What Causes Fluid on the Knee?

The knees are often one of the first casualties of aging, and oftentimes those wonky joints are caused by a condition called bursitis.

What is bursitis of the knee?

In layman's terms, bursitis of the knee occurs when a small sac of fluid (called a bursa) gets inflamed. Bursae are like cushions that ease the friction and pressure points between all of the connections within your body. All told, there are more than 150 of them, with five surrounding and protecting the knee specifically. Any (or all) of these bursae can become inflamed and cause discomfort. Without proper remediation, that discomfort can morph into severe pain and seriously limit your mobility.
What causes fluid on the knee?
Typically, bursitis knee symptoms gradually present themselves as increased tenderness and swelling in the joint. Your knee may feel warm to the touch, and it can hurt during movements or even while at rest. Just think about all the wear and tear your knee joint experiences over the days and months and years. Such constant usage — especially among adults who work jobs that require repeated kneeling and frequent joint pressure — means a higher probability of strain, irritation and friction.

Bursitis can also occur suddenly, like when you incur a bacterial infection of the bursa or suffer a direct blow to the knee. The latter example is most common in sports injuries; football, volleyball and wrestling are tough on the knees, and long-distance runners can experience inflammation in the "pes anserine" bursa, which is located below the joint on the inner side. Obesity, particularly in women with osteoarthritis, also increases the risk of irritating that pes anserine bursa.

Living with bursitis can range from a minor annoyance to a crippling restriction. There's been a slight uptick in cases due to a lack of general activity during the pandemic: Many people are working from home and some are not as active as they'd like to be, especially during those cold winter months. Whereas bursitis usually isn't totally debilitating, it can cause older adults to find everyday activities like walking, going up and down stairs, sitting for long periods of time and even sleeping uncomfortable.

Will fluid on the knee go away by itself?

Without intervention, it's not likely. You can take some preventive measures to help avoid bursitis flaring up in your knees, such as maintaining a healthy weight to minimize unnecessary pressure on the joint and wearing kneepads during sports or work in order to provide an extra layer of protection. Stretching your legs and giving the knees a good rest are also keys to keeping your knee bursae healthy.

Taking a mild anti-inflammatory or treating your knees with ice packs (or a bag of frozen vegetables) for 20 minutes a few times a day can significantly reduce swelling and inflammation. Knee braces and sleeves also provide valuable joint support and keep swelling down. It's wise to avoid putting undue pressure on the knees while you sleep, so try not to lie directly on the affected leg and instead prop the leg up if possible. And if you're among the majority of adults who sleep on their side, you can wedge a pillow between your knees to offer additional comfort.

How should fluid on the knee be treated?

More severe cases of bursitis require stronger treatments. Steroid injections and fluid draining procedures are common and can be done at your doctor's office. Physical therapy also is a good route for those who suffer persistent bursitis of the knee. It offers patients a chance to learn effective exercises and stretches to build up joint strength and make the area more flexible.

How long does bursitis last?

With the right treatment, bursitis of the knee often dissipates quickly. Even when home remedies don't work and a visit to your doctor is necessary, the swelling and discomfort usually abate within a few weeks.

At Reid Health Orthopedics and Spine, our family of amazing providers and specialists is committed to your orthopedic care and comfort. If you're having trouble managing your bursitis of the knee symptoms on your own and prefer a consultation with any of our industry-leading practitioners, we'll be right beside you to address your concerns and get you on the road to recovery.