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Published on: May 10, 2024
Material properties of human infant skull and suture at high rates
Brittany Coats1, Susan S Margulies
1Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104-6392, USA.
Insights
Pediatric cranial bone and suture exhibit distinct mechanical properties, with sutures deforming significantly more than bone before failure. This difference is crucial for understanding head injury mechanisms in young children from low-height falls.
Area of Science:
- Biomechanics
- Pediatric Traumatology
- Materials Science
Background:
- Distinguishing accidental from inflicted pediatric head trauma is challenging.
- Limited data exists on pediatric skull and suture properties during low-height falls.
- Anecdotal literature shows disparities regarding injuries from low-height falls in children.
Purpose of the Study:
- To investigate the material properties of pediatric cranial bone and suture.
- To compare pediatric and adult cranial biomechanics.
- To understand the role of sutures in pediatric head injury mechanisms.
Main Methods:
- Tested human infant (<1 year old) cranial bone and suture.
- Utilized three-point bending and tension tests at impact rates (1.2-2.8 m/sec).
- Analyzed donor age influence on material properties.
Main Results:
- Pediatric cranial bone stiffness increases with age.
- Pediatric cranial bone is 35x stiffer than pediatric cranial suture.
- Pediatric cranial suture deforms 30x more than bone before failure, and 243x more than adult bone.
- Significant strain capacity in pediatric skull before fracture.
Conclusions:
- Pediatric cranial sutures play a critical role in the head's response to low-height impacts.
- Differences in bone and suture properties allow for dramatic skull deformation, potentially leading to brain injury.
- Data enhances understanding of pediatric head injury mechanisms.
Abstract:
Clinicians are often faced with the challenging task of distinguishing between accidental and inflicted pediatric head trauma. There is currently a disparity in the anecdotal case study literature as to what kinds of injuries can occur in children from low height falls. There is also a paucity of material property data for pediatric skull and suture at rates similar to those expected in low height falls. We tested human infant (<1 year old) cranial bone and suture from 23 calveria in three-point bending and tension, respectively, at rates ranging from 1.2-2.8 m/sec. Donor age was found to have the largest influence on the elastic modulus and ultimate stress of cranial bone, with an increase in age increasing both material properties. In adults, cranial bone and suture have similar properties and the adult calveria deforms very little prior to fracture. In contrast, pediatric cranial bone is 35 times stiffer than pediatric cranial suture. In addition, pediatric cranial suture deforms 30 times more before failure than pediatric cranial bone and 243 times more than adult cranial bone. The large strains in the pediatric bone and suture result in a skullcase that can undergo dramatic shape changes before fracture, potentially causing substantial deformation in the brain. The sizeable difference between pediatric bone and suture material properties also underscores the crucial role that sutures play in the unique response of the pediatric head to impact in low height falls. These data provide necessary information to enhance our understanding of mechanisms of head injury in young children.
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