Reticulated Mesh Arrays for Bone Integration
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Solution Overview
Problem
Current biomedical implants, particularly load-bearing ones, face issues with biomechanical mismatch leading to stress concentration and retarded bone healing due to inadequate stress transfer and lack of bone tissue ingrowth, primarily because of insufficient porosity and mechanical incompatibility with bone tissue.
Innovation Solution
The development of reticulated solid-mesh structures and functionally graded monoliths using electron beam melting (EBM) with Ti-6Al-4V or Co-26Cr-6Mo-0.2C powders, which are designed to have controlled porosity and mechanical properties matching those of bone, allowing for bone ingrowth and improved stress distribution through CAD-driven layer-built components and a novel dry sonication method for powder removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If solid metal implants are used to provide mechanical strength, then strength is improved, but biomechanical mismatch occurs leading to stress concentration and retarded bone healing
Solution Approach 1:
The patent applies porous metal materials with controlled porosity (50-80%) to create implants that match the mechanical properties of bone tissue. The porous structure reduces the elastic modulus to be comparable with bone, enabling homogeneous stress transfer and facilitating bone tissue ingrowth through the interconnected pore network, thereby resolving the biomechanical mismatch between solid metal implants and bone tissue.
Solution Approach 2:
The patent creates composite structures combining metal matrices with porous architectures, effectively integrating the strength of metal with the bone-mimicking properties of porous structures. This composite approach allows the implant to simultaneously provide mechanical support and promote biological integration through controlled porosity and interconnected pore channels.
2Reliability
If porous metal structures are created to facilitate bone tissue ingrowth, then bone integration is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the implant into distinct regions with different porosity levels and pore size distributions, allowing optimization of bone ingrowth in specific areas while maintaining structural integrity in load-bearing regions. This segmented approach enables complex functional gradients without requiring entirely new manufacturing methods.
Solution Approach 2:
The patent utilizes parameter changes in the porous structure, including varying porosity (50-80%), pore size (100-500 micrometers), and pore shape throughout the implant, to optimize both bone integration and manufacturability. These parameter variations are achieved through controlled foaming processes that can be scaled for industrial production.
3Reliability
If high porosity is used to enable tissue ingrowth, then bone integration is improved, but mechanical strength decreases
Solution Approach 1:
The patent applies local quality by creating functionally graded porous structures where different regions have optimized porosity and pore characteristics tailored to their specific functions. Load-bearing regions have lower porosity and higher strength, while regions requiring bone ingrowth have higher porosity and larger interconnected pores, allowing simultaneous optimization of both mechanical strength and tissue integration.
Solution Approach 2:
The patent introduces dimensional variations in the pore structure, including pore size, shape, and connectivity across different spatial dimensions, to decouple the relationship between porosity and mechanical strength. By controlling the three-dimensional architecture of the porous network, the implant achieves adequate strength even at high porosity levels through optimized structural arrangement.
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
These structures facilitate enhanced bone integration and stress distribution, reducing the risk of implant loosening and revision surgeries by providing a biocompatible, porous framework for tissue ingrowth and stress transfer, while maintaining mechanical strength and compatibility with bone tissue.
Implementation Method 1
melting the three-dimensional structure from two or more layers of a metal powder with a high energy electron beam
Implementation Method 2
electron and laser beam melting
Implementation Method 3
removing the metal powder that is not melted by contacting the metal powder that is not melted with one or more ultrasonic devices and removing the metal powder that is not melted by sonication
Data Source
AI summary
Compositions and methods for making a three dimensional structure comprising: designing a three-dimensional structure; melting the three-dimensional structure from two or more layers of a metal powder with a high energy electron or laser beam is described herein. The position where the metal is melted into the structure is formed along a layer of metal powder, wherein the location and intensity of the beam that strikes the metal layer is based on the three-dimensional structure and is controlled and directed by a processor. The instant invention comprises a novel dry state sonication step for removing metal powder that is not melted from the three dimensional structure.