• An acute bacterial infection of a joint.
• Peak incidence in children is younger than 2 years of age.
• Risk factors:
  • history of trauma
  • preceding URI
  • immunodeficiency
  • hemoglobinopathy
  • Diabetes.
• Age is the most important determinant of cause.
  • In all age groups, S aureus is the primary organism accounting for more than 50% of cases.
  • Among neonates, enteric gram-negative organisms and group B Streptococcus are the most frequent causes.
  • Group A Streptococcus, S pneumoniae, and K kingae are common causes in children younger than 5 years old.
• Blood culture, joint fluid aspiration and analysis, gram stain, and culture of fluid is recommended.
• In pyogenic arthritis, the joint fluid is usually cloudy and has a leukocyte count of at least 50 x 10000/mcL, with a predominance of polymorphonuclear cells, low glucose concentrations, and high protein values.
• Treatment involves a combination of parenteral antibiotics, surgical drainage, and decompression of the affected joint.
• All children who have pyogenic arthritis of the hip or shoulder require prompt open surgical drainage and irrigation to prevent permanent joint damage as the increased intra-articular pressure can compromise blood flow resulting in avascular necrosis of the femoral or humeral head and predisposing the patient to dislocations.
• Open surgical drainage of other joints usually is not required.

References

Krogstad P. Osteomyelitis and septic arthritis. In: Feigin RD, Cherry JD, Demmler GJ, Kaplan SL, eds. Textbook of Pediatric Infectious Diseases. Philadelphia, Pa: WB Saunders Co; 2004713-736.

Tan TQ. Osteomyelitis and septic arthritis. In: Perkin RM, Swift JD, Newton DA, eds. Pediatric Hospital Medicine: Textbook of Inpatient Management. Philadelphia, Pa: Lippincott Williams & Wilkins; 2003:497-500.

Yagupsky P, Bar-Ziv Y, Howard CB, Dagan R. Epidemiology, etiology, and clinical features of septic arthritis in children younger than 24 months. Arch Pediatr Adolesc Med. 1995; 149:537-540.