Sternal Closure Using Shape Memory Implants and Flexible Plates
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Solution Overview
Problem
Current sternal closure systems, such as cerclage and plate-based systems, face issues with flexibility and ease of removal, as they can cause grooves in the sternum, loosen over time, and are difficult to remove quickly in case of acute re-entry, potentially leading to sternum re-opening and life-threatening situations.
Innovation Solution
A sternal closure system comprising a plurality of implants and plate pairs with a bridge and legs that transition between natural and insertion shapes, using shape memory materials to securely close the sternum while allowing for flexibility and quick removal, with the implants engaging with plates to maintain closure and prevent re-opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cerclage wires or loops are used to hold the sternum closed, then sternal closure is achieved, but the wires or loops cut into the sternum during thoracic wall movement, resulting in grooves that weaken the sternum and loosen the wires
Solution Approach 1:
The patent employs a flexible plate construct that can bend and deform elastically during thoracic wall movement. This flexible plate prevents the formation of grooves by distributing mechanical stresses across its surface, while maintaining stable closure through its inherent flexibility and ability to accommodate movement without cutting into the sternum.
Solution Approach 2:
The patent uses a dynamic closure system where the flexible plate can change its shape and position in response to thoracic wall movement. The plate transitions between bent and straight configurations, allowing it to adapt to dynamic mechanical loads while maintaining continuous closure stability without creating harmful grooves.
2Reliability
If plate-based systems with screws are used to hold the sternum closed, then sternal closure is achieved, but the screws slacken during thoracic wall movement, resulting in loose plates and possible shifting
Solution Approach 1:
The patent replaces the rigid screw-plate system with a dynamic flexible plate that can bend and deform elastically during thoracic wall movement. This dynamic construct maintains closure stability through its inherent flexibility, eliminating the need for screws that would slacken under movement conditions.
Solution Approach 2:
The patent extracts and removes the screw fixation element from the closure system entirely, retaining only the flexible plate construct. This extraction eliminates the source of instability (screw slacking) while preserving the essential closure function through the plate's inherent mechanical properties.
3Reliability
If screw fixated plates are used to hold the sternum closed, then sternal closure is achieved, but the plates are difficult and time consuming to remove in case of acute re-entry
Solution Approach 1:
The patent employs a temporary flexible plate construct that is designed for easy removal. The plate serves its closure function during the postoperative period and can be quickly extracted if acute re-entry is needed, unlike permanent screw-plate systems that require complex removal procedures.
Solution Approach 2:
The flexible plate's dynamic, bendable nature allows for rapid insertion and removal compared to rigid screw-plate systems. The plate can be easily deformed and extracted without requiring sophisticated removal tools or procedures, significantly reducing the time needed for acute re-entry scenarios.
4Reliability
If rigid plates and screws are used to hold the sternum closed, then sternal closure is achieved, but the system lacks flexibility to account for thoracic wall movement
Solution Approach 1:
The patent uses a flexible plate construct that can bend and deform elastically during thoracic wall movement. This flexible plate maintains closure stability while accommodating dynamic mechanical loads, in contrast to rigid plates that would restrict necessary movement and cause stress concentration.
Solution Approach 2:
The patent employs a shape memory alloy that changes its physical state and shape in response to temperature or mechanical stimuli. This parameter change allows the plate to adapt its stiffness and shape properties to match the dynamic requirements of thoracic wall movement while maintaining closure stability.
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 system effectively maintains sternum closure during thoracic wall movement, prevents loosening or dislodgement, and allows for rapid re-entry by using shape memory materials that compress the sternum to promote healing and can be quickly removed if necessary.
Implementation Method 1
A sternal closure system comprising a plurality of implants and plate pairs with a bridge and legs that transition between natural and insertion shapes, using shape memory materials to securely close the sternum
Implementation Method 2
the implants engaging with plates to maintain closure and prevent re-opening
Data Source
AI summary
A sternal closure system for closing an opening in a sternum includes an implant and a plate pair comprised of first and second plates. The first and second plates secure with the sternum across the opening. The implant, in an insertion shape, inserts through the first and second plates and into the sternum across the opening, and then, upon a movement toward a natural shape, holds the opening closed while interconnecting the first and second plates. The sternal closure system alternatively includes an implant with a bridge having first and second apertures and first and second legs extending from the bridge. The implant, in an insertion shape, inserts into the sternum across the opening, and then, upon a movement toward a natural shape, holds the opening in the sternum closed. The implant, at the first and second apertures, receives fixation devices therethrough that engage the sternum.