Edema of the knee joint causes, symptoms, diagnosis, treatment

Swelling of the knee joint is called an increase in its volume due to the accumulation of joint fluid, blood or pus. Provide swelling of the injury and chronic pathology of the knee. For this reason, diagnostic methods and treatment principles differ and depend only on the primary (main) ailment. The knee is a complex anatomical structure formed by the hip, tibia and patella. Thanks to the knee joint, a person can maintain balance, as well as move around. It is worth noting that it is on the knees that the main load and pressure of the entire body weight falls. For this reason, the knee joints are often injured, which provokes a typical clinic in the form of edema of the knee joint.

What kind of ailment?

Edema is an increase in the knee joint in volume due to the accumulation of joint fluid, blood or pus in it. There are swelling of the knee joints at any age, with the same frequency among women and men.

From the anatomy: Normally, there is a “lubricant” in each joint – a synovial fluid that provides smooth movements and protects the articular cartilage.

When the knee is injured or inflamed, the amount of liquid content in the joint bag increases dramatically (the joint “swells”). Such a reaction is a “response” to irritation of the articular membranes. In some cases, the synovial fluid can become infected, then pus forms in the joint cavity.

“Swelling” of soft tissues often joins the swelling of the knee joint, which significantly increases the volume of the joint. This is due to the concomitant inflammation of the surrounding tissues with injuries and other articular pathologies.

Why does it arise?

Among the most common causes of knee edema are:

  1. Injuries – bruises, fractures, tears of the ligament and tendon apparatus;
  2. Synovitis is an inflammatory process in the articular membrane, which normally produces synovial fluid;
  3. Bursitis is an inflammatory reaction in periarticular shock absorbing bags;
  4. Baker’s cyst – popliteal hernia filled with articular fluid;
  5. Knee arthritis (it also drives) – inflammation of the joint against the background of infection (tuberculosis, syphilis, gonorrhea, chlamydia), allergies (usually vaccination) or systemic illness (hemophilia, rheumatism, psoriasis, lupus, Reiter’s syndrome or ankylosing spondylitis);
  6. Osteoarthritis of the knee – gonarthrosis – appears due to congenital malformations, metabolic and hormonal disorders, as well as excessive stress (sports, overweight);
  7. Dissecting osteochondritis of the knee – Koenig’s disease – associated with the cleavage of part of the cartilage and its movement into the articular cavity (the so-called “mouse in the joint” is formed).

Each of these reasons, to one degree or another, leads to the redirection of the synovial membrane, as well as the occurrence of local inflammation. These factors are the “trigger” of increased formation of joint fluid and, as a result, swelling of the knee joint.


The clinical manifestations of edema of the knee joint vary depending on the cause of this pathological condition.

With severe knee injuries, edema increases gradually. Usually due to accumulation of synovial fluid or blood. The contours of the joint are smoothed, it takes the form of a ball, which limits movement in the knee. Often there is a balloting of the patella – its oscillation in the synovial fluid.

With dislocations, ruptures of ligamentous strands and fractures, edema is similar. However, the patient experiences severe pain, the joint is deformed, and the axis of the limb is often bent.

Typically, with synovitis, the knee increases in volume within hours / days. Patients complain of bursting pain, which intensifies during movements. The contours of the joint are smoothed out, the patella “bulges out”. The skin above the knee often gets warmer and redder.

If an infectious agent enters the joint cavity, the general condition of the patient deteriorates sharply: there is a fever, intense pain and delusional states.

As a rule, a soft roundish “bump” appears in the knee region, in the cavity of which a liquid is detected when feeling. The surrounding tissue is swollen and hot.

In most cases, bursitis has a chronic course: a painless rounded formation is observed, the skin above it is not changed, and the movements in the joint are made in full.

Baker’s cyst is a neoplasm under the knee joint, which is a cavity filled with articular fluid. Usually this “tumor” is asymptomatic, but in the later stages, pain occurs, aggravated by flexion of the knee.

With a significant increase in the cyst, a characteristic pressing pain is felt, and the formation itself can impede movement in the joint.

The general manifestations of arthritis include pain, the severity of which depends on the primary disease. Often noted “starting” pain that occurs only at the beginning of movements. Soreness of the joint is accompanied by swelling (the knee is increased in volume – “swollen”), as well as warming and redness of the skin above it.

The progression of arthritis often leads to knee deformity. In the later stages, restrictions on passive and active movements are often observed (up to contracture – complete immobilization).

A separate option is arthritis in hemophilia (hereditary blood coagulation), caused by frequent hemorrhages in the joint cavity.

The course of knee arthrosis is paroxysmal. So, patients complain of periodic pain or meteosensitivity of the knee joint. Swelling of the knee joint is usually mild, often there is a “crunch” during movements.

In advanced cases, the shape of the joint is disturbed, limb muscles are spasmodic, and motor activity is severely limited. Patients begin to limp, and subsequently cannot walk without additional support (canes, etc.).

