The Missing Revision Burden: Total Hip and Knee Replacement Revision Rates in the United States, 1996 to 2020.

Background: Rising volumes of primary hip and knee replacements, coupled with longer lifespans, have led to projections of revision surgeries becoming a significant cost and healthcare burden. However, techniques and technology have improved. The purpose of this study was to determine whether revision hip and knee arthroplasty incidence has risen as previously predicted in the United States. Methods: This retrospective serial cross-sectional study analyzed data on primary and revision hip and knee replacements from the National Inpatient Sample, a comprehensive US hospitalization database, from 1996 to 2020. Primary outcome was the incidence of primary and revision arthroplasty. Secondary outcomes were comparisons between observed revision volumes and predictions, as well as trends in indications for revision surgery. Results: From 1996 to 2019, the incidence of primary hip replacements increased by 156%, from 128 to 328 per 100,000 person-years. The incidence of revision hip replacements increased by 41%, from 24 to 34 per 100,000 person-years. The incidence of primary knee replacements increased 136% from 220 to 520 per 100,000 person-years, while the incidence of revision knee replacements rose by 147%, from 19 to 47 per 100,000 person-years. Modeling a 10% failure rate at 10 years, revision hip replacement volumes were 41% lower than expected. Modelling a 7% failure rate at 10 years, revision knee replacement volumes were 33% lower than expected. The proportion of revisions due to loosening and implant wear decreased significantly over the last decade: for hip replacements, from 34.3% to 20.7% (p < 0.001), and for knee replacements, from 49.2% to 28.5% (p < 0.001). Conclusion: The burden of revision surgeries, especially due to implant wear, is significantly lower than anticipated. These data suggest improving longevity, which may support surgeon and patient confidence in arthroplasty durability.