Artificial Disc Core Assembly for Natural Spinal Motion and MRI Compatibility
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Solution Overview
Problem
Current artificial disc replacement (ADR) systems impede normal spinal movement, cause tissue scarring, require precise implantation, and create MRI artifacts, with issues in test fitting and potential damage to vertebral endplates during insertion.
Innovation Solution
An ADR device with endplates and a core assembly, featuring a core member with varying curvature and a matrix member to allow natural motion, prevent endplate contact, and use non-metallic materials to reduce MRI artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic endplates are used to prevent contact between vertebrae during flexion and extension, then the structural strength is improved, but MRI artifacts are generated that interfere with imaging
Solution Approach 1:
The endplate material is changed from metallic to non-metallic (such as ceramic or polymer), fundamentally altering the material parameter to eliminate MRI artifacts while maintaining structural strength through careful material selection and design
Solution Approach 2:
The device uses composite construction with non-metallic endplate materials combined with the core assembly, allowing the endplates to be MRI-compatible while the internal core provides the necessary mechanical support and motion control
2Adaptability or versatility
If a mobile core is used to allow motion between vertebrae, then the range of motion is improved, but the core may become displaced or affected by tissue scarring leading to failure
Solution Approach 1:
The mobile core is divided into multiple segments or elements that can move relative to each other, allowing controlled motion while maintaining overall stability and preventing displacement through the segmented structure
Solution Approach 2:
The core assembly incorporates dynamic elements that adapt to physiological conditions, allowing the structure to maintain stability through controlled motion rather than rigid fixation, thereby preventing displacement and reducing tissue scarring
3Adaptability or versatility
If the endplates are designed to prevent contact during flexion, then the range of motion is improved, but non-metallic materials must be used which may have lower strength
Solution Approach 1:
Non-metallic endplate materials such as ceramic or high-strength polymer composites are used, providing both the MRI compatibility and structural strength required, while allowing full range of motion without metallic artifacts
Solution Approach 2:
The material parameters of non-metallic endplates are optimized through careful selection of ceramic or polymer compositions, achieving sufficient mechanical strength to prevent contact during flexion while maintaining MRI compatibility
Data Source
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AI summary
An artificial disc replacement device is disclosed. The device includes an upper endplate and a lower endplate, as well as a core assembly disposed between the endplates. The core assembly includes a core member with a curved engaging surface and a matrix member. The matrix member is more compressible than the core member. The curved engaging surface of the core member engages a recess in the upper endplate so that the upper endplate can translate along the curved engaging surface. The curved engaging surface has a greater curvature at its posterior end than at its anterior end to facilitate different ranges of motion during extension and flexion.