Asymmetrical Artificial Disc Correcting Spinal Deformities
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Solution Overview
Problem
Current artificial cervical disc replacement systems fail to maintain normal spinal alignment and correct deformities such as kyphosis or coronal imbalance, leading to adjacent segment disease and increased risk of degenerative changes.
Innovation Solution
An artificial disc with a nucleus that is not geometrically symmetrical, featuring a maximum vertical axis offset from the center, and end plates with asymmetrical designs and motion stops to allow for semi-constrained motion and variable instantaneous axis of rotation, enabling correction of sagittal and coronal deformities while maintaining natural spinal kinematics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetrical artificial disc design is used, then the device structure is simple and easy to manufacture, but it fails to correct spinal deformities such as kyphosis and coronal imbalance
Solution Approach 1:
The patent applies asymmetry by designing the artificial disc with an offset maximum vertical axis that is not located at the geometric center. This asymmetric configuration enables the disc to correct sagittal deformities (kyphosis) and coronal deformities (imbalancel while maintaining manufacturability through standardized asymmetric components.
2Device complexity
If a fixed instantaneous axis of rotation is used, then the mechanical structure is simpler, but it cannot maintain normal spinal kinematics and alignment
Solution Approach 1:
The patent implements dynamics by designing the artificial disc with a variable instantaneous axis of rotation rather than a fixed axis. The offset maximum vertical axis allows the rotation axis to vary dynamically during spinal motion, enabling the disc to maintain normal spinal kinematics and alignment throughout the range of motion while using a relatively simple mechanical structure without complex actuators or sensors.
3Adaptability or versatility
If the maximum vertical axis is offset from the center, then spinal deformities can be corrected, but the device becomes more complex and harder to manufacture
Solution Approach 1:
The patent resolves this contradiction by implementing asymmetry through an offset maximum vertical axis that is not located at the geometric center of the artificial disc. This asymmetric design enables correction of both sagittal deformities (kyphosis) and coronal deformities (imbalancel while maintaining reasonable manufacturability through standardized asymmetric components and conventional manufacturing processes.
Data Source
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AI summary
The present invention provides artificial disc prostheses, methods and instrumentation for implantation and revision. Each prosthesis may comprise superior and inferior end plates and a nucleus positioned between articular surfaces of the end plates. The end plates may have planar bone engagement surfaces with a plurality of self-cutting teeth. The articular surfaces of the end plates may be planar or include a flattened portion. The nucleus includes superior and inferior articular surfaces which may comprise flattened portions such that when the articular surfaces of the nucleus and the end plates are placed in a preferred orientation, the flattened and/or planar portions are aligned. Each prosthesis may provide flexion/extension, anterior/posterior translation, lateral bending, and/or axial rotation degrees of freedom. One embodiment comprises a prosthesis with a first joint providing flexion/extension and anterior/posterior translation, and a second joint providing lateral bending and axial rotation.