Porous Intervertebral Implant with Variable Pore Density
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Solution Overview
Problem
Existing intervertebral fusion implants face issues with undesirable fusion effects and dislocation due to uneven pore sizes and stresses, which are difficult to achieve with current metal-powder laser-sintering techniques, and require additional treatments like bioactive factors and polymeric materials for improved bone integration.
Innovation Solution
A porous intervertebral implant formed from metal balls with uniform particle diameters, featuring areas with different porosities and pore sizes achieved by varying the weight percentage of a pore-making agent in the metal powder particles, allowing for even stress distribution and multiple stiffness without polymeric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal-powder laser-sintering forming equipment is used to create porous structures, then bone growth capability is improved, but the structure becomes difficult to form with irregular inner portions and regular outer portions, resulting in uneven pore sizes and stresses
Solution Approach 1:
The implant is divided into multiple layers with different porosity levels. The outer layer has higher porosity for bone growth, while the inner layer has lower porosity for structural support. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall manufacturing feasibility.
Solution Approach 2:
Different regions of the implant are given different porosity characteristics tailored to their specific functional requirements. The outer surface has higher porosity to facilitate bone ingrowth, while the inner core has lower porosity to provide mechanical strength and stress distribution, creating local quality variations that resolve the contradiction between bone growth capability and structural integrity.
2Reliability
If porous structure is created to enable bone growth, then fusion degree is improved, but stress distribution becomes uneven leading to potential implant failure
Solution Approach 1:
The implant structure is segmented into multiple layers with varying porosity levels. This segmentation enables the outer layer to provide high bone growth capability while the inner layer maintains structural stability, thereby distributing stresses uniformly throughout the implant and preventing localized failure points.
Solution Approach 2:
The implant uses a composite structure combining metal balls with different porosity characteristics. This composite approach allows the material to simultaneously provide both bone growth promotion and stress distribution uniformity, resolving the contradiction between fusion enhancement and structural stability.
3Reliability
If additional treatments like bioactive factors and polymeric materials are used, then bone integration is improved, but device complexity and cost increase
Solution Approach 1:
The implant utilizes a porous metal structure where the porosity itself serves as the bone growth promoter. The controlled pore structure enables direct bone ingrowth without requiring additional bioactive factors or polymeric materials, thereby maintaining bone integration capability while reducing device complexity and eliminating the need for supplementary treatments.
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 implant achieves improved bone fusion and mechanical compatibility by evenly distributing pores and stress, enhancing stability and fusion effectiveness between vertebrae without the need for additional materials, mimicking the mechanical performance of human intervertebral discs.
Implementation Method 1
a porous intervertebral implant formed from metal balls with uniform particle diameters, featuring areas with different porosities and pore sizes achieved by varying the weight percentage of a pore-making agent in the metal powder particles
Data Source
AI summary
An intervertebral implant is a porous structure formed of a plurality of metal balls, and the intervertebral implant includes a bone support area and a bone growth area. The bone support area and the bone growth area each have a plurality of connecting holes, and a porosity of the bone support area is smaller than that of the bone growth area.