Radiographs Underestimate Lateral Center-Edge Angle and Tönnis Angle Measurements Compared to Computed Tomography Scan in Assessment of Borderline and Frank Acetabular Dysplasia
Authors: Nerys-Figueroa J, Kahana-Rojkind AH, Parsa A, Walsh EG, Lambers F, Domb BG
DOI: 10.1016/j.arthro.2024.10.038
Journal: Arthroscopy, 2025
Objective
To compare radiographic and CT-based measurements of the Lateral Center-Edge Angle (LCEA) and Tönnis Angle (TA) in patients with borderline and frank acetabular dysplasia.
Methodology
A retrospective study involving 371 hips, with side-by-side analysis of standard pelvic radiographs and CT scans to assess discrepancies in LCEA and TA measurements.
Key Findings
- CT consistently measured higher LCEA and TA values than standard x-rays.
- Radiographs tended to overestimate dysplasia when using LCEA and underestimate dysplasia using TA.
- These discrepancies can impact diagnosis, classification, and ultimately, surgical decision-making.
Conclusion
CT provides a more precise evaluation of acetabular coverage than plain radiographs. For accurate diagnosis and surgical planning—especially in borderline dysplasia—CT should complement radiographic assessment.
What Does This Mean for Providers?
Accurate assessment of acetabular morphology is critical in managing hip dysplasia. This study highlights that reliance on radiographs alone may misrepresent the severity of dysplasia, potentially leading to under- or overtreatment. Providers should incorporate CT imaging when evaluating complex or borderline cases to guide appropriate intervention and optimize surgical outcomes.