Fluid on the knee is a common issue that many people come to see our team about. Sometimes this is called “water on the knee”, knee swelling or knee effusion. The problem is that knee swelling becomes chronic, and in some cases does not disappear. Is fluid on the knee dangerous? Like many things in medical science, it depends. Read on, and I’ll discuss more about it.
How Does Fluid Accumulate in the Knee?
Fluid accumulation in the knee occurs when the body responds to injury within the joint. The knee joint contains synovial fluid, which lubricates and nourishes the joint. When the knee is injured or inflamed, the production of synovial fluid can increase, leading to an excess that results in swelling. Additionally, bleeding can occur from a tear (e.g. a torn ligament) that can cause the knee joint to swell with blood.
Learn about causes of fluid on the knee.
When to Seek Medical Attention
Signs of Severe Infection
Severe pain, high fever, and an inability to move the knee could indicate a serious infection like septic arthritis. Immediate medical attention is crucial in such cases to prevent further complications. Infection is a serious sign, don’t ignore it. If in doubt, go to A&E or the emergency department. Infection is rare, and most often seen in people with weak immune health, or who have had some kind of invasive procedure on the knee.
Persistent or Worsening Symptoms
If symptoms persist or worsen despite initial treatment, it is essential to seek medical advice. Chronic knee effusion can indicate underlying issues that need professional intervention.
Impact on Quality of Life
If knee swelling significantly affects what we call your ADLs (activities of daily living, including getting up from a chair, walking up and down stairs, getting in and out of a car, etc) then you need to seek advice and support with your doctor, physio or osteopath.
Children with a lump or swelling
Children with unremitting knee pain, night pain, or a hard knee swelling must go immediately to A&E or the emergency department for an X-ray.
Potential Dangers of Fluid on the Knee
Joint Damage
There’s not really evidence that persistent or untreated knee effusion can lead to long-term joint damage. However, chronic inflammation clearly indicates something underlying is the cause and this needs to be investigated. Aspirating the fluid and taking a look at it can be helpful.
Infection and Septic Arthritis
Untreated infections in the knee can spread and lead to septic arthritis, a severe condition that requires immediate medical treatment to prevent permanent joint damage and systemic infection. This requires urgent medical attention, and if you suspect it, go to A&E or ED.
Chronic Pain and Disability
Long-term fluid accumulation can cause chronic pain and stiffness. The ongoing inflammation and pressure on the knee structures can lead to persistent discomfort and mobility issues.
Impact on Mobility and Daily Activities
Knee effusion can significantly impact daily life by reducing mobility and making activities like walking, climbing stairs, and even standing painful and difficult. Get to an expert, get it sorted.
Final Thoughts on Is Fluid On The Knee Dangerous?
In most cases, fluid on the knee is a chronic issue that should resolve on its own, but has not. In the vast majority of cases, having fluid on the knee is not dangerous at all. However, as described above, there are a very small number of cases where it can be dangerous, such as infection or a hard lump in a child’s knee, or unremitting pain in a child’s knee.
In cases of trauma, there can be damage to structures within the knee joint such as a meniscus tear, or a ligament tear. While we would not consider these dangerous, it certainly could be highly problematic.
If you have persistent fluid on the knee, getting the fluid drained is usually recommended and further investigation is needed if the fluid comes back.