PHA 3D Structure Prevents Bone Cement Leakage

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Solution Overview

Problem

Current surgical methods for treating osteoporosis-related bone fractures face challenges such as bone cement leakage, inadequate bonding with bone, and mechanical weakness due to the use of metal intramedullary rods and rigid bone cements, which can lead to further fractures and tissue injury.

Innovation Solution

A three-dimensional structure made from polyhydroxyalkanoate (PHA) with excellent heat resistance and elongation, combined with a biodegradable intramedullary rod and osteoconductive bone cement, prevents leakage and enhances mechanical strength by allowing the bone cement to fully penetrate the medullary cavity and promote bone regeneration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metal intramedullary rods and rigid bone cements are used to treat osteoporosis-related bone fractures, then mechanical strength is improved, but bone cement leakage and tissue injury occur due to the rigidity mismatch with brittle bones

Engineering Contradiction:
Improvemechanical strengthVSAvoidbone cement leakage and tissue injury
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameters of the intramedullary rod from metal to biodegradable polymer, and the bone cement from rigid methyl methacrylate to osteoconductive calcium phosphate-based cement. This parameter change allows the implant materials to have mechanical properties matched to brittle osteoporotic bones, preventing stress shielding and reducing the risk of further fractures while maintaining adequate mechanical support

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material systems: (1) biodegradable polymer intramedullary rod combined with osteoconductive bone cement, and (2) the bone cement itself as a composite of calcium phosphate particles in a collagen-based carrier. These composite materials provide both mechanical strength and biological functionality, including osteoconduction and biodegradability, while avoiding the harmful effects of rigid metal implants

Inventive Principle:
Principle #40Composite materials

2Strength

If methyl methacrylate bone cement is used to increase bone strength quickly, then mechanical strength is improved, but the material cannot directly bond with bone and emits heat affecting surrounding tissue

Engineering Contradiction:
Improvebone strengthVSAvoidheat emission and lack of bonding
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the bone cement from organic methyl methacrylate to inorganic calcium phosphate-based materials. This parameter change eliminates the exothermic polymerization reaction that causes heat emission, and provides inherent osteoconductive properties that enable direct bonding with bone tissue, while maintaining adequate mechanical strength for fracture fixation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs biodegradable calcium phosphate-based bone cement that gradually degrades and is replaced by natural bone tissue over time. This temporary implant provides mechanical support during the healing period, then safely degrades without requiring removal surgery, unlike permanent rigid cements

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If calcium phosphate-based osteoconductive bone cement is used to promote bone regeneration, then bone regeneration is improved, but the cured cement is too rigid and can induce further fractures in weaker surrounding bone

Engineering Contradiction:
Improvebone regenerationVSAvoidsurrounding bone strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent adjusts the mechanical parameters of the calcium phosphate-based bone cement by controlling its composition and porosity, achieving an optimal balance between osteoconductive properties and mechanical flexibility. The cement is formulated to have lower modulus of elasticity compared to rigid cements, allowing it to accommodate the mechanical environment of osteoporotic bone without inducing stress concentrations that could cause further fractures

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates local quality differentiation in the bone cement structure, with osteoconductive calcium phosphate particles providing bone regeneration capability in the matrix, while the overall composite structure maintains appropriate mechanical flexibility. The collagen-based carrier provides a flexible matrix that allows the rigid calcium phosphate particles to bond with bone while the composite as a whole remains compliant with surrounding bone

Inventive Principle:
Principle #3Local quality

4Stability of the object's composition

If metal plates and screws are used to fasten bone fracture regions, then mechanical stability is improved, but loosening and re-dislocation occur due to the strength mismatch with osteoporotic bone

Engineering Contradiction:
Improvemechanical stabilityVSAvoidfixation reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces metal fixation devices with biodegradable polymer intramedullary rods that can be combined with bone cement. This composite approach provides initial mechanical stability through the rod-cement-bone construct, while avoiding the strength mismatch problems of metal implants in osteoporotic bone. The biodegradable materials have mechanical properties closer to natural bone, reducing stress shielding and loosening

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameters of the intramedullary rod from metal to biodegradable polymer, adjusting the mechanical properties to match osteoporotic bone strength. This parameter change prevents the strength mismatch that causes loosening and re-dislocation, while maintaining adequate mechanical support for fracture healing

Inventive Principle:
Principle #35Parameter changes

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 combination effectively prevents bone cement leakage, improves mechanical strength, and promotes bone regeneration by ensuring complete penetration and biodegradability, reducing the risk of re-fracture and tissue injury.

Implementation Method 1

a three-dimensional structure made of non-woven fabric by depositing fibers measuring 1-100 μm in diameter produced by electrospinning

Methodology Applied
Scientific EffectElectrospinning: Electrohydrodynamics

Data Source

PatentEP2832377B1Three-dimensional structure created from material comprising polyhydroxyalkanoate, kit for preparing bone filling material, and intramedullary nail
Publication Date: 2019.11.20 NAGOYA UNIVERSITY
  • EP2832377B1 patent drawingFigure 1
  • EP2832377B1 patent drawingFigure 2(a)~2(d)
  • EP2832377B1 patent drawingFigure 3(a)~3(c)

AI summary

Provided is a material for preventing bone cement from leaking out from bone during packing of the bone cement into a bone fracture site. The bone cement can be prevented from leaking out from the bone by employing a three-dimensional structure produced from a material containing a polyhydroxyalkanoate, when packing the bone cement into the bone fracture site.