Septic arthritis
A type of arthritis that develops due to the infection of the joint. It often leads to pain, swelling, and redness. Arthritis secondary to a bacterial or viral infection often occurs with a fever. There is usually no trauma or injury before the onset of pain.
Septic arthritis quickly causes extensive damage to the knee structures such as bones and cartilages. If you have knee pain along with swelling and fever, see your physician right away.
Other body conditions that cause knee pain.