Spinal Rod with Nested Elastic Assembly for Dynamic Stabilization
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Solution Overview
Problem
Existing spinal rods, whether rigid or semi-rigid, face challenges in providing adequate flexibility and stabilization, often leading to unnatural postures and stress concentration, which can result in poor healing and potential fractures.
Innovation Solution
A spinal rod assembly comprising a movable and stationary rod with an elastic assembly, including a first and second elastic element, where the second elastic element is partially accommodated by both rods and allows for flexibility in the frontal and sagittal planes, reducing stress shielding and enhancing spine fusion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid spinal rods are used for stabilization, then vertebral stabilization is improved, but flexibility and natural posture are lost
Solution Approach 1:
The spinal rod incorporates a dynamic structure with elastic elements (springs) that allow controlled deformation and movement. The rod can dynamically adapt to spinal movements while maintaining stabilization, transitioning from a static rigid structure to a dynamic semi-rigid system that balances both stabilization and flexibility requirements.
Solution Approach 2:
The spinal rod combines rigid materials (titanium alloy rod body) with elastic materials (springs/elastic elements) to create a composite structure. This allows the rod to exhibit both rigid stabilization properties and elastic flexibility, resolving the contradiction between being too rigid and too flexible.
2Adaptability or versatility
If soft spinal rods are used for flexibility, then natural movement is improved, but vertebral stabilization deteriorates
Solution Approach 1:
The rod employs dynamic elastic elements that provide flexibility for natural movement while maintaining sufficient stabilization force. The springs allow controlled deformation during movement but return to original position, ensuring continuous stabilization without compromising vertebral support.
Solution Approach 2:
The rod design changes the rigidity parameter by incorporating elastic elements with specific spring constants. This allows the rod to have adjustable flexibility-stabilization characteristics, providing enough flexibility for movement while maintaining adequate stabilization through the elastic recovery force of the springs.
3Adaptability or versatility
If helical structures are added to provide flexibility, then spinal movement is improved, but stress concentration increases
Solution Approach 1:
The elastic elements (springs) act as intermediary components between the rigid rod sections. These springs distribute stress uniformly through their elastic deformation, preventing stress concentration at specific points while still providing the necessary flexibility for spinal movement.
Solution Approach 2:
Instead of using helical structures that create stress concentration, the design changes to solid elastic elements (springs) with uniform stress distribution characteristics. This parameter change in the flexibility mechanism eliminates the stress concentration problem while maintaining flexibility.
4Adaptability or versatility
If springs are placed outside the rod structure, then flexibility is achieved, but stress transmission to the rod is insufficient
Solution Approach 1:
The elastic elements (springs) are nested inside the hollow rod structure. This nesting arrangement ensures that the springs are properly constrained and that their elastic force is effectively transmitted to the rod structure, solving the problem of insufficient stress transmission while maintaining flexibility.
Solution Approach 2:
The rod structure acts as an intermediary that transmits the elastic force from the nested springs to the vertebral system. The springs generate elastic force during deformation, and the rod structure efficiently transmits this force to maintain stabilization, resolving the insufficient stress transmission issue.
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 spinal rod assembly provides improved flexibility and stabilization, allowing for natural spinal movement and reducing stress concentration, thereby enhancing patient quality of life and spine fusion rates.
Implementation Method 1
an elastic assembly comprising a first elastic element and a second elastic element, wherein the elastic assembly is accommodated by the rod assembly, the first elastic element is between the cap and the stationary rod, a compression of the first elastic element by the movable rod shortens an overall length of the rod assembly, and the second elastic element provides a flexibility for movements of the movable rod and the stationary rod in a frontal plane and a sagittal plane
Data Source
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AI summary
The present disclosure relates to a spinal rod comprising a rod assembly and an elastic assembly. The rod assembly comprises a movable rod, a stationary rod and a cap, and the cap is between the stationary rod and the movable rod for fixing the movable rod and the stationary rod. The elastic assembly is accommodated by the rod assembly for providing a flexibility to the rod assembly. The spinal rod is able to respond to the lateral, anterior or posterior movements of the patient's spine on a range of limited angles.