Dynamic Spinal Fixator Interface for Subsidence Accommodation
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Solution Overview
Problem
Current spinal plate systems fail to adequately account for subsidence by not allowing sufficient angulation of screws relative to the plate and limited axial movement, which can lead to inadequate stabilization and fusion of vertebrae.
Innovation Solution
A dynamic fixator interface member that slides and rotates within a plate system, allowing for axial movement and angulation of screws to accommodate subsidence, featuring closed-ended slots and an anti-backout mechanism for secure fastening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current plate systems use fixed screw-plate interface, then manufacturing and installation are simplified, but they cannot accommodate subsidence and lead to inadequate stabilization
Solution Approach 1:
The patent applies the dynamics principle by making the screw-plate interface dynamic rather than fixed. The interface member can rotate relative to the plate about a transverse axis and slide axially along the longitudinal axis, allowing the system to adapt to subsidence while maintaining stabilization. This dynamic capability resolves the contradiction by improving reliability through adaptability without requiring complete redesign of the entire plate system.
Solution Approach 2:
The patent segments the screw-plate interface into separate functional components: a plate, an interface member, and a screw. The interface member is configured with slots that allow independent rotation and axial movement, separating the stabilization function from the anchoring function. This segmentation enables each component to perform its specific function optimally while accommodating subsidence.
2Reliability
If screws are fixed perpendicular to the plate, then installation is easier, but insufficient angulation allows inadequate graft contact and fusion
Solution Approach 1:
The interface member can rotate about the transverse axis, allowing screws to be angled relative to the plate surface. This dynamic angulation capability enables optimal screw orientation for graft contact and fusion while maintaining ease of installation through a standardized interface design.
Solution Approach 2:
The patent changes the angular parameter of screw insertion by allowing the interface member to rotate to different angles. This parameter change enables screws to contact grafts at optimal angles for fusion while the interface member itself remains easily installable in the plate.
3Reliability
If axial movement of screws is restricted, then structural stability is maintained, but subsidence cannot be accommodated and stabilization fails
Solution Approach 1:
The interface member is designed to slide axially within the plate while maintaining connection. This controlled axial movement allows the system to accommodate subsidence by allowing the interface member to move along with the vertebrae, while the connection to the plate maintains overall structural stability.
Solution Approach 2:
The interface member acts as an intermediary between the plate and the screw. It provides a controlled interface that allows axial movement to accommodate subsidence while transmitting forces between the plate and screw to maintain stability. The intermediary design resolves the contradiction by enabling movement without compromising overall structural integrity.
Data Source
AI summary
Systems and method for fixation to a spinal column are described. A system includes a plate having an anterior surface, a posterior surface, a longitudinal axis, a transverse axis and a through hole passing through the anterior and posterior surfaces; and a dynamic fixator interface member configured and dimensioned to connect to the plate within the through hole and to axially slide relative to the plate in directions of the longitudinal axis, and additionally, to rotate relative to the plate in directions about the transverse axis.