Commentary & Perspective

Commentary & Perspective on
"Validation of a Clinical Prediction Rule for the Differentiation Between Septic Arthritis and Transient Synovitis of the Hip in Children"
by Mininder S. Kocher, MD, MPH, et al.

Commentary & Perspective by
James H. Beaty, MD*,
Campbell Foundation, Memphis, Tennessee

The differentiation between septic arthritis and transient synovitis in a child with an acute irritable hip is essential in ensuring that appropriate treatment is given promptly and that unnecessary treatment is avoided.

Eich et al. reported in the European literature that the use of ultrasound and the values for body temperature, erythrocyte sedimentation rate, and C-reactive protein effectively identified septic arthritis in eight patients and transient synovitis in sixty-four¹. Lee et al. reported that alterations in signal intensity in the bone marrow were seen on the magnetic resonance images of eight of nine children with septic arthritis and on none of fourteen children with transient synovitis². Both of these methods of differentiation, however, required additional tests—ultrasound or magnetic resonance imaging—that are not commonly a part of the diagnostic work-up in most institutions in the United States. The clinical prediction rule described by Kocher et al. is based on common clinical signs and laboratory tests and so may be more easily applied.

The authors' earlier report clearly established the efficacy of their clinical prediction rule for differentiating between septic arthritis and transient synovitis of the hip, and this application of the rule to a different set of patients validated their data. The ability to stratify the risk of a patient having septic arthritis according to the number of predictors present is a useful diagnostic tool for pediatric orthopaedists, especially for those patients who have no predictors (minimal probability) or all four predictors (high probability). In patients who are in the mid-range, or in whom clinical findings are not in agreement with other criteria, the diagnosis is more questionable, and aspiration of the hip remains the definitive diagnostic tool and should be used whenever the diagnosis is in doubt. The use of C-reactive protein testing as a predictor, in addition to or rather than the erythrocyte sedimentation rate, may increase the sensitivity and accuracy of this clinical prediction rule.

The authors are to be congratulated for this prospective evaluation of their protocol that was established with a retrospective review. The similarity of results is further validation of their clinical prediction rule.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Eich GF, Superti-Furga A, Umbricht FS, Willi UV. The painful hip: evaluation of criteria for clinical decision-making. Eur J Pediatr. 1999;158:923-8.
2. Lee SK, Suh KJ, Kim YW, Ryeom HK, Kim YS, Lee JM, Chang Y, Kim YJ, Kang DS. Septic arthritis versus transient synovitis at MR imaging: preliminary assessment with signal intensity alterations in bone marrow. Radiology. 1999;211:459-65.

Copyright © 2004 by the The Journal of Bone and Joint Surgery, Inc.