Shear-Limiting Core Radial Flange for Disc Prosthesis
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Solution Overview
Problem
Current intervertebral disc prosthetics lack the ability to restrict specific movements between vertebral bodies, and existing solutions often require modification of multiple components to achieve desired movement characteristics, which can lead to endplate contact and potential damage.
Innovation Solution
An intervertebral disc prosthesis design featuring a superior and inferior endplate with a central core that includes a radial flange, allowing for selective restriction of motion by engaging the endplates differently, thereby preventing direct contact and allowing for customizable movement limitations using a shear-limiting core configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple components are modified to achieve desired movement characteristics, then movement restriction capability is improved, but device complexity and risk of endplate contact increase
Solution Approach 1:
The patent extracts the movement restriction function from the endplates and places it solely in the core component. The radial flange on the core provides the shear-limiting mechanism, while the endplates maintain their simple bearing function. This separation allows movement restriction capability without requiring modification of multiple components.
Solution Approach 2:
The radial flange on the core acts as an intermediary element between the superior and inferior endplates. It provides the shear-limiting function by engaging with the vertebral bodies directly, preventing endplate contact while restricting movement. This intermediary structure resolves the contradiction by providing movement control without complex endplate modifications.
2Ease of operation
If endplates are allowed to contact each other to restrict movement, then movement restriction is achieved, but reliability decreases due to potential damage
Solution Approach 1:
The radial flange on the core serves as a mediator that prevents direct contact between the superior and inferior endplates. When shear forces exceed the design limit, the flange engages with the vertebral bodies to restrict movement, thereby protecting the endplates from damaging contact forces while maintaining movement restriction capability.
Solution Approach 2:
The radial flange is designed beforehand to provide shear limitation, cushioning the system against excessive movements before they can cause endplate damage. This preventive design ensures that endplates are protected from harmful contact forces before they occur, maintaining both movement restriction and endplate reliability.
3Ease of manufacture
If a fixed core configuration is used, then manufacturing simplicity is maintained, but adaptability to different movement requirements decreases
Solution Approach 1:
The core is designed with a specific local feature (radial flange) that provides shear-limiting functionality. By varying the local geometry of the radial flange (such as flange height, thickness, or engagement surface area), different movement characteristics can be achieved while maintaining the basic core structure. This allows customization of movement restrictions without fundamentally changing the core manufacturing process.
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 design enables controlled movement restriction without endplate contact, providing a more natural movement pattern and allowing for various movement characteristics by using different core configurations with standard endplates, thus enhancing the prosthetic's functionality and durability.
Implementation Method 1
The radial flange is configured to engage the superior endplate and inferior endplate to restrict rotational motion of the superior endplate relative to the inferior endplate
Data Source
AI summary
An intervertebral disc prosthesis comprises a superior endplate, an inferior endplate, and an intermediate core positioned between the endplates. The core comprises a central disc portion and a radial flange. The central disc portion of the core is defined by a superior bearing surface and inferior bearing surface. The radial flange of the core includes a first portion that extends radially outward from the central disc portion of the core. The radial flange also includes a second portion that extends axially from the first portion of the flange. The second portion of the flange extends a substantially greater distance toward the inferior endplate than toward the superior endplate. In one embodiment, the second portion of the flange extends completely to the inferior endplate and engages the inferior endplate when the inferior endplate is in a neutral position relative to the core.