Adjustable Spinal Tether Modulates Flexion Loads
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Solution Overview
Problem
Current spinal treatments often result in excessive motion or loading at adjacent spinal segments, leading to further degeneration and complications such as loosening of prostheses and iatrogenic damage, particularly during flexion, which exacerbates discogenic pain and affects the stability of implanted devices.
Innovation Solution
A constraint device with adjustable tethers and compliance members is implanted to resist spinal segment flexion, modulating loads borne by prostheses and tissue, while allowing natural motion and physiology preservation, thereby reducing excessive loading and providing additional flexion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If spinal fusion is performed to stabilize the spinal segment, then stability of the treated segment is improved, but excessive motion or loading occurs at adjacent spinal segments leading to further degeneration
Solution Approach 1:
The constraint device is implanted at the adjacent motion segment before degeneration occurs, applying a preliminary restraining force to prevent excessive flexion motion. This anticipatory intervention counteracts the harmful mechanical stresses that would otherwise lead to adjacent segment degeneration, addressing the problem before it manifests clinically.
Solution Approach 2:
The constraint device acts as an intermediary element between the fused spinal segment and the adjacent motion segments. It mediates the mechanical interaction by selectively restricting harmful flexion motions while allowing other physiological movements, thereby protecting adjacent segments from excessive loading without completely immobilizing them.
2Stability of the object's composition
If traditional instrumentation is used to restrict flexion, then flexion stability is improved, but device complexity and number of failure modes increase
Solution Approach 1:
The invention extracts only the essential function needed for flexion restriction from complex traditional instrumentation systems. By isolating and implementing solely the flexion-restraining capability through a simple tether-based mechanism, the solution eliminates unnecessary components and reduces overall device complexity while maintaining effective flexion stability.
Solution Approach 2:
The constraint device utilizes flexible tether elements rather than rigid mechanical components. These flexible tethers provide the necessary restraint through tension while accommodating physiological motion, reducing complexity compared to rigid instrumentation systems while maintaining effective flexion control through material flexibility rather than mechanical complexity.
3Force
If rigid constraint is applied to restrict flexion, then flexion resistance is improved, but natural motion and physiology are compromised
Solution Approach 1:
The constraint device implements dynamic adaptability through adjustable tether tension and selective motion restriction. The system can dynamically adjust its mechanical properties to provide appropriate resistance to flexion while allowing other physiological movements, adapting to the patient's needs over time rather than imposing a fixed rigid constraint.
Solution Approach 2:
The device applies local quality by selectively restricting only the harmful flexion motion while permitting other physiological movements such as extension and rotation. This targeted approach ensures that natural motion and physiology are preserved in non-pathological directions while providing necessary restraint specifically where needed to prevent discogenic pain and prosthesis loosening.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The constraint device effectively reduces excessive loading on spinal segments, minimizes further degeneration, and enhances the stability of implanted devices, while being minimally invasive and cost-effective, with fewer failure modes compared to traditional instrumentation.
Implementation Method 1
a compliance member (16) providing a force resistant to flexion of the spinal segment
Data Source
AI summary
A spinal treatment system includes a constraint device having an upper tether portion, a lower tether portion and a compliance member coupled therebetween. The upper tether portion is coupled with a superior spinous process of a spinal segment in a patient and the lower tether portion is coupled with an inferior spinous process or sacrum of the spinal segment. The length or tension in the constraint device is adjustable so that the construct of the tether portions and the compliance member provides a force resistant to flexion of the spinal segment. The system also includes a first prosthesis coupled with the spinal segment, wherein the constraint device modulates loads borne by the prosthesis or by tissue adjacent thereto.