Bone Fastener Pivoting Head Sagittal Transverse Movement
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Solution Overview
Problem
Current spinal implant systems for treating disorders such as degenerative disc disease and osteoporosis often place excessive stress on spinal elements and lack effective sagittal and transverse movement capabilities, limiting their stability and adaptability.
Innovation Solution
A spinal implant system featuring a bone fastener with a pivoting head and saddle that allows for sagittal and transverse movement, enabling direct control and reduced stress on spinal elements, and includes a vertebral rod that can be positioned and secured using a setscrew mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bone fastener uses a fixed rigid structure to attach rods to vertebrae, then structural strength is improved, but adaptability to sagittal and transverse movements deteriorates
Solution Approach 1:
The bone fastener incorporates a dynamic head assembly with a saddle that can pivot and rotate relative to the shaft, allowing the structure to adapt to sagittal and transverse movements while maintaining structural integrity. The saddle's ability to move within defined ranges provides dynamic adaptability without compromising the overall strength of the fixation system.
Solution Approach 2:
The bone fastener is divided into distinct functional segments: a fixed shaft for vertebral attachment, a movable head assembly, and a saddle component. This segmentation allows each part to perform its specific function - the shaft provides anchor strength while the head and saddle provide movement adaptability, resolving the contradiction between rigidity and flexibility.
2Adaptability or versatility
If a bone fastener allows extensive movement in sagittal and transverse planes, then adaptability is improved, but stability deteriorates
Solution Approach 1:
The saddle is designed with controlled movement capabilities, allowing it to pivot and rotate within specific angular ranges rather than freely in all directions. This dynamic design provides necessary adaptability for spinal movement while the defined limits maintain stability and prevent excessive motion that could compromise fixation.
Solution Approach 2:
The bone fastener changes its degrees of freedom based on operational needs - the shaft provides fixed positioning with minimal movement, while the head and saddle provide controlled movement in specific planes. This parameter variation allows the system to achieve both stability and adaptability by adjusting mobility parameters in different spatial directions.
3Device complexity
If a bone fastener uses a simple fixed design, then device complexity is reduced, but ease of operation deteriorates
Solution Approach 1:
The bone fastener incorporates dynamic components (pivoting head, rotating saddle) that automatically adjust to the spatial relationship between vertebral rods and vertebrae during implantation. This reduces the need for complex pre-planning and precise positioning by the surgeon, as the device self-adjusts to accommodate anatomical variations and rod orientations.
Solution Approach 2:
The saddle and head assembly provide self-aligning capabilities through their movable joints, automatically positioning themselves to match the required orientation between the shaft and rod. This self-service feature simplifies the implantation process by reducing the skill level and time required for precise positioning, despite the increased structural complexity.
Data Source
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AI summary
A bone fastener comprises a proximal portion including an extension that includes an inner surface defining at least one projection. A pivoting member is moveable relative to the proximal portion. The pivoting member includes a first surface that defines an implant cavity with the inner surface of the proximal portion. A component is configured for disposal of the extension and includes at least one planar surface. A distal portion has a first end and a second end configured to penetrate tissue. The first end includes at least one planar surface configured to engage the at least one planar surface of the component. The proximal portion is rotatable relative to the distal portion in a first plane of a body and the pivoting member is rotatable relative to the proximal portion in a second plane of the body. Methods of use are disclosed.