Assessing the Reliability of Postoperative Cross-Table Radiographs Compared to CT Scans for Measuring Acetabular Anteversion Angle Following Total Hip Arthroplasty.

Abstract

This study aimed to evaluate acetabular anteversion following total hip arthroplasty (THA) using cross-table lateral radiographs and CT scans and to determine the reliability of cross-table lateral radiographs compared to computed tomography (CT) scans for measuring acetabular anteversion. We conducted a cross-sectional study of patients undergoing THA at Justice K.S. Hegde Charitable Hospital, Deralakatte, Mangalore, from January 2020 to June 2021. Radiographs are typically taken in both anteroposterior (AP) and lateral views after THA. However, for this study, a cross-table lateral view was used instead of the usual lateral radiograph to measure the angle of anteversion. The anteversion was calculated using the method described by Woo and Morrey. Additionally, CT scans were performed on all patients as part of the study protocol. The anteversion measured in these scans was compared to that in the cross-table radiographs to assess the latter's reliability for routine use. The risk of radiation exposure from CT scans was minimized by adhering to the ALARA (As Low as Reasonably Achievable) principle, with only axial sections of the acetabular cup being scanned. The results show that the radiographic acetabular anteversion and CT scan measurements have a mean difference of 0.3036. There is a positive correlation between these measurements. The p-value is not statistically significant (p=0.698). Therefore, the measurements are correlated with each other with a linear relationship (r=0.919). For anteversion measurements using the X-ray method, the mean was 27.16 degrees with a standard deviation of ±9.49. The median was 27.26 degrees, ranging from 10.27 to 42.58 degrees. In comparison, the CT method yielded a mean anteversion of 27.40 degrees with a standard deviation of ±8.50 degrees. The median was 27.64 degrees, ranging from 12.35 to 43.11 degrees. Cross-table lateral radiographs are a reliable and comparable method to CT scans for measuring acetabular anteversion following total hip arthroplasty.