Pedicle Screw Guiding Instrument with Radial Locking Mechanism
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Solution Overview
Problem
Existing instruments for guiding rods into pedicle screw receptacles face challenges in transmitting high compressive forces over long distances and are difficult to disassemble for cleaning without risking unintentional disassembly, which can lead to injury or instrument disassembly issues during operations.
Innovation Solution
The instrument features a radial stop and a locking element with a prestressing mechanism that allows for quick adjustment and secure engagement of the threaded rod with the internal thread segment, preventing unintentional disassembly and enabling easy disassembly for cleaning by using a stop and biasing elements to ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a screw mechanism is used to position the rod over long distances, then high compressive forces can be transmitted, but the adjustment becomes cumbersome and laborious
Solution Approach 1:
The adjustment mechanism is segmented into two distinct phases: a quick-adjustment phase using a spring-loaded threaded sleeve that allows radial movement without screwing, and a fine-adjustment phase using the screw mechanism for precise positioning. This segmentation allows the system to achieve both quick initial positioning and precise final adjustment.
Solution Approach 2:
The threaded sleeve is designed to be dynamically changeable in its engagement state with the threaded rod. It can transition from an engaged state (providing fine adjustment through screwing) to a disengaged state (allowing quick radial positioning without screwing), enabling the system to adapt its adjustment characteristics based on the operational phase.
2Force
If the threaded components are fully screwed together for secure engagement, then high forces are transmitted, but disassembly for cleaning becomes extremely difficult
Solution Approach 1:
The engagement between the threaded rod and threaded sleeve is made dynamically changeable. During operation, the components are fully engaged to transmit high forces. During cleaning, the threaded sleeve can be quickly disengaged radially from the threaded rod without requiring complete unscrewing, enabling easy disassembly and reassembly.
Solution Approach 2:
The connection system is segmented into the threaded rod and the threaded sleeve as separate, independently movable components. This allows the sleeve to be disengaged from the rod for cleaning purposes and re-engaged for force transmission, providing modular accessibility for maintenance.
3Loss of time
If a quick-adjustment mechanism with spring-loaded threaded sleeve is used, then adjustment time is reduced, but unintentional complete disassembly can occur during decoupling
Solution Approach 1:
A locking element is introduced that preemptively prevents unintentional complete disassembly. The locking element engages with a stop on the threaded rod to limit its axial movement, creating a mechanical barrier against excessive decoupling before it can cause injury or complete disassembly.
Solution Approach 2:
The locking element with stop provides a safety cushion by limiting the axial travel of the threaded rod. This prevents the rod from moving too far during the decoupling process, protecting surrounding structures and surgical personnel from potential injury while still allowing intentional quick adjustment.
4Speed
If the threaded rod is allowed to move freely for quick adjustment, then positioning speed increases, but complete disassembly may occur
Solution Approach 1:
The locking element with stop is positioned to preemptively block the threaded rod from moving beyond a safe distance. This preliminary protective measure allows the rod to move freely within the safe range for quick adjustment while preventing complete disassembly or excessive movement that could cause injury.
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
This solution allows for efficient transmission of high forces over long distances with fine adjustment and self-locking capabilities, preventing unintentional disassembly while facilitating easy and intentional disassembly for cleaning, enhancing safety and usability.
Implementation Method 1
a first pre-tensioning element (26) that applies a radial force
Implementation Method 2
a second pre-tensioning element (11) that applies a radial force
Implementation Method 3
a threaded rod (4) provided with an external thread (3) and positionable in the axial direction relative to the coupling unit (2)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an instrument (1) for guiding a rod into a receiving area of an implant, in particular a pedicle screw, comprising a coupling unit (19) for coupling the instrument (1) to the implant, in particular to a head of the pedicle screw, a threaded rod (4) which is provided with an outer thread (3) and which can be positioned axially relative to the coupling unit (19), and at least one inner threaded segment (8) which is arranged in an axially fixed manner relative to the coupling unit (19) and which can be brought into engagement or out of engagement with the outer thread (3) of the threaded rod (4). The threaded rod (4) has a stop (35), and the instrument (1) has a locking element (9) which is arranged in an axially fixed manner relative to the coupling unit (19) for interacting with the stop (35), wherein the locking element can be positioned in a radial direction relative to the threaded rod (4) and is pretensioned in the direction of the threaded rod (4) so as to engage with the stop (35) by means of a pretensioning element (26) which applies a radial force.