Pre- and postoperative cranial shape analysis in Craniosynostosis: The role of mechanical loading during CT imaging

BACKGROUND: Craniosynostosis is a congenital disorder characterized by premature fusion of one or more cranial sutures, resulting in abnormal skull growth and, in some cases, elevated intracranial pressure. Accurate assessment of cranial morphology is essential for diagnosis, surgical planning, and evaluation of postoperative outcomes. Three-dimensional computed tomography allows detailed visualization of cranial shape; however, measurements may be influenced by external forces during image acquisition, such as contact between the occipital region and the supporting surface. It remains unclear whether such forces produce measurable deformation in infants with immature, not fully ossified skulls. METHODS: In this study, preoperative and postoperative cranial CT scans were used to generate patient-specific 3D virtual models. Models were registered using anatomical landmarks in the orbital and nasal regions to standardize orientation. Surface difference analysis quantified regional morphological changes. Finite element modeling was employed to simulate cranial deformation under two loading conditions: intracranial pressure and external load representing the weight of the head in supine position. Displacement patterns were analyzed and compared to assess the relative impact of each loading condition. RESULTS: Results demonstrated that the most pronounced postoperative changes occurred in the parietal region, corresponding to surgical osteotomy lines, with mean displacement of 7.3 ± 3.6 mm. The frontal region remained stable, while the occipital region showed slight inward displacement (-4.6 ± 2.7 mm). FEM simulations revealed minimal deformation under external loading alone (maximum 0.09 mm), whereas intracranial pressure produced substantially larger, symmetric displacement, with maximum parietal displacement reaching 12.1 mm. Combined loading closely resembled intracranial pressure alone. The maximal deformation induced by external contact during CT scanning was more than two orders of magnitude smaller than that generated by intracranial pressure. CONCLUSION: These findings indicate that external forces during CT acquisition have negligible impact on cranial morphology measurements in pediatric patients, and observed postoperative changes primarily reflect true anatomical alterations. FEM provides a robust framework to quantify biomechanical effects and distinguish imaging artifacts from genuine morphological changes, supporting the reliability of CT-based assessment for clinical decision-making and surgical evaluation in craniosynostosis.