Generation and Experimental Outcomes of Closed Femoral Fracture in Mice

Fracture healing requires the integration of many cell types, growth factors, and cytokines that cannot be adequately studied using in vitro and in silico models. This has prompted the development of highly informative in vivo animal models to understand the complexities of fracture repair. Here, we describe a modified procedure for mice, first developed for rats by Bonnarens and Einhorn, that does not require a skin incision or suturing. This procedure involves boring a hole through the skin and articular surface of the femoral condyle with a 25-gauge needle, fixation with a K-wire, and creation of a transverse mid-diaphyseal fracture using a three-point bending fracture device. Fracture healing can be assessed using a variety of techniques, including microcomputed tomography, torsion testing, histological and histomorphometric analyses, and assessment of gene expression. There are many orthopedic trauma applications of this murine femoral fracture model ranging from assessment of safety and efficacy of novel therapeutics to the influence of specific genes on bone repair.