Water in the knee


If liquid or water collects in the knee, one usually speaks of a so-called Knee joint effusion.

The reason for this is that the liquid mostly within the capsule of the Knee joint is located, whereby it is by no means water in the actual sense, as it is colloquially referred to as such, but rather normal or changed, the body's own synovial fluid (Synovia), pus or blood.

A distinction can be made between one acute knee joint effusion and one chronicthat exists for a long time.

root cause

The cause of fluid build-up in the Knee joint or in the knee joint capsule is generally considered in the Increased production of synovial fluid (Synovia) of specially designed cells within the capsule (Synovial membrane), which accumulates because it cannot be adequately absorbed. So more is produced than can be transported away.

If this excess production occurs acutely, i.e. suddenly within a period of 3-14 days, it is usually through trauma justified. These include, for example, a Cruciate ligament tear, a popping out of the kneecap (Patellar luxation) from their natural position or Damage to the menisci.

Of the effusion is created as Reaction to the knee injury, he being both from normal Synovial fluid, but also bloody can be, since small vessels in the knee joint can always rupture during a trauma.

The water collects in the knee chronically, than over a longer period of time, usually play Infections an overriding role that can cause inflammation in the knee joint and stimulate the synovial membrane to produce more.

In the worst case scenario, an underlying infection can lead to a Collection of pus in the knee joint to lead (Empyema), which needs to be opened and emptied promptly.

Other causes of chronic knee effusion, especially in the elderly, can be an existing one arthrosis, one Gout disease or well-known rheumatic diseases be.

For younger people, one can also Overloading the knee joint through too much Sports or Incorrect loads during sports activities to a so-called Irritation pour lead, just like this one after Operations can arise in the knee area.

After operations

To operational interventions at the Knee joint can affect the affected patient reactive knee joint effusion form, which can persist for a period of 2-3 weeks.

The cause of this is, on the one hand, the result of the operation Irritation of the joint mucosa, which reactively forms more joint fluid, on the other hand it can often also after the operation Secondary bleeding come.

As a rule, the effusions after operations are accordingly harmless clear joint fluid effusions or Bruisingwho through complaints relieving punctures can be easily remedied, but in most cases go away on their own.

However, if there is one during the operation Infectious complication of the knee joint, this can manifest itself with an inflammatory effusion and in the worst case in a Collection of pus in the knee joint pass over.

Appointment with a knee specialist?

I would be happy to advise you!

Who am I?
My name is dr. Nicolas Gumpert. I am a specialist in orthopedics and the founder of .
Various television programs and print media report regularly about my work. On HR television you can see me every 6 weeks live on "Hallo Hessen".
But now enough is indicated ;-)

The knee joint is one of the joints with the greatest stress.

Therefore, the treatment of the knee joint (e.g. meniscus tear, cartilage damage, cruciate ligament damage, runner's knee, etc.) requires a lot of experience.
I treat a wide variety of knee diseases in a conservative way.
The aim of any treatment is treatment without surgery.

Which therapy achieves the best results in the long term can only be determined after looking at all of the information (Examination, X-ray, ultrasound, MRI, etc.) be assessed.

You can find me in:

  • Lumedis - your orthopedic surgeon
    Kaiserstrasse 14
    60311 Frankfurt am Main

Directly to the online appointment arrangement
Unfortunately, it is currently only possible to make an appointment with private health insurers. I hope for your understanding!
Further information about myself can be found at Dr. Nicolas Gumpert

With meniscus involvement

With a lesion of the Internal or external meniscus of Knee joint, in addition to pain at the edge of the knee joint, there is one swelling and one overheat of the knee, also to one Knee joint effusionthat arises reactively due to the damage.

Not all meniscal lesions are mandatory in need of surgery, small damage can also conservative with the help of Immobilization and Medication be treated.

However, causes the lesion persistent discomfort and leads them to one Knee joint effusion, which may even recur again and again due to repeated punctures, surgical intervention is then the method of choice.

Usually the meniscus damage is under a Knee reflection (Arthroscopy) Fixed.

As with other knee operations, there may be a postoperative Irritation pour come that over 2-3 weeks can persist and through the Irritation of the joint mucosa was provoked during the surgical procedure.

During pregnancy

During the pregnancy it can become one especially towards the end Overloading the knee joint come, which is conditioned by the fact that with the growing up of the child in the womb and the steady Weight gain the knee is also increasingly under pressure.

Similar to one overload During sporting activities, pregnancy can therefore also lead to a so-called Irritation pour which is caused by a reactive excess production of synovial fluid in the synovial membrane.

In addition, there is the increasing weight of the child Pressure on the vena cava exercises in the small pelvis, so that the return of the venous blood to the heart, for which it is normally responsible, is difficult and, among other things, to Fluid retention in the knees can come (also in hands and feet).

With the child

Also at Children can definitely Knee joint effusions occur, but the cause at such a young age is usually the underlying Knee inflammation (so-called Arthritis).

On the one hand, these can get through acute infections develop with bacteria, but also through chronic bacterial infections, such as the Lyme disease.

