What does “water on the knee” mean?
Having a little bit of fluid in your knee joint is normal — it provides lubrication to cut down on friction and promote smooth joint rotation.
But when the joint is injured, infected or affected by arthritis, (particularly inflammatory arthritis), it can take on more fluid than normal, causing the knee to become swollen. This condition is called knee effusion, commonly referred to as “water on the knee.”
The symptoms of knee effusion
Knee effusion typically causes the affected knee to look larger and puffier than a healthy knee. It can also limit knee flexibility and function. You might even have difficulty bending or straightening your knee, depending on how much excess fluid the joint has taken on, and the joint may naturally bend 15 to 25 degrees while the leg is at rest.
When you have knee effusion caused by osteoarthritis, your knee will hurt when bearing weight. When it’s caused by injury, you might have bruising on the front, sides or rear of your knee, and it may be incredibly painful to stand on it. Depending on the cause of your knee effusion, your swollen knee may exhibit no other symptoms, or it may be red, warm to the touch, deeply painful, stiff and difficult to move or put weight on.
What causes water on the knee?
Knee effusion is caused by arthritis or injury to the knee ligaments. The type of fluid that accumulates around your knee indicates the underlying cause. When your knee joint becomes injured, the body’s natural reaction is to surround it with protective fluid to prevent further damage. If it produces too much, knee effusion develops.
The most common traumatic causes of knee effusion are injuries to ligaments, cartilage and/or bones, or from general overuse. Participating in high-risk sports that involve rapid cut-and-run movements, like football or tennis, raise the chances of developing knee effusion. Your knee can even become injured over time if you’re overweight or obese.
Other issues that can lead to knee effusion include overuse of the joint, a torn ligament or torn cartilage, a broken bone, bacterial infection, septic bursitis, arthritis, gout, pseudogout, Osgood-Schlatter Disease, cysts and tumors.
Knee effusion can range from mildly annoying to painfully debilitating. But regardless of the intensity of the condition, it can lead to joint tissue damage, cartilage degradation and bone softening if left alone. That’s why it’s important to take preventive measures and seek treatment if your knee becomes swollen.
How to prevent water on the knee
The best way to prevent knee effusion is to avoid putting yourself in situations where you might injure your knee. That means staying away from activities that involve sudden, jolting movements and staying off rough running surfaces. Keeping your weight in check also helps reduce pressure on your knees.
Sports that are typically safe for knees include walking, swimming, skating, baseball, cross-country skiing and cycling. Stay away from sports like football, sprinting, soccer, rugby, hockey, squash, volleyball, basketball, snow skiing, tennis and jogging. If you’ve decided to participate in these sports despite the risk, be sure to protect yourself by wearing knee pads and stop often to stretch your legs.
How to treat knee effusion
Knee effusion is often easy to treat, and it responds quickly to treatment. Start simple with self-care measures like rest, elevation, ice and exercise. Remember: Only apply ice to your knee for 15 to 20 minutes at a time.
If these self-care measures aren’t working, it might be time to see your doctor. A physical therapist can work with you to strengthen and support your knee, and treatments will vary based on your specific condition.
However, for many, physical therapy isn’t enough, and the extra fluid in the knee has to be removed through a process called arthrocentesis, or joint aspiration. Sometimes, the damage is fixed via arthroscopy, a procedure where a small tube is inserted into your joint to help repair damage.
In some cases, doctors prescribe a series of corticosteroid injections, non-steroidal anti-inflammatory drugs or antibiotics. The goal of these treatments is to reduce inflammation or treat an infection. Finally, in some severe cases, removal of the bursa sac, knee surgery or joint replacement might be the answer.
Are you concerned that you might have knee effusion? Our skilled physicians are here to help you diagnose and treat your knee pain using minimally invasive surgical techniques. If so, schedule an evaluation with us today by submitting an online form or calling one of our friendly Patient Care Managers at 210.880.3823.