To evaluate the trends and cross-country inequalities of global osteoarthritis (OA) burden over the last 30 years, and further predicted its changes to 2035.The estimates and 95% uncertainty intervals (UIs) for incidence, prevalence, and disability-adjusted life-years (DALYs) of OA were extracted from Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019. We described OA epidemiology at global, regional, and national levels, analyzed 1990-2019 trends in OA burden from overall, local, and multi-dimension scopes, decomposed OA burden according to population size, age structure, and epidemiologic changes, quantified cross-country inequalities in OA burden using standard health equity methods recommended by World Health Organization, and predicted changes of OA burden to 2035.GBD 2019 estimated 527,811,871 (95% UIs: 478,667,549 to 584,793,491) prevalent cases, 41,467,542 (95% UIs: 36,875,471 to 46,438,409) incident cases and 18,948,965 (95% UsI:9,571,298 to 37,659,660) DALYs cases of OA worldwide in 2019, with the highest cases in East Asia and highest age-standardized rate (ASR) in high-income North America. The global burden of OA increased overall from 1990 to 2019 with the fastest growth observed in the first decade of the 21st century. Decomposition analysis revealed that OA knee (62.78%), women (60.47%), and middle sociodemographic index (SDI) quintile (32.35%) were responsible for the most significant DALYs, whose changes were primarily driven by population growth and aging. A significant increase in SDI-related inequalities was detected, and the gap in DALYs between the highest SDI country and the lowest SDI country increased from 179.5 (95% CI: 149.3 to 209.8) per 100,000 in 1990 to 341.9 (95% CI: 309.5 to 374.4) per 100,000 in 2019. Notably, although the ASR of incidence, prevalence, and DALYs of OA was predicted to decrease annually from 2020 to 2035, the case number of these metrics was predicted to keeping increasing, with predicted values of 52,870,737 (95% UI: 39,330,063 to 66,411,411), 727,532,373 (95% UI: 542,765,783 to 912,298,962), and 25,986,983 (95% UI: 19,216,928 to 32,757,038) in 2035, respectively.As a major public health issue, the global burden of OA showed an overall increasing trend from 1990 to 2019, which was primarily driven by population growth and aging. Countries with high SDI shouldered disproportionately high OA burden, and the SDI-related inequalities across countries exacerbated over time. This study highlighted great challenges in the control and management of OA, including both growing case number and distributive inequalities worldwide, which may be instructive for better making public health policy and reasonably allocating medical source.Copyright © 2024 Elsevier B.V. All rights reserved.