Magnetic resonance imaging vs. two- and three-dimensional computed tomography scans for assessment of glenoid inclination and version.

BACKGROUND

Accurate glenoid component placement is crucial for anatomic (aTSA) or reverse (rTSA) total shoulder arthroplasty. Preoperative glenoid assessment in computed tomography (CT) scans with or without planning software seems to be the established method to plan implant positions. Magnetic resonance imaging (MRI) scans can also display the glenoid bone for preoperative assessment while reducing radiation exposure. Therefore, the objective of this study was to manually assess the glenoid version and inclination in 2D MRI and CT scans in cases with degenerative shoulder pathologies. The results were compared to those of an automated 3D planning software to validate the imaging modality for preoperative glenoid assessment.

METHODS

MRI and CT scans of 146 patients (n = 41 aTSA; n = 105 rTSA) were included in this retrospective, single-center study. Glenoid version and inclination were measured manually according to Friedman et al and Maurer et al on CT and MRI scans by two observers. Subsequently, the results were compared to the automated measurements performed by planning software. A repeated-measures analysis of variance was performed to compare the measured angles, and the interobserver and intraobserver reliability were calculated using the intraclass correlation coefficients. The level of significance was set at  < .05.

RESULTS

The average glenoid inclination measured in CT scans was 7.94° ± 7.33°, in MRI scans it was 8.56° ± 7.34°, and in automated planning software it was 7.87° ± 7.60°. The analysis of variance revealed significant differences in mean inclination between 2D MRI and 2D CT ( < .0005) and between MRI and automated software ( = .011). No significant difference was found between 2D CT scans and automated planning software ( = 1.000). The mean glenoid version measured in 2D CT scans was -7.94° ± 10.86°, in 2D MRI scans it was -8.04° ± 10.80°, and -8.32° ± 11.53° in the automated planning software. There was no significant difference in between measurement methods ( = .339). Interobserver reliability analysis showed no statistical differences between the two observers. All measurements had excellent intraobserver reliability.

CONCLUSION

Preoperative assessment of glenoid version and inclination is crucial in ensuring precise implant positioning and orientation in aTSA and rTSA. This study observed a significant level of concordance between manual and automated measuring techniques utilizing MRI and CT scans. The mean glenoid inclination exhibited a statistically significant difference of less than 1° across the assessment modalities, and no difference for glenoid version was noted. It seems to be questionable if this finding is clinically relevant. MRI may serve as a viable and safe option for assessing glenoid morphology, version, and inclination if CT scans are not available.