Septic arthritis develops when bacteria spread from a source of infection through the bloodstream to a joint or the joint is directly infected by traumatic penetration or surgical procedures. The onset of the symptoms is usually rapid with joint swelling, intense joint pain, and low-grade fever. Risk factors include a concurrent bacterial infection, chronic illness, diseases or medications that suppress the immune system, rheumatoid arthritis, intravenousdrug abuse, artificial joint implants, recent joint trauma, or recent joint arthroscopy or surgery procedures.

Septic arthritis may be seen at any age. In children, it occurs most often in those less than 3 years of age. The hip is a frequent site of infection in young infants.

Septic arthritis is uncommon from age 3 to adolescence at which time the incidence of septic arthritis increases again (appearing as gonococcal arthritis in females with cervical gonorrhea). Adult septic arthritis differs little from that in younger children with the exception of certain organisms not usually seen in the adult (group B streptococcus and Haemophilus influenza).

Acute septic arthritis tends to be caused by organisms such as staphylococcus, streptococcus (pneumoniae) and group B streptococcus while chronic septic arthritis (which occurs less frequently) is caused by organisms such as Mycobacterium tuberculosis and Candida albicans. The knee and the hip are the most commonly infected joints.

• voluntary immobility of the limb with the infected joint (pseudoparalysis)
• cries when infected joint is moved (example: diaper change causes crying if hip infected)
• irritability
• fever

• intense joint pain
• joint swelling
• joint, redness
• voluntary immobility of the limb with the infected joint (pseudoparalysis)
• low-grade fever

• chills

• synovial fluid analysis or culture of joint fluid
• blood culture
• X-ray of affected joint

• joint degeneration