Abstract
BACKGROUND: Total knee arthroplasty (TKA) is a common procedure for late-stage degenerative changes, a situation for which magnetic resonance imaging (MRI) is typically not considered useful. In an era attempting to contain healthcare expenditures, the rate, timing, and predictors for MRI before TKA were assessed in a large, national, administrative data set. METHODS: The 2010 to Q3 2020 MKnee PearlDiver data set was used to identify patients undergoing TKA for osteoarthritis. Those with lower extremity MRI for knee indications within 1 year before TKA were then defined. Patient age, sex, Elixhauser Comorbidity Index, region in the country, and insurance plan were characterized. Predictors of having had an MRI were assessed by univariate and multivariate analyses. The costs and timing of the obtained MRIs were also assessed. RESULTS: Of 731,066 TKAs, MRI was obtained within 1 year prior for 56,180 (7.68%) with 28,963 (51.9%) within the 3 months of TKA. Independent predictors of having had an MRI included younger age (odds ratio [OR], 0.74 per decade increase), female sex (OR, 1.10), higher Elixhauser Comorbidity Index (OR, 1.15), region of the country (relative to South, Northeast OR, 1.08, West OR, 1.22, Midwest OR, 1.36), and insurance (relative to Medicare, Medicaid OR, 1.36 and Commercial OR, 1.35) with P < 0.0001 for each. The total cost of MRIs among patients who received a TKA is $44,686,308. CONCLUSION: Noting that TKA is typically done for advanced degenerative changes, MRI should rarely be indicated in the preoperative period for this procedure. Nonetheless, this study found that MRI was done within the year before TKA for 7.68% of the study cohort. In an era striving for evidence-based medicine, the almost $45 million dollars spent on MRI in the year before TKA may represent overutilization.