Global, regional, and national burden of knee osteoarthritis: findings from the Global Burden of Disease study 2021 and projections to 2045.

backgroundOsteoarthritis is a major contributor to the global disease burden, with the knee being the most commonly affected site. Comprehensive research on knee osteoarthritis (KOA) at a global scale carries significant implications for public health.

methodsThe estimates and 95% uncertainty intervals (UIs) for prevalence, incidence and disability-adjusted life years (DALYs) of KOA were extracted from Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021. We described KOA epidemiology at global, regional, and national levels, analyzed 1990-2021 trends in KOA burden from overall, local, and multi-dimension scopes, decomposed KOA burden according to population size, age structure, and epidemiologic changes, quantified cross-country inequalities in KOA burden using standard health equity methods recommended by World Health Organization, and predicted changes of KOA burden to 2045.

resultsGBD 2021 estimated 374,738,744 (95% UI: 321,858,982-428,353,220) prevalent cases, 30,845,891 (95% UI: 26,534,151-35,188,905) incident cases and 12,019,070 (95% UI: 67.08-266.87) DALYs cases of KOA worldwide in 2021. An overall increase in prevalence rates, incidence rates and DALYs rates were observed from 1990 to 2021. And the prevalence number, incidence number and rates were consistently higher in females compared to males. Decomposition analysis revealed that aging, population growth, and epidemiological changes contributed 15.6%, 74.72%, and 9.69% to the global increase in age-standardized prevalence rate, respectively. A decrease in Socio-Demographic Index (SDI)-related inequalities was detected. Notably, the case number of these metrics were predicted to keeping increasing, with predicted values of 658,088,384.48 (322,110,040.98-994,066,727.98), 47,256,502.97 (23,440,017.7-71,072,988.23) and 20,517,479.78 (10,056,930.68-30,978,028.88), respectively.

conclusionsThe global burden of KOA has shown a consistent upward trend from 1990 to 2021, primarily driven by population growth and aging demographics. Countries with high SDI faced a disproportionately high burden of KOA, although inequalities related to SDI among nations have decreased over time. This study underscores significant challenges in managing KOA, including the increasing number of cases and ongoing disparities worldwide.