Risk factors

Risk factors for septic arthritis include:

• Existing joint problems. Chronic diseases and conditions that affect your joints — such as osteoarthritis, gout, rheumatoid arthritis or lupus — can increase your risk of septic arthritis, as can previous joint surgery and joint injury.
• Having an artificial joint. Bacteria can be introduced during joint replacement surgery, or an artificial joint may become infected if germs travel to the joint from a different area of the body through the bloodstream.
• Taking medications for rheumatoid arthritis. People with rheumatoid arthritis have a further increase in risk because of medications they take that can suppress the immune system, making infections more likely to occur. Diagnosing septic arthritis in people with rheumatoid arthritis is difficult because many of the signs and symptoms are similar.
• Skin fragility. Skin that breaks easily and heals poorly can give bacteria access to your body. Skin conditions such as psoriasis and eczema increase your risk of septic arthritis, as do infected skin wounds. People who regularly inject drugs also have a higher risk of infection at the site of injection.
• Weak immune system. People with a weak immune system are at greater risk of septic arthritis. This includes people with diabetes, kidney and liver problems, and those taking drugs that suppress their immune systems.
• Joint trauma. Animal bites, puncture wounds or cuts over a joint can put you at risk of septic arthritis.

Having a combination of risk factors puts you at greater risk than having just one risk factor does.