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Published on: March 23, 2019
A Multi-Laboratory Study Towards Standardizing Spine Testing: Evaluating Reproducibility and Temporal Changes in
Jenna Wahbeh1, Jeremy G Loss2, Emma Coltoff3
1University of California, Los Angeles Department of Bioengineering, Los Angeles, CA; The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, The Luskin Orthopaedic Institute for Children in Alliance with UCLA, Los Angeles, CA.
Composite lumbar spine surrogates show promise but exhibit significant variability and degradation over time, impacting their reliability for biomechanical testing and highlighting the need for improved surrogate design and standardized protocols.
Area of Science:
- Biomechanical Engineering
- Spinal Biomechanics
- Orthopedic Research
Background:
- Cadaveric specimens present challenges for spinal biomechanical testing.
- Composite spine surrogates offer potential advantages but require validation.
- Inter-laboratory reproducibility and temporal variability of composite surrogates are largely unknown.
Purpose of the Study:
- To evaluate the inter-laboratory reproducibility of composite lumbar spine surrogates.
- To assess the temporal variability and durability of these surrogates under standardized testing.
- To identify limitations for future surrogate development and testing protocols.
Main Methods:
- Nine L2-L5 composite lumbar spine surrogates were tested across seven specialized laboratories.
- Standardized pure moment testing (±7.5 Nm) was applied in flexion-extension, lateral bending, and axial rotation.
- Testing sequences were varied to control for order effects, and specimen condition was monitored.
Main Results:
- Progressive facet joint damage occurred, with minimal degradation to other components.
- Specimen range of motion (ROM) significantly increased over time across all rotational modes (p < 0.05).
- High inter-specimen variability in ROM was observed, particularly in flexion and axial rotation (p < 0.05).
Conclusions:
- Composite spine models offer conceptual benefits over cadavers for biomechanical testing.
- Limitations in durability, performance consistency, and reproducibility were identified.
- Findings underscore the need for improved surrogate design and standardized spine testing protocols.
