Interobserver and intraobserver reliability of the modified waldenström classification system for staging of legg-calvé-perthes disease

Joshua E. Hyman, Evan P. Trupia, Margaret L. Wright, Hiroko Matsumoto, Chan Hee Jo, Kishore Mulpuri, Benjamin Joseph, Harry K.W. Kim, Virginia F. Casey, Pablo Castañeda, Paul D. Choi, Fábio Ferri De Barros, Shawn R. Gilbert, Prasad V. Gourineni, Theresa A. Hennessey, John A. Herring, Joseph A. Janicki, Derek M. Kelly, Jeffrey I. Kessler, A. Noelle LarsonJennifer C. Laine, Karl J. Logan, Philip W. Mack, Benjamin D. Martin, Charles T. Mehlman, Norman Y. Otsuka, Scott B. Rosenfeld, Wudbhav N. Sankar, Tim Schrader, Benjamin J. Shore, Ralf D. Stuecker, Stephen Sundberg, Junichi Tamai, John E. Tis, Klane K. White

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Background: The absence of a reliable classification system for Legg-Calvé-Perthes disease has contributed to difficulty in establishing consistent management strategies and in interpreting outcome studies. The purpose of this study was to assess interobserver and intraobserver reliability of the modified Waldenström classification system among a large and diverse group of pediatric orthopaedic surgeons. Methods: Twenty surgeons independently completed the first two rounds of staging: two assessments of forty deidentified radiographs of patients with Legg-Calvé-Perthes disease in various stages. Ten of the twenty surgeons completed another two rounds of staging after the addition of a second pair of radiographs in sequence. Kappa values were calculated within and between each of the rounds. Results: Interobserver kappa values for the classification for surveys 1, 2, 3, and 4 were 0.81, 0.82, 0.76, and 0.80, respectively (with 0.61 to 0.80 considered substantial agreement and 0.81 to 1.0, nearly perfect agreement). Intraobserver agreement for the classification was an average of 0.88 (range, 0.77 to 0.96) between surveys 1 and 2 and an average of 0.87 (range, 0.81 to 0.94) between surveys 3 and 4. Conclusions: The modified Waldenström classification system for staging of Legg-Calvé-Perthes disease demonstrated substantial to almost perfect agreement between and within observers across multiple rounds of study. In doing so, the results of this study provide a foundation for future validation studies, in which the classification stage will be associated with clinical outcomes.

Original languageEnglish (US)
Pages (from-to)643-650
Number of pages8
JournalJournal of Bone and Joint Surgery - American Volume
Issue number8
StatePublished - Apr 15 2015
Externally publishedYes

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine


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