The orthopedic disorder of the knee known as Knee effusion or commonly called “Water on the Knee”.

Orthopedics is a branch of medicine that deals with the treatment of the disorders or injuries of the bones, joints, and associated muscles. This article will focus on a condition or disease of the knee known as Knee effusion or much more commonly called “Water of the Knee.” The knee joint is made up bone, ligament, cartilage, fluids. Tendons and muscles help the knee joint move. When any one of these structures is damaged or diseased, it can cause pain and difficultly walking. Knee problems and injuries occur in people of all ages, which can interfere with standing and walking.

Some of the main causes of “water on the knee” or rather the cause of the swelling can include, injury to the knee ligaments or a traumatic accident in which after the body’s natural reaction is to flood the knee with a protective fluid, arthritis or an underlying disease or condition like, Cysts, Gout, Infection, Kneecap Bursitis, Over use or Tumors. Now the type of fluid that accumulates around the knee which is the cause of the swelling depends on the condition, disease or traumatic injury that is causing the swelling. In most cases the swelling can be cured easily.

Signs and symptoms of knee effusion (water on the knee) largely depend on the cause of excess fluid built-up in the knee joint. One of the most common symptoms of this condition is knee pain, as in Osteoarthritis usually presents when the knee joints are bearing weight. Pain typically eases with rest however some patients experience severe knee pain while others have no pain at all. In some cases one knee may swell much larger than the other one which may
present with or without pain. Stiffness is a also a common symptom when the knee joints “swells” with excess fluid, the knees may become difficult to bend or straighten in certain areas or the knee as a whole, fluid can also show under the knee when straightened as well. Bearing weight on the knee may be impossible with unbearable pain being present.

The diagnosis of knee effusion can be carried out in a few different ways, such as blood tests to determine if the inflammation is due to rheumatoid arthritis or a crystalline arthritis like joint infection, gout or pseudo-gout. In addition to lab analysis of the joint fluid, blood tests such as a C-reactive protein or uric acid, erythrocyte sedimentation rate (ESR) and a white cell blood count. If Lyme’s disease antibodies are detected forming in the blood that may also be a possible cause of this condition.


Joint aspiration which is a procedure known as arthrocentesis, in which fluid within the knee is withdrawn using a needle syringe and sent to a lab for analysis such as cell count, culture for bacteria and the presence of crystals like calcium pyrophosphate dehydrate crystals which is found in cases of gout.


Complications of this condition can hamper one’s ability to play sports such as basketball, tennis or football, to just walking short distances and also from participation in any activities that require knee mobility.
While treatment of knee effusion depends on the underlying cause of the swelling, there are general measures that usually provide relief, like analgesics, rest, ice and cold compressions and NSAIDS, which can reduce swelling and treat pain.

As stated previously, in most cases of knee effusion the swelling and pain aspect can be resolved with ease depending on the underlying cause. In case of the cause being Gout or Lyme’s disease, treatment for those disorders should clear up the problem in time.


Prevention of knee effusion as stated prior, depends on the conditions of the underlying cause, however certain general safeguards can be applied, such as not putting too much pressure or weight on the knee’s and not overdoing certain exercises such as prolonged running or jumping ,which can cause trauma to the knees causing effusion of excess synovial fluid. Also wearing shoes with sole cushions to absorb the shock of running and long distance walking can also be helpful.

In conclusion, knee effusion though very common can be a very painful and immobilizing experience, with symptoms that are not difficult to treat depending on the various conditions of the cause.

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