Inflatable Surgical Retractor for Low-Trauma Rib Retraction
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Solution Overview
Problem
Existing minimally invasive cardiac and thoracic surgeries face significant post-operative pain and morbidity due to the use of rigid metal rib spreaders that cause rib cracking and nerve damage, necessitating a retractor that can provide both soft tissue and bone retraction with minimal trauma.
Innovation Solution
A surgical retractor featuring inflatable annular rings and a flexible sheath that expand radially without significant axial expansion, utilizing two-way stretch fabric or pleated constructions to minimize trauma and rib injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid metal rib spreaders are used to spread ribs, then bone retraction is achieved, but rib cracking and nerve damage occur causing significant post-operative pain
Solution Approach 1:
The patent employs flexible rings made of elastomeric material instead of rigid metal spreaders. These flexible rings can deform and conform to the rib structure, distributing pressure evenly across the rib surface rather than concentrating force at specific points, thereby preventing rib cracking and nerve damage while maintaining effective retraction
Solution Approach 2:
The patent uses inflatable structures within the flexible rings that can be expanded with fluid or gas pressure. This pneumatic mechanism allows controlled, gradual expansion that gently separates ribs and soft tissues without sudden mechanical force, reducing the risk of trauma while achieving the necessary retraction space
2Volume of moving object
If mechanical rib spreaders are used to spread ribs, then surgical access space is created, but significant post-surgery pain and morbidity result
Solution Approach 1:
The flexible rings can expand to create the necessary surgical space while conforming to patient anatomy. The flexibility allows the device to adapt to individual rib cage geometries, providing effective retraction without the rigid pressure points that cause pain
Solution Approach 2:
The patent changes the physical state of the retraction mechanism from rigid to flexible, and from pre-set size to dynamically adjustable size through inflation. This allows the device to achieve optimal retraction volume for each patient while minimizing trauma through controlled, gradual expansion
3Strength
If rigid metal surfaces are used in rib spreaders, then structural strength is maintained, but localized pressure causes rib fracturing
Solution Approach 1:
The elastomeric flexible rings distribute mechanical loads over larger surface areas of the ribs. The material's elasticity allows it to deform under load, spreading the stress evenly across the rib surface rather than concentrating it at narrow contact points, preventing fracturing while maintaining structural integrity
Solution Approach 2:
The patent uses composite construction combining flexible elastomeric material with inflatable elements. This composite structure provides the necessary structural strength to maintain retraction force while the flexible outer layer distributes pressure evenly, avoiding the localized high-stress points caused by rigid metal surfaces
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 retractor provides effective tissue and bone retraction with reduced pain and trauma by distributing force over a larger area, minimizing rib cracking and nerve damage.
Implementation Method 1
a two-way stretch fabric material having stretch fibers oriented so as to permit the radial expansion without the axial expansion
Implementation Method 2
inflatable annular rings and an interconnecting sheath that is configured to be placed in a thoracic incision
Data Source
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Figure 5~6
AI summary
A surgical retractor has proximal and distal ends and an intermediate portion. The proximal and distal ends each have an inflatable annular ring. The intermediation portion has flexible sheath that is attached it its opposite ends to a respective annular ring. An access opening extends through the rings and the sheath along a longitudinal axis extending through the distal and proximal ends. The first and second inflatable annular rings are configured to expand radially from the longitudinal axis without expanding axially. The flexible sheath is configured to expand radially from the longitudinal axis without expanding axially.