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• Transient synovitis vs. Kingella kingae infection of the hip in children
  Pablo Yagupsky
  Published on: 9 February 2009

• Published on: 9 February 2009

  Transient synovitis vs. Kingella kingae infection of the hip in children

  • Pablo Yagupsky, MD, Paediatrician

  In a recent article published in the journal, Taekema et al. discussed the use of clinical criteria and laboratory tests to differentiate between septic arthritis and transient synovitis in children.2 Distinguishing between these two conditions is crucial to avoid local and systemic complications (if a joint infection is missed) or unnecessary hospitalization, surgical interventions, and antibiotic treatment (if transien...

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  In a recent article published in the journal, Taekema et al. discussed the use of clinical criteria and laboratory tests to differentiate between septic arthritis and transient synovitis in children.2 Distinguishing between these two conditions is crucial to avoid local and systemic complications (if a joint infection is missed) or unnecessary hospitalization, surgical interventions, and antibiotic treatment (if transient synovitis is misclassified as septic arthritis). After carefully reviewing available data, the authors concluded that the presence of fever, refusal to bear weight, and elevated acute-phase reactants should raise the suspicion of septic arthritis, whereas the likelihood of transient synovitis increases if these predictors are absent.2 In recent years, increasing use of blood culture vials for culturing synovial fluid exudates and nucleic acid amplification techniques have resulted in the recognition of K. kingae as an emerging pediatric pathogen and the most common etiology of skeletal system infections below the age of 3 years.3 Involvement of the hip has been observed in 25 of 116 (22%) patients with K. kingae arthritis, apyrexia or low-grade fever are common, and the majority of affected children appear to be only mildly or moderately ill.3 In addition, the blood white cell count (WCC), C-reactive protein level, and the erythrocyte sedimentation rate are frequently within normal limits or only slightly elevated3, and a joint fluid aspirate WCC <50,000/ml-1 has been found in 11 of 30 (37%) patients with culture-proven K. kingae arthritis detected in southern Israel since 1987. Although bacterial arthritis is not considered a self-limited disease, transient involvement of the joints during an episode of K. kingae bacteremia has been documented.1, 4 Children with this condition presented with a body temperature <380C, limping or refusal to walk or bear weight, but lacked objective signs of osteoarthritis or leukocytosis. Despite this apparently benign clinical presentation, blood cultures were obtained, and K. kingae was isolated, usually 3-4 days after collection. By the time blood cultures became positive, the skeletal complaints had resolved without antimicrobial therapy, suggesting an abortive joint infection. Even when no antibiotics were prescribed after the positive culture results were known, some patients made an uneventful recovery.1 Had blood cultures not been obtained, these children would have been diagnosed as suffering from transient synovitis, raising the possibility that patients in which this diagnosis is made have, in fact, hip joint infections caused by K. kingae. Adding blood cultures to the laboratory work-up of children with presumptive transient synovitis is strongly recommended, even in the absence of fever, constitutional symptom, or elevated acute-phase reactants. If the hip joint is aspirated, the specimen should be inoculated into a blood culture vial to improve the recovery of K. kingae.

  REFERENCES 1.Lebel E, Rudensky B, Karasik M, Itzchaki M, Schlesinger Y. Kingella kingae infections in children. J Pediatr Orthop B 2006; 15:289-92. 2.Taekema HC, Landham PR, Maconochie I. Towards evidence based medicine for paediatricians. Distinguishing between transient synovitis and septic arthritis in the limping child: how useful are clinical prediction tools? Arch Dis Child 2009; 94:167-8. 3.Yagupsky P. Kingella kingae: from medical rarity to an emerging paediatric pathogen. Lancet Infect Dis 2004; 4:358-67. 4.Yagupsky P, Press J. Unsuspected Kingella kingae infections in afebrile children with mild skeletal symptoms: the importance of blood cultures. Eur J Pediatr 2004; 163:563-4.

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  Conflict of Interest:
  None declared.

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