Polymeric Cable Sternotomy Closure for Stable Bony Compression
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Solution Overview
Problem
Conventional sternotomy closure methods using metallic wires and cables often fail to achieve high-quality bony union due to issues such as inadequate force application, poor stability, excessive gap extension, and potential for cutting through bone, leading to complications like non-union, fibro-osseous-union, and increased patient morbidity and mortality.
Innovation Solution
A sternotomy closure technique utilizing a polymeric cable with an elongated elastic core surrounded by a sheath of ultra-high molecular-weight polyethylene strands, which maintains proper bony compression and absorbs physiological distracting forces, ensuring stable fixation during the healing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic wire or cable is used for sternotomy closure, then the closure provides initial mechanical strength, but it tends to cut through bone and soft tissue due to movement and force
Solution Approach 1:
The patent changes the material parameter from metallic to polymeric, specifically using ultra-high molecular-weight polyethylene (UHMWPE) which has different mechanical properties including higher elasticity and lower tendency to cut through tissue. This material substitution resolves the contradiction by maintaining strength while reducing the harmful cutting effect.
Solution Approach 2:
The cable is constructed as a composite structure with multiple UHMWPE strands braided together, creating a material that combines high tensile strength with flexibility and elasticity. This composite structure allows the cable to withstand mechanical forces without cutting through the sternum or surrounding tissues.
2Productivity
If conventional metallic closure methods are used, then the procedure is simple and quick, but it fails to achieve high-quality bony union due to poor stability and excessive gap extension
Solution Approach 1:
The patent changes the material parameters of the closure cable to achieve optimal mechanical properties: high elasticity modulus for stability, appropriate tensile strength for force transmission, and controlled flexibility for gap management. These parameter optimizations enable both quick closure and high-quality bony union by maintaining stable compression without excessive gap extension.
3Strength
If metallic wire or cable is used for sternotomy closure, then the closure provides initial mechanical strength, but it loses fixation due to fatigue or breaks due to fatigue
Solution Approach 1:
The patent changes the material from metal to UHMWPE polymer, which has superior fatigue resistance properties. The polymeric cable can withstand repeated cyclic loading during patient movement and breathing without accumulating fatigue damage, thereby maintaining fixation strength throughout the entire healing period and eliminating the fatigue failure problem associated with metallic cables.
4Strength
If metallic wire or cable is used for sternotomy closure, then the closure provides mechanical support, but it releases metal ions that impact wound healing and systemic health
Solution Approach 1:
The patent changes the material composition from metallic to polymeric (UHMWPE), fundamentally eliminating the source of metal ion release. The polymeric cable provides equivalent or superior mechanical support while being biologically inert and non-corrosive, thus removing the harmful effect of metal ion release on wound healing and systemic health.
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 polymeric cable maintains consistent contact pressure across the sternotomy seam, reducing the risk of cut-through and promoting improved bony healing with reduced complications and patient discomfort.
Implementation Method 1
a polymeric cable with an elongated elastic core surrounded by a sheath of ultra-high molecular-weight polyethylene strands, which maintains proper bony compression and absorbs physiological distracting forces
Data Source
AI summary
A sternotomy closure technique is suitably carried out with a cerclage mechanism, which is capable of maintaining proper bony compression (within a desired range) across the sternum cut, in spite of a range of external forces and significant lateral distraction due to these external forces. The sternum fragments are aligned in apposition disposed around a longitudinal seam and secured with a resilient element. The resilient element is tensioned to a desired tension to compress the sternum to a desired compression range. The resilient element is then elongated and contracted while accepting multiple cycles of physiological distracting forces across the sternum while maintaining contact pressure across the longitudinal seam within a desired range for a length of time sufficient for bony healing. The resilient element is preferably a polymer cable comprising an elongated elastic polymeric core coaxially surrounded by a sheath woven from ultra-high molecular weight polyethylene strands.