Basic Science Symposium III: Animal Models for Orthopaedic Implant Evaluation

Preclinical research is the initial prerequisite to determining the efficacy of an implant for eventual translation into the clinical arena. Once a spinal implant has been validated through benchtop mechanical testing, analytical modeling, and in vitro evaluation, it is often useful to conduct an in vivo study using animal models to assess the interactions of the living tissue environment surrounding the spinal implant. Animal models are often implemented in the assessment of spinal implant behavior to identify potential problems with respect to tissue infiltration and adverse tissue and interface reactions. Biomechanical and biological investigations of the tissue and implant interface, as well as the surrounding supportive tissue structures, can provide early insight into the potential clinical performance once implanted into humans. However, the use of animals for implant evaluation remains controversial due to the varied anatomy, different healing rates, and complicated biomechanical environments. There are numerous challenges that exist with animal models such as determining (1) when an animal study is needed, (2) what the appropriate animal model is, (3) what the appropriate time points and outcome measures are, and (4) what the optimal sample size is. Another challenge for such studies is the need to downsize the spinal implants—a serious issue for some animal models.