Sintered Fiber Bone Implants with Directional Strength
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Solution Overview
Problem
Current bone implants fail to provide adequate guidance for bone growth and mechanical strength, particularly in older patients with decelerated healing processes due to osteoarthritic diseases, and lack directional strength and porosity control for optimal tissue integration and load-bearing capacity.
Innovation Solution
A method involving the arrangement of long metal or metal alloy fibers in multiple layers as nonwovens, with fibers aligned in preferred axial directions and altered using needling techniques, followed by sintering to create a graded, anisotropic structure with controlled porosity and mechanical properties, allowing for improved cell ingrowth and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If porous implants are produced by selective laser melting, then mechanical strength is improved, but structures in the order of 20 μm are not producible
Solution Approach 1:
The patent replaces the selective laser melting process with a sintering process for producing porous implants. The sintering method involves compacting and sintering porous bodies at temperatures between 900°C and 1200°C, which enables the production of fine structures down to 20 μm while maintaining mechanical strength. This substitution of the manufacturing process resolves the contradiction between achieving fine structural precision and maintaining mechanical integrity.
2Adaptability or versatility
If sintered fiber structures are produced with high porosity, then osteoinductivity is improved, but mechanical strength is reduced
Solution Approach 1:
The patent applies local quality by creating anisotropic porous structures with directionally aligned fibers. The porous bodies are produced with controlled pore sizes and distributions in different regions, allowing high porosity (60-80%) for osteoinductivity in bone contact areas while maintaining sufficient mechanical strength through directional fiber alignment and controlled sintering parameters. This enables different regions to have optimized properties for their specific functions.
Solution Approach 2:
The patent uses composite material structures combining metal fibers (titanium or titanium alloys) with controlled porosity. The fiber-reinforced porous structure combines the high strength of metal fibers with the osteoinductive benefits of porosity, achieving a balance between mechanical strength and biological performance through the composite architecture.
3Adaptability or versatility
If ungraded and disordered tissue structures are used, then ingrowth behavior is improved, but directional strength and load-bearing capacity are insufficient
Solution Approach 1:
The patent introduces asymmetry by producing anisotropic porous structures with directionally aligned fibers rather than disordered arrangements. The fibers are oriented in preferred directions to provide directional strength and load-bearing capacity while maintaining porosity for bone ingrowth. This asymmetric, directionally controlled structure resolves the contradiction between random ingrowth promotion and directional mechanical strength.
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 method produces implants with enhanced osteoinductivity and mechanical strength, enabling targeted bone growth and load distribution, addressing the limitations of existing implants by providing adjustable anisotropic mechanical properties and improved tissue integration.
Implementation Method 1
The sintered density is thereby varied, for example, by changing the temperature-time programs during the heat treatment for sintering
Data Source
AI summary
In the method for producing open-porous bone implants with freely accessible guide structures made from fibers, which are formed from a biocompatible metal or metal alloy, long fibers are superimposed in multiple layers, each in the form of a nonwoven, in which the fibers in each layer are arranged in a mutually preferred axial direction. Needling is carried out in at least one of the layers, by means of which individual fibers of the respective layer are aligned in an axial direction which differs by at least 60° from the preferred axial direction in which the other fibers of the layer are aligned. The superimposed layers are materially fitted to one another point by point via sinter bridges on fibers by sintering in a heating device.