Silorane Bone Cement Polymerization Stress Reduction
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Solution Overview
Problem
Current bone cements, particularly PMMA-based systems, face issues such as high polymerization stress, cytotoxicity, antigenicity, heat generation, and thermal necrosis, which can lead to complications like thermonecrosis and inadequate stabilization of fractures, especially in young patients with less trabecular porosity.
Innovation Solution
Development of biomaterial compositions using organosilicon monomers like siloranes with chemical or dual chemical/light curing systems, incorporating tetraoxaspiro[5.5]undecanes and fillers, which reduce polymerization stress, enhance biocompatibility, and lower exothermic reactions, allowing for stable delivery of heat-sensitive agents like antimicrobials and growth factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PMMA-based bone cement is used, then mechanical strength and fracture stabilization are achieved, but high polymerization stress and volumetric shrinkage cause internal pores and crack initiators
Solution Approach 1:
The patent changes the chemical composition parameters by replacing PMMA with silorane-based monomers and modifying the curing system. This parameter change reduces polymerization stress and volumetric shrinkage from 5-7% to lower levels, preventing internal pore formation and crack initiators while maintaining fracture stabilization capability
Solution Approach 2:
The patent uses composite material formulation by combining silorane monomers with specific fillers (barium sulfate, zirconium oxide, glass particles) and curing agents. This composite approach achieves both mechanical strength for fracture stabilization and reduced polymerization stress by distributing stresses across different material phases
2Strength
If PMMA-based bone cement is used, then mechanical interlock with bone is achieved, but monomer antigenicity and toxicity cause severe toxicity and potential carcinogenicity
Solution Approach 1:
The patent changes the chemical parameter by replacing the PMMA monomer system with silorane-based monomers that have lower antigenicity and toxicity. This substitution maintains the bone-resin interface strength through chemical bonding mechanisms while eliminating the severe toxic and carcinogenic effects of residual monomers
Solution Approach 2:
The patent employs a dual-curing system that ensures complete polymerization, leaving minimal residual monomer. This approach effectively eliminates the long-term toxic effects by ensuring the monomer does not persist in the final product, making the material safer for long-term implantation
3Strength
If PMMA-based bone cement is used, then fracture stabilization is achieved, but intense heat generation causes thermal necrosis
Solution Approach 1:
The patent changes the chemical composition to silorane-based monomers with inherently lower polymerization exotherm. This parameter change reduces the peak temperature during curing from 75-110°C to lower levels, preventing thermal necrosis of surrounding bone tissue while maintaining adequate fracture stabilization
Solution Approach 2:
The patent employs a dual-curing system (chemical + light curing) that distributes the polymerization process over time and through different mechanisms. This periodic action allows heat dissipation between curing phases and prevents concentrated thermal peaks that cause thermal necrosis
4Strength
If PMMA-based bone cement is used, then mechanical interlock is achieved, but volumetric shrinkage of 5-7% creates internal pores
Solution Approach 1:
The patent changes the polymerization chemistry from PMMA to silorane-based systems that exhibit significantly reduced volumetric shrinkage. This parameter change reduces shrinkage from 5-7% to lower levels, preventing the formation of internal pores and voids that would compromise the bone-resin interface and create crack initiators
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 silorane-based compositions exhibit reduced polymerization stress, improved biocompatibility, and lower exothermic temperatures, providing enhanced mechanical properties and stability while maintaining the ability to deliver sensitive agents, thus addressing the limitations of traditional bone cements.
Implementation Method 1
organosilicon monomers (such as a silorane) and a chemical curing system or dual chemical/light curing system for polymerizing the monomer(s)
Implementation Method 2
The compositions exhibit significantly less polymerization stress without an associated proportional reduction in mechanical properties... the biomaterial compositions exhibit enhanced biocompatibility and reduced cytotoxicity and genotoxicity
Data Source
AI summary
Biomaterial compositions comprising organosilicon monomers (such as silorane monomers) and chemical curing systems or dual chemical/light curing systems, in conjunction with optional tetraoxaspiro[5.5]undecanes (“TOSUs”) and/or fillers.