Calcium Phosphate Polymer Composite for Bone Repair
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Solution Overview
Problem
Current bone repair materials lack sufficient mechanical strength, controlled drug delivery, and biocompatibility, with existing calcium phosphate-reinforced polymer composites exhibiting low toughness and inadequate mechanical properties for load-bearing applications, and existing delivery systems failing to systematically control the release of multiple growth factors for enhanced bone healing.
Innovation Solution
A novel calcium phosphate/polymer fiber composite with different degradation rates, featuring a biomimetic coating and a core-sheath structure, where the core is coated with calcium phosphate and the sheath is made from low-melting temperature polymers, allowing for braiding and compression molding to create a composite with high mechanical strength and controlled drug release capabilities, mimicking the mechanical properties of natural bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If calcium phosphate-reinforced polymer composites are used to improve mechanical strength, then the material gains higher strength, but the toughness and mechanical properties remain inadequate for load-bearing applications
Solution Approach 1:
The patent employs a composite material system consisting of polymer fibers (such as PLLA, PGA, PCL) reinforced with calcium phosphate particles. This composite structure combines the high strength and stiffness of calcium phosphate with the toughness and ductility of the polymer matrix, achieving both improved mechanical strength and adequate toughness for load-bearing bone repair applications
Solution Approach 2:
The patent applies local quality enhancement by creating regions with different calcium phosphate concentrations and fiber orientations within the composite. The calcium phosphate particles are distributed non-uniformly to provide localized reinforcement where needed, while maintaining overall toughness through the polymer matrix continuity
2Device complexity
If a single material is used for bone repair, then the structure is simple, but it cannot provide both structural support and controlled drug delivery functions
Solution Approach 1:
The patent designs a multi-functional composite material that simultaneously provides mechanical structural support through the fiber-reinforced framework and controlled drug/growth factor delivery through the polymer matrix. The calcium phosphate particles also contribute to osteoconductivity and controlled ion release, making the single composite material capable of multiple essential functions for bone repair
Solution Approach 2:
The patent merges the structural support function (provided by fiber reinforcement), the drug delivery function (provided by the polymer matrix), and the osteoinductive function (provided by calcium phosphate particles and incorporated growth factors) into a single integrated composite material system, eliminating the need for separate components
3Speed
If growth factors are released quickly to achieve rapid bone healing, then the initial bone formation is accelerated, but the sustained osteoblastic differentiation is compromised
Solution Approach 1:
The patent implements periodic or sustained release of growth factors through the composite material. The polymer matrix provides controlled diffusion and degradation-based release, while the calcium phosphate particles can also release ions and incorporated growth factors over time. This creates a sustained release profile that maintains therapeutic levels of growth factors throughout the bone healing process, enabling both rapid initial formation and sustained osteoblastic differentiation
4Strength
If metallic implants are used to provide high mechanical strength, then the structural support is adequate, but stress shielding weakens adjacent bones
Solution Approach 1:
The patent changes the material parameters by using a polymer-calcium phosphate composite with mechanical properties that more closely match natural bone, rather than using high-strength metallic implants. The composite's lower modulus and closer match to bone properties allows for more uniform stress distribution, preventing stress shielding while still providing adequate mechanical support during the healing process
5Ease of manufacture
If absorbable polymers are used to avoid second surgery, then the need for removal is eliminated, but the mechanical strength is insufficient
Solution Approach 1:
The patent uses a composite material system where absorbable polymer fibers provide the base matrix and biodegradability, while calcium phosphate particles and fiber reinforcements provide the necessary mechanical strength. This composite approach maintains the advantage of absorbability (avoiding second surgery) while overcoming the weakness of insufficient strength through material composition and structural design
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 achieves a bending modulus comparable to cortical bone, enabling effective bone repair with sustained release of growth factors, enhanced osteoconductivity, and osteoinductivity, while being gradually replaced by natural bone tissue, thus addressing the limitations of existing materials and delivery systems.
Implementation Method 1
compression molded to allow the sheath to bond to the core
Implementation Method 2
The sheath is made from low-melting temperature polymers, allowing for braiding and compression molding to create a composite
Implementation Method 3
the core is coated with calcium phosphate
Data Source
AI summary
A bone-repair composite includes a core and a sheath. The core is a first primary unit including a combination of a first set of yarns coated with a calcium phosphate mineral layer. The first set of yarns being made from a first group of one or more polymers. The sheath is a second primary unit a combination of a second set of yarns or one or more polymer coatings. The second set of yarns being made from a second group of one or more polymers, wherein the composite is made by covering the core with the sheath, and the composite is compression molded to allow the sheath to bond to the core. The bone-repair composite has a bending modulus comparable to that of a mammalian bone, such that the ratio of the core to the sheath is provided to maximize the mechanical strength of the bone-repair composite to mimic the mammalian bone.