Causes / typical injury mechanism: Pediatric septic arthritis of the hip is a rare but life- and joint-threatening orthopedic emergency. Primary septic arthritis most commonly occurs as a result of hematogenous spread or when a nearby infection, such as osteomyelitis, spreads to the joint. Once the joint is infected, a cytokine cascade begins an acute phase response. This, combined with bacterial toxins, can lead to significant cartilage damage in as little as 8 hours.

Classic history and presentation: Patients can present with a refusal to bear weight on the affected limb and/or may refuse to move the limb at all (pseudoparalysis). There may be a recent history of illness or trauma.

Prevalence: Occurs annually in about 5-12 / 10 000 children. The peak age of incidence, in general, ranges from younger than 2 years to 6 years.