Open Electrosurgical Shears with Resilient Arm and Lockout
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Solution Overview
Problem
Existing electrosurgical instruments lack a compact and efficient mechanism for actuating a knife within jaws to sever tissue while ensuring proper closure and RF energy application, often resulting in inadequate closure forces and accidental tissue damage.
Innovation Solution
The design incorporates a resilient arm that flexes to provide greater closure forces for sealing and a compact firing assembly with a trigger close to the center, allowing easy actuation regardless of instrument orientation, along with a lockout mechanism to prevent knife activation until jaws are sufficiently closed and a automatic knife return mechanism to prevent over-actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional firing assembly with a distal trigger is used, then the instrument can actuate the knife, but the trigger is difficult to actuate when the instrument is held in different orientations and closure forces are insufficient
Solution Approach 1:
The trigger mechanism is repositioned from a distal location to a proximal location near the user's hand, changing the spatial dimension of actuation. This allows the trigger to be easily accessible regardless of instrument orientation, solving the ease of operation problem while maintaining sufficient closure force through the redesigned force transmission path.
Solution Approach 2:
The resilient arm is pre-bent to store elastic potential energy before actuation. When the trigger is pulled, this stored energy is released to provide enhanced closure force on the jaws, ensuring sufficient sealing force without requiring excessive manual effort from the user.
2Adaptability or versatility
If the knife can be freely actuated, then tissue severing is enabled, but accidental tissue damage may occur from premature or excessive knife activation
Solution Approach 1:
The lockout mechanism is configured to automatically engage the knife in a predetermined position before tissue contact occurs. This preliminary positioning ensures the knife is ready for severing but cannot be activated prematurely, preventing accidental tissue damage while maintaining the capability for controlled tissue severing when needed.
Solution Approach 2:
A lockout mechanism acts as an intermediary between the trigger and the knife actuation system. This intermediary component controls and regulates knife activation, allowing seamless transition between grasping, sealing, and severing modes while preventing unauthorized or accidental knife activation that could cause tissue damage.
3Adaptability or versatility
If the instrument includes both grasping and severing capabilities, then functionality is enhanced, but ensuring proper jaw closure before severing becomes more complex
Solution Approach 1:
The lockout mechanism serves as an intermediary that automatically verifies jaw closure before permitting knife activation. This mediator component simplifies the control logic by automatically detecting when jaws are properly closed and enabling severing only at that point, reducing the complexity of manual verification while maintaining safe multi-mode operation.
Solution Approach 2:
The instrument's control system automatically monitors jaw position and knife readiness without requiring manual verification by the user. The system self-regulates the sequence of operations, automatically enabling severing capabilities only when proper jaw closure is detected, thereby simplifying the user interface while ensuring safe operation across multiple modes.
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 configuration ensures consistent tissue sealing and severing with controlled closure forces, preventing accidental tissue damage and improving operational ease by ensuring proper jaw closure and automatic knife return.
Implementation Method 1
a resilient arm that flexes to provide greater closure forces for sealing
Implementation Method 2
one or more elements that transmit RF energy to tissue (e.g., to coagulate or seal the tissue)
Data Source
AI summary
A surgical instrument includes an end effector, a handle assembly, a knife drive assembly, and a lockout assembly. The end effector includes a pair of jaws, a knife, and an RF electrode. The handle assembly includes a housing associated with the first jaw, and an arm associated with the second jaw. The arm is pivotably coupled with the housing and pivots the second jaw between the open position and the closed position. The knife drive assembly includes a trigger slidably coupled with the housing, an actuating assembly, and a return assembly. The actuation assembly converts proximal translation of the trigger into distal actuation of the knife. The return assembly automatically actuates the knife from the fired position to the pre-fired position in response to the trigger reaching a predetermined proximal position. The lockout assembly prevents activation of the electrode and distal actuation of the knife while in the locked configuration.