Can rotational alignment of total knee arthroplasty be measured on MRI?

Background and purpose The aim of this study was to investigate the potential of MRI to determine rotational alignment after TKA in comparison to the gold standard, CT. Methods Rotational alignment was measured in the transverse plane on CT and MR-images in 14 patients prior to TKA revision. Differences between CT and MRI measurements were analysed. Results There was a strong correlation between CT and MRI measurements for both the tibial ( r = 0.929) and femoral ( r = 0.942) components with a mean difference of 0.47 ± 1.3 and 0.13 ± 3.2 degrees, respectively. Interpretation Despite artefact formation, it can be concluded that the rotational alignment of metallic TKA components can be measured by MRI as accurately as by CT.