How to Perform an Injection Into the Knee

Knee problems are common complaints heard 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 to remove fluid from the joint. Your doctor may recommend injecting a medication, such as Synvisc or cortisone, into the knee. Also, your doctor 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 how to perform an injection into the knee.

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 doctor must discuss your condition and what treatments are appropriate. Not all conditions are appropriately treated with injections. Your doctor 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 doctor's office, and usually, require 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 the most concerning side-effect of injections. This is a very rare complication, but it is possible. Sterilizing the skin with Betadine and/or alcohol can help to decrease (although not eliminate) the risk of infection. Your doctor will ask if you are allergic or have ever reacted to these skin cleansers so he 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 must be 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 the swelling from the knee. Studies have shown that the most reliable place to inject the knee is with the patient lying flat and the knee straight, and the needle 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. 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 this pain.


  1. Let your doctor know if you are nervous. If you are concerned about any aspect of the injection, let your doctor know. Often knowing what is coming, and understanding the procedure, will help put you at ease. If you are nervous about pain, ask your doctor to use a topical anesthetic. Most orthopedic surgeons perform several injections every day. Let your doctor 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 a lying down for the procedure. This will help you relax, breathe easier, and also may prevent a vasovagal reaction (passing out).
    1. Watch for signs of infection. As mentioned, infections are the most worrisome complication of knee injections. Let your doctor know if you have:​
      Worsening swelling or pain
    2. Redness of the knee
    3. Drainage from the injection site
    4. Fevers, chills, or sweats
    5. 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. Here is some information about how the injection is performed so you 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 doctor about being 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.

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