Septic arthritis is an extremely painful infection of a joint where germs infiltrate a joint and cause damage that leads to severe pain, warmth, and swelling. Bacteria and other microorganisms are the cause of septic arthritis and commonly target the knee, hip, or ankle. In the United States, 20,000 cases are reported each year in mostly young children and older adults. Septic arthritis is considered a medical emergency, as the microorganisms can destroy the joint in a few short days or can spread to other areas of the body.
There are four main causes of septic arthritis. The first is called contiguous spread. This occurs when a preexisting bone infection travels down the bone and reaches a joint. Direct implantation of bacteria can occur when a puncture or stab wound occurs in the joint. Heamtogenous source of septic arthritis develops when an infection enters the bloodstream from another area of the body and reaches a joint. The last cause takes place after joint surgery and is due to contamination.
Septic arthritis typically causes extreme discomfort and difficulty using the affected joint. Signs and symptoms can include fever, severe pain especially when moving the joint, swelling, joint warmness, and redness. Medications for other types of arthritis may mask the pain and fever. It is important to seek a doctor if these signs develop. It is especially important if signs and symptoms of infection such as fever and chills occur, as this may indicate a severe infection. To diagnosis septic arthritis, a doctor will consider the clinical presentation, vital signs, x-rays, and blood labs. Generally, septic arthritis is treated with joint aspiration, removal of infected tissue, and antibiotics.