Asymmetric Intervertebral Disk Prosthesis Mobility Control
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Solution Overview
Problem
Existing intervertebral disc prostheses face challenges in effectively limiting mobility in specific directions, such as flexion-extension, lateral inclination, and rotation, while maintaining simplicity in manufacturing and minimizing impact on bone substance during surgical procedures.
Innovation Solution
The use of a ball and socket system with asymmetrically designed movement-limiting means, including elastic elements and strategically placed dampers, allows for independent limitation of movements, with components like U-shaped dampers and tension straps that can be easily replaced, ensuring precise control over mobility and reducing surgical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If asymmetric shaping measures are used to limit rotation and inclination movements, then movement limitation precision is improved, but prosthesis component complexity increases
Solution Approach 1:
The prosthesis is divided into separate modular components: base plates, articulation elements, and independent movement limitation means. Each component can be manufactured separately with optimized geometries, then assembled to achieve the desired asymmetric movement limitation without requiring complex monolithic structures.
Solution Approach 2:
The movement limitation means are designed with asymmetric geometries that provide different restriction characteristics for different movement directions. For example, the articulation elements have asymmetric curvature radii that limit lateral inclination differently in right and left directions, while maintaining simple manufacturing through targeted geometric features rather than complex asymmetric forms.
2Ease of operation
If elastic dampers are used to limit mobility, then movement control is improved, but reliability decreases due to material degradation over time
Solution Approach 1:
The movement limitation means utilize geometric parameters (curvature radii, step heights, groove angles) that provide passive, wear-resistant movement control without relying on elastic materials. The asymmetric shaping of articulation surfaces inherently limits mobility in specific directions through mechanical geometry, eliminating material degradation issues.
Solution Approach 2:
The movement limitation means are designed as replaceable components that can be easily exchanged if wear occurs. The modular design allows replacement of articulation elements or limitation means without replacing the entire prosthesis, maintaining reliability through replaceability rather than permanent durability.
3Ease of operation
If movement limitation means are integrated into the prosthesis, then mobility control is improved, but ease of repair deteriorates due to complex replacement procedures
Solution Approach 1:
The prosthesis is designed with separable modules where movement limitation means can be independently replaced. The articulation elements and limitation means are detachable from the base plates, allowing surgical revision by replacing only the worn components rather than the entire prosthesis, significantly simplifying repair procedures.
Solution Approach 2:
The base plates serve multiple functions: anchoring the prosthesis to vertebral bodies, providing a mounting surface for articulation elements, and serving as replacement anchors for revised limitation means. This universal design allows the same base plate structure to support different articulation and limitation configurations throughout the prosthesis lifespan.
4Ease of manufacture
If symmetric elastic dampers are used, then manufacturing simplicity is improved, but movement limitation precision deteriorates due to inability to provide asymmetric restrictions
Solution Approach 1:
The articulation elements feature asymmetric geometric features including different curvature radii for left and right lateral inclination, asymmetric step heights for flexion-extension limitation, and asymmetric groove configurations for rotational control. These asymmetric geometries are manufactured using standard techniques on individual components, then assembled to provide precise asymmetric movement limitation without requiring complex symmetric dampers.
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
This solution provides a simple, effective means to limit mobility in intervertebral disc prostheses, allowing for tailored movement adjustments without compromising bone integrity, facilitating easier surgical revisions and maintaining patient-specific mobility needs.
Implementation Method 1
the elasticity of the arms in the lateral inclination plane is higher or lower than that of the arms in the flexion plane
Implementation Method 2
The use of elastic dampers is also known from DE 203 15 611 U1
Implementation Method 3
Intervertebral disc prostheses with a ball and socket system, which are simple in terms of manufacturing technology and are three-dimensionally movable
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
According to the invention, flexion-extension movements and/or lateral inclination and/or rotation about the vertical axis of an intervertebral disk prosthesis are limited in an asymmetric manner tailored for each patient.