Septic arthritis (or infectious arthritis) is a bacterial infection inside a joint. Joints are usually germfree (sterile). When bacteria get into a joint, they cause inflammation (swelling, redness) and pain. Infection usually affects only one joint at a time: knee, hip, wrist, shoulder, elbow, or ankle.
Anyone can have a joint infection, but it’s most common in children younger than 3 and adults older than 80.
Untreated septic arthritis can damage and destroy the joint and lead to joint replacement surgery.
Usual causes are abnormal changes in a joint from other forms of arthritis, a poorly working immune (infection-fighting) system, and an artificial joint (joint replacement). The immune system problem may be caused by medicines and other conditions, such as diabetes, kidney disease, or cancer.
Infected joints swell quickly and are very painful and hard to bend. High temperature, chills, shakes, muscle aches, and fatigue occur. Depending on the joint, people may be unable to walk or use their arms.
The health care provider may suspect a joint infection on the basis of the medical history and physical examination. The doctor will diagnose a joint infection by removing fluid from the joint with a needle and testing it in the laboratory for evidence of infection.
Magnetic resonance imaging (MRI), nuclear scans and computed tomography (CT) are also commonly used when your health care provider suspects an infection in a joint.
Three stages of therapy are needed: antibiotics, joint drainage, and restoring normal motion to the joint.
Antibiotics are usually given through a vein for the first 2 weeks and then by mouth for 2 to 4 weeks or more.
Joint fluid should generally be drained to help resolve the infection. Most joints can be drained by sticking a needle into the joint and taking fluid out. This procedure is called arthrocentesis. Other joints are harder to drain this way and insteadneed drainage by an operation.
After the first few days of treatment, people with joint infections should start therapy to restore normal joint motion. Physical therapists help with restoring normal movement. Therapy should continue until after the pain leaves and the joint works normally.
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