How a Knee Injection Is Performed

Knee problems are common complaints evaluated by orthopedic surgeons. Often people seek the help of an orthopedist for knee pain, swelling, or difficulty bending the joint. One way to help diagnose and treat a variety of knee conditions is to inject the joint or remove fluid from the joint.

Your healthcare provider may recommend injecting a medication, such as Synvisc or cortisone, into the knee. In addition, your practitioner may recommend removing fluid from the knee joint through a needle. Often, these procedures can be performed simultaneously, as the fluid is first removed from the knee joint, followed by an injection of medication into the knee. Here is information about what to expect when you undergo a knee injection.

Doctor performing a knee injection on patient
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How a Knee Injection Is Done

  1. Determine if an injection is appropriate. First and foremost, your healthcare provider must discuss your condition and what treatments are appropriate. Not all conditions are appropriately treated with injections. Your practitioner can discuss the cause of your knee pain and what treatments are available.
  2. Obtain the proper medication. Most orthopedic surgeons have cortisone stored in the office. Hyaluronic acid (e.g. Synvisc, Orthovisc, etc.) might not be stored in your healthcare provider's office, and usually requires insurance preapproval. These medications may need to be obtained prior to an injection appointment.
  3. Sterilize the skin. The skin must be properly sterilized to minimize the chance of infection. Infection of the joint is a rare but serious side effect that can be related to injections. Sterilizing the skin with Betadine and/or alcohol can help to decrease (although it won't eliminate) the risk of infection. Your healthcare provider will ask if you are allergic or have ever reacted to these skin cleansers so he or she can use the right product.
  4. Numb the skin (optional). Topical numbing sprays are often sufficient to dull the pain associated with an injection. When simply injecting the knee (and not removing fluid), a small needle can be used to inject medication. When a joint aspiration is necessary to remove fluid from the knee, a larger needle is typically used. In these cases, some patients may find relief if a small amount of lidocaine (Novocaine) is injected into the skin prior to the aspiration.
  5. Insert the needle into the knee joint. A needle is then inserted into the joint to inject the medication or remove fluid from the knee. Often the doctor will inject with the patient lying flat and the knee straight, while the needle is placed from the outside, under the kneecap. Other injection sites may also be used.
  6. Remove excess fluid from the knee. If the joint is swollen (a so-called "knee effusion"), the excess fluid should be removed prior to injecting the medication. Excess fluid in a joint may dilute the medication, making the treatment less effective. Furthermore, knee swelling is associated with pain, and removing the excess fluid can lead to pain relief.
  7. Inject the medication. The medication is then injected into the knee. The amount of medication injected depends on the treatment. Most types of hyaluronic acid (e.g. Synvisc, Orthovisc) are 2 CCs, but the amount injected can vary by type. Cortisone injections vary depending on surgeon preference and are often injected simultaneously with Novocaine.
  8. Place pressure on the injection site and bend the knee. Once the injection is performed, gentle pressure over the injection site will prevent bleeding. Bending the knee can help circulate the medication.
  9. Apply an ice pack if pain persists. Most often, injections do not slow down your lifestyle. Some patients may experience a "flare up" of the knee after the injection. Usually, a simple ice pack placed on the knee can help to alleviate any pain.


  1. Let your healthcare provider know if you are nervous. If you are concerned about any aspect of the injection, let your practitioner know. Often knowing what is coming and understanding the procedure will help put you at ease. If you are nervous about pain, ask your healthcare provider to use a topical anesthetic. Most orthopedic surgeons perform several injections every day. Let your practitioner know if you are nervous; they may not know if you are having anxiety.
  2. Lie down. If you are feeling anxious, make sure you are lying down for the procedure. This will help you relax, breathe easier, and may also prevent a vasovagal reaction (passing out).
  3. Watch for signs of infection. As mentioned, infections are very uncommon, but are the most worrisome complication of knee injections. Let your healthcare provider know if you have:​
  • Worsening swelling or pain
  • Redness of the knee
  • Drainage from the injection site
  • Fevers, chills, or sweats
  • Any other concerning symptoms

A Word From Verywell

Injections are a common tool used by orthopedists to diagnose and treat a variety of knee joint conditions. When you know how the injection is performed, you'll know what to expect from this procedure. Despite this knowledge, many people remain nervous about having a needle placed into their knee joint. The best advice is to tell your healthcare provider if you're nervous. He or she can use that information to slow down, take their time, and talk you through the injection procedure to make sure you feel as comfortable as possible.

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.