Septic (infection) arthritis is inflammation of the joint due to the presence of microorganisms (usually bacteria) in the joint. The germs usually reach the joint through the blood stream from remote sources in the body such as respiratory or urinary infection. However, in some cases infection occurs directly though a wound or following surgeries e.g. hip and knee replacement. Damaged joints (e.g. those damaged by rheumatoid arthritis) are more susceptible to infection.
Septic arthritis commonly occurs in patients with lower immunity e.g. patients with diabetes and renal diseases. Infants and older adults are more likely to be involved. The most common joints affected are the knees and hips.
Septic arthritis causes severe pain and limitation of the range of motion of the affected joint. The affected joint is typically hot and swollen. The patient is usually feverish.
When septic arthritis is suspected, the doctor may take a sample of the joint fluid by a needle (aspiration) and examine the fluid to confirm the diagnosis, determine the type of bacteria involved and the antibiotic to which it is sensitive.
As septic arthritis can cause rapid damage of the cartilage and bone within the joint, early treatment is important. Treatment usually include draining the joint using a needle or surgically. Intravenous antibiotics are also used to eliminate the bacteria.