How does infection get into a joint?
Most often, bacteria are brought by blood from another source: a skin abscess, urinary tract infection, pneumonia, or a sore tooth. The second way is direct penetration through a penetrating wound, a bite, an injection into a joint or surgery, including endoprosthetics. The third is the transfer of inflammation from the adjacent bone during osteomyelitis. The joint is a closed cavity with a rich blood supply and without a dense barrier, so bacteria multiply quickly in it, and the resulting enzymes begin to destroy articular cartilage within a few days.
- Bacteria carried in blood from another site
- Penetrating wound or bite
- Joint injection or surgery
- Transition of inflammation from bone
- Most often one large joint is affected
- Rapid destruction of cartilage without treatment
Who's at risk
The risk is higher in people with already diseased joints: rheumatoid arthritis, gout, osteoarthritis, and those with a joint prosthesis. A significant role is played by the weakening of protective forces: diabetes mellitus, taking glucocorticoids and drugs that suppress the immune system, cancer, HIV infection, chronic kidney and liver diseases. A separate group is people who use drugs intravenously, who often have atypical joints affected. In children, septic arthritis is more common than is commonly thought and requires special vigilance.
- Rheumatoid arthritis and other joint diseases
- Prosthetic joint
- Diabetes mellitus
- Taking drugs that suppress the immune system
- Intravenous drug use
- Elderly and children's age
Symptoms
The typical picture develops quickly: within a few hours or one or two days, the joint becomes painful, swollen, and the skin over it becomes red and hot. Any movement causes sharp pain, so the person holds the limb in a bent position, in which there is less pressure inside the joint. There is usually fever, chills and general weakness, although the temperature may be low in older people and people on immunosuppressive therapy. In children, the only sign is sometimes a refusal to step on their feet or restlessness when swaddling.
- Rapid swelling and redness of one joint
- Hot skin over the joint
- Sharp pain when moving and at rest
- Forced position of the limb
- Fever and chills
- In children - refusal to lean on their leg
Diagnostics: why a puncture is needed
The decisive study is joint puncture to obtain synovial fluid. It is assessed visually, the cellular composition is examined, the smear is stained to identify bacteria, and it is necessarily sent for culture to determine sensitivity to antibiotics. This is the only way to confirm the diagnosis and choose the right treatment. Additionally, blood cultures, complete blood count, C-reactive protein and ESR are taken. X-rays may be normal in the first days, so they are used to exclude other causes, and ultrasound helps to identify effusion and perform the puncture more accurately.
- Joint puncture with fluid examination
- Culture of joint fluid with antibiotic sensitivity
- Blood cultures before starting antibiotics
- Complete blood count, C-reactive protein, ESR
- Ultrasound of the joint to detect effusion
- X-ray to rule out other causes
- Crystal testing to differentiate from gout
Treatment
Treatment is carried out in a hospital and begins immediately. Two mandatory directions are removal of pus from the joint and intravenous antibiotics. Pus is removed by repeated punctures, lavage or arthroscopically, and in cases of damage to the hip joint and in children, surgical intervention is often required. The antibiotic is first selected empirically, and after obtaining a culture, it is changed to a targeted one; The total duration of treatment is several weeks, some of which are in tablets. In case of infection of a prosthetic joint, the tactics are special and discussed by the orthopedist. Early, careful movement development helps preserve function.
- Hospitalization and urgent drainage of the joint
- Intravenous antibiotics with transition to tablets
- Correction of therapy based on culture results
- Arthroscopic or open intervention according to indications
- Pain relief and rest in the first days
- Early therapeutic exercises under the supervision of a specialist
- Sanitation of the source of infection, which became the source