Surgical Forceps Jaw Force Limiter Mechanism
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Solution Overview
Problem
Forceps used in laparoscopic surgery often experience high jaw forces that can lead to breakage of the end effector assembly, as they compress and open tissues, necessitating a mechanism to limit clamping forces.
Innovation Solution
The forceps incorporate a lost motion connection between the moveable and fixed handles, featuring a yoke and drive shuttle with flanges that allow relative axial motion when excessive forces are applied, preventing the jaws from moving beyond a predetermined force, thus preventing breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the forceps are designed to compress tissue firmly, then the clamping force is improved, but the end effector assembly may break due to excessive force
Solution Approach 1:
The patent implements a force limiting mechanism that changes the force parameter from uncontrolled high force to controlled predetermined force. The mechanism includes a force limiter with a deflectable member that bends when force exceeds a predetermined threshold, thereby limiting the maximum clamping force applied to tissue and preventing end effector breakage.
Solution Approach 2:
The force limiting mechanism acts as a protective cushioning element before excessive force can damage the end effector. The deflectable member is positioned in advance to absorb and limit force, preventing the transmission of excessive forces that would cause breakage while still allowing adequate clamping force for tissue grasping.
2Reliability
If the force limiting mechanism is added to prevent breakage, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The force limiting mechanism is nested within the existing forceps structure. The force limiter is positioned between the actuator and the end effector assembly, utilizing the existing mechanical components and pathways. This nested integration adds the force limiting function without requiring a completely separate external mechanism, thereby minimizing the increase in overall device complexity.
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 solution effectively limits jaw forces, preventing breakage of the end effector assembly during clamping and opening operations, ensuring the forceps can securely grasp and release tissue without damage.
Implementation Method 1
the flanges of the yoke deflect outwardly to allow relative axial motion between the yoke and the shuttle
Data Source
AI summary
A forceps includes a first jaw member, a second jaw member, a drive rod assembly and a moveable handle attached to a fixed handle. The first jaw member and the second jaw member are in opposing relation relative to one another, and at least one of the first jaw member and the second jaw member is relatively movable from a first open position to a second clamping position when the first jaw member and the second jaw member cooperate to grasp tissue therebetween. Moving the moveable handle relative to the fixed handle moves the drive rod assembly for imparting movement of at least one of the first jaw member and the second jaw member from the first position and the second position. The moveable handle has an actuator with a lost motion connection between the first and second jaw members and the actuator.