Bone Implant Porous Structure with Rotated Tetrapod Layers
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Solution Overview
Problem
Current bone implants with diamond-like lattice structures have uniform stiffness in all directions, which is not compatible with the direction-dependent stiffness of natural bone, leading to potential degradation and inadequate load-bearing capabilities.
Innovation Solution
A porous structure composed of regularly arranged tetrapod elements with alternating layers, where each layer's tetrapods are rotated relative to the adjacent layer, creating a non-uniform stiffness in different directions, mimicking the natural bone's mechanical properties and promoting better biocompatibility and ingrowth of bony tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a diamond-like lattice structure with uniform geometry is used, then the structural stiffness is high and uniform in all directions, but the implant stiffness does not match the direction-dependent stiffness of natural bone, leading to potential bone degradation
Solution Approach 1:
The patent applies asymmetry by rotating alternate layers of tetrapod elements by 45 degrees relative to adjacent layers, transforming the uniform diamond-like lattice into an anisotropic structure. This rotational offset creates different stiffness characteristics in different directions, enabling the implant to match the direction-dependent stiffness of natural bone while maintaining overall structural strength through the preserved tetrapod geometry and interconnected pore structure.
2Manufacturing precision
If a regular diamond-like lattice structure is used, then the manufacturing precision and reproducibility are high, but the biocompatibility is reduced due to uniform stiffness not matching natural bone properties
Solution Approach 1:
The patent applies local quality by introducing directional variation in stiffness through alternating layer rotation, while maintaining uniform material composition and controlled pore size throughout the structure. This allows different regions of the implant to exhibit different mechanical properties (anisotropic stiffness) that match local bone characteristics, improving biocompatibility without sacrificing manufacturing precision since the rotational pattern is systematically controlled during fabrication.
3Adaptability or versatility
If the tetrapod layers are rotated relative to adjacent layers, then the stiffness varies in different directions matching natural bone, but the structural complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the implant structure into discrete alternating layers of tetrapod elements, where each layer can be independently oriented. This segmentation allows the complex anisotropic stiffness requirement to be achieved through simple, repetitive rotational patterns (45 degrees between alternate layers) rather than complex continuous variations, making the design both functionally sophisticated and manufacturable through systematic layer-by-layer construction.
Data Source
AI summary
A bone implant includes a body having a porous structure and having a size and shape configured for fitting to a bone, preferably in a bone defect. The porous structure is comprised of regularly arranged elementary cells whose interior spaces form interconnected pores, the elementary cells are formed by basic elements arranged in layers, wherein the basic elements are shaped like tetrapods, the tetrapods in each layer being arranged in parallel orientation and being positioned in-layer rotated with respect to tetrapods of an adjacent layer. The layers with rotated and non-rotated tetrapods are alternatingly arranged. Thereby a porous structure can be achieved which features improved mechanical characteristics, leading to improved biocompatibility.