Injectable Tricalcium Phosphate Composite for Bone Substitution
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Solution Overview
Problem
Current bone substitutes, such as polymethylmethacrylate and calcium phosphate cements, face issues like tissue necrosis due to heat generation, poor mechanical properties, and separation of phases during injection, making them unsuitable for effective bone repair and replacement.
Innovation Solution
A composite material comprising a tricalcium phosphate ceramic phase and a polyvinyl alcohol hydrogel fluid phase, which can be injected and hardened in situ, offering mechanical properties similar to natural bone and improved injectability by modulating the polymer and inorganic phase ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymethylmethacrylate is used as an injectable bone substitute, then mechanical strength is improved, but tissue necrosis occurs due to heat generation
Solution Approach 1:
The patent converts the harmful exothermic polymerization reaction into a beneficial controlled setting reaction by using calcium phosphate cement chemistry, which sets via controlled precipitation and crystallization of calcium phosphate minerals, eliminating tissue necrosis while maintaining mechanical strength
Solution Approach 2:
The patent changes the chemical reaction parameters from rapid exothermic polymerization to controlled endothermic/exothermic balance calcium phosphate setting reaction, adjusting the setting mechanism to occur at physiological temperatures that do not cause tissue damage
2Reliability
If calcium phosphate cement is used as an injectable bone substitute, then biocompatibility is improved, but mechanical properties deteriorate due to brittle behavior
Solution Approach 1:
The patent creates a composite calcium phosphate cement system combining multiple calcium phosphate phases (tricalcium phosphate, dicalcium phosphate, hydroxyapatite) with controlled porosity and crystalline structure, achieving both biocompatibility and improved mechanical properties through phase composition optimization
Solution Approach 2:
The patent utilizes the naturally porous structure of calcium phosphate cement and optimizes pore size distribution and connectivity to enhance mechanical interlocking with bone tissue while maintaining adequate strength, transforming the weakness of porosity into a mechanical advantage
3Ease of operation
If tricalcium phosphate paste is injected prematurely, then injectability is improved, but disintegration occurs in contact with biological fluids
Solution Approach 1:
The patent performs preliminary mixing and conditioning of the calcium phosphate cement paste to achieve optimal viscosity and flow characteristics before injection, ensuring the paste maintains its structural integrity during injection and only undergoes controlled setting after placement in the defect site
Solution Approach 2:
The patent introduces a controlled aqueous environment or delaying agent that mediates between the paste formulation and biological fluids, allowing the paste to maintain stability during injection and transport while enabling controlled hydration and setting after placement
4Stability of the object's composition
If tricalcium phosphate paste is injected too late, then structural stability is improved, but manageability deteriorates due to hardening
Solution Approach 1:
The patent creates a dynamic paste formulation with time-dependent rheological properties that transitions from flowable to set state, allowing adequate working time for injection and positioning while ensuring complete setting and stability within a predictable timeframe for clinical procedures
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 composite material achieves enhanced mechanical properties and injectability, allowing for effective bone substitution with improved deformability and toughness, reducing the risk of tissue damage and phase separation, and providing a stable interface with natural bone.
Implementation Method 1
a polyvinyl alcohol hydrogel fluid phase
Implementation Method 2
their ability to harden in the presence of the water used for preparation
Data Source
AI summary
The invention relates to a new injectable composite material suitable for use as a bone substitute. The composite material according to the invention comprises a reactive ceramic phase based on tricalcium phosphate and an organic phase comprising a polyvinyl alcohol hydrogel . By varying the concentration of the two phases it is possible to modulate the mechanical and injectability properties of the material.