A Validated Single-View Radiographic Alternative to Computed Tomography for the Measurement of Femoral Anteversion: A...

Although preoperative templating in total hip arthroplasty is helpful to ensure appropriate component position, there is no single-view radiographic method to determine femoral anteversion (FA) preoperatively. The aim of the present study was to validate the use of radiographic measurement of FA using a modified Budin view.

This prospective study reports on 105 limbs from 65 patients. Computed tomography (CT) scans and radiographs were obtained to measure native FA. Radiographs were obtained using the modified Budin protocol with 90° flexion at the knee and 90° flexion and 30° abduction at the hip. Pearson correlation analyses, paired-samples t-test, and Bland-Altman plots were performed to assess correlation and agreement between methods. Data were grouped into subsets based on CT-derived FA in 5° intervals. Groups included all limbs, FA < 35°, FA < 30°, and FA < 25°.

For all limbs, Bland-Altman analysis revealed a fixed bias (mean bias, -0.8°; 95% confidence interval, -1.4° to -0.2°) and showed that radiographic methods underestimated FA. Subset analyses were performed and revealed excellent correlation between CT and radiographic measurements for all subgroups (r = 0.97, P < .001). Paired-samples t-tests revealed no significant difference between methodologies for any of the subgroups. Radiographic and CT methods showed excellent agreement, and the bias between methods was within 0.5° for all subgroups. There was no fixed bias and thus no systematic difference in methods within any of the subgroup analyses.

Radiographic measurement of FA using a modified Budin view is a valid and reliable technique.