Assessment of a Web-Based Tool for Precision Measurement of Acetabular Component Orientation in Total Hip Arthroplasty

Purpose: Hip dislocation after total hip arthroplasty can be linked to the orientation of acetabular component placement, characterized by acetabular inclination and anteversion angles obtained from pelvic radiographs. We introduce a novel web tool to streamline the subjective and lengthy process of manual measurement. This tool assists in collecting data that will be used to train an AI model for automation.

Methods/Materials: One board-certified orthopedic surgeon annotated anteroposterior radiographs of 80 patients who underwent unilateral hip arthroplasty from 1/12/2017 to 12/18/2017. Manual and web tool measurements included abduction angle (degrees), S/TL ratio, and Liaw’s anteversion angle (degrees). One board-certified orthopedic surgeon used the web tool to mark 6 points on the radiographs: each end of the teardrop line, each end of the horizontal diameter of the acetabular cup, 1 point along the circumference of the acetabular cup, and 1 point along the acetabular head. A line connecting the teardrop line, an ellipse around the acetabular cup perimeter, and an ellipse around the coronal view of the acetabulum were automatically mapped to measure the abduction angle and S/TL ratio, which were inputted into Liaw’s formula to calculate acetabular angle and safe zone determination. Results were obtained in under 10 seconds per radiograph. Differences between manual and web tool measurements were compared using a paired t-test. P< 0.05 was considered statistically significant.

Results: There were no statistically significant differences in abduction angle (43.59±5.97 annotated vs 42.82±5.49 web tool, p=0.251), anteversion angle (20.75±7.81 vs 22.80±10.79, p=0.080), and S/TL ratio (0.43±0.15 vs 0.44±0.16, p=0.456) between annotated and web tool measurements.

Conclusions: Preliminary results show the web tool is accurate compared to manual annotation. This tool improves efficiency of angle measurement for intraoperative use and data collection. Future work includes training AI models for automatic angle detection, safe zone determination, and adapting to mobile devices. The web tool may contribute to other areas of radiology where geometry bears relevance to outcomes.