Paper detail

Three-Dimensional Automated Assessment of the Distal Radioulnar Joint Morphology according to Sigmoid Notch Surface Orientation

The aim of this study was to develop a new method for generating reproducible 3D measurements for the quantification of the distal radioulnar joint morphology. We hypothesized that automated 3D measurement of the ulnar variance and the sigmoid notch angle are comparable to those of the gold standard, while overcoming some of the drawbacks of conventional 2D measurements. Radiological data of healthy forearm bones of 53 adult subjects were included in the study. Automated measurements for the assessment of the sigmoid-notch morphology based on 3D landmarks were developed incorporating the subject-specific estimation of the cartilage surface orientation. A common anatomical reference was defined among the different imaging modalities and a comparison between the sigmoid notch angle and UV measurements was performed in radiographs, CT scans and 3D models. Finally, the developed UV measurements in 3D were compared to the method by radiographs in an experimental setup with 3D printed bone models. The proposed automated 3D analysis of notch subtype showed a significantly larger notch radius for negative notch angle compared to positive sigmoid notch angle subjects. Similar UV measurements were obtained in healthy joint morphologies with a high correlation between the radiographs and 3D measurements, for sigmoid notch angle and UV . In the experimental setup with a modified radial inclination, the UV was on average 1.13 mm larger in the radiographs compared to the 3D measurements, and 1.30 mm larger in the cases with a modified palmar tilt. The developed 3D measurements allowed to reliably quantify differences in the sigmoid notch subtypes.