Cause of Septic Arthritis
The cause of septic
arthritis is a bacterial infection within a joint or joints (90 percent of such infections affect only one joint). These bacteria cause inflammation within the joint that can ultimately lead to damage to the cartilage (the slippery coating at the end of bones), underlying bone, and joint capsule.
There are several different types of bacteria that are known to cause septic arthritis. Among infants under one year of age, the most common cause of septic arthritis is
Staphylococcus aureus or Group B Strep. In cases involving adults, the most common cause of septic arthritis is an infection with
Neisseria gonorrhoeae (the bacteria that cause
gonorrhea).
Risk Factors for Septic Arthritis
A risk factor is anything that increases a person's chances of developing a disease. Having risk factors for septic arthritis does not guarantee that a person will develop the condition; it just increases his or her chances of developing it.
- Age (infants and young children are at greatest risk for septic arthritis)
- Infection in another part of the body, especially infection within bone (known as osteomyelitis)
- Alcoholism or IV drug abuse
- Immunosuppressive medicines
- Rheumatoid arthritis, gout, or osteoarthritis
- Previous joint damage
- A history of recent steroid injections into the joint
- Having recently undergone certain surgical procedures (such as a knee replacement, hip replacement, or knee arthroscopy).