Utilization rates of knee arthroplasty in OECD countries revised

In 2015, we reported rapid growth and variation in knee arthroplasty across OECD countries, especially in patients ≤64 years, projecting a four-fold increase by 2030. Since then, clinical practice and external conditions have evolved. This study re-examines trends through 2022 and expands previous analyses. We analyzed data from 25 OECD countries (2005-2022) using OECD and national sources. Age-specific utilization rates (≤64 vs. ≥65 years) were derived from population-adjusted incidence. We calculated compound annual growth rates (CAGR), mean annual differences (MAD), and tested robustness via sensitivity analyses. We calculated within- and between-country associations of obesity/overweight with utilization. From 2011 to 2022, volume increased (CAGR: +2.33% [2.33; 2.34]; MAD: 37,700 [35,700; 39,600]), although slower than between 2005 and 2011 (CAGR: +4.75% [4.73; 4.78]; MAD: 58,100 [55,500; 60,700]). Patients aged 64 and younger now account for ∼50% of procedures (CAGR: +4.46% [4.28; 5.81]; MAD: 32,300 [30,700; 33,900]), while growth slowed in older adults (CAGR: +0.61% [0.60; 0.61]; MAD: 5400 [5000; 5700]). A percentage point rise in obesity was linked to +1.1-1.9% higher utilization, stronger in older cohorts and lower-income settings. COVID-19 led to around -22% (∼406,500 [386,600; 426,300] procedures) drop in 2020, followed by a faster recovery in younger adults. Growth remains below our original projection in 2015. Growth to 2022 has fallen short of the earlier 2015 projection. Still, utilization remains on an upward trajectory, with a growing share of procedures among younger patients, now accounting for >50% of volume. Cross-country variation has narrowed vs. our earlier analysis, with lower volume countries catching up. Obesity remains associated with higher utilization, with the strengths of this association varying by national income. Post-COVID-19 recovery patterns are consistent with sustained demand and higher relative contribution from younger, lower-risk populations.