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Published on: October 9, 2014
Introducing the external link model for studying spine fixation and misalignment: part 2, Biomechanical features
Charles N R Henderson1, Gregory D Cramer, Qiang Zhang
1Palmer Center for Chiropractic Research, Davenport, Iowa, USA. henderson_c@palmer.edu <henderson_c@palmer.edu>
Summary
The external link model effectively mimics chiropractic subluxation by inducing lasting spine stiffness and misalignment in rats, even after link removal. This model aids in studying spinal fixation and joint dysfunction.
Area of Science:
- Biomechanical research
- Spinal biomechanics
- Chiropractic research
Background:
- The chiropractic subluxation is a historical concept involving spinal fixation and misalignment.
- An experimental model is needed to study the effects of these spinal changes.
Purpose of the Study:
- To characterize intervertebral stiffness and alignment changes using an external link model.
- To evaluate the model's utility in mimicking chiropractic subluxation.
Main Methods:
- A controlled test-retest design was employed using rats with linked spine segments.
- Dorsal-to-ventral spine stiffness was measured, and flexion/extension misalignment was assessed via radiographs.
- Statistical analyses, including multiple linear regression, were performed.
Main Results:
- Linked spine segments exhibited significantly higher stiffness than controls, persisting after link removal.
- Longer periods of linking and unlinking increased residual stiffness.
- Longer linking periods resulted in greater spinal misalignments during extension testing.
Conclusions:
- The external link model serves as a valuable tool for investigating spine fixation and misalignment.
- Residual stiffness and misalignment after link removal align with subluxation theory.
- The model's findings are consistent with clinical chiropractic observations.