Macroporous Calcium-Phosphate Cement for Bone Repair
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Solution Overview
Problem
Current calcium phosphate cements for bone repair lack macroporosity and compressive strength, leading to slow bioresorbability and potential stress fractures, which hinder bone regeneration and tissue integration.
Innovation Solution
A novel cement powder comprising biocompatible and bioresorbable polymers combined with calcium phosphate compounds, which upon mixing and setting, forms an apatitic calcium phosphate cement with macroporosity above 100 μm and compressive strength above 10 MPa, facilitating rapid resorption and integration with natural bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional calcium phosphate cements are used for bone repair, then the material provides basic structural support, but the cement lacks macroporosity and has frangible compressive strength leading to stress fractures
Solution Approach 1:
The patent introduces macroporosity (pores >100 μm) into the calcium phosphate cement through controlled pore formation during setting. This porous structure reduces the material's brittleness and prevents stress fracture propagation while maintaining adequate compressive strength for bone repair applications.
Solution Approach 2:
The invention creates a composite calcium phosphate cement system combining multiple calcium phosphate phases (amorphous calcium phosphate, dicalcium phosphate dihydrate, octacalcium phosphate, hydroxyapatite) with controlled pore structures. This composite approach enhances both strength and fracture resistance compared to conventional single-phase cements.
2Duration of action of stationary object
If conventional calcium phosphate cements are used for bone repair, then the material provides structural support, but the cement exhibits slow bioresorbability rate
Solution Approach 1:
The macroporous structure (>100 μm pores) dramatically increases the surface area-to-volume ratio and creates channels for fluid penetration, enabling rapid water uptake and ion exchange. This accelerates the hydrolysis and resorption of calcium phosphate phases, reducing the time required for complete bioresorption from months to weeks.
Solution Approach 2:
The patent controls the setting reaction to form a specific pore size distribution and phase composition that optimizes water penetration and enzymatic access. By adjusting the liquid-to-powder ratio and setting conditions, the cement achieves a balance between initial strength and rapid subsequent resorption rate.
3Strength
If PMMA-based bone cements are used, then the cement provides high compressive strength, but the polymerization reaction generates free radicals and heat that damage surrounding tissues
Solution Approach 1:
The patent employs a transient organic peroxide initiator (lauroyl peroxide) that decomposes completely during the setting reaction, leaving no persistent harmful residues. The short-lived radical species generated initiate polymerization of the polymeric component but are consumed in the reaction, avoiding long-term free radical damage to surrounding tissues.
Solution Approach 2:
The invention modifies the polymerization kinetics by using a low-concentration organic peroxide initiator and controlling the liquid-to-powder ratio, which reduces the exothermic heat generation. The setting reaction proceeds at a controlled rate that prevents thermal damage while achieving adequate strength development.
4Volume of stationary object
If macroporosity is introduced in CPCs using conventional methods, then pore formation is achieved, but the compressive strength becomes frangible and prone to stress fractures
Solution Approach 1:
The patent optimizes the pore size to be macroporous (>100 μm) but controls the pore wall thickness and interconnectivity to maintain structural integrity. The porous network is designed with sufficient strut density to prevent stress concentration and fracture propagation while allowing adequate porosity for tissue ingrowth and rapid resorption.
Solution Approach 2:
The invention creates a composite structure where multiple calcium phosphate phases (amorphous, crystalline, intermediate phases) are distributed within the porous matrix. This composite phase distribution enhances the mechanical properties of the pore walls, providing fracture resistance while maintaining macroporosity.
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 resulting cement exhibits high resorbability and elasticity, allowing for effective bone repair, augmentation, and regeneration, while minimizing tissue damage and promoting osteogenic properties.
Implementation Method 1
The polymers of the organic component swell in contact with the liquid phase
Implementation Method 2
The inorganic component precipitates after dissolution in the liquid phase in a calcium-deficient apatite
Implementation Method 3
This thus obtained apatite is degraded by chemical and cellular processes favoured by microporosity
Data Source
AI summary
The present invention is directed to a novel cement powder comprising an organic component consisting of one or more biocompatible and bioresorbable polymers and an inorganic component consisting of one or more calcium phosphate compounds. The invention also relates to the apatitic CPC resulting from the mixing of said cement powder with a liquid phase and setting.