Spinal Fixing Device Chuck Elastic Diameter Adjustment
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Solution Overview
Problem
Existing polyaxial pedicle screws experience unintended twisting or bending due to insufficient tightening torque and external impacts, which can compromise the stability of the spinal fixing device during patient activity or external loads.
Innovation Solution
A spinal fixing device with a chuck having an elastically changeable diameter and a curved inner surface, allowing the bone screw's head to be securely fixed to a spine rod, featuring a concave or inclined surface for elastic transformation and enhanced coupling, preventing rotation and movement between the screw and housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polyaxial type pedicle screw is used to allow predetermined rotation between screw and housing, then ease of insertion is improved, but unintended twisting or bending occurs due to insufficient tightening torque and external impacts
Solution Approach 1:
The chuck is designed with an elastically changeable diameter that transitions from a contracted state during insertion to an expanded state during fixation. This dynamic structure allows the chuck to adapt its diameter based on the operational phase, providing both ease of insertion and reliable fixation.
Solution Approach 2:
The chuck's diameter changes elastically from a smaller size during insertion to a larger size during fixation. This parameter change enables the chuck to accommodate the bone screw head securely while maintaining ease of insertion, resolving the contradiction between operational ease and fixation reliability.
2Ease of manufacture
If the chuck has a fixed diameter, then manufacturing is simplified, but the ability to allow intentional movement before fixing is reduced
Solution Approach 1:
The chuck incorporates an elastically changeable diameter that allows intentional movement during the fixation process. This dynamic feature provides adaptability while maintaining a relatively simple manufacturing process compared to complex mechanical adjustment mechanisms.
Solution Approach 2:
The chuck's diameter changes elastically to allow intentional movement before fixation. This parameter change enables versatility and freedom of operation without requiring complex manufacturing processes, resolving the contradiction between manufacturing simplicity and operational adaptability.
3Strength
If the peripheral portion is made rigid, then structural integrity is improved, but elastic transformation and coupling force are reduced
Solution Approach 1:
The peripheral portion is designed with elastic properties that allow diameter change during fixation. This elastic transformation generates coupling force between the chuck and bone screw head, improving fixation strength while maintaining overall structural integrity through the housing structure.
Solution Approach 2:
The chuck's curved inner circumferential surface works with the spherical bone screw head to create effective coupling. The curvature allows elastic transformation while maintaining contact between the chuck and screw head, generating sufficient coupling force without compromising structural integrity.
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 device provides greater freedom of operation and improved stability by allowing intentional movement before fixing, enhancing the coupling force and structural integrity, reducing assembly complexity, and increasing the range of motion while maintaining stability.
Implementation Method 1
a surface like a concave surface or an inclined surface having a gradually varying diameter is formed on the inner circumferential surface of the seat portion and the outer circumferential surface of the peripheral portion is convex so as to allow the end of the peripheral portion to elastically shrink through the pressure generated between the peripheral portion and the seat portion by pressurization of the chuck by the spine rod
Data Source
AI summary
The present invention relates to a spinal fixing device in which a head portion of a bone screw to be inserted into a vertebra is bound to a housing, and the housing is fixed to a spine rod. The spinal fixing device includes: the housing having a seat portion inside and having a mounting groove for mounting the spine rod; a chuck to be inserted into the seat portion, in which a peripheral portion having an elastically changeable diameter and a curved inner circumferential surface is formed along the circumference of the chuck at one side; and the bone screw having a spherical head portion to be inserted into the peripheral portion, wherein a surface having a gradually varying diameter is formed on the inner circumferential surface of the seat portion and the outer circumferential surface of the peripheral portion is convex so as to allow the end of the peripheral portion to elastically shrink through the pressure generated between the peripheral portion and the seat portion by pressurization of the chuck by the spine rod, thereby restricting the rotation of the head portion. According to the present invention including said feature, the chuck is combined so as to restrict the head portion of the bone screw and has the peripheral portion having an elastically shrinkable diameter, and thus the movement between the screw and the housing is allowed according to the intention of an operator before being fixed to the spine rod and the movement between the housing and the bone screw can be more effectively inhibited when fixed to the spine rod.