Redefining Bone Fracture Treatments: Injectable TATO Composites as degradable implantable fixators

QC 20250321

Embargo till och med 2026-04-11 godkänt av skolchef Amelie Eriksson Karlström via e-post 2025-03-21

Abstract

Metal plates and screws have been used as the gold standard for Open ReductionInternal Fixation (ORIF) treatments of complex bone fractures for decades.However, the drawbacks of these implants necessitate a transition towards morepatient-personalized treatments. Injectable adhesive composites that can curerapidly on demand via photopolymerization have shown great potential in tissuerepair surgeries. Such systems allow for a high level of in situ customization,which replaces the current need for surgeons to stockpile large quantities ofdifferent metal implants. The use of step growth thiol-ene coupling (TEC)chemistry to polymerize these composites allows for high monomer conversion,reducing safety concerns from the leach out of non-reacted monomers.To develop stiff and strong resins, triazinetrione (TATO) monomers werechosen to form crosslinked networks in conjunction with hydroxyapatite (HA).Degradability was introduced into the composite in two different ways. In thefirst approach, isosorbide-based polycarbonates in different weight percentageswere included in the composite formulation, resulting in improved degradationrates while surpassing the mechanical properties needed for hand rehabilitationexercises. In the second approach, the introduction of ester moieties wascombined with the partial replacement of HA with the more resorbableinorganic fillers tricalcium phosphate and bioactive glass. This led to a family ofcomposites with a wide range of degradability profiles and mechanicalproperties, highlighting the tunability of these materials.Inspired by dental composites, TATO-based primers containing allylfunctionalizedmonomers with either n-hydroxysuccinimide (NHS) orphosphonic acid (Phn) groups were developed. These monomers allowed forenhanced adhesion to bone and photopolymerization via TEC with the TATObasedcomposite, resulting in an adhesive composite patch system capable offixating bone fractures without the use of metal screws. The incorporation ofthese monomers allowed the primers to interact with collagen or hydroxyapatitepresent in the bone surface, resulting in shear strengths on bone substrates thatoutperformed existing commercially available superglues. These resultsdemonstrate how acrylate-free primers and composites can be used inbiocompatible, strong and biodegradable fixation patches, suitable for fracturefixation in non- or low-load bearing bones.

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