Excess fluid around the joint can cause swelling, pain, and stiffness.
Common causes of fluid build-up on the knee include:
What Is Cartilage?
Cartilage is a flexible tissue on the ends of bones that allows bones to glide smoothly over each other.
An illustration by Jessica Olah for Verywell Health
Injuries
Injury is the most common cause of fluid on the knee in active, healthy people.
Infection
Infections can also cause fluid and pain.
They can happen as a complication from surgery or inflammation, and can be due to dangerous bacteria.
Infections in the joint can be extremely painful and come on rapidly.
They require prompt medical care.
Does Draining Fluid From Knee Hurt?
Local anesthetic (one applied directly to the knee) should keep joint aspiration from being very painful.
You may have some discomfort for a few days afterward, but it shouldn’t be severe.
Injections of corticosteroidsinto the joint can help reduce pain and inflammation from injury or arthritic joint damage.
For underlying conditions such as rheumatoid arthritis, typical treatment includesmedications that suppress an overactive immune system.
If at-home treatment methods or any prescribed medications don’t work, tell your healthcare provider right away.
Injuries, infections, and medical conditions such as arthritis can cause this.
Frequently Asked Questions
Yes, fluid on the knee is common after knee replacement surgery.
Expect your healthcare provider to explore various causes, though, including rheumatoid arthritis and infection.
It depends on the injury.
It depends on what’s causing it.
Yes, it can get worse without treatment.
See a healthcare provider right away.
National Library of Medicine.Synovial fluid analysis.
Johns Hopkins Medicine.Joint aspiration.
2019;27(17):e758-e766.
Bunt CW, Jonas CE, Chang JG.Knee pain in adults and adolescents: The initial evaluation.Am Fam Physician.
2018;98(9):576-585.
2021;10(2):158. doi:10.3390%2Fpathogens10020158
