Here’s why fluid sometimes builds up in the knee, plus the various treatments available to help you recover.
Some amount of fluid around your knee is necessary — it helps cushion your bones and keeps the joint limber. But if too much fluid accumulates, it can lead to an effusion (or an abnormal collection of fluid between tissues of the body) that can cause pain, swelling, and stiffness.
Here’s everything you need to know about fluid in the knee, including why it builds up and what to do about it.
What Is a Knee Effusion?
A knee effusion occurs when the joint swells with more fluid than is normal. This can cause symptoms such as:
Pain
Trouble moving the joint
Fever
A feeling of heaviness in the joint
Redness
Stiffness
Warm skin
What Causes Fluid Buildup in the Knees?
There are a number of reasons you can develop fluid in your knee. The most common causes are:
Infection
Inflammation, often from conditions like arthritis or gout
Overuse
Injury
A tumor in the area
Is Fluid in the Knee Serious?
The seriousness of the fluid buildup depends on the cause of the effusion. You should visit your doctor if you experience severe pain, an obvious injury, or experience any of the following issues:
Fever
Inability to move your joint
Inability to bear weight on your joint
Loss of feeling in your joint
If you have a chronic underlying condition like arthritis or gout, you might not be able to get rid of effusions for good. Fortunately, though, there are treatments to help ease or prevent excess fluid in the knee if you regularly deal with this issue (more on that later).
How Do You Get Rid of Fluid in the Knee?
The best treatment for an effusion depends on the cause. Here are some of the most common solutions:
Rest and Elevate
One of the main ways to reduce fluid in the knee joint is to rest, especially if the cause of the effusion is overuse or injury. That means holding off on activities and perhaps even using support while you walk, such as a cane or crutches.
While you’re resting, elevate your leg to further reduce knee swelling. Elevating your knee above the level of your heart, preferably with the knee straight, can help fluid drain from the joint.
Apply Ice
Applying ice or a cold compress to your knee may help reduce pain and fluid buildup, particularly if you have an injury or arthritis. When using ice or freezer packs, don’t place them directly on the skin — instead, wrap them in a towel before placing them on your knee.
Wear a Knee Brace
In some cases, a knee brace can help stabilize and heal your joint. For instance, if you have an effusion due to a ligament injury, you may benefit from a wrap.
Talk to your doctor before trying a brace or wrap, though, to make sure it’s the right approach to reducing fluid in your knee.
Consider Over-the-Counter Medications
Over-the-counter nonsteroidal anti-inflammatory drugs like ibuprofen (Advil, Motrin) or naproxen (Aleve) may also help relieve the pain in your knee, especially if it’s the result of an injury or arthritis. If over-the-counter medications are ineffective, ask your doctor about prescription medications.
If your knee effusion is due to rheumatoid arthritis or gout, your doctor may prescribe medicine specific to those conditions. Similarly, an effusion caused by septic arthritis or an infection may require antibiotics.
Drain the Fluid
In certain cases, your doctor may recommend removing the excess fluid in your knee by inserting a needle into the joint (a procedure called arthrocentesis). This can help reduce swelling and may also help determine the cause of the effusion, as your doctor will likely send a sample of the fluid to the lab for analysis.
Try Healing Exercises
Another potential method for getting rid of fluid in your knee is through physical therapy exercises. Your doctor may recommend this treatment if your effusion is the result of an injury and you need to rebuild strength and mobility in the area.
The exercise you do ultimately depends on the type of injury you have. Talk to your physical therapist to get a customized set of knee exercises.
Massage Your Knee
Massage can be an effective way to relieve pain and inflammation from osteoarthritis-related knee trouble.
How to massage fluid out of your knee depends on the severity and cause of the effusion, so follow your doctor or physical therapist’s instructions for the best, safest technique.
The Takeaway
Excess fluid in the knee joint causes pain, swelling, and stiffness, and can stem from various causes, such as injury, overuse, infection, or underlying conditions like arthritis.
For mild cases, rest, elevation, and cold therapy can help. However, severe pain, an inability to move or bear weight, or a fever warrant immediate medical attention.
Solutions range from medication and physical therapy to braces or fluid drainage, depending on the root cause of the effusion. It is important to see a doctor to get a diagnosis and instructions for proper care.
