The Accuracy of a Mechanical Cup Alignment Guide in THA Through Direct Anterior and Posterior Approaches Measured with CT-Based Navigation.

The purpose of this study was to compare the accuracy of a mechanical cup alignment guide using CT-based navigation between a direct anterior approach (DAA) in both supine and lateral positions and a posterior approach (PA) in the lateral position. A trial cup was placed with a mechanical guide that aimed at 47° of radiographic inclination and 14° of anteversion. The average cup inclination and anteversion were measured using CT-based navigation. The average radiographic anteversion in the DAA supine and lateral group was larger, and that in the PA group was smaller than the target angle. In conclusion, there are no differences in the accuracy or precision of cup angles among the DAA supine, DAA lateral position, and PA groups using a mechanical guide.