Knee effusion is the clinical term for excess fluid building up in or around the joint of the knee. It is also called water on the knee. An effusion is a painful condition that can limit mobility and function of the knee.
There are many different causes for a knee effusion. Most often it is caused by a knee injury such as a broken bone, tear of the ligament, or any injury from overuse of the joints in the knee. Arthritis can also cause the condition, as it can cause joints to swell. Bacterial infections, tumors, cysts and gout can all also lead to inflamed knee joints and knee pain.
Sometimes a knee effusion can be little more than an annoyance that is temporary and goes away on its own or with medication, other times the pain from water on the knee can be so severe that its impossible to put weight on it. The knee injury will usually inhibit mobility, with the joint becoming very stiff. If there is enough excessive fluid in the knee it may even be substantially larger than the other knee. Joint swelling from water on the knee is most prominent around the bones of the knee.
A knee effusion can happen to anyone, but certain groups are more prone to the injury than others. Sports like basketball and baseball, where quick changes in direction are involved, can contribute to a knee injury. Being overweight causes excessive pressure to be placed on the joints, which can lead to a knee injury such as this. While people of any age can get a knee effusion, it is more common in those over 55 years old.
Treatment for a knee effusion can vary depending on the severity of the inflammation. If the condition is caused by an infection then all that might be needed to treat the condition is a prescription of antibiotics. Other times a doctor might prescribe anti-inflammatory medication to help reduce swelling and promote healing of the knee.
In more severe cases of water on the knee surgery might be required. In extreme cases the affected joint may need to be replaced entirely with a knee replacement surgery. Most often though, less drastic measures are needed. Sometimes all that needs to be done is a draining of the fluid. Surgery to go into the knee and repair the affected areas while leaving the rest of the knee alone is another option.