Burden and Temporal Trends of Osteoarthritis in Germany from 1990 to 2021, with Projections to 2041: Findings from the Global Burden of Disease Study.

Background: Osteoarthritis (OA) is a leading cause of disability globally, particularly affecting aging populations. This study assessed temporal trends in OA burden in Germany from 1990 to 2021 and projected future burden to 2041. Methods: A secondary analysis of the Global Burden of Disease (GBD) 2021 data was conducted. Metrics analyzed included age-standardized incidence rate (ASIR), age-standardized prevalence rate (ASPR), and disability-adjusted life years (DALYs). Temporal trends were assessed using estimated annual percentage change (EAPC) and joinpoint regression. Decomposition analysis was used to examine the main drivers of the increase in incidence. Pearson's correlation assessed temporal co-variation with the Sociodemographic Index (SDI), and ARIMA models projected burden to 2041. Results: Between 1990 and 2021, incident OA cases increased by 36%, prevalent cases by 48%, and DALYs by 49%. Across all three measures, the relative increase was greater in males than in females (incidence: 50% vs 28%; prevalence: 73% vs 36%; DALYs: 74% vs 37%). Despite these steeper relative increases in males, females had higher absolute burden in 2021 for incidence, prevalence, and DALYs (468,653 vs 319,059; 7,571,715 vs 4,696,892; and 272,903 vs 164,888, respectively). Knee OA was the dominant subtype and accounted for the highest incidence and prevalence, exceeding 7.2 million prevalent cases in 2021. Germany's DALY rates exceeded global rates in all age groups except 45-59 years. Decomposition analysis suggested that the increase in incidence was mainly attributable to changes in age structure (23.9%), population growth (6.4%), and epidemiologic change (5.7%). Joinpoint regression identified several significant shifts in temporal trends, with renewed increases after 2010. ASIR, ASPR, and age-standardized DALY rates (ASDaR) showed positive temporal correlations with the SDI. ARIMA projections suggested continued upward trends in ASIR, ASPR, and ASDaR attributed to OA, with projected values by 2041 reaching approximately 580.0 (95% CI: 554.7-605.3), 7309.1 (95% CI: 7110.9-7507.2), and 260.6 (95% CI: 252.3-268.9) per 100,000 persons, respectively. Conclusion: The burden of OA in Germany has increased substantially over the past three decades and is projected to continue rising through 2041. Although the relative increase in incidence was greater in males, the absolute burden remained higher in females. The projected rise in OA burden underscores the need for targeted healthcare planning and resource allocation. National strategies should account for demographic aging to support effective long-term OA management.