Endoscopic Stitching Device Cam Wheel Mechanism
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Solution Overview
Problem
Endoscopic suturing and stitching are challenging due to the small openings through which procedures must be performed, requiring a simple and effective device to facilitate suturing of bodily organs or tissues during minimally invasive surgical procedures.
Innovation Solution
An endoscopic stitching device with a handle assembly and elongate shaft assembly, featuring a drive conversion mechanism that includes a cam wheel, pivot block, links, and a pawl, which converts axial displacement of a main rod into reciprocating motion of blades and jaws to enable efficient suturing through a cannula, eliminating the need for a separate toggle mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional suturing device with separate toggle mechanism is used, then the suturing function can be achieved, but the device complexity increases and ease of operation deteriorates due to the small openings constraint
Solution Approach 1:
The patent combines the toggle mechanism and blade drive members into a single integrated cam wheel structure. The cam wheel performs multiple functions: it acts as the toggle mechanism for jaw opening/closing, simultaneously drives the blades reciprocatingly, and controls the overall suturing sequence. This merging eliminates the need for separate toggle and blade drive components, reducing device complexity while maintaining ease of operation through a single actuator (the main rod).
Solution Approach 2:
The cam wheel is designed as a multi-functional component that simultaneously performs multiple roles: (1) toggle mechanism for jaw actuation, (2) blade drive mechanism for reciprocating motion, (3) sequence controller for the suturing process, and (4) mechanical advantage provider through its cam profile geometry. This universality allows the device to achieve complex suturing motions through a single component, improving ease of operation without proportionally increasing device complexity.
2Device complexity
If axial displacement mechanism is used to control jaws and blades, then the device structure is simplified, but the ability to achieve reciprocating blade motion deteriorates without a separate toggle mechanism
Solution Approach 1:
The cam wheel utilizes parameter changes in its geometric profile to transform the linear axial displacement of the main rod into complex multi-directional motions. The cam profile is specifically designed with varying radii and angles that convert the single-degree-of-freedom axial input into two-degree-of-freedom output motions: (1) jaw opening/closing rotation and (2) blade reciprocating translation. This parameter transformation allows the simplified axial displacement mechanism to achieve the versatility of reciprocating blade motion without requiring a separate toggle mechanism.
Solution Approach 2:
The cam wheel acts as an intermediary mechanism between the simple axial displacement input (main rod) and the complex dual-motion output (jaw actuation + blade reciprocation). Instead of directly coupling the main rod to both jaw and blade mechanisms, the cam wheel mediates this interaction by translating the axial input into the appropriate rotational and translational outputs through its cam profile geometry, thereby maintaining both simplicity and adaptability.
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 device allows for precise and efficient suturing and stitching by converting axial displacement into reciprocating motion of blades and jaws, reducing hand fatigue and enhancing operability during endoscopic procedures.
Implementation Method 1
The drive conversion assembly includes a cam wheel, a pivot block, first and second links interconnecting the pivot block with the cam wheel
Implementation Method 2
The pawl is operatively coupled to the main rod, wherein the pawl is configured to engage the pivot block to cause rotation of the pivot block
Implementation Method 3
the pawl may be spring biased toward an initial position
Data Source
AI summary
A stitching device includes a handle assembly and an elongate shaft assembly. The handle assembly includes a main rod and a drive conversion assembly including a cam wheel, a pivot block, first and second links, and a pawl. The pawl is operatively coupled to the main rod, and is configured to engage the pivot block to cause rotation of the pivot block which, in turn, causes reciprocating displacement of the first and second links. The elongate shaft assembly includes first and second blade drive members coupled to the cam wheel. The tool assembly includes first and second jaws and first and second blades. The first and second blades are operatively coupled with the respective first and second blade drive members, wherein axial displacement of the main rod transitions the first and second jaws between open and closed positions and causes reciprocating axial displacement of the first and second blades.