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: Major reasons for septic arthritis are haematogenous pathogen spread, intraarticular injections, penetrating injuries and open-surgeries. In contrast arthroscopic intervention plays only a subsidiary role. Jerosch et al. reported infection rates of up to 0.42% following arthroscopy. Recently the German institute for ambulatory arthroscopy (BVASK) reported an incidence rate of 0.13% following ambulatory arthroscopy. They evaluated 51.079 surgeries in 66 centers between 2001 and 2008. They furthermore stated, that depending on the duration of the surgery, the number of previous interventions, the extent of the intraoperative procedure as well as previous steroid injections the infection rate seems to increase. In this context several authors additionally found combinations of arthroscopic and open surgery techniques to increase the risk for septic arthritis. Different joints reveal specific incidence rates. The lowest of approximately 0.8% is found for the elbow, followed by the knee with 1% and the shoulder with up to 3.4%. Regarding hip arthroscopy Mc Carthy et al. reported not a single case of septic arthritis in 1500 patients. The ankle joint appears to have the highest incidence of septic arthritis of up to 5.7%.