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. 2025 May 9:14:103355.
doi: 10.1016/j.mex.2025.103355. eCollection 2025 Jun.

Critical size defect in a rat calvaria model using trephination: An animal model for investigating potential bone regenerative scaffolds

Jeffrey Huang  1 , Jithendra Ratnayake  2 , George J Dias  1
Affiliations

Critical size defect in a rat calvaria model using trephination: An animal model for investigating potential bone regenerative scaffolds

Jeffrey Huang et al. MethodsX. .

Abstract

Animal studies have been a key in vivo investigation in translating bioregenerative material into human clinical trials. The critical size defect (CSD) in a rat's calvaria is a popular methodology for demonstrating and investigating the regenerative properties of a biomaterial. Various surgical approaches have been discussed in the literature on creating CSD and can vary based on species, age and anatomical location. This paper aims to provide a reliable and reproducible step-by-step guide for creating a critical-size defect on the calvaria of a laboratory rat using trephination. This paper will:•Cover the surgical approaches and management in the pre-, intra- and post-operative phases.•Provide figures to help visually guide readers in carrying out the operation.•Cover basic general anaesthetic issues and resolutions.

Keywords: Biomaterials; Bone regeneration; Bony defect; Calvaria; Critical size defect; Critical size defect trephination in rat calvaria using a chitosan-hydroxyapatite scaffold; Rat study; Small animal model; in vivo study.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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