A bacterial infection of a joint, or septic arthritis, can be very serious and could potentially cause permanent, major damage if not detected early and treated appropriately. The hip and the knee are most commonly involved. The cause may be obvious (for example, a puncture wound from a nail), but more often the source of the infection is unknown. Most likely bacteria are carried through the blood-stream and deposited in the lining of the joint. Septic arthritis may also begin when a bone infection (osteomyelitis) extends from bone into a joint.
Symptoms of septic arthritis vary, depending on the age of the child. In young infants, the only sign may be irritability until it becomes clear that the baby does not tolerate movement of the affected joint. The toddler might develop a limp and within a short time refuse to walk. She may appear quite ill with a high fever, and any attempt to move the joint produces severe pain. The school-age child might complain of pain in a joint after playing sports or other vigorous drained and washed out. This is usually done in the operating room with the child anesthetized. The child will also need to be treated with antibiotics, which will first be given intravenously. After several days the antibiotic may be given orally.
This bone infection may produce symptoms similar to those in septic arthritis. The child will be acutely ill and irritable, with fever and a sore, tender limb that she may refuse to use. The doctor may do special tests in addition to routine blood work to confirm the diagnosis and identify the specific bacteria causing the infection. Because X-rays taken early in the disease may appear completely normal, the physician may order amore sensitive test called a bone scan. This study may identify any area of bone that is inflamed or has been recently damaged. If an area of redness and swelling is visible, the physician may also at-tempt to aspirate a sample of infected material through a needle after numbing the area with local anesthesia.
When osteomyelitis is diagnosed, it will be treated with a prolonged course of intravenous antibiotics followed by a longer course of oral antibiotics. In some cases, surgical removal of infected material is necessary.