Dimensional, Geometrical, and Physical Constraints in Skull Growth

Abstract

After birth, the skull grows and remodels in close synchrony with the brain to allow for an increase in intracranial volume. Increase in skull area is provided primarily by bone accretion at the sutures. Additional remodeling, to allow for a change in curvatures, occurs by resorption on the inner surface of the bone plates and accretion on their outer surfaces. When a suture fuses too early, normal skull growth is disrupted, leading to a deformed final skull shape. The leading theory assumes that the main stimulus for skull growth is provided by mechanical stresses. Based on these ideas, we first discuss the dimensional, geometrical, and kinematic synchrony between brain, skull, and suture growth. Second, we present two mechanical models for skull growth that account for growth at the sutures and explain the various observed dysmorphologies. These models demonstrate the particular role of physical and geometrical constraints taking place in skull growth.

An Overview of Modelling Craniosynostosis Using the Finite Element Method

“…For example, Weickenmeier et al [2017] compared their modelling findings quantitatively with clinical data only in terms of the cephalic index for different types of craniosynostosis. Similarly, the study of Nagasao et al [2011] compared their FE prediction of orbital distance in 3 different groups (normal skull, metopic synostosis, and metopic synostosis following forehead reconstruction) with their clinical data.…”

“…They measure spring forces in the range of 5-8 N. A study by Weickenmeier et al [2017] predicted calvarial growth for different types of craniosynostosis.…”

“…Most of the research modelled immediate postoperative reconstruction and only loaded their models with a constant intracranial pressure Nagasao et al, 2010Nagasao et al, , 2011You et al, 2010;Larysz et al, 2012;Wolański et al, 2013;Zhang et al, 2016;Li et al, 2017]. The only study that modelled calvarial growth during development is Weickenmeier et al [2017].…”

“…The number of computations is related to the number and type of elements in the model, i.e., mesh convergence. Most of the studies have used the input parameters related to material properties of their models based on previous experimental studies [Nagasao et al, 2010[Nagasao et al, , 2011You et al, 2010;Zhang et al, 2016;Li et al, 2017;Weickenmeier et al, 2017]. However, they generally have not reported details of mesh convergence.…”

“…A study by Weickenmeier et al [2017] used such an approach to model several types of craniosynostosis, i.e., predicting the preoperative calvarial morphology. On the other hand, CT and MRI have also been used to develop a more detailed representation of the skull [e.g., Nagasao et al, 2010;Wolański et al, 2013;Li et al, 2017;Borghi et al, 2018].…”