How can you get septic arthritis – how do you get an infection in a joint if there is no cut or anything?

It does seem a little strange that you can get an infection in a closed joint like a knee or hip, but it does happen. If you have an infection in another part of your body, such as a urinary tract infection, the bacteria that caused the infection may enter your blood stream and move about your body. Because your joints aren’t built to resist infection, there isn’t much protection from the bacteria if it makes its way to the joint. Once it reaches the joint, it can cause an infection in the fluid that usually lubricates the area, allowing for smooth movement.