MRI use leading up to total knee arthroplasty: a retrospective cohort study

Demand for total knee arthroplasty (TKA) is increasing as it remains the gold-standard treatment for end-stage osteoarthritis (OA) of the knee. Magnetic resonance imaging (MRI) scans of the knee are not indicated for diagnosing knee OA and represent a possible delay to orthopaedic surgeon referral and unnecessary expenditure. The purpose of this study was to determine the proportion of patients who underwent an MRI in the two years prior to their primary TKA for OA and determine patient and physician associations with increased MRI usage.

This is a population-based cohort study using administrative data from Ontario, Canada. All patients over 40 years old who underwent their first primary TKA between April 1, 2008, and March 31, 2019, were included. Statistical analyses were performed using SAS and included the Cochran-Armitage test for trend of MRI prior to surgery. A predictive multivariable regression model was used to determine features correlated to receiving an MRI.

There were 194,989 eligible first-time TKA recipients, of which 38,244 (19.6%) received an MRI in the two years prior to their surgery. The majority of these (69.6%) were ordered by primary care physicians. Patients who received an MRI were younger, had fewer comorbidities and were more affluent than patients who did not (p < 0.001). MRI use prior to TKA increased from 2008 to 2018 (p < 0.001).

Despite MRIs rarely being indicated for the work-up of end-stage OA, nearly one in five patients have an MRI in the two years prior to their TKA. This may be increasing healthcare expenditure and surgical wait-times.