Bone edema of the knee

What is knee edema?

Bone edema is an accumulation of fluid within the bone, which can occur, for example, as a result of injuries or bone diseases. The bones on the knee joint are among the most common areas where osteoedema can occur. However, it is not a question of a uniform clinical picture, but a description of conspicuous accumulations of water in the bones, if these are detected by means of an imaging procedure.

Possible complaints that can arise with bone edema on the knee are pain and restricted movement of the joint. It may also be that there are no symptoms at all and the bone edema is only discovered by chance during an examination.


Bone edema of the knee is not a defined disease, but a pathological change in the bone due to water retention, which can be attributed to very different causes. A common group of causes is knee injuries, for example when playing football or other sports.

The destruction of small elements of the bone architecture creates cavities that fill with water and thus trigger bone edema on the knee. Inadequate blood flow to the bone can also be the cause of bone damage and the resulting bone edema.

In addition to these most common triggers, side effects of medication or metabolic diseases are other possible causes of bone edema in the knee. In general, the knee, the largest movable joint in the body, is more often affected by bone edema than most other parts of the body due to the high stress it is exposed to.

You might also be interested in this article: Circulatory disorders in the legs


An accident is one of the most common causes of bone edema on the knee. If the bones are injured, for example during sports or in a traffic accident, small damage to the bone structure often occurs. As a result, small voids can form. Tissue fluid or blood usually collects in this.

In an otherwise healthy person and with normal blood flow to the knee, the damage to the bone will be repaired by the body in the following days and weeks. The destroyed bone substance is rebuilt and the fluid storage responsible for the bone edema is reabsorbed.

Special treatment is therefore usually not necessary in the case of bone edema on the knee as a result of an accident. Targeted treatment is only required if a bone fracture occurs or symptoms persist.

Knee osteoarthritis

In the case of knee osteoarthritis, i.e. a disease of wear and tear of the knee joint, fluid can be stored in the bones due to damage to the articular cartilage. This is known as reactive bone edema of the knee, as it develops as a result of a pre-existing disease of the joint.

In contrast to many other causes of bone edema, the pathological changes due to knee osteoarthritis can already be recognized by a normal x-ray of the joint. The treatment of the bone edema in knee osteoarthritis is usually done through a combination of drug treatment and exercise, for example through physiotherapy. Surgical joint replacement should be considered in the case of severe osteoarthritis.

For more information on this topic, see the article: Knee osteoarthritis

Concomitant symptoms

Various accompanying symptoms are possible with bone edema of the knee, but in some cases there are no symptoms at all. Most often there is pain, which is particularly evident when exercising such as walking. In addition, there may be swelling or reddening of the affected bone.

The pain can also radiate and be felt, for example, in the upper or lower leg. Furthermore, bone edema on the knee can limit the mobility of the joint so that it can no longer be fully extended or flexed. In connection with the pain, this can severely impair the gait pattern.


Pain is the main symptom that can express bone edema in the knee. The pain is typically dependent on the load. This means that the symptoms particularly occur when the affected knee joint is subjected to force, such as when walking. On the other hand, when resting, such as lying down, there is often little or no pain.

This means that diseases that cause pain regardless of stress can be ruled out. However, knee edema can manifest itself very differently in every person. While some sufferers describe the pain as unbearable, others feel almost no discomfort.

In general, stress-dependent knee pain is a common symptom, but it is only in very rare cases caused by bone edema. Muscular causes or joint degeneration diseases such as osteoarthritis are much more common.

Water in the knee joint

Water in the knee joint is also known as knee joint effusion. This occurs mainly due to inflammation of the knee. This in turn can have various causes, such as an infection with bacteria or a rheumatic disease (see; Rheumatism). Bone edema of the knee is usually not the cause of water in the knee joint.

Bone edema describes water retention, but this is usually within the cavities of the bone and not as free water in the knee joint. However, bone damage, for example due to illness, can also result in both bone edema and knee joint effusion. In contrast to bone edema, water in the knee can already be detected by an ultrasound examination.

Read more about this under: Knee joint effusion


The diagnosis of bone edema of the knee is often difficult because the possible symptoms such as pain or restricted mobility are unspecific and in most cases also have other causes. In addition, the bone edema often causes no symptoms for a long time. In order to make a diagnosis, a conversation with the doctor and a physical examination are particularly important at the beginning.

If the doctor thinks it makes sense, he will also arrange for an imaging examination. Usually a conventional X-ray examination of the knee is carried out first. However, if there is a suspicion that bone edema may be present, a reliable diagnosis can only be carried out using an MRI (magnetic resonance tomography). However, since the examination is very complex and expensive and bone edema is a rare disease, an MRI should only be performed in justified individual cases.


Special treatment for knee edema is not always necessary. As a result of an injury, the water retention usually regresses by itself even without therapy. Nevertheless, some supportive treatment measures can be useful in order to achieve faster healing and to prevent secondary damage from occurring.

An essential part of the therapy is often the temporary relief of the knee joint, for example by using forearm crutches and frequent elevation of the leg. Occasional cooling can also alleviate possible swelling. To treat pain and swelling, anti-inflammatory pain pills are often used for a limited time.

