Articulating Surgical End Effector With Segmented Firing Drive
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Solution Overview
Problem
Surgical instruments with articulatable end effectors face challenges in achieving a wide range of articulation while accommodating various drive systems, due to size constraints imposed by trocar cannulas, and must retain the end effector in position during procedures while withstanding external forces.
Innovation Solution
The surgical instrument employs a firing system with upper and lower flexible spine assemblies and a rotary drive screw, which includes a radially/longitudinally segmented power screw nut arrangement, allowing for high articulation angles and balanced load transfer, and an articulation joint with a constant velocity drive shaft assembly and elastomeric joint assembly to maintain stability and facilitate precise movement of the firing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an articulatable end effector is designed to achieve a wide range of articulation angles, then the articulation capability is improved, but the device complexity and size increase, making it difficult to accommodate within trocar cannula size constraints
Solution Approach 1:
The drive system is divided into multiple segments including a segmented power screw nut arrangement with distributed engagement points along the firing member. This segmentation allows the drive force to be distributed across multiple contact points, reducing the complexity of any single articulation joint while achieving wide articulation capability through the coordinated action of segmented components
Solution Approach 2:
The patent transitions from a traditional linear drive arrangement to a rotary drive system that operates in a rotational dimension. The rotary drive screw converts rotational motion to linear motion of the firing member, allowing articulation to occur in multiple dimensions while maintaining a compact profile that fits within trocar cannula constraints
2Stability of the object's composition
If the end effector is designed to retain position during procedures while withstanding external forces, then the stability is improved, but the friction and wear on the articulation joint increase
Solution Approach 1:
The distributed engagement points of the segmented power screw nut arrangement act as counterbalancing contact points that share the load of withstanding external forces. Instead of concentrating force at a single articulation joint, the counter-distributed engagement points create a balanced force distribution that reduces friction and wear at any individual contact point while maintaining overall position stability
Solution Approach 2:
The rotary drive system provides dynamic control of the firing member position through continuous rotational adjustment. This dynamic control mechanism allows the system to actively maintain position stability against external forces rather than relying solely on static friction at a single joint, thereby reducing wear while preserving stability
3Device complexity
If a traditional linear drive system is used, then the structure is simpler, but the friction and unbalanced loads on the articulation joint increase
Solution Approach 1:
The patent replaces a traditional linear drive system with a rotary drive mechanism. This substitution transforms the mechanical action from direct linear pushing (which creates unbalanced loads) to rotational motion that is converted to linear motion through a screw mechanism. The rotary system inherently balances loads through its symmetric geometry and distributed force application, reducing friction and wear despite increased structural 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
Enables efficient and precise articulation of the surgical end effector over a wide range, maintaining stability and reducing friction and wear, thereby improving the ability to cut and staple tissue effectively.
Implementation Method 1
a rotary drive screw, which includes a segmented power screw nut arrangement
Implementation Method 2
a constant velocity drive shaft assembly
Implementation Method 3
upper and lower flexible spine assemblies
Data Source
AI summary
Surgical end effectors with first and second jaws that are opened and closed with an axially movable firing member. The firing member is configured to apply a first closure motion to the second jaw to move the second jaw from an open position to a closed position as the firing member is moved in a distal direction from a home position to an ending position. The firing member is further configured to move the second jaw towards the first jaw when the firing member is moved in a proximal direction from the home position.