Rack-and-Pinion Knife Deployment in Electrosurgical Forceps
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Solution Overview
Problem
Existing electrosurgical forceps require precise tissue severing after treatment, often involving a knife that needs to be accurately controlled to avoid premature deployment during tissue treatment.
Innovation Solution
The electrosurgical forceps incorporate a knife deployment mechanism with a trigger system that includes a rack and gear configuration, a knife lockout mechanism, and a switch assembly to ensure the knife is deployed only when the jaw members are sufficiently closed, and a knife return spring to retract the knife safely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a knife deployment mechanism is added to electrosurgical forceps, then tissue severing capability is improved, but device complexity increases
Solution Approach 1:
The knife deployment mechanism is integrated within the existing forceps structure, combining the knife function with the jaw closure mechanism. The knife is housed within the shaft members and deployed through the existing trigger system, merging multiple functions into a unified device rather than adding separate components.
Solution Approach 2:
The trigger mechanism serves multiple functions: it controls jaw closure, activates the knife deployment, and coordinates the lockout mechanism. This multi-functional design allows a single component to perform several operations, reducing overall device complexity while maintaining enhanced capability.
2Reliability
If a knife lockout mechanism is implemented, then premature knife deployment is prevented, but device complexity increases
Solution Approach 1:
The lockout mechanism is pre-configured to automatically engage when the forceps are open and disengage when the jaws are closed. This preliminary positioning ensures that the knife cannot be deployed prematurely, as the lockout is already in place before the surgeon attempts to activate the knife.
Solution Approach 2:
The lockout mechanism automatically engages and disengages based on the jaw position without requiring separate manual intervention. The mechanical linkage between the jaw closure and lockout mechanism allows the system to self-regulate, reducing the need for additional control components.
3Object-affected harmful factors
If the trigger is designed to cover the trigger slot during actuation, then user safety is improved, but ease of operation decreases
Solution Approach 1:
The trigger is designed to dynamically change its position relative to the trigger slot during actuation. When the trigger is pulled, it moves to cover the slot, preventing finger pinching. This dynamic movement ensures safety without requiring a completely different trigger design that would compromise operability.
Solution Approach 2:
The trigger itself acts as an intermediary barrier between the user's finger and the trigger slot. By moving to cover the slot during actuation, the trigger mediates the potential harmful interaction, protecting the user while still allowing the surgical function to be performed.
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 prevents premature knife deployment during tissue treatment, ensuring precise tissue severing and reducing the risk of user injury by minimizing the trigger's exposure, thus enhancing safety and operational control.
Implementation Method 1
The knife deployment mechanism includes first and second rack members operably coupled to one another by a gear disposed therebetween. The trigger is operably connected to the first rack member and the knife is operably coupled to the second rack member such that movement of the trigger moves the knife in an opposite direction relative thereto.
Implementation Method 2
the knife lockout includes a flange operably connected to the first shaft member and depending therefrom in opposition to the second shaft member such that approximation of the first and second shaft members forces the flange against the second shaft member to disengage the knife lockout
Implementation Method 3
a knife return spring operably coupled to the knife deployment mechanism and configured to bias the knife toward the retracted position
Data Source
AI summary
A forceps includes first and second shafts each having a jaw disposed at a distal end thereof configured to rotate about a pivot to move the jaws between open and closed positions, the shafts defining a longitudinal axis therebetween. A knife deployment mechanism including a rack and pinion mechanism or a series of links is disposed within the first shaft and includes a trigger moveable along the longitudinal axis to deploy a knife between the jaws. A knife lockout is configured to move upon approximation of the first and second shafts between an engaged position preventing deployment of the knife and a disengaged position allowing deployment of the knife. A knife kickout mechanism is disposed within the first shaft in opposition to the second shaft and is configured to force the knife forward upon movement of the first and second shafts from an approximated position to a more open position.