Bone Cement Viscosity Control for Leakage Reduction
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Solution Overview
Problem
Conventional bone cements with high viscosity require high force injection systems, leading to potential leakage and reduced tactile feedback for surgeons, while lower viscosity cements may result in inadequate interdigitation with bone, compromising mechanical strength and increasing waiting times.
Innovation Solution
A bone cement composition with a solid component including a contrast agent, polymerization initiator, calcium phosphate-based bone substitute material, and solid polymer, and a liquid component with a monomer, polymerization accelerator, and optional inhibitor, achieving an initial injectable viscosity greater than 50 Pa-s within two minutes or less, suitable for manual injection with minimal leakage and extended application time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high viscosity bone cement is used, then leakage is reduced, but high force injection systems are required that exceed human physical limits and reduce tactile feedback
Solution Approach 1:
The patent modifies the chemical composition parameters of the bone cement, specifically using poly(methylacrylate-co-methylmethacrylate) copolymer with controlled molecular weight (200kDa to 1000kDa) and composition ratios, to achieve high viscosity that enables manual injection while reducing leakage. This chemical parameter optimization allows the cement to have sufficient viscosity without requiring high-force injection systems.
Solution Approach 2:
The patent employs a composite material system consisting of copolymer beads, homopolymer powder, monomer, and initiator. This composite approach combines materials with complementary properties: the copolymer provides viscosity control, the homopolymer contributes to mechanical strength, and the monomer-initiator system enables controlled polymerization. The synergistic interaction of these components achieves the desired balance between viscosity and injectability.
2Object-affected harmful factors
If high viscosity bone cement is used, then leakage is reduced, but injection force exceeds human physical limits
Solution Approach 1:
The patent optimizes the molecular weight parameters of the copolymer (200kDa to 1000kDa range) and the composition ratios of copolymer to homopolymer to achieve high viscosity that reduces leakage while remaining within manual injection force capabilities. The controlled polymerization kinetics through initiator concentration adjustment also helps manage the force required during injection.
3Object-affected harmful factors
If high viscosity bone cement is used, then leakage is reduced, but waiting time for sufficient viscosity increases, reducing total work time
Solution Approach 1:
The patent incorporates pre-formed copolymer beads into the cement composition before injection. These pre-synthesized beads provide immediate viscosity contribution upon mixing, eliminating the need to wait for viscosity development through polymerization alone. This preliminary inclusion of viscous components allows the cement to reach injectable viscosity quickly while maintaining low leakage potential.
4Object-affected harmful factors
If high viscosity bone cement is used, then leakage is reduced, but interdigitation between cement and bone decreases, compromising mechanical strength
Solution Approach 1:
The patent creates local quality variations within the cement composition by including both copolymer beads (for viscosity) and homopolymer powder (for strength). The copolymer provides high viscosity to reduce leakage, while the homopolymer contributes to mechanical strength and interdigitation. This spatial and functional differentiation of material properties within the composite allows simultaneous optimization of leakage resistance and mechanical performance.
Solution Approach 2:
The composite material system combines copolymer and homopolymer components with complementary properties. The copolymer phase provides viscosity control for leakage reduction, while the homopolymer phase enhances mechanical strength and bone interdigitation. The synergistic interaction between these different material phases resolves the contradiction between leakage reduction and mechanical strength maintenance.
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 bone cement allows for immediate manual injection with reduced waiting times, prolonged application periods, and minimized leakage, maintaining mechanical strength and safety without the need for high-pressure systems, enabling effective vertebroplasty procedures.
Implementation Method 1
a solid component including a contrast agent, polymerization initiator, calcium phosphate-based bone substitute material, and solid polymer, and a liquid component with a monomer, polymerization accelerator
Data Source
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AI summary
A bone cement is provided that includes a solid component and a liquid component. The solid component and liquid component are mixed together to form the bone cement. After completion of the solid and liquid component mixing, the bone cement has an initial viscosity effective for manual application or manual injection onto or into a targeted anatomical location, e.g., bone, and the cement has stable viscosity range that over both time and temperature is effective for uniformly filling the targeted anatomical location, for example an osteoporotic bone or a fractured vertebral body, with minimal to no leakage of the cement from the targeted anatomical location. Additionally, both the initial viscosity and the stable viscosity of the bone cement are within a range that renders the bone cement effective for injection with a manually operated syringe or multiple syringes.