Spinal Disc Prosthesis Fluid Coupler Edge Loading
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Solution Overview
Problem
Current spinal prosthesis implants do not effectively reduce undesired tensile stresses under unilateral loads and fail to manage edge loading with controlled reinforcement, limiting their functionality in replicating the natural disc material's function between vertebrae.
Innovation Solution
A spinal implant with a donut-shaped compressible elastic hollow body filled with an incompressible fluid, secured between two plates, and stabilizing links along the edges to prevent over-compression, which reduces tensile stresses and accommodates edge loading by shifting fluid within the cavity to maintain constant volume and resist bending moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional solid disc prosthesis is used, then structural strength is maintained, but tensile stresses under unilateral loads are not reduced and edge loading cannot be managed
Solution Approach 1:
The patent employs a fluid-filled hollow body (cushioning coupler) where incompressible fluid is contained within an elastic wall structure. This hydraulic system allows the prosthesis to dynamically redistribute loads, reducing tensile stresses under unilateral loading while maintaining overall structural strength through fluid pressure distribution.
Solution Approach 2:
The prosthesis combines multiple materials with different properties: an elastic hollow body material for compliance and stress distribution, an incompressible fluid for volume maintenance and pressure transmission, and stabilizing links for structural reinforcement. This composite structure resolves the contradiction between strength and stress management capability.
2Adaptability or versatility
If a compressible prosthesis is used, then edge loading can be accommodated, but over-compression under bending moments occurs without controlled reinforcement
Solution Approach 1:
The prosthesis is divided into functional segments: the compressible elastic hollow body for edge loading accommodation and the separate stabilizing links for compression control. This segmentation allows each component to perform its specific function independently, enabling the compressible structure to handle edge loads while the stabilizing links prevent over-compression.
Solution Approach 2:
The stabilizing links are pre-positioned along the edges of the prosthesis to provide counteracting reinforcement before over-compression can occur. These links act as preliminary protective elements that engage when bending moments approach critical levels, preventing excessive compression while allowing normal edge loading compliance.
3Strength
If the cushioning coupler is made highly compressible, then it replicates natural disc function, but it cannot resist bending moments without stabilizing reinforcement
Solution Approach 1:
The stabilizing links serve as intermediary elements between the compressible hollow body and the external loading forces. These links mediate the transmission of bending moments, providing the necessary reinforcement to resist external forces while allowing the hollow body to maintain its compressible, natural-disc-like behavior under normal physiological loading.
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 effectively reduces or eliminates tensile stresses and allows controlled reinforcement, enhancing the spinal implant's ability to manage various loads and maintain stability by using a fluid-filled compressible body and stabilizing links, thereby improving the functionality of the spinal prosthesis.
Implementation Method 1
The hollow body can be filled with an incompressible fluid
Implementation Method 2
the liquid content in the cavity of the hollow body shifts within the annular cavity and leads to an expansion of the body in that region
Implementation Method 3
The cushioning coupler is a compressible elastic hollow body
Data Source
AI summary
A spinal implant for insertion between adjacent vertebrae to function as a disc prosthesis. The prosthesis is formed from two plates fastened to adjacent vertebrae facing each other. The facing sides of the plates have a donut shaped cushioning coupler to replicate the displaced disc material. Stabilizing links are positioned along the edge of the plates to prevent over compression of the shaped cushioning coupler in a bending moment. Adjustable mounting brackets are used to secure the implant to the spine.