Septic Arthritis is also known as infectious arthritis, bacterial, or fungal arthritis. It is the purulent invasion of a joint by an infectious agent which produces arthritis. The condition is an inflammation of a joint that's caused by infection. Typically, septic arthritis affects one large joint in the body, such as the knee or hip. Less frequently, septic arthritis can affect multiple joints. Septic arthritis is considered a medical emergency. If untreated, it may destroy the joint in a period of days. The infection may also spread to other parts of the body.
Pathophysiology: The major consequence of bacterial invasion is damage to articular cartilage. This may be due to the particular organism's pathologic properties, such as the chondrocyte proteases of S aureus, as well as to the host's polymorphonuclear leukocytes response. The cells stimulate synthesis of cytokines and other inflammatory products, resulting in the hydrolysis of essential collagen and proteoglycans. Infection with N gonorrhoeae induces a relatively mild influx of white blood cells (WBCs) into the joint, explaining, in part, the minimal joint destruction observed with infection with this organism relative to destruction associated with S aureus infection.
Statistics: A population-based multicenter study was performed in southeastern Norway between June 1, 2004, and May 31, 2005. The total population of children under 16 years of age was 255,303. Physicians were asked to refer their patients with suspected arthritis to the local department of pediatrics or rheumatology. The children were assessed on the basis of clinical, radiologic, and laboratory examinations at inclusion and followed up at 6 weeks, 6 months, and thereafter as long as clinically indicated. A chart review was performed to identify patients with arthritis who had not been included prospectively.
The total annual incidence of arthritis was 71 per 100,000 children. Transient arthritis, juvenile idiopathic arthritis, postinfectious arthritis, and infectious arthritis were found in 43, 14, 9, and 5 of 100,000 children, respectively. The incidence was higher in children under the age of 8 years than in older children (107 vs 34 per 100,000). Arthritis occurred more frequently in boys than in girls before the age of 8 years but not thereafter. The median age of onset was lower in children with infectious arthritis than in those with other types of arthritis. Monarthritis was less frequent in patients with juvenile idiopathic arthritis than in the other subgroups (64% vs 83%-100%). Ten percent of the patients had poststreptococcal reactive arthritis, and only 1 had enteropathic arthritis. Autoantibodies and the presence of HLA-B27 were associated with juvenile idiopathic arthritis.
The annual incidence of childhood arthritis was 71 per 100,000 children. We found several factors that may help in differentiating between subgroups of arthritis.