Surgical Stapler Trigger Mechanism for Variable Retraction Speed
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Solution Overview
Problem
Existing surgical staplers require complex trigger mechanisms for both closing the jaw member and advancing/retracting the cutting member, making them difficult to operate and limiting the surgeon's ability to evaluate the jaw position before staple deployment.
Innovation Solution
A surgical instrument with a single trigger that uses a ratchet assembly system allowing selective advancement and retraction of the cutting member, enabling separate control over staple deployment and tissue incision, and a switching mechanism for differentiating between these functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single trigger is used to control both jaw closing and staple firing, then device complexity is reduced, but the force required to actuate the trigger becomes excessively high
Solution Approach 1:
The trigger mechanism is segmented into two separate triggers: a first trigger (closure trigger) that controls jaw closing through a closure system, and a second trigger (firing trigger) that controls staple deployment and cutting member advancement through a firing system. This segmentation divides the previously combined high-force operation into two separate, lower-force operations, resolving the contradiction between device simplicity and excessive actuation force.
2Productivity
If both jaw closing and staple deployment are performed in the same trigger actuation, then productivity is improved, but the surgeon loses the ability to evaluate jaw position before staple deployment
Solution Approach 1:
The surgical procedure is segmented into distinct phases controlled by separate triggers: jaw closing (first trigger) followed by staple firing (second trigger). This allows the surgeon to complete jaw closure, evaluate the jaw position and tissue clamping, and then proceed to staple deployment only when satisfied with the positioning. The segmentation preserves surgical control and evaluation capability while maintaining procedural efficiency.
3Ease of operation
If multiple triggers are used for different functions, then ease of operation for each function is improved, but the surgeon must release one trigger and reposition their hand to grasp another trigger
Solution Approach 1:
Both the first trigger (closure trigger) and second trigger (firing trigger) are merged into a single pistol grip handle assembly, positioned such that the surgeon can operate both triggers sequentially without releasing the handle or repositioning their hand. This spatial merging eliminates the time loss associated with hand repositioning while maintaining the functional separation and control advantages of multiple triggers.
4Manufacturing precision
If the cutting member is retracted at a slower rate, then manufacturing precision is improved, but the time required for retraction increases
Solution Approach 1:
The cutting member retraction system employs a variable rate mechanism where the retraction speed is dynamically adjusted: initially slower to ensure precise positioning and controlled withdrawal from tissue, then faster for the remainder of the retraction stroke to minimize total retraction time. This dynamic rate adjustment resolves the contradiction between positioning precision and retraction time by optimizing speed at different phases of the retraction 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
Facilitates easier and more precise operation by allowing surgeons to control staple deployment and cutting with a single trigger, reducing the force required and providing time to evaluate jaw position before tissue engagement.
Implementation Method 1
a first ratchet assembly configured to advance a cutting member in the end effector and a second ratchet assembly configured to retract the cutting member
Implementation Method 2
a first gear having a first pitch radius and the second drive system can include a second gear having a different pitch radius where the first and second gears can rotate the drive shaft at different rates
Data Source
AI summary
A surgical instrument including a drive mechanism configured to advance a staple driver and/or cutting member at a first rate and retract the staple driver and/or cutting member at a different rate. In at least one embodiment, the rate at which the driver and cutting member is advanced and/or retracted is the distance that the driver and/or cutting member is translated per actuation of a trigger, for example. In various embodiments, the cutting member can be retracted at a faster rate as compared to the rate in which it is advanced. In such embodiments, the surgical instrument can, owing to the slower advancing rate, provide a greater torque or advancing force to the cutting member while, owing to the faster retracting rate, reduce the time required for the surgeon to retract the cutting member.