Surgical Stapling Instrument Return Mechanism
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Solution Overview
Problem
Existing surgical staplers face challenges in preventing the end effector from being articulated relative to the shaft assembly after the jaw members are closed, which can apply shear forces to soft tissue, and require significant force to extend the return spring for retracting the cutting member, leading to premature return issues.
Innovation Solution
A surgical instrument with a locking mechanism that fixes the relative relationship between the shaft assembly and end effector, including a closure system to prevent articulation after closure, and a firing drive with a flexible band and brake to manage the cutting member's movement, reducing shear forces and improving control over the cutting member's retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return spring is used to retract the cutting member, then the cutting member can be returned to its starting position, but significant force is required to extend the return spring which can prematurely return the cutting member
Solution Approach 1:
The system dynamically switches between two retraction mechanisms: the return spring provides continuous biasing force during normal operation, while the brake mechanism engages to provide controlled stopping force when needed. This dynamic combination allows the system to overcome the limitation of using only a spring, which cannot provide precise positioning control.
Solution Approach 2:
The solution combines two different mechanical mechanisms (spring and brake) into a composite retraction system. The spring provides elastic energy storage and release, while the brake provides friction-based holding capability. This composite approach leverages the strengths of both mechanisms to achieve reliable, controlled retraction without requiring excessive force.
2Adaptability or versatility
If the end effector is articulated relative to the shaft assembly after jaw members are closed, then the end effector can be repositioned, but shear force is applied to the soft tissue captured between the jaw members
Solution Approach 1:
The locking mechanism preemptively prevents articulation of the end effector relative to the shaft assembly once the jaw members are closed. By engaging the lock before any repositioning attempt, the system eliminates the possibility of applying shear force to the captured tissue, while still allowing articulation to occur during the open state when no tissue is present.
3Ease of operation
If the closure system is used to close the end effector, then the jaw members can be brought together, but the end effector may still be articulated after closure
Solution Approach 1:
The system merges two separate functions into a single integrated mechanism: the closure system brings the jaw members together, and the locking mechanism simultaneously prevents articulation. This combination ensures that closure and position stability are achieved together in one operational sequence, eliminating the need for separate actions.
Data Source
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AI summary
A surgical instrument including a band configured to move a cutting member within an end effector. The instrument can further include a reel, wherein at least a portion of the band can be wound around the reel, and wherein the cutting member can be configured to unwind the band from the reel when the cutting member is advanced within the end effector. The instrument can further include a first actuator selectively engageable with the reel to rotate the reel, wind the band around the reel, and retract the cutting member. The instrument can further include a second actuator engageable with the reel in the event that the first actuator cannot rotate the reel.