Stulberg classification system for evaluation of Legg-Calvé-Perthes disease: intra-rater and inter-rater reliability.

BACKGROUND: Researchers and clinicians commonly use the classification system of Stulberg et al. as a basis for treatment decisions during the active phase of Legg-Calvé-Perthes disease because of its putative utility as a predictor of long-term outcome. It is generally assumed that this system has an acceptable degree of reliability. This assumption, however, is not convincingly supported by the literature. METHODS: The purpose of the present study was to assess the inter-rater and intra-rater reliability of the classification system of Stulberg et al. with use of a pre-test, post-test design. During the pre-test phase, nine raters independently used the system to evaluate the radiographs of skeletally mature patients who had been managed for Legg-Calvé-Perthes disease. The intervention between the pre-test and post-test phases consisted of a consensus-building session during which all raters jointly arrived at standardized definitions of the various joint structures that are assessed with use of the classification system. The effect of these definitions on reliability then was assessed by reevaluating the radiographs during the post-test phase. RESULTS: The pre-test intra-rater reliability coefficients ranged from 0.709 to 0.915, and the post-test coefficients ranged from 0.568 to 0.874. The pre-test inter-rater reliability coefficients ranged from 0.603 to 0.732, and the post-test coefficients ranged from 0.648 to 0.744. Contributing to the variance was a lack of agreement concerning the assessment of joint structures and the way in which the raters translated these evaluations into a classification according to the system of Stulberg et al. CONCLUSIONS: Although intra-rater reliability was marginally acceptable, the degree of variability between the classifications assigned by different raters even after the intervention - calls into question the reliability of the system of Stulberg et al.; consequently, the validity of any treatment decisions, outcome evaluations, or epidemiological studies based on this system is also in question.

Use of animal models in musculoskeletal research.

Understanding of the human musculoskeletal system and common clinical disorders of bones, joints and soft tissues has been enhanced by the use of experimental animal models. Articles reporting on the results of these biomedical experiments frequently include conclusions that are based on the assumption that the biology of the animal model is similar to that of a human being for the disease process under investigation. The purpose of this investigation was to study the criteria and the considerations for selection of an animal model in musculoskeletal research. Selected journals from the musculoskeletal literature published between January 1991 and November 1995 were scrutinized for the use of animal models, and several criteria used in the selection of the various animal models were investigated. The selection criteria analyzed in this study included the biologic characteristics of the model, budget issues, the reproducibility of a musculoskeletal disease, and animal handling factors. A computer-assisted search of the musculoskeletal literature published from 1965 to 1995 was also performed to screen for reports comparing mammals used as animal models in terms of these selection criteria. Our findings imply that the selection of animal models in research of the musculoskeletal system is based partly on non-standardized criteria that are not necessarily based on the biology of the disease process being studied. In addition, there are limited comparative data on the selection and use of different animals for musculoskeletal research. We believe the selection of models should be more standardized based on both biological and non-biological criteria. Researchers would then be able to put in a more meaningful perspective the results of research using animal models and their clinical implications.