Septic arthritis is a serious infection of the joints caused by bacteria. This infection causes the joint to be filled with pus cells. These pus cells release substances directed against the bacteria. However, this action can damage the joint structures, bone, and surrounding cartilage.

Septic arthritis develops when bacteria spreads from the source of infection through the bloodstream to a joint. It can result from:

  • Infection due to an injection
  • Surgery
  • Other infections

Septic arthritis can also be caused from injury or trauma. It can result from:

  • A penetration wound
  • An injury that affects the joint
  • Joint surgery/replacement

Septic arthritis can strike at any age. However, it occurs most often in children aged three and younger. In infants, the hip is a frequent site of infection. In toddlers, it is the shoulders, knees, and hips. In children, the most common bacterial causes are:

  • Staphylococcus aureusstaph infection
  • Streptococcus species, such as group B strep infection
  • Streptococcus pneumoniae—a common bacterial cause of pneumonia

Septic arthritis rarely occurs from early childhood through adolescence. After that, it occurs more often. In adults, it most commonly affects weight-bearing joints, such as the knees. In adults, the most common causes are:

  • S. aureus
  • Neisseria gonorrhoeae—the bacteria that causes gonorrhea

Joint Damage in Knee
Knee arthitis
Copyright © Nucleus Medical Media, Inc.