Related Experiment Video
Updated: Aug 27, 2025
The Transition to an Anterior-Based Muscle Sparing Approach Improves Early Postoperative Function but is Associated with a Learning Curve
Published on: September 7, 2022
Assessing component orientation of total hip arthroplasty using the low-dose bi-planar radiographs
Zhuyi Ma1, Hao Tang1, Yixin Zhou2
1Department of Orthopaedics, Beijing Jishuitan Hospital, Fourth Clinical College of Peking University, No.31 Xinjiekou East Street, Xicheng District, Beijing, China.
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.
