Avaliação histológica na osteoartrite de joelho de ratos: validação e reprodutibilidade de uma nova classificação

Abstract

The objective of this study was to develop, validate and make reproducible a new histological evaluation of the knee joint complex of rats. To acquire the sample (experimental procedure), 20 rats were divided into 5 groups: Control, Osteoarthritis 3 months, Osteoarthritis 6 months, Osteoarthritis 9 months and Osteoarthritis 12 months. The animal model of osteoarthritis was the transection of the anterior cruciate ligament of the knee. After the period of exposure to the disease of each group, the knee joints of all animals were collected and processed for the preparation of histological slides, which were stained with Harris Hematoxylin and Safranin Fast Green, and selected those that best represented OA . The generation of the items of the new evaluation, which addressed the entire articular complex at different OA times, was developed following the guiding principles for the development of a classification system (Pritzker et al., 2006), which includes not only standardization of the evaluation system itself, but also, the conditions that the histopathology is evaluated. From the preparation of the new evaluation, a training of the evaluators and the evaluation of the photomicrographs according to the New Histological Assessment was carried out and after two months the Mankin (1971) evaluation. Subsequently, the statistical analyzes, reliability through the Intra-Class Correlation Coefficient and the correlation of both evaluations were done. The new evaluation presented excellent inter- and intra-observer reliability with an Intraclass Correlation Coefficient (ICC) of 0.992 and 0.994, respectively, among all evaluators. The interobserver reliability was comparable for experienced and inexperienced observers and both obtained a CCI of 0.993. Significant correlations were found between the new histological evaluation and Mankin's, with a mean correlation coefficient (CC) of 0.95. Therefore, the new histological evaluation of the joint complex is a valid and reliable tool to evaluate the degeneration of the joint complex at different time of osteoarthritis and is suitable for inexperienced and experienced researchers.