Vertebral Rotation via Polyaxial Screw Sequencing
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Solution Overview
Problem
Current methods for correcting spinal deformations in the transverse plane, such as scoliosis or kyphosis, risk weakening or rupturing vertebral screws due to excessive transverse stress and lack precision in stress application.
Innovation Solution
A method using polyaxial screws, linking rods, clamping parts, tightening nuts, and set screws to rotate vertebrae progressively and controlledly, without additional leverage instruments, by implanting screws on both sides of the spine curvature and tightening them in a specific sequence to achieve rotation without excessive stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a vertebrae adjusting device is used to exert torque on the vertebrae for transverse plane correction, then the spinal deformation can be corrected, but great transverse stress is exerted on the screws causing weakening of anchoring or even vertebral ruptures
Solution Approach 1:
The correction process is divided into two independent phases: first, the vertebrae are rotated to the corrected position using a vertebral adjusting device; second, the polyaxial screws are tightened progressively in a controlled sequence. This segmentation allows the correction to be achieved without subjecting the screws to excessive transverse stress during the correction process itself.
Solution Approach 2:
The vertebrae are rotated to the desired corrected position before the polyaxial screws are tightened. This preliminary action of positioning the vertebrae first, then securing them with screws in a controlled sequence, prevents excessive stress on the screw anchoring while maintaining correction effectiveness.
2Ease of operation
If a vertebrae adjusting device is used to exert torque on the vertebrae, then transverse plane correction can be achieved, but the surgeon has difficulty precisely evaluating the amount of stress applied
Solution Approach 1:
The progressive tightening sequence of the polyaxial screws provides built-in feedback on stress distribution. By tightening screws in a controlled sequence rather than simultaneously, the system allows real-time monitoring and adjustment of stress levels, enabling the surgeon to precisely evaluate and control the amount of stress applied to each screw and the vertebrae.
3Ease of operation
If additional leverage instruments are connected to the vertebrae to achieve rotation, then rotation can be performed, but the device complexity increases
Solution Approach 1:
The polyaxial screws serve multiple functions: they provide anchoring for the vertebrae, enable controlled rotation through their polyaxial design, and act as structural elements of the fixation system. This multi-functionality eliminates the need for separate leverage instruments, reducing device complexity while maintaining rotational capability.
Data Source
AI summary
A method for rotating a vertebra or vertebrae in a spine that is curved using a vertebral osteosynthesis device that includes polyaxial screws, linking rods, clamping parts, tightening nuts, and set screws. The method includes the steps of: implanting two series of the screws, clamping parts, and linking rods; completely tightening the tightening nuts of a first series of screws on the convex side of the spine curvature; completely tightening the set screws of a second series of screws on the concave side of the spine curvature; tightening the tightening nuts of the second series; and tightening the set screws of the first series.