Surgical Cutting Instrument With Nested Scissor-Jack Mechanism
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Solution Overview
Problem
Surgical instruments lack a compact design with sufficient mechanical advantage to effectively cut elongated elements within a surgical setting, particularly in limited spaces, and are not suited for pre-insertion cutting of elements like bone anchors and rods.
Innovation Solution
A surgical instrument with pivoting arms and a force mechanism, featuring a scissor-jack mechanism with linkages and a threaded element, allows for precise cutting of elongated elements by pivoting the arms between open and closed orientations, enabling cutting within a surgical site while maintaining the force mechanism outside the patient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a surgical instrument is designed with a compact size for use in limited surgical spaces, then the instrument can be inserted into the patient for in-situ cutting, but the instrument lacks sufficient mechanical advantage to effectively cut elongated elements
Solution Approach 1:
The surgical instrument employs a nested structure where the first arm is positioned within the longitudinal channel of the second arm, and the cutting elements are housed within the distal sections of the arms. This nesting allows the instrument to maintain a compact overall size for surgical insertion while containing the mechanical advantage generating structures within the overlapping arm sections, resolving the contradiction between compact size and sufficient cutting force.
Solution Approach 2:
The instrument utilizes a dynamic pivot mechanism that allows the first and second arms to pivot relative to each other about a pivot member positioned in the overlapping distal sections. This dynamic pivoting action, driven by the force mechanism, enables the arms to generate mechanical advantage during the cutting stroke while maintaining a compact configuration when not in use, effectively providing sufficient cutting force within a limited space.
2Volume of moving object
If the force mechanism is positioned within the instrument for compact design, then the instrument fits in limited spaces, but the force mechanism cannot provide sufficient mechanical advantage for cutting
Solution Approach 1:
The force mechanism is nested within the overlapping region of the first and second arms, where it can generate mechanical advantage through the pivoting action without increasing the overall instrument volume. The links and threaded element are contained within the structural envelope of the arms, allowing sufficient power generation within a compact configuration.
Solution Approach 2:
The force mechanism utilizes the longitudinal dimension of the overlapping arm sections to generate mechanical advantage, rather than requiring additional lateral space. The threaded element engages with the links in a configuration that converts rotational motion into linear force along the longitudinal axis, effectively using the available dimensional space to maximize mechanical advantage.
3Adaptability or versatility
If the instrument is designed for cutting elongated elements in-situ during surgery, then the cutting portion can be inserted into the patient, but the instrument cannot be used for pre-insertion cutting of elements like bone anchors and rods
Solution Approach 1:
The surgical instrument is designed with universal applicability by positioning the cutting elements at the distal ends of the pivoting arms, allowing the instrument to cut elongated elements regardless of their location or orientation. The adjustable pivot mechanism and force mechanism provide sufficient mechanical advantage for cutting both thin bone anchors and thicker rods, enabling the same instrument to perform pre-insertion cutting, in-situ cutting, and post-insertion trimming without requiring length modifications.
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 instrument provides a compact, mechanically advantageous solution for cutting elongated elements in-situ, ensuring precise cutting and easy removal of excess sections, suitable for both in-patient and pre-insertion use, with a design that minimizes space requirements and maintains control over cut sections.
Implementation Method 1
The force mechanism may include a connector with a threaded aperture that is positioned over the threaded section
Implementation Method 2
A pivot member may be positioned in the distal sections of the first and second arms at a point where the arms are in the overlapping arrangement. The pivot member may be fixedly attached to the first arm and movable relative to the second arm.
Data Source
AI summary
A surgical instrument for cutting an elongated element. The surgical instrument may have a compact size for use in-situ during a surgical procedure. The surgical instrument is also configured to provide the necessary mechanical advantage to cut the elongated element. The surgical instrument may include first and second arms that are pivotally connected together at a pivot. The arms include blades positioned at or towards distal ends of the arms that act together to cut the elongated element. A force mechanism is positioned between the arms to pivot the arms between an open orientation and a closed cutting orientation. The force mechanism may be positioned directly between the arms to reduce the overall size of the instrument.