Osteomyelitis and Septic Arthritis

Abstract

Osteoarticular infections are relatively infrequent bacterial infections seen most commonly during childhood. Acute hematogenous osteomyelitis most typically occurs during the first 5 years of life, while acute hematogenous septic arthritis peaks at the slightly younger age of 3 years. Bone and joint infections in children primarily occur from hematogenous seeding, but infection related to penetrating trauma, surgery, implantable devices, and contiguous spread from other anatomic sites occurs across all age groups. Overall, the most common pathogen cultured from infected bones and joints is Staphylococcus aureus, although other organisms play a more prominent role in specific age groups and clinical settings. Clues pointing to a diagnosis of an osteoarticular infection include physical examination findings of fever, pain, edema, and warmth in the affected area. In addition, reluctance or refusal to use the affected extremity is commonplace. Magnetic resonance imaging is the diagnostic method of choice as it provides exquisite bone and soft tissue detail. Plain radiographs may be diagnostic in patients who have had symptoms for >10 days and in newborns, where the bony cortex is so thin that destructive erosion can often be seen early on. Attempts to isolate the offending organism should include blood cultures and cultures of the joint fluid, the bone, and any associated abscess since identification and susceptibility testing help guide antibiotic therapy. Even when aggressive attempts are made to secure a microbiologic isolate prior to treatment with antibiotics, cultures can be negative. Empiric antibiotic treatment should target the typical pathogens seen in osteoarticular infections, followed by targeted therapy if and when the infecting pathogen is identified and susceptibility results are available. In some settings, arthrotomy, with joint irrigation, or bone debridement is necessary aspects of management. In the setting of severe infection, several visits to the operating room may be required.