Eccentric Cam Surgical Forceps Jaw Control
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Solution Overview
Problem
Existing electrosurgical forceps face challenges in maintaining optimal pressure and gap distance between electrodes to achieve effective tissue sealing, particularly in large vessels, which can lead to short circuits or inadequate sealing.
Innovation Solution
The forceps incorporate a cam assembly with an eccentric cam and an annular cam, which reduces the force required to close the jaw members, allowing for precise control of pressure and gap distance between the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high force is applied to close the jaw members, then adequate compression force is achieved for tissue sealing, but the required hand force becomes excessively high making the instrument difficult to operate
Solution Approach 1:
The cam mechanism transforms the static force transmission into a dynamic mechanical advantage system. As the cam rotates during jaw closure, the contact point between the cam and follower changes position, continuously adjusting the mechanical advantage ratio. This allows the system to provide high compression force at the critical sealing moment while requiring minimal hand force during operation.
Solution Approach 2:
The cam assembly acts as an intermediary mechanical element between the user's hand force and the jaw members. It converts the user's input force into amplified compression force through its geometric configuration, eliminating the need for the user to directly apply high force to the jaws while still achieving adequate tissue compression.
2Reliability
If the gap distance between electrodes is reduced for effective sealing, then tissue sealing effectiveness improves, but the risk of electrode contact and short circuit increases
Solution Approach 1:
The cam mechanism provides mechanical feedback control of the gap distance. As the cam rotates and the follower moves along its profile, the system automatically maintains the electrodes at the optimal gap distance for sealing. The geometric constraints of the cam profile prevent the electrodes from contacting each other while ensuring adequate compression, eliminating the need for user judgment and preventing short circuits.
3Reliability
If the jaw members are compressed to achieve tissue sealing, then hemostasis and tissue joining are achieved, but the force required exceeds what can be comfortably applied by hand
Solution Approach 1:
The cam mechanism transforms the static force transmission into a dynamic mechanical advantage system. As the cam rotates during jaw closure, the contact point between the cam and follower changes position, continuously adjusting the mechanical advantage ratio. This allows the system to provide high compression force at the critical sealing moment while requiring minimal hand force during operation.
Solution Approach 2:
The cam profile is designed with specific geometric parameters that change along its rotation path. The radius of curvature, contact angle, and follower position are carefully selected to provide the optimal balance between mechanical advantage and operational smoothness. This allows the system to deliver high compression force when needed while maintaining comfortable hand operation throughout the closing motion.
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
This design enables more efficient tissue sealing by reducing the hand force needed to compress the jaw members, thereby improving the consistency and effectiveness of the tissue seal.
Implementation Method 1
The cam assembly is supported in the housing and includes an eccentric cam cable and an eccentric cam. The eccentric cam cable is operably coupled to the movable handle and positioned to rotate the eccentric cam upon movement thereof, wherein rotation of the eccentric cam reduces an amount of force on the movable handle required to move the jaw members to the closed position
Data Source
AI summary
A forceps includes a housing, an elongated shaft assembly, and a cam assembly. The housing includes a movable handle pivotally coupled to the housing. The elongated shaft assembly is coupled to the housing and extends distally to support jaw members at a distal end thereof. One or both of the jaw members is selectively moveable relative to the other jaw member between a spaced apart position for manipulating tissue and a closed position for compressing tissue therebetween. The cam assembly is supported in the housing and includes an eccentric cam cable and an eccentric cam. The eccentric cam cable is operably coupled to the movable handle and positioned to rotate the eccentric cam upon movement thereof, wherein rotation of the eccentric cam reduces an amount of force on the movable handle required to move the jaw members to the closed position to compress tissue disposed between the jaw members.