Intervertebral Prosthesis Core Retention and Motion
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Solution Overview
Problem
Existing intervertebral disc prostheses face challenges such as insecure core retention, limited range of motion, wear and tear issues, and inadequate adherence to vertebral bone, which affect their performance and longevity.
Innovation Solution
The proposed intervertebral prosthesis includes a core retained between two plates via central projections and a central opening, allowing the plates to slide over the core while preventing contact between the plates, thereby enhancing motion range and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the core is clamped between plates with annular ridges, then the core is retained, but the retention is insecure and allows excessive lateral play
Solution Approach 1:
The retention mechanism is segmented into multiple independent elements: central projections on the plates that engage with a central opening in the core, supplemented by annular ridges. This segmentation provides both secure retention and controlled motion, resolving the contradiction between reliable core retention and adequate range of motion.
2Ease of operation
If keys and grooves are used to allow sliding movement, then lateral motion is permitted, but vertical sliding is restricted and plate contact occurs
Solution Approach 1:
The core acts as an intermediary element between the two plates, with its central opening mediating the interaction between central projections from opposite plates. This intermediary mechanism allows controlled sliding movement while preventing direct plate contact, thereby reducing wear and improving reliability.
3Reliability
If fusion spacers are used to achieve vertebral fusion, then bone growth is promoted, but patient mobility is limited and implantation is difficult
Solution Approach 1:
Instead of fusing the vertebrae together (immobile solution), the invention inverts the approach by preserving natural vertebral motion through the articulating plates and mobile core, while still providing structural support and promoting bone growth through the lateral portions and bone contact surfaces.
Data Source
AI summary
An intervertebral prosthesis for insertion between adjacent vertebrae includes an upper plate, a lower plate and a core. The core is retained between the upper and lower plates by a retention feature in the form of central projections on the plates and a corresponding opening in the core. The retention feature is designed to allow the plates to slide over the upper and lower surfaces of the core in the anterior/posterior direction and in the lateral direction and to allow the plates to rotate with respect to each other and the core. The retention feature is also designed to prevent contact between the first and second plates during sliding movement of the plates over the core. Each central projection has a diameter that is smaller than a smallest diameter of a central opening of the core.