Pedicle Screw Coupling with Independent Rod Fixation
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Solution Overview
Problem
Existing polyaxial screw and coupling devices for spine fixation systems lack flexibility, reliability, and long-term durability, making it difficult to align and position spinal rods accurately, and they do not allow independent fixation of screw and rod angulation.
Innovation Solution
A pedicle screw construct with a coupling device that provides angular freedom and independent fixation of the spinal rod relative to the pedicle screw, allowing a 45° arc of articulation and 360° rotation, featuring a coupling head, tubular sleeve, and collar for secure positioning and retention of the spinal rod.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed screws are inserted along a misaligned curvature, then spinal fixation is achieved, but it is difficult to simultaneously position the coupling devices such that the spinal rod receiving portions are aligned for rod passage without distorting the screws
Solution Approach 1:
The coupling device is designed with polyaxial freedom, allowing the spinal rod receiving portion to move dynamically relative to the implanted screw. This enables the coupling device to self-align with the spinal rod during insertion without requiring precise pre-positioning, thereby resolving the contradiction between ease of operation and alignment precision.
2Adaptability or versatility
If polyaxial screw and coupling devices are used to allow limited movement, then freedom of movement with respect to angulation is improved, but the devices become complex, inadequately reliable, and lack long-term durability
Solution Approach 1:
The coupling device is segmented into distinct functional components: a body portion that receives the screw, a rod receiving portion that interfaces with the spinal rod, and a locking mechanism. This segmentation allows each component to be optimized for its specific function while maintaining overall simplicity and reliability.
Solution Approach 2:
The invention extracts the polyaxial freedom function from complex multi-component mechanisms found in prior art and implements it through a simplified geometric design of the coupling device body, allowing movement while maintaining structural integrity and long-term durability.
3Adaptability or versatility
If prior art polyaxial screw and coupling devices are used, then limited freedom of movement is achieved, but they do not allow independent fixation of screw to coupling device angulation and rod fixation
Solution Approach 1:
The coupling device provides dynamic adjustment capability, allowing the surgeon to independently set the angulation between the screw and coupling device, and separately fix the spinal rod to the coupling device. This dynamic fixation process enhances both adaptability and reliability by allowing optimal positioning followed by secure locking.
Data Source
AI summary
A pedicle screw coupling construct for a pedicle screw construct provides fixation of angular orientation thereof relative to a pedicle screw independent of fixation of a received spinal rod to the coupling construct. The pedicle screw construct forms one component or element in a spinal fixation system. The independent fixation coupling construct also provides for fixation of the angular orientation of the coupling construct while the coupling construct has received the spinal rod. In another form, a coupling head or construct is configured to allow a pedicle screw shaft to pass therethrough but retain the pedicle screw head for rotation of the coupling head about the pedicle screw head. The coupling head or construct is also configured to allow at least a 45° arc of pivot or articulation about a pedicle screw shaft relative to a longitudinal axis of a spinal rod received in the body. This allows the head with a received spinal rod to fold, bend or pivot relative to the pedicle screw shaft, particularly to a greater degree than the prior art.