STRATIFICATION OF KNEE OSTEOARTHRITIS: TO THE PROBLEM OF PHENOTYPES

Abstract

The presented review is devoted to the actual problem of knee osteoarthritis (OA) stratification and consists of descriptive and systemic analysis parts. In the first part, the evolution of OA concepts and the development of phenotypic approach is reflected. It is noted that OA followed long path from age-related “wear and tear” to inflammatory disease with high heterogeneity, which triggered enormous number of attempts to group this disease in the last decade. As no unified approach has been proposed in its classifying, rheumatology has collected an abundance of ambiguous data obtained in studies on knee OA. Recent advances in phenotyping made obvious the need to systematize proposed earlier classifications and to evaluate their compliance with the modern concept, which was done in the second part of review. Systematic search strategy was used in the referenced databases MEDLINE/PubMed and Google Scholar without a time frame with the following keywords "osteoarthritis", "phenotypes", "classification", "subtypes", "subsets", "subgroups", "endotypes", and 58 different classifications were extracted, analyzed and stratified into the following boxes: phenotypes, endotypes, and other classifications. Among the proposed OA classifications, clinical groups were the most common, followed by structural, laboratory, molecular, genetic, and progression trajectories. Only few of proposed OA kinds can rightly be called phenotypes whereas most of classifications aimed to distinguish predictors or risk factors for this disease. It can be assured that the variety of accumulated information will soon lead us to novel approaches of phenotype-associated management strategy for OA patients.