Doctors speak of a joint effusion (ICD code: M25.4) when there is an increased accumulation of fluid in a joint space. This increased accumulation of fluid is often visible externally as swelling, but the joint effusion usually disappears on its own.
People affected by joint effusion often complain of pain in the joint in question. If the accumulation of fluid remains undetected for too long and is not treated in time, it can lead to consequential damage. The affected joint can become overstretched or unstable.
© freshidea / Fotolia
The synovial fluid is essential for the functionality of every joint, no matter how small. Normally, we don't even feel that we have synovial fluid. We only notice it when there is too much or too little of it. The amount of synovial fluid is controlled by the joint. In a healthy joint, it is constantly produced by the synovial membrane (synovial membrane in medical terms) and is also broken down again to the same extent.
The joint fluid has the following tasks, among others:
- it serves as a lubricating film for the joint surfaces
- it reduces friction and shocks and
- it nourishes the joint cartilage
In a diseased joint, too much synovial fluid is usually produced. A disruption in the breakdown of the synovial fluid and thus an increase in its quantity is an absolute exception.
In principle, joint effusion can occur with any change in the joint. Such changes to the joint include
- Signs of wear and tear on the joint surfaces,
- inflammatory diseases and
- injuries (traumas).
However, increased strain, e.g. after a marathon run, can also cause joint effusion.
The diseases and stresses mentioned above cause irritation of the synovial membrane (synovial membrane in medical terms), to which the body reacts by increasing the production of synovial fluid. Physiologically, this process is perfectly correct, as the fluid performs various important functions in the joint capsule and is intended to protect the overloaded joint surfaces.
Depending on the cause of the joint effusion, there are several different types:
- chronic
- septic and
- traumatic joint effusion
These differ in appearance and consistency:
- chronic: clear, light-colored, viscous
- septic: yellow, cloudy, thick and viscous
- traumatic: reddish due to blood admixtures
Therefore, the examination of the joint fluid can already provide important information about the cause and the mechanism of development.
What is the most common form of joint effusion?
Chronic joint effusion is the most common form. In this form of joint effusion, the body produces more joint fluid (synovial fluid), which accumulates in the joint. This form of joint effusion is also referred to as serous joint effusion, as increased serum leaks into the joint due to the irritating situation. Serum makes up a large proportion of joint fluid and is produced in greater quantities in chronic effusion. It is often a harmless finding without serious underlying disease or damage to the joint. The cause in these cases is overloading.
In some cases, however, there is also a connection with rheumatic diseases such as rheumatoidarthritis or joint wear and tear (osteoarthritis). Metabolic diseases such as gout, blood clotting disorders or tumor diseases are also risk factors.
Sports injuries and other traumas, on the other hand, usually lead to joint bleeding and so-called traumatic joint effusions. Bloody joint effusions are observed in particular when there is additional damage to important structures in the joint cavity, e.g. tears in inter-articular discs such as the meniscus in the knee joint, cartilage shearing or tears in muscle attachments. Bloody joint effusions are referred to in medicine as hemarthrosis.
Septic joint effusions, i.e. inflammations in the joint capsule with pathogens, are a very serious and severe condition that is fortunately extremely rare. Septic joint effusions can occur as a complication after an operation, for example. However, the puncture of a chronic joint effusion can also lead to the formation of a septic effusion if pathogens enter the joint through the puncture (= puncture) and infect it. For this reason, the indication for puncture is extremely critical. Doctors also refer to purulent joint effusions as pyarthrosis or joint empyema.
The most common symptoms or complaints of a joint effusion include pain and a feeling of tightness. In addition, there is often visible and palpable swelling in the affected joint. The swelling also makes the joint less mobile. The swelling also often causes the skin over the joint to tighten and the contours to change.
The phenomenon of the so-called dancing patella (kneecap) is also frequently observed with joint effusion in the knee joint. In this case, the kneecap floats on the accumulated fluid. In some cases, the accumulation of fluid can even be felt.
If the joint effusion is caused by inflammation, symptoms such as fever, chills, overheating and reddening of the joint as well as a general feeling of illness may also occur.
