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  • Bacterial (septic) arthritis occurs most commonly in children younger than 3 years. Staphylococcus aureus is the most common cause of bacterial arthritis in all age groups.

  • Prepatellar bursitis (septic) is seen in children with local cellulitis and often local trauma. Children will present with local signs of infection and preservation of joint function. Focus treatment on local aspiration and drainage and target antibiotics at S. aureus.

  • Discitis presents in children most commonly with abnormal gait or lower back pain. Clinical improvement comes with early anti-inflammatory medications and antibiotics targeted at S. aureus and Kingella kingae.

  • Clinical manifestations of infectious tenosynovitis range from pain with passive extension to tenderness along the tendon sheath. Management includes surgical intervention and antibiotic therapy.

  • Osteomyelitis typically develops after a period of bacteremia and presents with fever and progressively increasing bone pain or limp. S. aureus is the most common cause of acute hematogenous osteomyelitis in children; however, K. kingae is increasingly identified in preschool-aged children with osteoarticular infections.


Infections of the joint are most commonly bacterial but may be caused by an array of organisms (fungal, mycobacterial, or viral). The term septic arthritis encompasses bacterial arthritis, pyogenic arthritis, suppurative arthritis, purulent arthritis, and pyarthrosis. Primary septic arthritis is a result of hematogenous (most common) or direct inoculation. Secondary septic arthritis results from the spread of osteomyelitis into an adjacent joint, typically through the intracapsular portion of the metaphysis in joints like the hip, shoulder, elbow, or ankle.1 Infections of the knee (most common), hip, and ankle account for at least 80% of cases. Early diagnosis and treatment of a septic hip is essential in preserving function. Delay in treatment increases the risk of complications, including osteonecrosis of the capital femoral epiphysis, osteomyelitis, chondrolysis, sepsis, and chronic osteoarthritis.

Septic arthritis occurs most commonly in children younger than 3 years of age, and boys more often than girls (male-to-female ratio of 1.2–2:1). Staphylococcus aureus is the dominant causative agent of infection1,2 (see Table 62-1 for causative organisms). The prevalence of community-acquired methicillin-resistant S. aureus (CA-MRSA) is rising, with reports of a three- to tenfold increase in septic arthritis and acute osteomyelitis since the beginning of this century. Various reports from urban pediatric centers across the North America have documented not only a rising incidence, but also more extensive local soft-tissue destruction, more rapid spread of infection, and a higher overall mortality rate.2–4 Studies have shown that CA-MRSA leads to an increased length of hospital stay and increased complications (i.e., persistent bacteremia, DVT, septic pulmonary emboli), greater need for surgical intervention, admission to an ICU for circulatory compromise, and residual morbidities.2–4

TABLE 62-1Organisms Most Commonly Seen with Septic Arthritis

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