Septic arthritis typically causes extreme discomfort and difficulty using the affected joint. The joint could be swollen, red and warm, and you might have a fever. If septic arthritis occurs in an artificial joint (prosthetic joint infection), signs and symptoms such as minor pain and swelling may develop months or years after knee replacement or hip replacement surgery. Also, a loosening of the joint may occur, which causes pain while moving the joint or while putting weight on the joint. Typically, the pain goes away when at rest. In extreme cases, the joint may become dislocated.