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

Abstract

Background Three-dimensional computed tomography (3D CT) reconstruction is the reference standard for measuring component orientation. However, functional cup orientation in standing position is preferable compared with supine position. The low-dose bi-planar radiographs can be used to analyze standing cup component orientation. We aimed to assess the validity and reliability of the component orientation using the low-dose bi-planar radiographs compared with the 3D CT reconstruction, and explore the differences between the functional cup orientation in standing radiographs and supine CT scans. Methods A retrospective study, including 44 patients (50 hips) with total hip arthroplasty (THA), was conducted. CT scans were taken 1 week after surgery and the low-dose bi-planar radiographs were taken in the follow-up 6 weeks later. Component orientation measurement was performed using the anterior pelvic plane and the radiographic coronal plane as reference, respectively. Results The study showed no significant difference in cup anteversion (p = 0.160), cup inclination (p = 0.486), and stem anteversion (p = 0.219) measured by the low-dose bi-planar radiographs and 3D reconstruction. The differences calculated by the Bland–Altman analysis ranged from − 0.4° to 0.6° for the three measured angles. However, the mean absolute error was 4.76 ± 1.07° for functional anteversion (p = 0.035) and 4.02 ± 1.08° for functional inclination (p = 0.030) measured by the bi-planar radiographs and supine CT scans. Conclusions The low-dose bi-planar radiographs are the same reliable and accurate as 3D CT reconstruction to assess post-THA patients’ component orientation, while providing more valuable functional component orientation than supine CT scans.

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

“…These results are equivalent to an SDC of 3.9° which is lower than our results. Comparisons between bi-plane X-ray measurements and CT scan showed differences of 1.3 ± 6.5° with 31% of patients over 5° of differences 28 , of 4 ± 4° 31 , between − 5 and 7° 32 , and finally limits of agreements of − 5.0 to 4.2° 33 and − 17.53° to 10.82° 12 . 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.…”

“…However, 17% and 34% of patients had more than 5° of difference for inclination and anteversion respectively, indicating that differences at the patient level can be large between CT and EOS measurements 28 . Moreover, limits of agreement of − 5.4° to 6.6° were found in a third study between CT and EOS measurements 33 . Still, correlations above 0.7 were found when comparing cup angles measured with CT and EOS 28 .…”

The accuracy and precision of acetabular implant measurements from CT imaging

“…However, Davda et al (2015) used 3D-CT as their gold standard measurement, for comparison. Equally, Ma et al (2022) compared the orientation measurements taken using low-dose bi-planar radiographs (EOS imaging) with 3D-CT, but their results endorsed the use of EOS imaging for post-THA component orientation measurements. This study is the first to compare 3D-CT with a laboratory digitising arm, which is a gold standard for measurements in engineering.…”

“…Measurement of hip implant positioning using 3D-CT has become the gold standard approach (Kaiser et al, 2021). Numerous studies have investigated the orientation of hip implants from post-operative CT scans and planar radiographs (Davda et al, 2015;Ma et al, 2022). However, the presence of metal artifacts and identification of anatomical landmarks on the reconstructed 3D pelvic model can introduce errors in the measurements of the implant position (Brownlie et al, 2020).…”

Individualized megaimplants in acetabular revision arthroplasty: what have we learned in the last 15 years?

“…In such scenarios, the inclusion of CT with 3D reconstruction becomes imperative for patient evaluation (Fig. 2) (23,24). It is possible to create an individualized implant design simultaneously with the CT scan.…”