In septic arthritis, the knee is most commonly infected, followed by the hip. An early peak in incidence appears to occur in the first months of infancy, with an overall average age of 3 to 6 years. Males and females seem to be at equivalent risk. Bacteria can reach the joint by hematogenous or direct spread from an adjacent focus. The hip joint is particularly susceptible, as it is intracapsular and shares blood supply with adjacent femoral metaphysis. Staphylococcus aureus and streptococcal species are the most common offending agents. Joint and growth plate destruction result from bacterial enzymes, inflammation, and pressure from purulent fluid collection in a confined space. Reduced leg length and decreased joint mobility are common sequelae. Symptoms include fever, ill appearance, joint or limb pain, leukocytosis, and elevated erythrocyte sedimentation rate. Diagnosis is confirmed by joint aspiration and culture. It is not uncommon to obtain culture-negative purulent exudate, in which case antibiotic therapy is targeted towards the most common organisms.