Koenig’s disease is characterized by splintering of part of the cartilage and its movement into the knee cavity. Frequent microtraumas provoke the ailment (mainly due to professional sports activities). At first, patients are concerned about mild discomfort, after which pain and signs of inflammation (synovitis) appear.

A complete picture of the disease occurs when the chipped part of the cartilage is infringed between the articular surfaces of the bones. In this case, sharp pain is felt, and the knee itself is immobilized – it is blocked. These symptoms are accompanied by severe swelling of the knee joint, as well as redness of the skin above it.


Diagnostic measures for edema of the knee are reduced to:

  • a clinical examination, which allows you to determine the presence of fluid in the joint (a symptom of fluctuations) and oscillation of the patella (balloting);
  • laboratory examination with the determination of characteristic markers (rheumatic tests, blood urate, etc.);
  • puncture (puncture) of the joint with a fence of its contents. In this case, the liquid is examined for the presence of infectious agents. If bacteria have been detected, their sensitivity to antibiotics is determined;
  • X-ray examination or computed tomography for dislocations, fractures, arthrosis and dissecting osteochondritis;
  • magnetic resonance imaging, which allows you to visualize the “soft” structure with synovitis, bursitis, Baker’s cyst and arthritis;
  • arthroscopy – the study of the joint using optical equipment (video camera) inserted into the joint bag through a micro section. It is used when other research methods are ineffective or impossible.


The direction of therapy depends on the root cause of swelling of the knee joint.

When injuring the knee, it is necessary to immobilize the joint, apply a pressure bandage, raise the affected lower limb and exclude any load on it. For pain relief, it is recommended to apply cold compresses for 15 minutes every 3 hours (only in the first two days!).

Subsequent treatment depends on the nature of the injury: with bruising and incomplete ruptures of ligamentous cords – rest and thermal procedures; with dislocation and fractures – reduction of the joint or bone fragments, as well as immobilization. If complex injuries or massive tears of the ligamentous apparatus are observed, surgical intervention is necessary.

With non-infectious inflammation, the knee is bandaged tightly, and the limb is raised. Physiotherapy is prescribed to patients: electro- or phonophoresis, UHF and ultraviolet irradiation.

If purulent inflammation is observed in the knee, a puncture of the joint bag with removal of the contents is required. A joint cavity is washed with antibiotics. With a prolonged course of the disease, removal of the articular membrane is recommended – its excision.

Swelling of the knee joint with bursitis is treated with rest and cold compresses. Patients are prescribed anti-inflammatory drugs (Ibuprofen, Diclofenac), as well as painkillers (Analgin, Ketorolac). If the infection joins, the bag is opened and its contents removed.

Given the tendency of bursitis to relapse, it is recommended that planned surgical treatment with excision of the periarticular sac.

Therapy of Baker cysts consists in the introduction of steroidal (hormonal) anti-inflammatory drugs (Hydrocortisone) into its cavity. In some cases, puncture the education with “pumping out” of its contents. If these methods are ineffective, they resort to surgical removal of the cyst.

Drug therapy consists in the use of non-steroidal anti-inflammatory (Phenylbutazone, Indomethacin) and antibiotics (Cefotaxime, Amoxicillin with purulent inflammation). Patients are advised to take chondroprotectors (Teraflex, Don) and physiotherapy: phonophoresis, as well as laser and magnetic exposure.

In advanced cases, surgical treatment is necessary: ​​resection (removal) of the membranes or the joint itself with subsequent endoprosthetics.

Therapy of arthrosis is an anti-inflammatory effect (Diclofenac, Meloxicam). Muscle relaxants are prescribed to reduce muscle spasm (Midocalm), as well as chondroprotectors (Synvix, Ostenil). As physiotherapy, heat, a laser and ultraviolet are used. In the later stages, an operation to replace the knee joint with an artificial implant is indicated.

Conservative therapy is in most cases ineffective. Typically, patients are recommended surgery to remove the “articular mouse” or fixation of the cartilage fragment with special metal devices. In some cases, part of the cadaveric bone or its own cartilage can be used to restore the articular surface.

preventive measures

Prevention of knee edema is:

  • avoidance of injuries;
  • timely treatment of inflammation of the articular and periarticular bags – synovitis and bursitis;
  • diagnosis and therapy of popliteal hernia – Baker cysts;
  • correction of knee arthritis against the background of infection (tuberculosis, syphilis, gonorrhea, chlamydia), allergies (with vaccination) or systemic illness (hemophilia, rheumatism, psoriasis, lupus, Reiter’s syndrome or ankylosing spondylitis);
  • early diagnosis of arthrosis of the knee due to congenital malformations, metabolic and hormonal disorders, as well as excessive load;
  • surgical treatment of dissecting knee osteochondritis.

Remember, swelling of the knee joint is not an independent disease, but a symptom of a more serious illness. At the same time, a rapid increase in the joint most often indicates active inflammation, requiring immediate treatment.

Shishkevich Vladimir, orthopedic and traumatologistShishkevich Vladimir, orthopedic and traumatologist, project editor-in-chief ExpertNews.

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