© grieze / Fotolia
As with most diseases, the first and most important examination method for joint effusion is to take a medical history. By asking specific questions, the cause of the joint effusion can often be determined or narrowed down to a few of the many possibilities. Possible questions include
- Where is the pain?
- Does the pain get better or worse with exertion?
- How severe is the pain?
- How long has the pain been present?
- Was there an accident?
- Has the joint been punctured or injected?
- Is there or has there been a fever?
- How pronounced is the swelling of the joint?
This is followed by a physical examination and, in particular, an examination of the affected joint.
An ultrasound examination (sonography) is also one of the most important measures at the beginning of the diagnostic process. The advantages of sonography are that it is quick, has no side effects and can be repeated as often as required. Joint effusions can be reliably visualized and it is usually possible to differentiate between serous, bloody and purulent effusions.
Additional blood tests can provide information about inflammation or diseases such as gout.
If these examinations have not yet produced a clear result, additional imaging procedures such as X-rays, computer tomography (CT) and magnetic resonance imaging (MRI) can be ordered. Compared to sonography, however, these examinations are more complex and, with the exception of magnetic resonance imaging, can only be carried out using X-rays and contrast media. This can sometimes lead to serious complications.
Joint puncture and arthroscopy (joint endoscopy) are performed if previous examinations have not yet led to a precise diagnosis. Both procedures are invasive methods, as they create access to the joint and therefore interfere with the "integrity" of the body. These invasive procedures should therefore only be carried out if they are essential to clarify the diagnosis or are already being used as treatment. During arthroscopy, joint cartilage can be smoothed and injured structures (e.g. meniscus) can be sutured and reattached. By puncturing the joint, joint fluid can be removed and the pressure pain reduced. The fluid is then often examined in the laboratory for bacteria, cell material and other components.
Joint endoscopy for the precise diagnosis of joint diseases. © bilderzwerg / Fotolia
Should every joint effusion be punctured?
In the case of an effusion, the joint is often punctured with long, thick needles in order to remove fluid and thus initially relieve the swelling and pain. A puncture can also be used to examine the joint fluid under a microscope and look for the cause of its formation. Normally, this synovial fluid is clear and viscous. In the case of a joint effusion, it can become cloudy, watery, bloody or purulent.
However, the puncture can also result in a worsening of the symptoms, increasing the joint pain and allowing bacteria and other pathogens to enter the joint cavity. The latter can have very serious consequences and can even lead to purulent joint effusion (joint empyema). The latter is a very serious condition and usually requires surgical treatment. A joint puncture should therefore only be performed in exceptional cases, namely when a microscopic examination of the joint fluid is indicated. A simple puncture just to reduce swelling and pain is contraindicated in view of the possible complications mentioned above.
The treatment of a joint effusion depends very much on its cause. Although a puncture provides rapid relief, it is not suitable for permanent treatment. In most cases, the joint fluid forms again quickly after the puncture and the symptoms recur.
If the joint effusion is due to overloading, temporary rest of the joint is recommended, which leads to a significant reduction or complete disappearance of the effusion after just a few days.
If signs of wear and tear are the cause, measures such as rest can also be helpful. Other measures such as cooling, compression and, in particular, movement exercises are often also used successfully.
Painkillers and anti-inflammatory medication are prescribed to relieve the pain.
A purulent joint effusion(joint empyema) is an emergency! Action must be taken quickly and the accumulation of pus caused by pathogens must be removed by means of surgical opening, suction and irrigation of the joint cavity. This is particularly important in the case of previously operated joints and especially with artificial joint prostheses.
The prognosis for a joint effusion depends very much on its cause. Simple overloading or even injury to small structures in the joint cavity generally do not lead to any permanent impairment and the joint effusion recedes without consequences. The situation is different in the case of a purulent joint effusion when a joint prosthesis is in place. This can have serious consequences and even lead to the loss of the affected limb. For this reason, the indication for implanting an artificial joint prosthesis is strictly defined and the necessity for this is always thoroughly examined. To avoid consequential damage, visit the orthopaedist as early as possible if you notice swelling in a joint.
