EVALUATION OF MAGNIFICATION AND CORRECTION OF FEMORAL HEAD SIZE ON RADIOGRAPHS
Main Article Content
Abstract
Background: Hip radiography is commonly used in evaluating hip morphology and surgical planning. However, image magnification can distort the actual size of the femoral head.
Objectives: To evaluate the discrepancy in femoral head size on radiographs compared to CT and to determine the correction factor.
Methods: A cross-sectional study of 121 patients at Hung Vuong General Hospital in 2025. The femoral head diameter on radiographs and CT was measured independently by three radiographers. Statistical analyses included ICC, Bland-Altman plots, mean absolute error, and multivariable linear regression.
Results: Inter-observer reliability was very high (ICC = 0.992). The mean size on radiographs was 51.64 ± 3.89 mm, which was larger than on CT (44.24 ± 3.22 mm). The mean discrepancy prior to correction was 7.4 mm. The mean magnification factor was 1.148. Following correction, the error was reduced to 0.74 mm. BMI and age were significantly associated with the magnification factor (p < 0.05).
Conclusion: Radiographs tend to magnify the size of the femoral head. Applying a correction factor improves measurement accuracy and assists in surgical planning.
Keywords
femoral head, radiograph, CT, magnification, hip joint
Article Details
References
2. Olmedo-Garcia VM, Gonzalez-Lucena G, Rodriguez-Merchan EC. Assessment of magnification of digital radiographs in total hip arthroplasty. J Orthop Surg Res. 2018;13(1):229. doi:10.1186/s13018-018-0922-0.
3. Archibeck MJ, Cummins T, Carothers JT, et al. Inaccuracies in the use of magnification markers in digital hip radiographs. J Arthroplasty. 2016; 31(10):2295-2298. doi:10.1016/j.arth.2016.02.030.
4. Zhang X, Wang Y. Intraclass correlation coefficient in orthopedic measurements: a systematic review. Clin Orthop Relat Res. 2018;476(8):1673-1682.
5. Nguyen HT, Pham TT. Radiographic assessment of femoral head in Vietnamese population. Vietnam J Orthop. 2017;34(2):45-52.
6. Heep H, Jauch SY, Maas A, et al. A simple and convenient method to determine the magnification of digital X-rays for preoperative planning in total hip arthroplasty. Orthopedics. 2012;35(5):e712-e715. doi:10.3928/01477447-20120426-24.
7. Peng C, et al. 3D reconstruction of hip joint from biplanar radiographs using deep learning techniques. Med Phys. 2020;47(9):4012-4023. doi:10.1002/mp.14300.
8. Jodeiri A, et al. Deep learning-based prediction of anatomical parameters from radiographs: comparison with CT measurements. Eur Radiol. 2021;31(8):5678-5687. doi:10.1007/s00330-020-07654-9.