What Causes Water on the Knee?

What Causes Water on the Knee?
Water on the knee is the layman’s term for a medical condition called knee effusion. Knee effusion is characterized by swelling of the knees, either in one or both legs, and knee pain. Knee effusion happens for one of three reasons: an injury, a disease or overusing the knees.

Dr Dan Albright knee painWater on the knee is the layman’s term for a medical condition called knee effusion. Knee effusion is characterized by swelling of the knees, either in one or both legs, and  knee pain. Knee effusion happens for one of three reasons: an injury, a disease or overusing the knees.

Causes of Water on the Knee

Knee effusion occurs when the tissues around the knee joint or the tissue surrounding the joint fill up with fluid. Different fluids can fill these spaces depending on the cause. The fluid could be blood, synovial fluid or even uric acid. Here are some ways that an individual can develop knee swelling.

1.   Knee Injuries

People are injured all the time in their daily lives. When a person falls or gets involved in an accident, they tear muscles and ligaments or bones may be fractured. These injuries can cause knee pain and swelling. As a result water on the knee may develop in one of two ways.

The first way is that broken bones could interfere with the blood vessels in a person’s leg. That, in turn, results in bleeding within the knee joint. Over time the blood accumulates and causes the knee to swell. The second way is an accumulation of synovial fluid (a liquid excreted to maintain the joint's smooth motion).

2.  Arthritis

Osteoarthritis and rheumatoid arthritis are conditions that typically affect older adults. When a person with arthritis overuses their knees, the glands in the joint secrete more fluid (think lubricant) than usual. The fluid builds up over time,and the individual develops knee effusion.

3.  Gout and Pseudogout

Both gout and pseudogout lead to accumulation of crystals within the knee joint. When any fluid seeps into the joint, it forces the joint to expand and results in knee swelling, accompanied by knee pain.

4.  Prepatellar Bursitis

Some injuries are chronic; they take a long time to manifest and can lead to bursitis. Bursitis is when fluid from the knee joint starts accumulating in surrounding tissue. The result is that the tissue swells, leading to knee effusion.

5.  Tumors

As tumors grow in the knee joint, they compress surrounding tissue and blood vessels, making them build up fluid and therefore swell.

It is not necessary to see a doctor immediately for mild knee pain.  Elevating and icing the knee and taking over-the-counter pain relievers (Advil, Tylenol, etc.) is usually all that is needed.  If there is severe pain, pain and swelling do not respond to home care or the knee is red and warm to the touch then see a doctor.

Tests may be needed to determine the cause of the fluid build-up.  Once the cause is determined, then the doctor can prescribe the proper treatment.  If knee effusion is left untreated, permanent damage to the knee could result.

For more information, contact Dr. Dan Albright at 919-863-6808.