Intervertebral Disc Prosthesis Undercut Retention Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing intervertebral disc prostheses fail to perfectly replicate the damping characteristics of natural vertebral discs, experience rapid wear of flexible damping elements, risk of intermediate core expulsion, and are complex to assemble.
Innovation Solution
The prosthesis features a receiving part with a cavity and a deformable flexible element, where the cavity has an undercut shape and the element has a housing with a stud, allowing easy assembly and reducing shear forces, with a design that mimics the non-linear damping of natural discs through specific curvature and recesses, minimizing wear and expulsion risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intermediate core is made mobile relatively to both plates to enable damping movements, then the damping characteristics are improved, but the risk of core expulsion increases
Solution Approach 1:
The intermediate core is nested within the receiving part cavity, with the flexible element contained between the first shell and the receiving part. The undercut shapes of both the cavity and housing create nested retention structures that prevent expulsion while allowing movement.
Solution Approach 2:
The flexible element acts as an intermediary between the first shell and the receiving part, enabling damping movements while the undercut retention structures serve as intermediaries to prevent core expulsion. The guiding means also act as intermediaries to constrain movement paths.
2Reliability
If the flexible element is made deformable to enable damping movements, then the damping performance is improved, but the wear of the flexible element increases
Solution Approach 1:
The rounded walls with different radii of curvature create a non-linear damping effect that reduces stress concentrations on the flexible element. The curved surfaces distribute forces more evenly, reducing wear while maintaining damping performance.
Solution Approach 2:
The patent changes the geometric parameters of the cavity and housing (undercut shapes, rounded walls with specific radii) to optimize both damping performance and flexible element durability. The parameter mismatch between the two rounded walls creates controlled clearance that reduces friction and wear.
3Object-affected harmful factors
If the cavity and housing have undercut shapes to retain the flexible element, then the risk of expulsion is reduced, but the assembly complexity increases
Solution Approach 1:
The flexible element is pre-deformed to enable it to forcibly cross the edges of the undercut openings during assembly. The stud is also pre-designed with a larger end section to facilitate insertion through the housing opening. This preliminary preparation simplifies the assembly process despite the complex undercut geometry.
Solution Approach 2:
The deformable flexible element and stud perform self-assembly by forcibly crossing the undercut edges during installation. The design allows the components to self-retain once assembled, eliminating the need for additional fastening mechanisms.
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 solution enables the prosthesis to accurately reproduce natural vertebral disc damping movements with reduced wear and a lower risk of intermediate core expulsion, while simplifying assembly and maintaining effective damping with low wear of the flexible element.
Implementation Method 1
The rounded wall of the flexible element comes into contact with the rounded wall of the receiving part, until it comes into contact with this wall. Thus, non-linear damping is obtained
Implementation Method 2
said flexible element being deformable so as to be able to forcibly cross the edge of said first peripheral wall delimiting this opening
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
This prosthesis (1) includes two plates (2, 3) and an intermediate damping core(4) placed between both of these plates (2, 3), this core (4) comprising a first shell (6) and a flexible element (11) placed between this first shell (6) and a part (5; 2) for receiving this core, said first shell (6) and said first receiving part (5; 2) comprising means (18, 26) for guiding their mutual movement for bringing them closer or moving them away from each other. According to the invention, -said receiving part (5; 2) comprises a cavity (19) intended to snugly receive the flexible element (11), this cavity (19) being delimited by a first peripheral wall (18) and by a bottom wall, said first peripheral wall (18) having an external peripheral face; and -said first shell (6) has a second peripheral wall (26) forming an internal face, this internal face, when said first shell (6) and the receiving part (5; 2) are in their assembling condition, coming into close proximity to said external peripheral face and being able to slide along the latter.