Geographic Differences in Rates of Primary Total Knee Arthroplasty in Young and Older Adults: A Comparison of 3 US States

Objective Rates of total knee arthroplasty (TKA) among Medicare beneficiaries (adults aged ≥ 65 yrs) vary across the United States, with higher rates in the Midwest and West than in the South. It is not known if a similar variation is present among younger patients, or if findings in Medicare reflect selective postponement of TKA in some regions.

Methods Data on all primary TKA performed in adults aged ≥ 20 years in 3 states (Iowa, Utah, and Florida) in 2016 were obtained from state inpatient databases. Rates of TKA were computed based on population census data. Age-, sex-, and race-standardized rates were compared between Iowa and Florida, and between Utah and Florida, among adults aged 20–64 years and adults aged ≥ 65 years.

Results There were 10,074, 8954, and 43,908 primary TKAs in Iowa, Utah, and Florida, respectively. Standardized rates were higher in Iowa and Utah than in Florida among both adults aged 20–64 years (Iowa:Florida rate ratio [RR] 1.89, 95% CI 1.79–1.99; Utah:Florida RR 2.31, 95% CI 2.18–2.45) and those aged ≥ 65 years (Iowa:Florida RR 1.41, 95% CI 1.35–1.47; Utah:Florida RR 1.77, 95% CI 1.70–1.85). Results were similar in sensitivity analyses limited to White patients, urban residents, and those with a diagnosis of knee osteoarthritis.

Conclusion TKA rates were higher in Iowa and Utah than in Florida among both younger adults and those aged ≥ 65 years, indicating that geographic differences are not specific to elderly patients.