Histopathologic and Spectrometric Evaluation of Bony Components of Synostotic Suture and Parietal Bone in Children with Sagittal Synostosis.

Abstract

Sagittal synostosis, the premature fusion of sagittal suture, is the most common form of craniosynostosis. The premature suture line closure restricts bone growth in the direction perpendicular to the suture line with frontal bossing, bitemporal narrowing, and often a characteristic palpable ridge along the fused sagittal suture. This study aimed to understand the characterization of the ossification process both in the synostotic suture and adjacent parietal bone. The surgical procedure for the 28 patients diagnosed with sagittal synostosis consisted of removing the synostotic bone as a whole, if possible, "Barrel-Stave" relaxation osteotomies, and strip osteotomies to the parietal and temporal bones perpendicular to the synostotic suture. The synostotic (group I) and parietal (group II) bone segments are obtained during osteotomies. Atomic absorption spectrometry was used to determine the amount of calcium in both groups, which is an indicator of ossification. Scanning electron microscopy and immunohistochemistry were employed to assess trabecular bone formation, osteoblastic density, and osteopontin, which is one of the in vivo indicators of new bone formation. Histopathologically, trabecular bone formation scores did not indicate any significant difference between the groups. However, the osteoblastic density and calcium accumulation in group I were higher than those in group II, and the difference was significant. Osteopontin staining scores in cells showing membranous and cytoplasmic staining with osteopontin antibodies significantly increased in group II. In this study, we found reduced differentiation of osteoblasts despite their increase in number. Moreover, the osteoblastic maturation rate was low in synostotic sutures, bone resorption becomes slower than new bone formation, and the remodeling rate is low in sagittal synostosis.