Background and Objectives: It is unknown whether the tibial tuberosity–tibial intercondylar midpoint (TT–TIM) distance can be interchangeably measured on axial computed tomography (CT) and magnetic resonance imaging (MRI). The objective of this retrospective cross-sectional comparative study was to evaluate the intermethod agreement of the TT–TIM distance on axial CT and MRI and its bias towards tibial rotation (TR), age, sex, and body side.
Materials and Methods: On axial CT and MRI of 15 consecutive knee pairs where each pair belonged to the same patient with no pathology affecting the tibial circumference and tibial tuberosity, TT–TIM distance and TR were measured by two blinded radiologists at 2-week intervals. Upon checking the symmetry of distributions (Shapiro–Wilk test), differences between matched knee pairs (Wilcoxon signed-rank test), intermethod (Bland–Altman plot) and interrater agreement (intraclass correlation coefficient [ICC]), and correlations (Spearman rank correlation) were assessed.
Results: The mean intermethod difference in TT–TIM distance was not statistically significant (−0.4 mm [−1.82, 0.96];
p = 0.52). The TT–TIM distance did not differ between knee pairs (
p = 0.68), its interrater agreement was almost perfect (ICC > 0.81), and no bias towards TR (
p > 0.66), age (
p > 0.14), sex (
p = 0.66), and body side (
p > 0.37) was found.
Conclusions: The TT–TIM distance can be interchangeably measured on axial CT and MRI with almost perfect interrater agreement, unbiased towards TR, age, sex, and body side.
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