The Facts About Septic Arthritis

Considered as the most dangerous form of acute arthritis, septic arthritis is caused by a bacterial infection in the joint cavity. Usually there is a primary site of infection from where bacteria spread. The site of infection is often along adjacent bone or soft tissue. Bacterial spread is usually through the bloodstream going to the joints. It is estimated that in the general population of 100,000 people, about 2 to 10 of them suffer from septic arthritis. On the other hand, 30 to 70 cases of septic arthritis can be seen in a population of 100,000 rheumatoid arthritis patients. A variety of factors can predispose a person to septic arthritis. Any simultaneous presence of bacterial infection such as genitourinary tract or upper respiratory tract infection can increase a person's vulnerability to septic arthritis. Additionally, serious chronic illnesses including renal failure, malignancy, cirrhosis and diabetes can increase septic arthritis susceptibility. Susceptibility increases with people who have a depressed immune system, or those who have previous immunosuppressive therapy. Accordingly, elderly individuals and alcoholics are also at higher risk of developing septic arthritis. People who are into prolonged use of intravenous drugs, including those who are addicted to heroin, have higher chance of contracting septic arthritis as well.

Septic arthritis comes suddenly with symptoms like intense pain, inflammation and swelling of the affected joint. These symptoms are often accompanied with fever and chills. The infected joint may cause voluntary immobility of the limb. Septic arthritis often affects large joints; specifically the knee. New born or infants who are affected with acute septic arthritis may become irritable and cry relentlessly whenever there is movement; especially when there is hip involvement. Pain is usually present in the groin, upper thigh and buttocks when septic arthritis affects the hip. In adults, knee involvement affects around 50 percent of all cases. The hips, wrist and ankles are also commonly affected with septic arthritis. Some patients may not show external signs of inflammation. Sometimes there is the presence of polyarthritis before the localization of infection. Muscle spasms are a very common occurrence of septic arthritis.

Doctors use several methods to diagnose septic arthritis. Positive identification of the presence of the causative microorganism in the joint fluid using Gram's stain suggests septic arthritis. There are also other additional methods used to diagnose septic arthritis. These measures include x-ray, radioisotope joint scan and white blood cell count. X-rays detect changes in the joint between 1 and 2 weeks after the onset of infection. On the other hand, radioisotope joint scan is used to check for changes and the presence of infection and inflammation in the less accessible joints like the spinal articulations.

Antibiotic therapy is generally the choice of treatment for septic arthritis. This should commence as soon as the causative microorganisms are identified. Elimination of the infection through antibiotic therapy is the primary goal of treatment. It has been observed that patients who were immediately treated with doses of antibiotic within 7 days from the onset of infection had higher cure rate compared with those who were treated a month after infection started. There is an arrest of infection if samples from the synovial fluid show a decreased white blood cell count within 5 to 7 days of antibiotic therapy.