Special drugs that act on the bone substance, such as bisphosphonates, can in some cases be a therapeutic option for knee edema. Furthermore, in some cases, it is not physical rest but targeted exercise training that is an important part of the treatment. This promotes blood circulation and stimulates bone metabolism, which should lead to a reduction in bone edema on the knee.

In addition to physiotherapy treatments, joint-friendly sports such as swimming or cycling are suitable. If there is a lack of nutrients that are important for bone metabolism, such as vitamin D or calcium, this should definitely be compensated.


In principle, treatment with homeopathic remedies is a possible alternative for complaints caused by bone edema on the knee. This can be done either alone or in addition to another therapy. Due to the multitude of possible causes and the individually different appearance of the symptoms in the case of bone edema on the knee, no uniform recommendation can be made as to which homeopathic preparation should be taken.

A doctor performing homeopathic treatment will choose the remedy based primarily on the patient's complaints.


Bisphosphonates, among other things, can be used to treat bone edema. This drug inhibits the breakdown of bone substance and is therefore used to treat bone diseases with increased bone loss, such as osteoporosis.

If the osteoedema of the knee is based on a disease in which there is a reduction in bone substance, it can therefore make sense to use bisphosphonates for therapy. However, in most cases of bone edema in the knee, this is not indicated. Due to the possible side effects of taking bisphosphonates, this should only be done in justified cases.

Heat or cold

In most cases of osteoedema of the knee, it makes sense to occasionally cool the joint. However, it may sometimes be appropriate to use heat instead. Cold is especially indicated after an injury or to relieve symptoms such as pain, swelling, or redness.

The application of cold should be chosen, especially if the symptoms are new or increasing. However, if, for example, osteoarthritis of the knee, i.e. a wear and tear disease, is responsible for the bone edema, an improvement in symptoms may be achieved through heat. It is best to ask the attending physician whether and in what form cold or heat should be used for treatment.


A very aggressive treatment alternative for bone edema on the knee is drilling into the affected bone. If the pressure exerted by water retention is so strong that the symptoms cannot be alleviated or the bone substance threatens to die off, drilling is the last resort.

In addition to relieving pressure, the bone should be stimulated to form new cells. However, you should only decide on this procedure after all other treatment options for bone edema of the knee have been exhausted.


In the case of protracted complaints due to bone edema on the knee, acupuncture can be used to achieve pain relief. Compared to treatment with medication, for example, acupuncture is an alternative form of therapy with few side effects. However, it can only alleviate the symptoms and not treat the cause.

If necessary, acupuncture can also be used in combination with other therapy methods. The stimulating stimulus of the needles is intended to stimulate an increased release of the body's own pain-relieving messenger substances.

Read more on the subject below: Acupuncture

Duration of illness

No general statement can be made about the duration of a bone edema on the knee. It depends on the cause of the water retention and can range from a few days to several months. In some cases, bone edema on the knee does not completely recede and it therefore remains permanently.

However, the development of possible complaints is more important than the duration. The initiation or change of treatment should be considered, for example, if the pain continues to increase or does not subside after several days or weeks.

How long will you be on sick leave?

Since bone edema in the knee can have very different causes, how long you are ill with it is also very different. The doctor will make the decision to issue a certificate of incapacity for work and its duration dependent on the one hand on the symptoms and on the other hand on the planned treatment measures.

In many cases, physical rest is indicated, so that a sick leave may be indicated for a few days, especially when doing physical work. How long you are ultimately ill depends on what triggered the bone edema on the knee and the success of the treatment. After an accident you are usually healthy again after a few weeks.

How long is it not allowed to do sports?

How long you shouldn't do sports with osteoedema on the knee depends on the cause of the water retention in the bone and the resulting symptoms. In the event of pain or restricted movement of the joint, exercise should initially be avoided until the symptoms subside.

Nevertheless, a light load on the knee makes sense in many cases, as this stimulates the bone metabolism and the healing of the bone edema can be promoted. How long one should avoid sport is therefore a decision on a case-by-case basis, which is best made together with the attending physician.

Bone edema after an arthroscopy

A bone edema on the knee after an arthroscopy, i.e. a reflection of the joint, is a very rare but possible complication of the procedure. Damage to the cartilage surfaces can lead to the death of bone substance (see also: (Osteonecrosis) and the penetration of water into the resulting cavities.

However, symptoms after knee arthroscopy are rarely caused by bone edema and other causes are more likely. Therefore, one should consult the treating doctor in the event of pain or other symptoms.

Read more on the subject below: Arthroscopy of the knee joint

Bone marrow edema syndrome

Bone marrow edema syndrome is the medical complex of the various possible symptoms and consequences of bone edema. The knee is one of the typical locations, but in principle any bone can be affected.

The bone marrow edema syndrome is not a uniform disease but a summary of bone damage from various causes, all of which can present themselves with a similar clinical picture. The focus is on the mostly load-dependent pain in the knee joint.

Read more on the subject below: Bone marrow edema