Knee bursitis is an inflammation of one of the periarticular bags (burs) located in the knee area. It can be aseptic or purulent, acute, subacute or chronic. With aseptic bursitis, a limited tumor-like formation occurs in the area of the bag, non-intense pain, joint stiffness, local hyperemia and hyperthermia are possible. With purulent bursitis, the affected area is edematous, hot, there are pronounced pains and signs of general intoxication. In simple cases, the diagnosis is made on the basis of clinical signs. Sometimes a bursa puncture, radiography, CT, MRI, ultrasound or arthrography is required to clarify the diagnosis. Treatment of aseptic bursitis is usually conservative, purulent – operative.
Knee bursitis is an inflammatory process in the periarticular bag. It can be infectious or non-infectious (aseptic). It proceeds acutely, subacutely or chronically. It most often affects people whose activities are associated with an intense load on their legs (athletes) or with prolonged kneeling (roofers). In the past, this pathology was often observed in housewives (“housewife’s knee”) and pilgrims (“pilgrim’s knee”). Men suffer more often than women.
In the vast majority of cases, the cause of the development of aseptic bursitis is a single injury to the knee joint, repeated microtrauma or overload of the joint. Overload usually occurs in athletes. For example, jumpers sometimes develop intrapatellar bursitis due to repeated peak loads on the knee joint. A single injury is more often observed in athletes, people leading an active lifestyle and representatives of professions related to physical labor. Repeated microtrauma is characteristic of those who, due to professional or household duties, often have to kneel for a long time. In addition, chronic aseptic bursitis is sometimes detected in scleroderma, arthritis and gout. Inflammation in such cases develops a second time, as a result of the deposition of salts in the synovial bursa.
The cause of infectious knee bursitis can be an open wound, both penetrating and not penetrating into the cavity of the bag. In the first case, the pathogen enters the bursa directly from the external environment, in the second – contact, through tissues. Pathogens can also enter the bag with blood flow (for example, with sepsis) or with lymph flow (with purulent wounds, boils, abscesses, osteomyelitis or phlegmon). Predisposing factors contributing to the development of bursitis are considered allergic reactions, autoimmune diseases, intoxication, endocrine diseases (for example, diabetes mellitus), some kidney diseases, taking steroid drugs and metabolic disorders. In some cases, the cause of bursitis cannot be established.
The periarticular sac (bursa) is an anatomical formation located near a protruding part of the bone (usually in the joint area or near it). The cells of the inner shell of the bags produce a fluid that facilitates the sliding of the tendon. At the same time, the bag as a whole plays the function of a kind of shock absorber that protects the tendon from excessive pressure or friction. Normally, there is a small amount of fluid in the bursa. With inflammation, the cells begin to produce more fluid, a local tumor-like formation occurs in the area of the bag. The knee joint has about a dozen bursae, but three bags are more often affected: prepatellar, infrapatellar and goose.
In traumatology and orthopedics, the following most common types of bursitis are distinguished:
- Prepatellar (suprapatellar) or patellar bursitis – the bag located under the skin on the surface of the patella becomes inflamed. Usually, such bursitis develops after an injury (a fall, a blow to the front surface of the knee) or after prolonged kneeling.
- Infrapatellar or popliteal bursitis – inflamed bag located under the patella. The disease often occurs when the ligaments of the knee joint are damaged.
- Goose bursitis or Becker’s cyst – the bag located on the back surface of the joint, in the popliteal fossa, becomes inflamed. As a rule, it develops with increased stress on the joint due to overweight.
According to the type of inflammation, there are:
- Serous bursitis – aseptic inflammatory process.
- Purulent bursitis – there are pathogenic microorganisms in the cavity of the bag that cause the formation of pus.
Downstream, all bursitis are divided into acute, subacute and chronic.
With prepatellar aseptic bursitis, non-intense pain occurs with predominant localization on the anterior surface of the joint. There may be stiffness when walking. In the area of the kneecap, a limited tumor-like formation of a mildly elastic consistency is determined, slightly painful on palpation. Sometimes there is a slight local hyperemia, an increase in local temperature and a slight swelling. Movements in full or not clearly limited.
Infrapatellar aseptic bursitis usually proceeds with erased symptoms. The patient is concerned about stiffness and non-intense pain when walking or staying in a standing position for a long time. An external examination reveals a slight increase in the volume of the joint. Goose bursitis, as a rule, is manifested by indistinct pains when descending or climbing stairs. Visually, the tumor is sometimes not detected, with a significant increase in the bursa, an elastic soft-elastic formation in the popliteal fossa is revealed.
When the contents of the bursa are infected, the clinical picture is brighter. The patient is concerned about a sharp, sometimes twitching pain, perhaps a feeling of tension and bursting. The tumor-like formation is tense, sharply painful. The surrounding tissues are swollen, hyperemic, and the skin temperature in the affected area is noticeably elevated. Regional lymph nodes are enlarged. The movements are painful, so the patient spares the leg. There is often a violation of the support. With purulent bursitis, local symptoms are combined with a picture of general intoxication. It is possible to increase the temperature to febrile numbers, weakness, weakness, lethargy, headache and chills.
The diagnosis of “bursitis of the prepatellar bag” and “bursitis of the goose bag”, as a rule, does not cause difficulties. The diagnosis is made on the basis of clinical signs, if necessary, to clarify the nature of inflammation, a puncture of the bursa is performed with subsequent examination of the punctate. If bursitis of the goose bag is suspected, an MRI is prescribed in some cases.
Bursitis of the intrapatellar sac is more difficult to diagnose, since the popliteal bursa is hidden under the kneecap and this area cannot be visually examined or palpated. To confirm the diagnosis in such cases, radiography of the knee joint can be used, however, this study is not informative enough, since the bag is not visible on radiographs, and its increase can only be judged by the change in the distance between the patella and other bone structures. Much more accurate results can be obtained by performing an knee MRI. In addition, arthrography or CT of the knee joint may be prescribed to clarify the diagnosis.
If necessary, consultations with a rheumatologist, allergist, endocrinologist and other specialists can be prescribed to identify the cause of bursitis of any localization. If purulent bursitis is suspected, the patient is referred to a surgeon, given a referral for a general blood test to identify signs of inflammation, and a puncture of the bursa is performed to clarify the nature of the pathogen and the selection of adequate antibacterial therapy.
Treatment of aseptic bursitis is usually outpatient, carried out by an orthopedic traumatologist. The patient is recommended rest, elevated position of the limb and cold compresses. If necessary, painkillers and drugs from the NSAID group are prescribed. In the acute period, ultrasound with hormonal or nonsteroidal anti-inflammatory ointments and electrophoresis with hydrocortisone are used. During the recovery period, the patient is referred to UHF. In chronic aseptic goose bursitis, surgical treatment is indicated – excision of the bursa. Surgical intervention is carried out as planned in a hospital (in a traumatology or orthopedic department).
With purulent bursitis, patients are hospitalized in the surgery department. Perform an emergency operation – opening the bursa. The pus is removed, drainage is subsequently carried out, the bursa is washed with solutions of antiseptics and antibiotics. In addition, the patient is prescribed antibacterial therapy. The antibiotic is selected taking into account the sensitivity of the pathogen isolated from the fluid obtained during the operation.