Intervertebral Disc Prosthesis Three-Plate Design
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Solution Overview
Problem
Current intervertebral disc prosthetics lack features such as a three-piece design with a core sandwiched between plates, easy grasping and retention by insertion tools, and enhanced stability and fixation mechanisms, which are desirable for improved implantation and functionality.
Innovation Solution
The intervertebral disc prosthesis features a first plate with a socket and a second plate with a recess, where the core is press-fit into the recess, allowing the first plate to rotate and be securely fixed to the second plate, with notches and tabs for tool retention and a lordotic angle for better fit and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a three-piece design with core sandwiched between plates is used, then stability and fixation are improved, but device complexity increases
Solution Approach 1:
The prosthetic disc is divided into three separate components: a superior plate, an inferior plate, and a core component. This segmentation allows each part to be optimized independently while working together to provide enhanced stability and fixation. The core is sandwiched between the two plates, creating a modular assembly that improves reliability without requiring a completely new design approach.
Solution Approach 2:
The core component is nested within the recess of the inferior plate, with the superior plate fitting over the core. This nested arrangement creates a compact three-piece structure where the core is secured to the inferior plate through a press-fit arrangement, and the superior plate rotates upon the core, achieving both stability and ease of assembly.
2Ease of operation
If notches and tabs are added for tool retention, then ease of implantation is improved, but device complexity increases
Solution Approach 1:
The notches and tabs are pre-formed as integral features of the superior and inferior plates during manufacturing. These features are prepared in advance to receive and retain the prongs of an insertion tool, enabling easy grasping and implantation without requiring additional attachments or complex manipulation during the surgical procedure.
3Strength
If the core is press-fit into the recess, then fixation strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The press-fit arrangement utilizes controlled dimensional parameters where the core component has a diameter slightly larger than the recess opening, creating a friction fit that provides strong fixation. The recess is defined by a circular wall and flat floor with specific dimensional relationships that, when manufactured with standard precision tolerances, achieve the necessary fixation strength without requiring ultra-precise manufacturing.
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 design facilitates easier implantation, enhanced stability, and improved fixation of the prosthesis, allowing for better shock absorption and secure attachment to vertebral bodies, addressing the limitations of existing prosthetics.
Implementation Method 1
The plug of the core is configured to be press-fit into the recess by a friction fit or a snap fit
Implementation Method 2
The plug of the core is configured to be press-fit into the recess by a friction fit or a snap fit
Implementation Method 3
The socket of the first plate provides an articulating surface configured to engage the dome-shaped bearing surface of the core, thus allowing the first plate to rotate upon the core
Implementation Method 4
at least one tooth positioned on a face of the first plate and at least one tooth positioned on a face of the second plate. The teeth are configured to secure the intervertebral disc prosthesis to the vertebral bodies
Implementation Method 5
the first plate and the second plate of the intervertebral disc prosthesis are tapered from an anterior edge to a posterior edge such that they collectively define a lordotic angle of 7°, with 3.5° contributed from each plate
Data Source
AI summary
An intervertebral disc prosthesis comprises a first plate including a socket and a second plate comprising a recess. A core is sandwiched between the socket and the recess. The core includes a domed surface and a plug portion. The first plate is configured to rotate upon the domed surface of the core. The second plate is substantially fixed to the core, with the plug portion engaging the recess. The core may be press-fit into the second plate during assembly of the intervertebral disc prosthesis. The first plate and second plate both include tabs that define notches, wherein the notches are configured to engage prongs of a disc insertion tool. Teeth provided on the first plate and the second plate assist in fixing the first plate and the second plate to the vertebral bodies.