Epidemiology

Information concerning the epidemiology of septic arthritis is limited because of several factors. Acute septic arthritis is an uncommon disease; therefore, few reports of series containing more than 50 cases have been published, and most of the published reports are from retrospective cohorts . Moreover, the case definitions employed have, in general, restricted these studies to the investigation of bacteriologically confirmed cases.

The overall estimated incidence of septic arthritis in industrialised countries ranges from 2 to 6 cases per 100,000 person-years in the general population . In particular, the reported incidence of septic arthritis in Western Europe varies from 4 to 10 cases per 100,000 patient-years in the general population . Moreover, the incidence increases in populations with low socioeconomic status, as has been demonstrated by studies conducted in both Northern Europe and Australia . In Australia, the prevalence is reported to be 29 cases per 100,000 patient-years in the aboriginal population, with a relative risk of 6.6 in comparison with the Australian population in the Northern Territory .

Although individuals of all ages can be affected, septic arthritis is more prevalent in children and the elderly, and males are more frequently affected than females . In children, the incidence ranges from 5 to 12 cases per 100,000 person-years . Approximately one-third of the patients with septic arthritis are children younger than 2 years of age, and the disease has a lower incidence in patients younger than 3 months.

Mortality due to septic arthritis in hospitalised patients is reported to be approximately 2–10% of the total mortality in general hospitals in the United States of America .

In recent years, the incidence of septic arthritis has appeared to increase. Several factors may have contributed to this increase, including increased orthopaedic-procedure-related infections, an ageing population and an increase in the use of immunosuppressive therapy .