What is the most significant risk factor for the development of septic arthritis?

Previous joint surgery is considered the most significant risk factor for the development of septic arthritis because surgical procedures can introduce pathogens into the joint space, either directly or through the bloodstream. Joint surgery can disrupt the normal barriers that prevent infections, making it easier for bacteria to invade the joint. In particular, any invasive procedure that directly manipulates the joint, such as arthroscopy or joint replacement, carries an elevated risk for subsequent infection.

While factors such as age, obesity, and excessive physical activity can contribute to joint problems or the overall health of an individual, they are not as directly linked to the risk of septic arthritis as previous joint surgery is. Older age might correlate with a general decline in immune function, and obesity can contribute to a variety of health issues, but they do not have the same clear and direct connection to the introduction of pathogens as surgical interventions do. Excessive physical activity can lead to joint injuries and other problems, but it does not inherently increase the risk of developing septic arthritis in the same way that a previous surgical history does.