Multimodal Mechanical, Tissue, Architectural, and Histological Evaluation of the Bone and Sutures of the Parietal Bone in an Infant With Craniosynostosis.

Overview

The human skull is a complex structure that protects the underlying tissues, including the brain. Certain rare conditions and diseases, such as craniosynostosis-which affects 1 in 2,000 to 2,500 children-impair these functions and lead to increased intracranial pressure, posing a neurological risk. The most common form of craniosynostosis is scaphocephaly (50%), which manifests as premature closure of the sagittal suture, halting growth at that site and causing an abnormal skull shape and altered local biomechanical properties. The parietal bone is a flat, regular bone that embryologically originates from the neurocranium. Its characteristics vary according to age, sex, and morphotype. Studies on the multimodal characterization of the properties of growing cortical bone focus on the characterization of growing fibulae and femurs. A comparison was made with adult bone, allowing for the establishment of specific pediatric characteristics. The mechanical, morphological, architectural, and tissue properties of the skull vary considerably between adults and children. They are uniquely adapted to the rapid growth and development of the brain. The analysis of the mechanical, architectural, and tissue properties of the parietal bone in infants involves evaluating its ability to resist applied forces and stresses, analyze its shape, composition, and the quality of the bone tissue itself, including aspects such as mineralization, collagen fiber structure, and bone mineral density. A study conducted on samples obtained from parietal resections in infants operated on for scaphocephaly evaluated the microstructural and mechanical characteristics of this region of the skull vault, allowing for the determination of mechanical and morphological characteristics. However, the samples were located near the stenosis, with the sampling site determined macroscopically by the surgeon. The characteristics of the parietal bone in infants with scaphocephaly were also evaluated and show properties correlated with the degree of ossification regardless of age. However, the available data have a significant limitation: existing characterizations are based on pathological samples taken near the stenotic area, or on models of growing long bones that do not reflect the specific characteristics of the cranial vault. To date, there is no certainty regarding the mechanical, architectural, and tissue properties of the parietal bone considered healthy regardless of craniosynostosis in infants, taking into account the developmental constraints specific to the first months of life. These properties are, however, strongly influenced by the compressive forces experienced during birth and then by the gradual changes in gravitational and postural forces associated with motor development (head control, sitting, crawling, and walking on all fours). These data could help improve our understanding of normal cranial physiology and its variations in the presence of pathology. The primary objective is to describe the mechanical, architectural, tissue, and histological properties of the parietal bone in infants with craniosynostosis. To evaluate ex vivo, both near and far from the stenosis, the mechanical, architectural, tissue, and histological properties of the parietal bone and sutures in infants aged 3 to 12 months with craniosynostosis.