Laparoscopic Pinion Blade Drive Mechanism for Longer-Jaw Transection
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Solution Overview
Problem
Longer jaws in electrosurgical forceps require a longer actuation stroke for transecting sealed tissue, which can be awkward or cumbersome for operators.
Innovation Solution
A surgical instrument with a handle assembly and a drive mechanism that includes a first and second rotating component with a gear ratio, allowing for a longer stroke through a pinion gear system to efficiently advance a blade, reducing the required actuation force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If longer jaws are used in electrosurgical forceps, then the sealing capability is improved, but the actuation stroke required for blade transection becomes excessively long and cumbersome
Solution Approach 1:
A cable-driven transmission mechanism serves as an intermediary between the actuator and the blade. The cable transmits force over the long distance required by longer jaws while maintaining manageable actuation forces. This mediator allows the actuator to be positioned optimally for operator comfort while still achieving the necessary blade stroke length for transecting tissue sealed by longer jaws.
Solution Approach 2:
The patent transitions from direct linear actuation to a cable-driven system that operates through a different dimensional pathway. Instead of moving the blade directly along the jaw axis, the cable runs through a complex routing path that accommodates the longer jaw length while keeping the actuator stroke manageable through spatial redistribution of the transmission path.
2Length of moving object
If a longer actuation stroke is used to transect tissue with longer jaws, then the blade can reach through the sealed tissue, but the operation becomes awkward and cumbersome for the operator
Solution Approach 1:
The cable acts as a flexible intermediary that decouples the blade stroke length from the actuator stroke length. The cable can be routed through guides and pulleys to achieve long blade travel while the operator pulls a shorter, more comfortable stroke on the actuator. This mediator absorbs the dimensional mismatch between required blade stroke and comfortable actuator stroke.
Solution Approach 2:
The cable-driven system introduces dynamic flexibility to the transmission mechanism. Rather than a rigid direct connection that would require proportional actuator stroke length, the flexible cable allows for dynamic routing and force transmission, enabling the blade to traverse the full length of longer jaws while the actuator maintains a compact, operator-friendly stroke distance.
3Reliability
If electrosurgical forceps with longer jaws are used, then hemostasis and sealing are enhanced, but the mechanical advantage for blade actuation is reduced
Solution Approach 1:
The cable transmission system serves as a force-multiplying intermediary. By routing the cable through strategic pulleys and guides, the system creates mechanical advantage that reduces the actuation force required at the handle while still delivering sufficient force to advance the blade through the tissue sealed by longer jaws. The cable acts as a force transformer that compensates for the reduced mechanical advantage inherent in longer jaw configurations.
Solution Approach 2:
The cable routing incorporates curved paths through pulleys and guides rather than straight-line transmission. This curvature allows for optimization of the force vector directions, creating favorable mechanical advantage angles that reduce the actuation force required. The curved transmission path enables the cable to leverage rotational motion and directional changes to amplify the operator's input force.
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
The pinion gear system provides a longer blade stroke with reduced actuation force, facilitating precise and efficient transection of sealed tissue.
Implementation Method 1
The drive mechanism includes a first rotating component defining a first circumference, wherein the first rotating component is coupled to the actuator about the first circumference such that the manipulation of the actuator through the actuation stroke induces rotational motion in the first rotating component. The drive mechanism also includes a second rotating component defining a second circumference wherein the second rotating component is coupled to the first rotating component such that rotational motion in the first rotating component induces rotational motion in the second rotating component.
Implementation Method 2
The second circumference is greater than the first circumference... The pinion gear system provides a longer blade stroke with reduced actuation force
Data Source
AI summary
A surgical instrument comprises a handle assembly including an actuator. An elongate shaft extends distally from the handle assembly and defines a longitudinal axis. A reciprocating member extends at least partially through the elongate shaft, and is mounted for longitudinal motion through the elongate shaft in response to manipulation of the actuator. A drive mechanism includes a first rotating component coupled to the actuator to induce rotational motion in the first rotating component. A second rotating component is coupled to the first rotating component such that rotational motion in the first rotating component induces rotational motion in the second rotating component. The second rotating component is coupled to the reciprocating member such that rotational motion of the second rotating component induces longitudinal motion in the reciprocating member.