Knee Effusion

The medical term for having fluid in your knee is effusion. This is often due to an internal derangement of the knee. This means something is wrong inside the knee. Some of the causes of fluid in the knee may be torn cartilage, a torn ligament, or bleeding into the joint from an injury. Your knee is likely more difficult to bend and move. This is often because there is increased pain and pressure in the joint. The time it takes for recovery from a knee effusion depends on different factors, including:

  • Type of injury.

  • Your age.

  • Physical and medical conditions.

  • Rehabilitation Strategies.

How long you will be away from your normal activities will depend on what kind of knee problem you have and how much damage is present. Your knee has two types of cartilage. Articular cartilage covers the bone ends and lets your knee bend and move smoothly. Two menisci, thick pads of cartilage that form a rim inside the joint, help absorb shock and stabilize your knee. Ligaments bind the bones together and support your knee joint. Muscles move the joint, help support your knee, and take stress off the joint itself.


Often an effusion in the knee is caused by an injury to one of the menisci. This is often a tear in the cartilage. Recovery after a meniscus injury depends on how much meniscus is damaged and whether you have damaged other knee tissue. Small tears may heal on their own with conservative treatment. Conservative means rest, limited weight bearing activity and muscle strengthening exercises. Your recovery may take up to 6 weeks.


Larger tears may require surgery. Meniscus injuries may be treated during arthroscopy. Arthroscopy is a procedure in which your surgeon uses a small telescope like instrument to look in your knee. Your caregiver can make a more accurate diagnosis (learning what is wrong) by performing an arthroscopic procedure.

If your injury is on the inner margin of the meniscus, your surgeon may trim the meniscus back to a smooth rim. In other cases your surgeon will try to repair a damaged meniscus with stitches (sutures). This may make rehabilitation take longer, but may provide better long term result by helping your knee keep its shock absorption capabilities.

Ligaments which are completely torn usually require surgery for repair.


  • Use crutches as instructed.

  • If a brace is applied, use as directed.

  • Once you are home, an ice pack applied to your swollen knee may help with discomfort and help decrease swelling.

  • Keep your knee raised (elevated) when you are not up and around or on crutches.

  • Only take over-the-counter or prescription medicines for pain, discomfort, or fever as directed by your caregiver.

  • Your caregivers will help with instructions for rehabilitation of your knee. This often includes strengthening exercises.

  • You may resume a normal diet and activities as directed.


  • There is increased swelling in your knee.

  • You notice redness, swelling, or increasing pain in your knee.

  • An unexplained oral temperature above 102° F (38.9° C) develops.


  • You develop a rash.

  • You have difficulty breathing.

  • You have any allergic reactions from medications you may have been given.

  • There is severe pain with any motion of the knee.


  • Understand these instructions.

  • Will watch your condition.

  • Will get help right away if you are not doing well or get worse.