Double-Headed Pedicle Screw Independent Yoke Pivoting
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Solution Overview
Problem
Existing spinal fixation devices, such as pedicle screws, do not allow movement during spine flexion and extension, leading to discomfort for patients.
Innovation Solution
A double-headed pedicle screw design featuring a threaded shaft with multiple yoke assemblies that can pivot independently, allowing for movement relative to the sagittal plane and facilitating connection with rods or immobilization structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional pedicle screw is used to provide stable spinal fixation, then the fixation strength and stability are improved, but the patient experiences discomfort during spine flexion and extension due to inability of the screw to move
Solution Approach 1:
The pedicle screw is designed with movable yoke assemblies that can pivot independently relative to the threaded shaft portion, transforming the static fixed structure into a dynamic system that adapts to spinal movement during flexion and extension, thereby maintaining comfort while preserving fixation stability
Solution Approach 2:
The screw head is divided into multiple independent yoke assemblies (first yoke assembly and second yoke assembly) that can pivot independently, allowing each segment to move separately to accommodate spinal motion while the threaded shaft portion remains securely fixed in the vertebra
2Device complexity
If a fixed pedicle screw design is used to ensure structural strength, then the device complexity is reduced, but the adaptability to spinal movement is worsened
Solution Approach 1:
The design incorporates pivotable yoke assemblies that enable the screw head to dynamically adapt to spinal movement, significantly improving adaptability while adding only moderate structural complexity through the inclusion of pivot mechanisms and multiple yoke components
Data Source
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AI summary
A double-headed pedicle screw (10) is provided. The double-headed pedicle screw includes a threaded shaft portion (11) and a two yoke assemblies (24a, 24b) supported by the threaded shaft portion. Each of the yoke assemblies includes a recess (50) configured to receive a portion of a rod (52), alignment structure, or immobilization structure therein. Each of the yoke assemblies is configured for pivoting movement relative to the threaded shaft portion independent of the pivoting movement of the other yoke assemblies.