Animal Models as Foundational Tools in Preclinical Orthopedic Implant Research.

Orthopedic implants have a critical role in modern medical practice, being useful in bone regeneration, joint arthroplasty, and healing fractures. The success of osseointegration depends on implant properties (composition, stability, geometry, biocompatibility) and host factors (local reactivity, comorbidities). Preclinical evaluation in animal models is essential before clinical application. In orthopedic implantology, the selection and real utility of a range of animals are important, with an emphasis placed on bone-implant interface, biomechanical function, and long-term integration. Smaller animals such as rabbits and rats have widespread use in early biocompatibility and osseointegration testing, but larger animals such as pigs, sheep, and canines have a larger physiological bone similarity and can, therefore, be utilized for bearing loads in testing. Considering the utility and disadvantages of certain species-including suitability for new biomaterials, coatings, and biomechanical function-this article discusses testing methodologies such as push-out/pull-out tests, histomorphometry, and micro-CT and their utility in testing the integration of implants and regeneration of bone. Conclusions confirm a multi-species model in use in preclinical testing for the development of implants and improvements in clinical success. Unlike previous reviews, this article emphasizes translational strategies, integrates ethical perspectives in model selection, and discusses the synergistic use of imaging modalities with biomechanical tests for comprehensive assessment.