But also as part of a so-called Rheumatic fever, one reactive arthritis/ Joint inflammation after an infection with streptococcus bacteria, it can lead to a Effusion come in the knee joints.

The same also applies to infections with certain Viruses (Parvo-B19, Rubella, EBV etc.) or Gastrointestinal bacteria (Shigella, Salmonella, Campylobacter).


An accumulation of fluid in the knee joint leads primarily to a visible swelling of the knee, the extent of which depends on the volume. The pressure of the fluid inside the joint capsule usually irritates the nerves located in it, so that pain in the knee joint can occur.

These can occur at rest, during exercise or when pressure is exerted on the knee.

This - just like the mass of the fluid in the joint space - can lead to significant restrictions on movement in the knee joint, so that bending the leg is only possible with discomfort.

A general feeling of tension in the knee joint can also be noticed, which is due to the general swelling.

If the fluid becomes infected (e.g. by bacteria), in addition to swelling and pain, the other typical signs of inflammation can also become noticeable, including reddening and overheating of the knee joint.

You might also be interested in: Chronic knee pain


Knee diagnostics

Depending on how much fluid there is in the knee joint, a knee joint effusion can already be noticed with the naked eye or at the latest during the clinical examination of the patient by a doctor.

For example, if more than 50 ml of fluid has accumulated in the knee joint, a so-called "dancing patella (Kneecap) ”.

The examiner can feel an elastic spring back of the kneecap (positive ballottement) with frontal pressure and feel that the kneecap floats on the effusion.

A further diagnostic sign in the physical examination can be a slight bulge on the outside of the knee joint if the examiner expresses both the upper part of the joint capsule and the part of the joint capsule on the inside of the knee joint. This second method can be used from a liquid volume of 10 ml.

A puncture, i.e. taking fluid from the knee joint using a puncture needle, can always be used when a fluid sample should provide information about the quality of the fluid and whether there are pathogens in it that could possibly cause or influence this accumulation can.

Read more about this at: Knee puncture

In addition to the physical examination, imaging procedures can also objectify an accumulation of fluid. In addition to a simple ultrasound examination of the knee, X-ray, computed tomography and magnetic resonance tomography recordings are also able to show the "water" in the knee.

In individual cases, a blood sample can also be taken for further diagnostic clarification, so that increased inflammation parameters can be detected in the laboratory, for example if an infection is the trigger of the effusion.

What can you do? - therapy

In order to effectively counteract the "water" in the knee, the cause of the knee joint effusion should generally be investigated.

Most of the time, the effusion can only be removed if the underlying trigger is removed (e.g. cruciate ligament or meniscus lesions).

The generally applicable therapy methods include above all elevating the affected leg or knee or even temporarily immobilizing the joint, which helps the body to break down and reduce the fluid in the joint capsule on its own.

Cooling the knee with a cooling pack or cold compresses / compresses can also help.

However, if the accumulation of fluid persists or leads to severely impaired functional restrictions in the knee joint, joint puncture can also help in some cases.

This involves withdrawing fluid from the joint capsule, which is carried out by a doctor using a puncture needle. However, if the accumulation of fluid occurs again after a puncture has been performed (Relapse), the cause should be investigated more closely.

Read more about this at: Knee puncture

If there are signs of inflammation so that an infection is suspected to be the cause of the fluid accumulation, anti-inflammatory drugs can also be used, which can sometimes also reduce fluid levels (e.g. ibuprofen, diclofenac).

A purulent knee joint effusion (empyema), on the other hand, must always be relieved, which means that the joint must be surgically opened and the pus becomes, otherwise it would lead to the destruction of the joint.

Quark wrap

As a supportive home remedy, the use of cold quark compresses can alleviate the symptoms of knee joint effusion and sometimes even reduce the effusion.

Various ingredients in quark, but especially the lactic acid bacteria, can inhibit the release of inflammatory substances.

In addition, the damp cold has a pleasantly cooling, decongestant and pain-relieving effect.

If the quark dries up during the treatment, it stimulates blood flow, which supports and accelerates the regeneration and fluid breakdown process in the knee joint.

A cool quark topping is prepared by applying normal quark to a cloth or compress. The quark cloth is then placed on the affected area, but there should be at least one layer of fabric between the skin and the quark. Finally, the quark pad can be fixed with a light bandage.

The wrap can / should be removed again when the quark has dried up. The procedure can be repeated several times a day.


The use of Anoint In the case of an existing knee joint effusion, it can only be useful if, in addition to the Knee swelling also signs of inflammation noticeable so that an infection of the effusion fluid can be assumed.

They are then usually used Ointments with anti-inflammatory content (e.g. Voltaren ointments with the anti-inflammatory agent Diclofenac), which is applied to the knee using a bandage.

However, this topical application of anti-inflammatory ointments is always less effective than the oral intake of anti-inflammatory drugs, since the systemic distribution of the active ingredient Reaches the scene better and more effectively via the blood than local application via the skin barrier.