Knee Effusion

The knee joint is surrounded by a capsule, and inside this capsule there is a fluid that lubricates the joint, called synovial fluid. The normal volume of synovial fluid found within the knee is 3.5 mL, and an increase in volume is characterized by joint effusion.

Joint effusion is a sign observed by the doctor during the orthopedic evaluation and is common in several situations, such as:

• Cartilage injury,

• Synovitis,

• Arthritis,

• Ligament injury,

• Meniscus injury,

• Osteoarthritis,

• Rheumatism.

The capsule surrounding the knee joint has numerous nerve endings that capture information and send it to the brain. Once a significant joint effusion occurs, the joint capsule stretches, and these nerve endings send information to the brain. All of this can cause knee pain, a symptom often associated with joint effusion.

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Increased intra-articular fluid volume in the knee can also cause mechanical blockage of knee movement and, consequently, difficulty flexing and extending the knee. In some specific situations, it may be necessary to drain the excess fluid to relieve pain and restricted movement, as well as to send the fluid for analysis.

If you notice an increase in knee volume, it's worth seeing an orthopedic doctor for a thorough evaluation and to rule out any more serious problems!

Find out more in the video below: