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BioMed Research International
Volume 2014, Article ID 348635, 5 pages
Research Article

A Standardized Critical Size Defect Model in Normal and Osteoporotic Rats to Evaluate Bone Tissue Engineered Constructs

1AO Research Institute Davos, Clavadelerstraß 8, 7270 Davos Platz, Switzerland
2RISystem AG, Talstraße 2A, 7270 Davos, Switzerland
3Vetsuisse Faculty, University of Bern, Länggassstraße 128, 3001 Bern, Switzerland

Received 19 October 2013; Revised 1 February 2014; Accepted 1 February 2014; Published 11 March 2014

Academic Editor: Aaron W. James

Copyright © 2014 Livia Poser et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Tissue engineered constructs should be tested for their efficacy not only in normal but also in osteoporotic bone. The rat is an established animal model for osteoporosis and is used often for bone healing studies. In this study a defined and standardized critical size defect model in the rat suitable for screening new tissue engineered constructs in normal and osteoporotic bone is described and validated. Normal and ovariectomised Wistar rats received a unilateral middiaphyseal 5 mm defect in the femur, which was instrumented with a radiolucent PEEK plate fixed with angular stable titanium screws and left untreated. All animals were euthanized eight weeks after defect surgery and the bone healing was evaluated using radiographs, computed tomography measurements, and histology. The developed fixation system provided good stability, even in osteoporotic bone. The implants and ancillary instruments ensured consistent and facile placement of the PEEK plates. The untreated defects did not heal without intervention making the model a well-defined and standardized critical size defect model highly useful for evaluating tissue engineered solutions in normal and osteoporotic bone.