Calcium Bone Cement Non-Dispersion via Polyacrylic Acid
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Solution Overview
Problem
Bone cement pastes used in minimally invasive procedures tend to disperse when contacted with water or body fluids, leading to clinical complications such as cement embolism, due to their high liquid-to-powder ratio and low viscosity.
Innovation Solution
Incorporating a small amount of poly(acrylic acid) into the calcium-based bone cement formula, which enhances its non-dispersive ability, allowing for a more dilute paste to be used without dispersion issues during injection, thereby improving delivery and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a less viscous (more dilute) paste is used to facilitate delivery through thin, long tubes, then ease of delivery is improved, but the paste has higher tendency to disperse upon contact with water or body fluid
Solution Approach 1:
The patent changes the chemical composition parameters of the bone cement paste by incorporating poly(acrylic acid) at specific concentrations (0.01-1% by weight). This parameter change modifies the paste's rheological properties and interaction with body fluids, enabling it to maintain structural integrity while remaining sufficiently dilute for minimally invasive delivery through thin catheters.
Solution Approach 2:
The patent creates a composite bone cement formulation combining calcium phosphate source, calcium sulfate source, and poly(acrylic acid). This composite material approach allows the paste to exhibit both the flowability needed for delivery and the cohesive strength to prevent dispersion upon contact with body fluids, resolving the contradiction between ease of delivery and non-dispersive ability.
2Reliability
If a more viscous paste is used to prevent dispersion, then non-dispersive ability is improved, but delivery through thin, long tubes becomes more difficult
Solution Approach 1:
The patent modifies the paste's physical-chemical parameters by adding poly(acrylic acid), which changes the balance between viscosity and dispersiveness. This allows the paste to maintain adequate viscosity to prevent dispersion while remaining fluid enough for easy delivery through thin catheters, eliminating the need to choose between the two opposing requirements.
3Ease of operation
If a dilute paste with higher LIP ratio is used to facilitate minimally invasive delivery, then ease of delivery is improved, but the risk of cement embolism increases
Solution Approach 1:
The patent changes the compositional parameters by incorporating poly(acrylic acid) at controlled concentrations, which modifies the paste's behavior in body fluids. This parameter change allows the use of dilute pastes for minimally invasive delivery while preventing the dispersion that would lead to embolism, thus maintaining safety despite the lower LIP ratio.
Solution Approach 2:
The patent employs poly(acrylic acid) as a temporary, biodegradable additive that provides immediate protection against dispersion during the critical delivery phase and then naturally degrades. This approach safely addresses the embolism risk without requiring permanent structural modifications or additional long-term interventions.
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 addition of poly(acrylic acid) significantly reduces the risk of dispersion, enabling easier and safer minimally invasive delivery of the cement paste while maintaining adequate working and setting times, resulting in a hardened composite with enhanced strength and biocompatibility.
Implementation Method 1
adding a very small amount of poly(acrylic acid) in the calcium-based bone cement can dramatically lower the possibility/risk of dispersion of the resulting cement paste
Implementation Method 2
the bone cement formula further comprises, based on the total weight of the bone cement formula, 0.01-1%, preferably 0.03-0.5%, of poly(acrylic acid)
Implementation Method 3
a powder component and a setting liquid component, wherein the powder component includes a calcium sulfate source and a calcium phosphate source
Implementation Method 4
which will cure or harden in a hole or cavity in need of treatment
Data Source
AI summary
A calcium-based bone cement formula having a powder component and a setting liquid component with a liquid to powder ratio of 0.20 ml/g to 0.50 ml/g is provided, wherein the powder component includes tetracalcium phosphate. The bone cement formula further contains, based on the total weight of the bone cement formula, 0.01-1% of poly(acrylic acid) having a repeating unit of —(CH2—C(COOH)H)n-, wherein n=50-50000.