Fluid in the knee

Fluid in or around the knee joint is common. In most cases, this is a direct response of the body to an injury or an inflammatory reaction. The medical term is knee effusion.

How does fluid build up in the knee?

Fluid in the knee is usually a sign that there is damage. Examples include a sprained ligament, a torn meniscus, a torn cruciate ligament, or a dislocated kneecap. These are all examples of injuries in which fluid in the knee is one of the first features. The knee feels unstable and the pain increases with movement and loading of the knee.

Because of the fluid in the knee, it is not possible, or not fully possible, to bend and straighten the knee. The combination of fluid in the knee, warmth, redness, and pain at the front of the kneecap may indicate joint inflammation or bursitis of the knee.

The combination of morning stiffness and/or crackling sounds (crepitus) when moving the knee and an older age points to osteoarthritis. In this, the articular cartilage has decreased in quality and thickness.

How is the cause of fluid in the knee diagnosed (diagnosed)?

The diagnosis is made based on an interview between the physical therapist or doctor and the patient about how the symptoms started and multiple physical tests. These tests are intended to detect damage to ligaments, meniscus, or cartilage.

In case of doubt, it may be necessary to make an X-ray or an MRI scan to determine the cause of the swollen knee. When the knee is very swollen, it is often slightly bent. This is the 'stand van Bonnet'. This position is the least painful and gives the swelling the most space.

To further examine the fluid in the knee, a doctor can perform a joint aspiration. Via a needle, the doctor draws the fluid from the knee, which is then examined for markers of inflammation. A joint aspiration often provides immediate pain relief. After all, the fluid is gone or reduced. Unfortunately, this is usually only short-lived and the fluid returns as long as the cause has not been resolved.

Treatment of fluid in the knee

To reduce the fluid in the knee, it is wise to load the knee less. Taking regular rest and elevating the leg help to reduce pain and swelling. As soon as possible, it is good to gradually increase the load again.

Once the cause of the fluid in the knee is clear, treatment will start. In the case of a joint inflammation or bursitis, anti-inflammatory drugs and rest are usually prescribed. In damage to the ligaments or the meniscus, surgery is sometimes needed to restore the function of the knee.

If no surgery is needed, treatment consists mainly of exercise therapy with the physical therapist. The exercises then aim to strengthen the muscles around the knee. The goal is to improve the function of the knee joint.