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Abstract In vitro mechanical testing of intervertebral discs is crucial for basic science and pre‐clinical testing. Generally, these tests aim to replicate in vivo conditions, but simplifications are necessary in specimen preparation and mechanical testing due to complexities in both structure and the loading conditions required to replicate in vivo conditions. There has been a growing interest in developing a consensus of testing protocols within the spine community to improve comparison of results between studies. The objective of this study was to perform axial compression experiments on bovine bone‐disc‐bone specimens at three institutions. No differences were observed between testing environment being air, with PBS soaked gauze, or a PBS bath (P > .206). A 100‐fold increase in loading rate resulted in a small (2%) but significant increase in compressive mechanics (P < .017). A 7% difference in compressive stiffness between Labs B and C was eliminated when values were adjusted for test system compliance. Specimens tested at Lab A, however, were found to be stiffer than specimens from Lab B and C. Even after normalizing for disc geometry and adjusting for system compliance, an ∼35% difference was observed between UK based labs (B and C) and the USA based lab (A). Large differences in specimen stiffness may be due to genetic differences between breeds or in agricultural feed and use of growth hormones; highlighting significant challenges in comparing mechanics data across studies. This research provides a standardized test protocol for the comparison of spinal specimens and provides steps towards understanding how location and test set‐up may affect biomechanical results.
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Spine biomechanical testing methodologies: The controversy of consensus vs scientific evidence
Abstract Biomechanical testing methodologies for the spine have developed over the past 50 years. During that time, there have been several paradigm shifts with respect to techniques. These techniques evolved by incorporating state‐of‐the‐art engineering principles, in vivo measurements, anatomical structure‐function relationships, and the scientific method. Multiple parametric studies have focused on the effects that the experimental technique has on outcomes. As a result, testing methodologies have evolved, but there are no standard testing protocols, which makes the comparison of findings between experiments difficult and conclusions about in vivo performance challenging. In 2019, the international spine research community was surveyed to determine the consensus on spine biomechanical testing and if the consensus opinion was consistent with the scientific evidence. More than 80 responses to the survey were received. The findings of this survey confirmed that while some methods have been commonly adopted, not all are consistent with the scientific evidence. This review summarizes the scientific literature, the current consensus, and the authors' recommendations on best practices based on the compendium of available evidence.
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- Award ID(s):
- 1751212
- PAR ID:
- 10452042
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- JOR SPINE
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2572-1143
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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