Acrylic Bone Cement Delayed Polymerization Inhibitor
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Solution Overview
Problem
Conventional PMMA cements used in vertebral body augmentation procedures have working times of less than 10 minutes, which is insufficient for effective injection and handling during vertebroplasty and kyphoplasty procedures, necessitating a need for extended working times to manage the rapidly curing cement.
Innovation Solution
A bone cement formulation with a bimodal or trimodal particle size distribution and a delayed release of an anti-oxidant, such as Vitamin E, is used to control the viscosity increase, providing a rapid initial rise, a prolonged stable working time, and a later increase in viscosity, allowing for extended procedural time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional PMMA cement formulation is used, then the cement cures rapidly providing structural strength, but the working time is less than 10 minutes which is insufficient for injection and handling
Solution Approach 1:
The patent applies preliminary action by incorporating an anti-oxidant (such as Vitamin E) into the cement formulation before use. This anti-oxidant preemptively scavenges free radicals that would otherwise initiate polymerization, thereby delaying the curing process and extending the working time window for injection and handling procedures
Solution Approach 2:
The anti-oxidant acts as an intermediary substance between the monomer and initiator components. It interferes with the free radical generation process, mediating the polymerization reaction to occur more slowly and controllably, thus extending the usable working time while still achieving adequate curing strength
2Strength
If the cement viscosity increases rapidly to provide structural support, then the cement hardens quickly, but the injection window becomes too short for safe and effective injection
Solution Approach 1:
The anti-oxidant is incorporated in advance into the cement formulation to preemptively delay the viscosity increase. By scavenging free radicals before they can initiate rapid polymerization, the cement maintains a lower viscosity for an extended period, providing sufficient time for safe and effective injection procedures
Solution Approach 2:
The patent changes the chemical parameters of the cement system by introducing an anti-oxidant that alters the polymerization kinetics. This modifies the viscosity-time profile of the cement, extending the injection window while still achieving the necessary structural support through controlled curing
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 formulation provides a longer working window, allowing surgeons to complete vertebral body augmentation procedures with increased safety and efficiency by maintaining a suitable viscosity for injection and handling, reducing the risk of leakage and improving clinical outcomes.
Implementation Method 1
adding a small amount of an anti-oxidant to a PMMA cement has the effect of delaying the initiation of the increase in viscosity of the cement
Implementation Method 2
Vitamin E first scavenges reactive oxygen species (thus preventing the free radical reaction and completely delaying any viscosity increase)
Implementation Method 3
the surgeon mixes a powder component having PMMA particles with a liquid component having MMA monomer. These two components react over the space of about 10 minutes to provide a hardened acrylic cement
Data Source
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AI summary
A bone cement formulation having i) a PMMA powder fraction designed for quick reaction and ii) a polymerization inhibitor provided in a delayed release form. This allows the cement to obtain an initial viscosity suitable for injection and a long working time.