A Comparison of Vascularity, Bone Mineral Density Distribution, and Histomorphometrics in an Isogenic Versus an Outbred Murine Model of Mandibular Distraction Osteogenesis


Edward G. Carey, Sagar S. Deshpande, Alexander R. Zheutlin, Noah S. Nelson, Alexis Donneys, Stephen Y. Kang, Kathleen K. Gallagher, Peter A. Felice, Catherine N. Tchanque-Fossuo, Steven R. Buchman


Vascularity, bone mineral density distribution, and histomorphometrics between the inbred, isogenic Lewis rat and the outbred, nonisogenic Sprague Dawley rat within mandibular distraction osteogenesis (MDO) must be compared in order for future researchers to compare results generated from these two animals. We hypothesize that little difference will be found between the two strains within these metrics.

The investigators implemented a comparative study between the Lewis and Sprague Dawley rat strains within MDO. The sample was composed of 17 male Lewis and 17 male Sprague Dawley rats, which underwent surgical external fixation and distraction. Rats’ hemimandibles were distracted to a total distance of 5.1 mm. After 28 days of consolidation, 9 rats from each group underwent bone mineral density distribution analysis. The remaining rats from each group were analyzed for vascular and histologic metrics. Descriptive and bivariate statistics were computed and the p-value was set at 0.05.

We demonstrated successful mandibular distraction osteogenesis in all animals, with no significant difference found in histologic or bone mineral density distribution metrics. No significant differences were found in any of the vascular metrics, with the exception of vascular separation that was not normalized to mandibular volume (p = 0.048).

This study demonstrates that little dissimilarity exists between the isogenic Lewis and the outbred Sprague Dawley models of mandibular distraction osteogenesis. Given this, researchers may confidently compare gross results between the two strains while taking into consideration the very small differences between the models. For studies that require an isogenic strain, the Lewis rat is an apt surrogate for the Sprague Dawley strain.

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