Fluid in Knees

Fluid on the knee, also known as "water on the knee" or knee effusion, is the accumulation of fluid around or in the knee joint. Fluid in the knee is usually accompanied by knee pain and loss of range of motion, making it difficult to walk or undergo other physical activities. It can even make it difficult to sleep. Read below for more information about fluid in knees.

Types of Knee Fluid

There are several types of fluid that may be found in the knee.

Blood - If the fluid in knee is an excessive amount of blood, it is usually due to a recent injury.

Joint Fluid - Joint fluid helps lubricate the knee joint as it is used. Certain conditions may cause the body to produce an excess of joint fluid, causing knee effusion.

Other Body Fluids - When areas of the body are injured or inflamed, the body's natural reaction is for that area to swell with fluids that help combat bacteria and to promote healing.

Common Causes of Fluid In The Knee

There are various issues that may cause fluid in knees. Here are some of the most common:

Knee Trauma or Injury - Trauma occurs when the knee joint is impacted from an outside force, resulting in injury to the knee. The type of fluid to enter the knee from a traumatic injury is usually blood or excess joint fluid, though other types of fluid in the knee may be present. The most common forms of knee injury to cause fluid in knees are:

  • Meniscus Tears (Cartilage Tears)
  • Broken Bones
  • Bone Fractures
  • Ligament Injuries, such as ACL Tears
  • Overuse Injuries

Arthritis - The are several types of arthritis that may cause fluid on the knee. The most common types that cause excessive knee fluid are:

  • Osteoarthritis - the natural wear and tear of the cartilage around the knee due to aging
  • Rheumatoid arthritis - a chronic inflammation of the joints due to an autoimmune disease
  • Gout - a type of arthritis where a patient's nutritional intake may cause uric acid to build up in the joints

Infection or Inflammation - When areas of the knee are inflamed, this causes the knee to swell with fluid as the body combats the injury or bacteria in the area. A common form of inflammation that causes fluid in knees is bursitis. Bursa are cushioning sacs around the body which when inflamed may cause swelling or excess knee fluid.

Diagnosing a Fluid in the Knee

Visually, a knee with fluid will usually look swollen and puffy. If your physician suspects that fluid in the knee may be an issue, he or she may extract some fluid from the knee using a sterile syringe to assess what type of fluid is present. A lab test may be requested to test for the presence of infection or other types of issues. Your doctor may also suggest an imaging test, such as X-ray (to check for broken, fractured or dislocated bones), MRI (to check for ligament injuries) or ultrasound (to check for arthritis, bursitis or tendon and ligament injuries) which will help him or her evaluate the situation.

Treatment for Fluid in Knees

As with any injury, it's important to consult your doctor for the appropriate treatment for your situation. Here are some treatments and pain management options you may expect for fluid on the knee:

Aspiration - Your doctor may drain the knee to relieve the pressure of the knee fluid. If blood is present, then it is often sent to the lab to analyze the fluid to ensure that infection is not present. The knee may continue to fill with fluid after being aspirated.

PRICE Method - If knee trauma or injury is the cause of the knee fluid, then your doctor may recommend that you use the PRICE method of Protection, Rest, Ice, Compression and Elevation. The combination of these is often used as first aid treatment to minimize fluid in the knee after a traumatic injury. (Note: For icing or cold therapy, check out these cold therapy products.)

Medications - There are different types of medications that may be used to treat the excess of knee fluid, depending on the cause of the issue. For example:

  • Over-the-counter medications - Pain medications such as ibuprofen or aspirin may be used to help reduce inflammation
  • Steroids - These may be taken orally or injected directly into the knee joint. This may be used if over-the-counter medications are not effective at reducing pain.
  • Antibiotics - If your knee fluid is caused by infection, then antibiotics may be necessary to fight the bacteria

Surgery - If the above methods do not work, or if your injuries/condition is severe enough, there are some cases where your physician may recommend surgery. Typically the types of surgery will be:

  • Knee Arthroscopy - A few small incisions will be made and the doctor will perform minimally invasive surgery to repair damage to the knee using a tiny camera.
  • Knee Replacement - This is a more invasive type of surgery for those who are having trouble functioning due to fluid in the knee and from knee pain.

Your doctor may suggest a combination of the above treatments in order to reduce fluid in the knee. For more information about knee effusion, check out our article on swollen knees.