Suture Retriever-Sheath Dilator Tool for Flexor Tendon Repair
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Solution Overview
Problem
Surgical repair of severed flexor tendons is challenging due to the retraction of tendons through the flexor tendon sheath, where the sheath contracts without the tendons, making it difficult to pass the severed tendons back through for repair.
Innovation Solution
A suture retriever-sheath dilator tool with a shaft that increases in thickness and width, featuring a convex upper surface and concave lower surface, allowing for dilation of the flexor tendon sheath and pulleys, facilitating the passage and reattachment of severed tendons by applying radial pressure and utilizing elastic material for flexibility and resiliency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flexor tendon sheath is left without tendons, then the sheath contracts to reduce space, but this contraction makes it difficult to pass severed tendons back through for repair
Solution Approach 1:
The dilator is inserted into the contracted flexor tendon sheath before tendon passage to pre-expand the sheath and pulleys. This preliminary dilation action creates sufficient space and reduces friction, enabling subsequent easy passage of the severed tendon ends through the previously contracted sheath for repair
Solution Approach 2:
The dilator serves as an intermediary tool between the contracted sheath and the tendon. By inserting the dilator into the sheath, it mediates the interaction between the tendon and sheath, temporarily occupying the space and applying radial pressure to expand the sheath walls, thereby facilitating tendon passage without direct tendon-sheath friction
2Strength
If the severed tendon ends are left to swell, then the tendon volume increases, but this swelling makes it more difficult to pass through the contracted sheath
Solution Approach 1:
The sheath is dilated in advance before the swollen tendon ends need to be passed through. This preliminary expansion of the sheath creates adequate space accommodation for the swollen tendon, preventing passage difficulties that would otherwise result from the combination of tendon swelling and sheath contraction
Solution Approach 2:
The physical parameters of the sheath (specifically its internal diameter and volume) are changed by dilation. This parameter change transforms the sheath from a contracted state that cannot accommodate swollen tendons to an expanded state that can easily accommodate the swollen tendon ends for passage
3Strength
If a rigid dilator is used, then the dilator provides structural support for dilation, but the rigid structure cannot navigate the curved path through pulleys
Solution Approach 1:
The dilator transitions from a static rigid structure to a dynamic flexible structure that can adapt its shape. The flexible shaft allows the dilator to bend and follow the curved anatomical path through the pulleys while maintaining sufficient structural integrity to provide radial support and achieve dilation of the sheath walls
Solution Approach 2:
The dilator employs a flexible shaft construction that resembles a flexible shell structure. This flexible shaft can bend and conform to the curved pathway through the pulleys while maintaining enough rigidity to provide the necessary structural support for effective sheath dilation, combining adaptability with structural integrity
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 tool effectively dilates the contracted flexor tendon sheath, allowing easier passage and reattachment of severed tendons, reducing the complexity and difficulty of the repair process.
Implementation Method 1
the shaft being formed of an elastic flexible material, the shaft having a pre-insertion cross section along a portion of the length of the shaft that is configured to apply pressure to the inner surface of the tendon sheath when the tool is inserted into the sheath
Implementation Method 2
inserting the distal end of the shaft of the tool into the tendon sheath so that at least a portion of the shaft applies radial pressure to the inner surface the tendon sheath
Data Source
AI summary
A tool serves to facilitate one or more of dilation of a flexor tendon sheath and corresponding pulleys, attachment of a severed flexor tendon thereto, passage of the severed flexor tendon through the flexor tendon sheath and the corresponding pulleys, and reattachment of the severed flexor tendon. The tool includes a tip portion, a shaft portion, and a handle portion. During use of the tool, the tip portion and at least a part of the shaft portion can be passed through the flexor tendon sheath, and the handle portion is can be used to control such passage. The tip portion and the shaft portion can be used to dilate the flexor tendon sheath. The severed flexor tendon can be attached to the tip portion, and the tool can be withdrawn from flexor tendon sheath to pass the severed flexor tendon to a repair site.