Plastic Surgery Research Council
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TENSILE STRESS WITH THE ABSENCE OF FRANK DISTRACTION CAN STILL PREVENT THE PHYSIOLOGICAL FUSION OF THE POSTERIOR FRONTAL SUTURE IN THE RAT.
Presenter: Niki E Springett, Student
Co-Authors: Oliver R; Peltz TS; Gianoutsos MP; Walsh WR
Prince of Wales Hospital University of New South Wales

Craniosynostosis is the pathological fusion of one or more cranial sutures. Cranial sutures are growth centres that enable the infant skull to achieve adult proportions. The treatments are surgical and complications include blood loss, transfusions, infection, bony irregularities and brain injury. One approach is spring cranioplasty. Following suturectomy a spring forcibly disassociates the opposing bones. Distraction osteogenesis describes how the underlying dura responds by stimulating bony deposition. Bone ceaselessly remodels in response to mechanical stresses, the conversion of mechanical stimuli into biological information is termed mechanotransduction. We queried whether the presence of tensile stress could induce morphological and biological changes in the absence of frank distraction. Methods: We successfully placed stainless steel omega springs across the posterior frontal suture on 18 12-day old rats. The force applied maintained suture patency without distraction or suturectomy. We sacrificed the groups on day 32, fixed them in formalin and then dissected them. We performed MicroCTs and X-rays. We proceeded with routine paraffin histology using hematoxylin and eosin, and tetrachrome stains. Our quantitative analyses were carried out using identical magnifications and software. Immunohistochemistry was performed on all slides simultaneously. Results: In contrast to the control group where all rats exhibited fused sutures at 32 days, the sutures remained patent in 14 of 18 rats in the treated group. The sutures showed continued bone remodeling and the immunohistochemistry exhibited differing expression profiles when compared to the control group. Qualitative analysis had interobserver consistency.

Conclusion: Tensile stress alters suture fate. The benefits of understanding the biological pathways are twofold. Firstly, the development of novel therapies could treat craniosynostosis medically or by augmenting surgery. Secondly, the skull s regenerative potential declines rapidly during infancy. Addressing calvarial defects in the population remains challenging, which may be an area of future contribution.


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