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Disc geometry measurement methods affect reported compressive mechanics by up to 65.
Shiyin Lim1, Reece D Huff1, Joanna E Veres2
1Department of Mechanical Engineering University of California, Berkeley Berkeley California USA.
JOR Spine
|October 7, 2022
Summary
Measuring intervertebral disc geometry inconsistently significantly impacts mechanical property results. Standardizing measurement methods is crucial for reliable comparisons in disc research.
Area of Science:
- Biomechanical Engineering
- Orthopedic Research
- Spinal Mechanics
Background:
- Mechanical testing is vital for evaluating intervertebral disc (IVD) health.
- Inconsistent testing protocols hinder direct comparison of results across studies.
- Normalizing mechanical properties by disc geometry is proposed for comparability, but geometric measurement methods vary.
Purpose of the Study:
- To investigate the impact of different disc geometry measurement techniques on reported mechanical properties.
- To determine if variations in measuring disc height and area affect normalized mechanical outcomes.
Main Methods:
- Disc height and area were measured using computed tomography (CT), digital calipers, and ImageJ.
- Three distinct methods were used for disc height and six for disc area.
- Mechanical properties were calculated and normalized using the different geometric measurements.
Main Results:
- Ex situ caliper measurements of disc height were over 30% less than in situ CT measurements.
- Ex situ ImageJ measurements of disc area were over 30% larger than CT measurements.
- These geometric variations led to up to a 65% reduction in normalized compressive stiffness.
Conclusions:
- Methods for measuring disc geometry significantly influence normalized mechanical properties.
- Accounting for geometric measurement techniques is essential when comparing mechanical testing results.
- Standardization of geometric measurement protocols is recommended for intervertebral disc research.
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