INVESTIGATION OF THE INFLUENCES OF BIOMECHANICAL FORCE ON THE ULTRASTRUCTURE OF HUMAN SAGITTAL CRANIOSYNOSTOSIS

This study presents comparisons of the ultrastructure of synostotic an d open portions of synostotic sagittal sutures using histomorphometry, scanning electron microscopy, and microcomputed tomography. By using stereologic and histomorphometric analysis, this study proposes to dem onstrate evidence of the influence of biomechanical force on the sutur e during the process of sagittal craniosynostosis. Finally, we propose to link the pathologic changes transforming normal suture fusion to c raniosynostosis with concurrent changes in the polarity of suture fusi on initiation. Seven infants (four boys and three girls) with sagittal craniosynostosis, ranging in age from 1.4 to 4.8 months (mean = 3.0 m onths), underwent sagittal synostectomies. The synostotic bone specime ns were sectioned into three regions: an open suture, partial synostos is, and complete synostosis. Microcomputed tomographic and scanning el ectron microscopic scanning as well as histomorphometry was performed on all specimens to obtain detailed qualitative and quantitative infor mation regarding the trabecular microarchitecture of the synostosed su ture. Microcomputed tomographic analysis determined the bone volume fr action, trabecular thickness, trabecular separation, bone surface to b one volume ratio, and anisotropy for all specimens. Our results showed significant differences in all of these quantitative measurements whe n comparing the complete synostotic suture with the open portion of th e synostotic sutures (p < 0.05). Microcomputed tomographic stereologic analysis showed evidence of the influence of biomechanical force on t he synostotic and open portions of the synostotic sutures. Results of scanning electron microscopy show a definite qualitative difference in the trabecular pattern of the partial and complete synostotic suture when compared with the open portion of the synostotic sagittal suture. In this study, we performed both qualitative and quantitative compari sons of the ultrastructure of the complete synostotic and nonsynostoti c sagittal sutures using stereologic and histomorphometric techniques. We also demonstrated evidence of the influence of biomechanical force on the synostotic sagittal suture. Finally, we established a link bet ween the pathologic changes transforming normal suture fusion to crani osynostosis and concurrent changes in both the vector and direction of suture fusion initiation.