Asymmetric Radii Intervertebral Disc Prosthesis
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Solution Overview
Problem
Current intervertebral disc prostheses fail to accurately adapt to the anatomy and biomechanics of the lumbar and cervical spine, leading to inadequate motion ranges and potential long-term instability, which can result in further complaints and complications for patients.
Innovation Solution
The development of a two-part and three-part intervertebral disc prosthesis with convex and concave articulation surfaces, where the radii of curvature differ between sagittal and frontal views, allowing for greater contact area and motion adaptation, and featuring edge designs that ensure soft rotation limitation and reduced material strain, thereby enhancing durability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current intervertebral disc prostheses are used with standard spherical articulation surfaces, then the device structure is simple, but the motion range is insufficient and does not match natural spine biomechanics
Solution Approach 1:
The patent applies asymmetry by differentiating the radii of curvature between the convex and concave articulation surfaces. Specifically, the convex surface has a first radius of curvature while the concave surface has a second radius of curvature that differs from the first, creating an asymmetric joint geometry that enables more natural spinal motion patterns while maintaining structural simplicity
Solution Approach 2:
The patent implements parameter changes by varying the radii of curvature of the articulation surfaces. By adjusting the first and second radii of curvature to different values, the prosthesis can adapt its motion characteristics to match natural intervertebral disc biomechanics, providing improved motion range without excessive complexity
2Stability of the object's composition
If rigid rotation limitation is implemented in the prosthesis, then stability is improved, but material strain increases leading to reduced durability
Solution Approach 1:
The patent uses spheroidality by implementing curved articulation surfaces with specific radii of curvature. The convex and concave surfaces are designed with spherical or spheroidal geometry that naturally limits rotation through geometric constraints rather than rigid stops, reducing material strain while maintaining rotational stability throughout the prosthesis lifespan
3Object-affected harmful factors
If the contact area between articulation surfaces is reduced, then the device complexity is lowered, but material strain increases causing abrasion and facet joint disorders
Solution Approach 1:
The patent applies spheroidality by designing the articulation surfaces with spherical or spheroidal geometry. This curved surface design naturally distributes contact stresses over larger areas during motion, reducing material strain and preventing abrasion while maintaining a relatively simple overall device structure
Data Source
AI summary
Disclosed is an intervertebral disc prosthesis for the total replacement of a natural intervertebral disc within the lumbar and cervical spine, comprising of articulating sliding partners. The upper sliding partner has means for a firm assembly to an upper vertebral body and the lower sliding partner has means for a firm assembly to a lower vertebral body. At least one sliding surface is between two sliding partners. Two- and three-part functional designs are planned and both having in common, that, as a result of the shape of the articulating surface(s), the laterolateral and dorsoventral motion amplitudes differ. The resulting angles including the rotation around a fictitious vertical axis can be defined to a desired extent.