The Measurement of the Lateral Center-Edge Angle Is Underestimated on Radiographs Compared With 3-Dimensional Computed Tomography
Authors: Nerys-Figueroa J, Kahana-Rojkind AH, Parsa A, Maldonado D, Quesada-Jimenez R, Domb BG
DOI: 10.1016/j.asmr.2024.101005
Background
Accurate measurement of the lateral center-edge angle (LCEA) is essential for assessing acetabular coverage in hip pathology. LCEA is typically measured on plain radiographs, but discrepancies compared to 3D CT imaging may impact diagnosis and treatment planning.
Methods
A retrospective analysis of 100 hips from 96 patients compared LCEA values obtained from radiographs using four anatomical reference points—femoral heads (FHs), acetabular teardrops, ischial tuberosities (ITs), and floor—with CT-based LCEA measurements at the acetabular 12-o’clock position.
Key Findings
- Radiographic LCEA measurements consistently underestimated CT-based LCEA.
- Using femoral heads as the radiographic reference yielded the closest approximation to CT values (mean difference 2.3° ± 2.4).
- The smallest variation was between measurements referencing femoral heads and ischial tuberosities (1.0° ± 0.8).
- Although statistically significant, the degree of underestimation is unlikely to be clinically significant in most cases.
Conclusion
Radiographs tend to slightly underestimate the lateral center-edge angle compared to 3D CT, but using the femoral head as the radiographic reference point improves accuracy. These differences are generally small and unlikely to affect clinical decision-making substantially.
What Does This Mean For Providers?
- When evaluating acetabular coverage on radiographs, consider using the femoral head as the anatomical reference for LCEA measurement to enhance accuracy.
- Recognize that radiographs may slightly underestimate LCEA compared to CT, but the difference is typically small enough to not change most clinical decisions.
- CT remains the gold standard for precise 3D assessment but is not always necessary for routine evaluation.
- Understanding these nuances helps avoid over- or under-diagnosis of dysplasia or over-coverage based solely on radiographs.