The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Cranial suture complexity alters sutural mechanical behavior: an FEA investigation

CARLOS J. ZAMBRANO1, ROSALIND J. SADLEIR2 and DAVID J. DAEGLING1.

1Department of Anthropology, University of Florida, 2Department of Biomedical Engineering, University of Florida

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Sutural complexity is hypothesized to reflect the loading environment of the cranial vault. While direct mechanical tests of how complexity affects suture mechanics have been limited, most investigations associate the presence of increased complexity as a compensatory mechanism for increased masticatory or paramasticatory activity. Owing to methodological difficulties and sampling limitations of in vivo study, stress and strain within and around sutures are usually characterized through theoretical approaches.

We use finite element analysis (FEA) to investigate how sutural complexity alters sutural mechanics as well as stress and strain in adjacent cranial bone. Using published material property data and assuming isotropy and homogeneity, four separate 2D FEA models representing the human sagittal suture and parietal bones were constructed and loaded in COMSOL 3.5®. Two of the models function as idealized baseline benchmarks (linear and sine wave sutures), while the other two are based on actual ectocranial suture morphology.

Our models indicate that suture complexity is positively associated with sutural and vault stiffness. Simple suture morphology demonstrates more strain within the sutural gap and less stress in surrounding bone. Conversely, complex sutures display less strain within the sutural matrix while producing stress concentrations in bone local to sutural margins. These results suggest that -- under conditions of isotropy and homogeneity -- complexity stiffens the joint but at a cost of localized increased stress in adjacent bone. We speculate that reduction of elastic modulus of bone local to sutural margins may serve to mitigate these stress concentrations in vivo.

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