Three-Dimensional Voronoi Structures for Bone Ingrowth Control
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Solution Overview
Problem
Current methods for manufacturing porous metal structures for bone ingrowth lack precise control over pore size distribution and porosity, limiting their effectiveness in promoting bone ingrowth while maintaining structural integrity.
Innovation Solution
The development of a porous three-dimensional structure with a lattice configuration that allows for controlled pore size and porosity through a Voronoi pattern, which is modified to achieve organicized struts and nodes, enabling a porosity range of 60% to 85% and pore sizes between 0.5 mm to 2 mm, with struts having varying cross-sectional shapes and thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional additive manufacturing techniques are used to create porous structures, then high-density parts can be produced, but control over pore size distribution and porosity is limited
Solution Approach 1:
The structure is divided into repeating unit cells, each containing struts and pores. By controlling the geometry of individual unit cells (strut length, diameter, and arrangement), precise control over overall pore size distribution and porosity is achieved. The unit cell approach segments the complex porous structure into manageable, controllable elements.
Solution Approach 2:
The invention varies geometric parameters of the unit cell structure, specifically the ratio of strut length to diameter, to control porosity and pore size. By adjusting these parameters within the unit cell design, the structure achieves targeted porosity ranges (60-85%) and pore sizes (0.5-2 mm) while maintaining manufacturing feasibility.
2Ease of manufacture
If unit cell geometric structures have large pore size or low porosity to maintain structural integrity, then manufacturing is easier, but bone ingrowth effectiveness is reduced
Solution Approach 1:
The invention optimizes the strut length-to-diameter ratio parameter within the unit cell to achieve a balance between structural integrity and bone ingrowth. By carefully selecting this parameter, the structure maintains sufficient strength for manufacturing and handling while providing adequate pore size and porosity for bone ingrowth.
Solution Approach 2:
The porous metal structure combines the structural integrity of dense metal frameworks with the bone-ingrowth benefits of porous geometries. The unit cell design creates a composite-like structure where solid struts provide mechanical strength while interconnected pores enable biological integration.
3Ease of manufacture
If additive manufacturing minimum strut diameter constraints are applied, then manufacturing is feasible, but pore size and porosity control is limited
Solution Approach 1:
The structure uses a unit cell segmentation approach where multiple small struts within each unit cell collectively achieve the desired overall porosity and pore size. This allows compliance with minimum strut diameter manufacturing constraints while still creating larger effective pore spaces through the arrangement of multiple struts.
Solution Approach 2:
The invention controls porosity and pore size not just through strut diameter but through the three-dimensional arrangement and spacing of struts within unit cells. By utilizing spatial distribution in multiple dimensions, the structure achieves targeted porosity (60-85%) and pore size (0.5-2 mm) while maintaining strut dimensions compatible with additive manufacturing capabilities.
Data Source
AI summary
A method of manufacturing an orthopaedic prosthetic component can include identifying a porous three-dimensional Voronoi structure shaped to be implanted in a patient's body. The porous three-dimensional Voronoi structure can include a plurality of struts, a number of pores, a first surface, and a second surface. The plurality of struts can define randomized interconnected organicized cells. Respective groups of struts intersect so as to define a respective plurality of nodes. The method can include the step of modifying modifying at least one of the struts or at least one of the nodes such that the porous three-dimensional structure comprises a lattice structure other than a Voronoi pattern. Instructions can then be generated to fabricate the porous three-dimensional structure.