these, as there’s not enough evidence that they work.

Examples of other types of injections include:

  • hyaluronic acid injections, also known as viscosupplementation
  • prolotherapy

In addition, the ACR/AF strongly recommends avoiding the following, as there’s currently a lack of standardization in these treatments.

You may not know exactly what type of injection you’re receiving or what the effect might be.

Always discuss the pros and cons of any treatment with your doctor before starting, so that you can make an informed decision.

You can usually receive a knee injection in your doctor’s office. The procedure only takes a few minutes.

You’ll be seated during the procedure, and your doctor will position your knee. They may use ultrasound to help guide the needle to the best location.

Your doctor will:

  • clean the skin on your knee and treat it with a local anesthetic
  • insert the needle into your joint, which might cause some discomfort
  • inject the medication into your joint

Though you may feel some discomfort, the procedure is rarely painful if your doctor has experience administering this type of injection.

In some cases, your healthcare provider may remove a small amount of joint fluid to reduce pressure.

They’ll insert a needle attached to a syringe into the knee joint. Then, they’ll draw out the fluid into the syringe and remove the needle.

After removing the fluid, the doctor can use the same puncture site to inject the medication into the joint.

Finally, they’ll place a small dressing over the injection site.

Recovery

After the injection, you’ll usually be able to go straight home.

Your doctor may advise you to:

  • avoid strenuous activity for the next 24 hours
  • avoid swimming
  • avoid hot tubs
  • avoid any prolonged exposure to something that would allow an infection to be introduced through the needle track, which should be closed up within 24 hours
  • monitor for side effects, such as an allergic reaction or an infection (swelling and redness)
  • take OTC pain relief medication to reduce discomfort

Your knee may feel tender for a few days. Ask if there are any driving restrictions.

Here are some of the pros and cons of knee injections.

Corticosteroid injections

Pros

  • Corticosteroid injections may provide immediate relief from pain and inflammation.
  • Relief may last several months.
  • In some cases, symptoms may disappear for good after one injection.

Cons

  • They’re typically short-term solutions, and the pain will return.
  • If OA is severe, they may simply not be effective.
  • Some people do not experience relief.
  • Over time, their effectiveness can decrease.
  • Steroid use can lead to adverse effects.

A direct injection of steroids may provide immediate relief that lasts for several months, but it’s usually only a short-term solution.

You may need another injection in a few months, and its effectiveness may decrease in time.

In addition, not everyone gets relief after a corticosteroid injection, especially if they already have severe damage.

The main and immediate side effect of an injection can be bleeding within the joint if a small blood vessel is nicked during the arthrocentesis.

Long-term side effects of frequent steroid treatment can include:

  • a breakdown of cartilage
  • bone thinning at the particular joint, but this is likely a rare occurrence

For these reasons, doctors usually recommend waiting at least 3 months before having another injection and limiting the injections to a single joint to 3-4 per year.

Some experts have questioned whether steroid injections are a good option.

Research published in 2019 suggested that steroid injections may increase the risk of joint damage and speed up the development of OA.

In 2017, scientists concluded that steroid injections might cause a thinning of the cartilage that cushions the knee joint.

A 2020 study found that people who underwent physical therapy for a year had better results than those who received steroid injections.

Fluid aspiration

Removing excess fluid can provide relief from pain and discomfort.

Side effects may include:

  • bruising and swelling at the aspiration site
  • a risk of infection
  • damage to blood vessels, nerves, and tendons

Always ensure that your healthcare provider has experience with this type of treatment before going ahead.

After the injection, monitor your knee for any signs of injection issues and contact your doctor if you have concerns.

Injections, medication, and other treatments, along with knee surgery, can help in severe cases, but experts strongly recommend using these alongside lifestyle choices that can benefit your joint health.

These include:

  • managing your weight, as extra weight puts pressure on the joints
  • exercising to keep your knee muscles strong
  • opting for low-impact activities, such as water exercise
  • starting with OTC options, such as ibuprofen, before progressing to prescription drugs
  • applying topical creams that contain nonsteroidal anti-inflammatory drugs (NSAIDs) or capsaicin
  • applying heat and cold pads to relieve pain and inflammation
  • using a knee brace or Kinesio tape to support your knee
  • using a cane or walker to help you balance
  • doing tai chi, yoga, or other activities that help boost flexibility and reduce stress
  • getting enough rest
  • following a healthy diet
  • having physical — or occupational — therapy to help you cope with the challenges of OA

Corticosteroid injections can provide significant relief, but they will not cure OA of the knee. The effectiveness also varies between individuals, and some people may benefit more than others.

If your arthritis has already progressed significantly, injections and other medications may no longer provide relief.

In this case, you may want to talk to your doctor about partial or total knee replacement surgery.