Porous Calcium Phosphate Bone Agent with Discrete Pore Sizes
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Solution Overview
Problem
Current bone formation agents face challenges in achieving adequate mechanical strength while maintaining high porosity and reducing the risk of foreign-body reactions and microorganism colonization, which can impede bone regeneration.
Innovation Solution
A porous calcium phosphate bone formation agent with an isotropic sintered structure and statistically distributed pores in multiple discrete size ranges, featuring a non-interconnecting macropore network and stable sintering necks to prevent foreign-body reactions and ensure mechanical strength, is developed. The agent has a porosity with irregular polygonal geometry and discrete pore size distributions, limiting interconnecting pores to less than 10 μm and adjusting the pore ratios for optimal strength and resorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high porosity is achieved in bone formation agents, then resorption rate and osteoconductive properties are improved, but mechanical strength deteriorates
Solution Approach 1:
The patent applies local quality by creating distinct pore size zones within the material structure. Small pores (0.5-10 μm) are distributed throughout to provide osteoconductive properties and control resorption, while larger pores (10-100 μm) are strategically positioned to enhance mechanical strength without compromising overall porosity. This spatial differentiation of pore functions resolves the contradiction between high porosity and mechanical strength.
Solution Approach 2:
The patent employs composite material principles by combining calcium phosphate particles of different sizes and pore structures to create a multi-component system. The composite structure includes sintered particles with controlled pore distributions, where each component contributes specific properties: fine particles provide surface area for bone growth, while coarser particles maintain structural integrity. This composite approach enables simultaneous achievement of high porosity and adequate mechanical strength.
2Productivity
If interconnecting macropores are increased to improve resorption, then bioresorption rate is enhanced, but foreign-body reactions and microorganism colonization increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling pore size dimensions and connectivity parameters. The critical parameter threshold of 10 μm is established to differentiate between beneficial small pores and harmful large interconnected pores. By adjusting pore size distribution parameters and limiting macropore connectivity, the material achieves optimal resorption rate while preventing foreign-body reactions and microorganism colonization that occur with excessive macropore interconnection.
Solution Approach 2:
The patent converts the potential harm of interconnected macropores into benefit by strategically limiting their size and connectivity. Instead of eliminating all large pores, the invention transforms them into controlled, non-interconnecting structures that maintain resorption functionality while eliminating the harmful effects of uncontrolled macropore networks. The pore structure is designed so that larger pores provide resorption pathways without creating continuous channels that facilitate foreign-body reactions and infection.
3Area of stationary object
If particle size is reduced to increase surface area, then osteoconductive properties are improved, but sintering strength and structural stability deteriorate
Solution Approach 1:
The patent applies local quality by creating a heterogeneous particle size distribution where different particle sizes fulfill different functions. Fine particles (smaller than 63 μm with d50 of 5-20 μm) provide high surface area for osteoconductive properties and bone cell attachment, while coarser particles are incorporated to provide structural framework and sintering strength. This spatial and functional differentiation of particle sizes resolves the contradiction between surface area and sintering 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 solution enhances mechanical strength and prevents foreign-body reactions, allowing for effective bone regeneration with reduced risks of microorganism colonization and improved resorption rates, ensuring the bone formation agent maintains structural integrity during the wound-healing phase.
Implementation Method 1
promotes growth of bone in the defect as an osteoconductive guideway
Implementation Method 2
in part are slowly dissolved in body fluid and in part are subjected to cellular breakdown
Implementation Method 3
an isotropic sintered structure and, between the sintered particles of the calcium phosphate, statistically distributed pores
Data Source
AI summary
The invention relates to a bone formation agent of porous calcium phosphate having an isotropic sintered structure and, between the particles of the calcium phosphate, statistically distributed pores in a plurality of discrete size ranges. The bone formation agent has at least two, preferably three, discrete pore size distributions. Its porosity has an irregular geometric shape. The sintered particles of the calcium phosphate have a particle size smaller than 63 μm with a d50 value in the range from 5 to 20 μm. The interconnecting pore share in the overall porosity is limited to pore sizes less than 10 μm. The bone formation agent can be used in the form of a granulate or shaped body for bone regeneration. In the case of granulates, the maximum pore diameters are matched to the granulate diameter. The invention relates also to a method of producing the bone formation agent.