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Published on: October 9, 2014
Introducing the external link model for studying spine fixation and misalignment: current procedures, costs, and
Charles N R Henderson1, Gregory D Cramer, Qiang Zhang
1Palmer Center for Chiropractic Research, Davenport, Iowa 52803, USA. henderson_c@palmer.edu
Summary
The external link model (ELM) allows controlled study of spinal subluxation. Refined titanium components reduce costs and improve reusability, though construct failure rates remain comparable to other spinal implants.
Area of Science:
- Biomedical Engineering
- Animal Models
- Spinal Biomechanics
Background:
- The external link model (ELM) is a novel animal model designed for studying spinal subluxation.
- It allows for reversible and non-traumatic control of key biomechanical features like fixation and misalignment.
- This article details current ELM procedures and practical considerations.
Purpose of the Study:
- To present a detailed description of current external link model (ELM) procedures.
- To review practical issues including cost, time, and failure rates associated with the ELM.
- To introduce refinements in spinous attachment units (SAUs) for improved ELM performance.
Main Methods:
- Descriptive report of established ELM surgical techniques.
- Introduction of updated 3-piece titanium spinous attachment units (SAUs).
- Tabulation of cost-effectiveness and construct failure rates from recent ELM studies.
Main Results:
- New 3-piece titanium SAUs offer multiple reimplantations without failure, unlike older 1-piece stainless steel designs.
- The cost per ELM procedure ranges from $69 to $579, depending on component availability.
- The overall construct failure rate for the ELM is 24.2% (6.6% surgical, 17.8% post-surgical).
- Over 500 Sprague-Dawley rats have been successfully implanted with SAUs for ELM research.
Conclusions:
- The refined ELM procedures and titanium SAUs enhance the model's practicality and cost-effectiveness.
- Proficiency in performing ELM implantations can be achieved with basic animal research training after 3-4 observations and 4-6 independent procedures.
