Anteversion Angle Measurement in Suspected Torsional Malalignment of the Femur in 3-Dimensional EOS vs Computed Tomography—A Validation Study

Abstract

Background: Computed tomography (CT) scan is the standard for assessment of femoral torsion. This observational study was conducted to evaluate the comparability of the EOS radiation dose scanning system (EOS imaging, Paris, France) and the CT scan in patients with suspected torsional malalignment of the femur. Methods: Patients with suspected torsional malalignment of the femur were included in a study for surgical planning. The primary endpoint was to compare the 3-dimensional radiological (EOS) imaging system with the CT scan to determine femoral anteversion (AV) angle. Three independent raters performed measurements. Comparability of CT scan and EOS values was assessed by Pearson correlation, t test, interobserver reliability, and intraobserver reliability (Cronbach alpha). Results: About 34 femora were examined. Interobserver reliability/intraobserver reliability was 0.911 of 0.955 for EOS and 0.934 of 0.934 for CT scan. EOS system revealed an AV angle of 12.2 ± 10.0 (À15.0 to 32.0 ). CT examinations showed an AV angle of 12.6 ± 9.2 (À3.2 to 35.6 ). About 11 hips featured physiological AV, 14 hips showed decreased AV (<10 ) or retroversion (<0 ), and 9 hips showed increased AV (>20 ). Overall, a strong Pearson correlation of t ¼ 0.855 and a highly significant correlation in the t test for both methods was seen. In patients with decreased AV, retroversion, or increased AV, Pearson correlation only resulted in a moderate/low correlation of t ¼ 0.495 and t ¼ 0.292. The t test showed no significant correlation at malrotation. Conclusion: In torsional malalignment, EOS does not have correlation with CT measurements. In contrast to CT scan, EOS allows femoral torsion measurement independent of legs' positioning.

Reliability of the pelvis and femur anatomical landmarks and geometry with the EOS system before and after total hip arthroplasty

“…Interestingly, the limits of agreement presented by Cho et al 12 have the same order of magnitude as the SDC found in the present study. Correlations between measurement of femoral torsion with CT scan and bi-plane X-rays were found to be strong (R > 0.8) 10 , 34 but Mayr et al showed that for patients with decreased (< 10°) and increased (> 20°) anteversion the correlation was only moderate to low, respectively 34 . Although it was shown that CT scan was influenced by femur position, contrary to bi-plane X-rays 26 , 34 , the higher measurement error with bi-plane X-rays tempers the recommendation of using this method over CT scan for accurate measurement of femoral torsion.…”

The Impact of Hip Dysplasia on CAM Impingement

“…To minimize this error, all measurements of the plain radiography were performed by an orthopedic-surgeon trained observer and all measurements of the computed tomography by a specialized musculoskeletal trained radiologist. A consensus reading was not performed since the interobserver and intraobserver reliability were described as 0.911 and 0.955 for EOS, respectively, 0.934 and 0.934 for CT scan to measure the rotational alignment [ 30 ].…”

Assessing component orientation of total hip arthroplasty using the low-dose bi-planar radiographs

“…1A) [12], while the other with the radiographic coronal plane (functional coronal plane). Some previous studies have already evaluated the accuracy of measurements of femoral, tibial, and femorotibial torsion using the low-dose bi-planar radiographs [13][14][15][16][17]. Demzik et al [18] analyzed inter-rater and intra-rater repeatability, and the reliability of pelvic parameters.…”