Sternal Wire Sheath Assembly Abrasion Prevention
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Solution Overview
Problem
Surgical wires used in sternotomy procedures often abrade and damage the sternal bone due to high tension and soft bone nature, leading to complications like wire loosening, non-union, and infection, especially in patients with poor bone quality or high BMI.
Innovation Solution
A protective sheath assembly is designed to cover the surgical wire, reducing direct contact with the bone by increasing the surface area of contact and dissipating stresses, which can be customized to fit the bone and includes features like a core channel, relief areas, and optional teeth for traction, to prevent abrasion and facilitate healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If surgical wire is used to compress sternal segments, then the sternal segments are held securely together for healing, but the wire abrades and damages the sternal bone surface due to high tension and soft bone nature
Solution Approach 1:
A protective sheath is introduced as an intermediary component between the surgical wire and the sternal bone surface. The sheath covers the wire along its length, preventing direct contact between the wire and bone while allowing the wire to maintain compressive force on the sternal segments. This resolves the contradiction by mediating the interaction between the wire (which provides compression) and the bone (which is vulnerable to abrasion).
Solution Approach 2:
The protective sheath is designed as a flexible thin-walled structure that can conform to the contours of the sternal bone while covering the wire. The sheath's flexibility allows it to accommodate the curved geometry of the sternum and the compression forces applied by the wire, while its wall structure prevents wire-induced abrasion on the bone surface.
2Ease of operation
If wire surface area is kept minimal, then the wire remains thin and easy to insert, but the wire has high propensity to abrade and damage the bone surface
Solution Approach 1:
The sheath acts as a mediator that increases the effective surface area in contact with the bone without requiring the wire itself to be thicker. The wire remains thin for easy insertion, while the sheath provides the protective surface area that prevents abrasion, thus resolving the contradiction between wire thinness and abrasion resistance.
Solution Approach 2:
The solution moves the surface area function from the wire dimension to the sheath dimension. Instead of increasing wire diameter to reduce stress concentration, the sheath provides the necessary surface area in a separate dimensional layer, allowing the wire to remain thin while still protecting the bone surface.
3Strength
If additional wires are placed side by side to counteract higher biomechanical stresses, then the compressive force is improved, but the complexity of the wiring procedure increases
Solution Approach 1:
The protective sheath provides multi-functionality: it protects the bone surface from abrasion, maintains the compressive force generated by the wire, and can be used with a single wire to achieve the same protective effect as multiple wires. This reduces procedural complexity while maintaining biomechanical strength.
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 sheath assembly effectively reduces the risk of wire-induced bone damage, enhances healing by allowing biologic fluid passage, and simplifies the surgical process by minimizing complications such as wire loosening and infection.
Implementation Method 1
the sheath may reduce or prevent the tensioning element from abrading and damaging the bone surface when the tensioning element is under tension
Implementation Method 2
The sheath substantially increases the surface area of contact on the bone and therefore dissipates stresses in an improved manner compared to a tensioned exposed tensioning element
Implementation Method 3
enhances healing by allowing biologic fluid passage
Data Source
AI summary
A sheath is provided. The sheath includes a core channel, and the core channel is configured to receive a tensioning element. The tensioning element is configured to circumscribe a bone, and the sheath is configured to be placed around a bone when the tensioning element received in the core channel circumscribes the bone. The sheath is configured to prevent direct contact between the tensioning element and the bone as the tensioning element is tensioned.