Rotation matters: CT and MRI yield different tibiofemoral rotation angles in patellofemoral patients. An investigational plateau-anchored MRI method is descriptively associated with a smaller mean CT-MRI difference.
retrospective_cohort · Level III
Where this comes from
- Record sourced from PubMed, PMID 41953756.
- Also identified by DOI 10.1002/jeo2.70708 and PMC identifier 13054234.
- Licence recorded as CC BY.
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Abstract
To compare tibiofemoral rotation (TFR) measured on magnetic resonance imaging (MRI) and computed tomography (CT) in patellofemoral (PF) patients and descriptively report mean differences using an alternative plateau-anchored MRI measurement method. Surgical candidates for tibial derotational osteotomy with both CT and MRI were retrospectively reviewed. Demographics/surgical indication/tibial torsion were recorded. TFR was measured on CT/MRI using standard posterior condylar-posterior tibial axis technique. A plateau-anchored MRI method utilizes the angle between the distal femoral posterior condylar axis and the axis connecting the proximal tibial plateau's most medial and lateral aspects. Paired <i>t</i> tests compared TFR between modalities and MRI methods; subgroup analyses evaluated diagnosis. Pearson correlation assessed association between CT-based TFR and tibial torsion. Fifty-eight knees/46 patients (50 female; mean age 21 ± 7 years; body mass index [BMI] 25 ± 6 kg/m<sup>2</sup>) were analysed. Indications: PF instability ± pain: 20 knees, pain without instability: 38 knees. Mean MRI TFR: 2.11°; CT TFR 8.28°; plateau-anchored MRI method 9.80°. Mean difference between standard MRI and CT was -6.18° (95% confidence interval [CI] -7.48 to -4.88; <i>p</i> < 0.001); the difference between plateau-anchored MRI and CT was 1.51° (95% CI 0.01-3.01; <i>p</i> = 0.048). Bland-Altman plots showed good inter- and intra-observer agreement. In exploratory subgroup analyses (PF instability ± pain vs. pain without instability), no statistically significant differences were observed in the CT-MRI mean TFR differences. Tibial torsion (38.9° ± 7.0°) did not correlate significantly with CT-based TFR (<i>r</i> = 0.25; <i>p</i> = 0.06). CT and MRI yield systematically different TFR values in the same PF patients; standard MRI yielding lower values than CT. A plateau-anchored MRI method yielded a smaller mean difference relative to CT than the standard MRI method in this cohort. These results should not be interpreted as demonstrating interchangeability, accuracy, or clinical readiness of the plateau-anchored method. Level II.