Absorbable Surgical Coil Fastener With Composite Shell And Core
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Solution Overview
Problem
Prior magnesium alloys used in surgical fasteners exhibited low yield and tensile strengths, limiting their effectiveness and application in surgical procedures.
Innovation Solution
Development of surgical fasteners utilizing higher strength magnesium alloys and composite structures, including a coil body with a shell and core made from different materials, and the use of a support within a channel to prevent deformation during deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If prior magnesium alloys are used in surgical fasteners, then the fasteners can be made biocompatible and absorbable, but the yield and tensile strengths are too low for effective surgical application
Solution Approach 1:
The patent employs composite materials by combining magnesium alloy with a bioabsorbable polymer coating. The magnesium alloy core provides the necessary mechanical strength (yield strength 314-506 MPa) while the polymer coating maintains biocompatibility and controlled absorbability. This composite structure resolves the contradiction by allowing both high strength and biological compatibility to coexist in the same fastener device.
Solution Approach 2:
The patent changes the material parameters by developing a specific magnesium alloy composition containing dysprosium (5.0%-25.5%), neodymium and/or europium (0.01%-5%), zinc (0.1%-3.0%), and zirconium (0.1%-2.0%). These compositional parameter changes increase the yield strength to 314-506 MPa while maintaining the alloy's biocompatible and bioabsorbable properties, thus resolving the strength limitation of prior magnesium alloys.
2Length of moving object
If the coil body is made thin to reduce surgical trauma, then the transverse dimension is reduced, but the structural stability during deployment is compromised
Solution Approach 1:
The patent applies preliminary action by inserting a support structure into the coil body channel before deployment. This support prevents buckling and maintains structural stability during the deployment process, allowing the use of thinner coil bodies (0.018-0.035 inches) without compromising stability. The support is removed after deployment, leaving the final fastener structure intact.
Solution Approach 2:
The patent utilizes a thin-walled coil body structure with transverse dimensions of 0.018-0.035 inches that is designed to be flexible yet stable. The coil body includes a channel that can accommodate a support structure, and the thin-walled design allows for reduced surgical trauma while maintaining adequate structural integrity through the combination of magnesium alloy material properties and geometric design.
3Stability of the object's composition
If a support structure is added to prevent buckling during deployment, then the structural stability is improved, but the device complexity increases
Solution Approach 1:
The patent applies the nesting principle by placing the support structure inside the coil body channel. The support is inserted through the head opening and nested within the coil body, providing internal reinforcement without adding external components. This nested configuration maintains structural stability during deployment while minimizing device complexity, as the support becomes an integral part of the deployed fastener structure.
Solution Approach 2:
The patent applies the extraction principle by removing the support structure from the channel after deployment is complete. The support serves its temporary function of preventing buckling during deployment, then is extracted (removed) to leave only the necessary fastener components in place. This reduces the final device complexity while maintaining stability during the critical deployment phase.
Data Source
AI summary
A surgical fastener deployment system may include a plurality of coil fasteners having a head and coil body. In some embodiments, the head is comprised of a bioabsorbable polymer. In one embodiment, the coil body may be comprised of a shell and a core and one of the shell and the core may be comprised of one of a magnesium alloy or a bioabsorbable polymer, and the other of the shell and core is formed of the other of the magnesium alloy and the bioabsorbable polymer. The coil body may also include an internal channel which may have a support coil disposed within.