Spinal Plate Ridges and Notched Screws for Fusion Stability
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Solution Overview
Problem
Current spinal plates used in vertebral fusion procedures often suffer from instability due to limited screw placement, which can lead to reduced stability and increased risk of screw loosening, and may damage surrounding anatomical structures with sharp features.
Innovation Solution
The development of advanced bone plates with ridged features and optional spikes that enhance stability by reducing lateral sliding and promoting bony integration, combined with notched-head bone screws to prevent screw rotation and loosening, and innovative tools for precise placement and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If spikes or sharp features are added to the plate to increase stability, then the stability of the bone-plate interface is improved, but the risk of puncturing or damaging blood vessels, nerves, or other delicate anatomical structures increases
Solution Approach 1:
The patent removes the spikes from the plate design entirely. Instead of using sharp protruding features, the invention employs a spiked insert that is inserted through a hole in the plate and into the bone, with the spike portion extending beyond the plate surface only when needed for engagement. This extraction of the harmful sharp feature from the plate body eliminates the risk of puncturing delicate structures during plate placement while maintaining the stability function.
Solution Approach 2:
The patent introduces a separate spiked insert as an intermediary component between the plate and the bone. The insert includes a portion that engages with the plate and a spiked portion that engages with the bone. This intermediary design allows the plate to have a smooth, safe surface for placement while the separate insert provides the necessary stability function without direct contact between the plate and delicate structures.
2Reliability
If blocking set screws are used to prevent bone screws from backing out, then the prevention of screw loosening is improved, but the bone screws can still rotate and loosen while held in place
Solution Approach 1:
The patent employs asymmetric notches cut into the bone screw shaft at specific angles (e.g., 45 degrees). These notches are designed to engage with corresponding features on the plate or insert, creating an asymmetric mechanical interlock that prevents rotation. The asymmetric geometry ensures that the screw can be inserted and secured but cannot rotate or loosen under load, addressing both prevention of backing out and maintenance of interface stability.
3Device complexity
If fewer screws are used due to size restrictions or design limitations, then the device complexity is reduced, but the stability of the plate decreases
Solution Approach 1:
The patent divides the stability function into separate components: the plate provides structural support and alignment, while separate spiked inserts provide the anchoring function. Each insert can be independently positioned and secured, allowing for optimized placement that maximizes stability without requiring excessive numbers of screws. The segmentation of functions allows fewer screws to achieve the same stability level.
Solution Approach 2:
The patent transitions from a two-dimensional plate-screw interface to a three-dimensional configuration by inserting spikes through the plate and into the bone. This dimensional change creates engagement in multiple directions (longitudinal and lateral), providing enhanced stability with fewer attachment points. The vertical insertion dimension allows for better distribution of mechanical loads across fewer screws.
Data Source
AI summary
Spinal plates with additional features to improve the stability of the interface between the plate and the underlying bone. A bone plate may include one or more sharp ridges along the periphery of its underside. When attached to bone, the ridge digs into the bone and increases stability. A bone plate may alternatively or additionally include one or more holes for optional spikes, which may be inserted once the plate is attached to the bone. By separating the spikes and including them as an optional component, the plate may enhance stability while reducing or eliminating the chance of the spike injuring the patient. Furthermore, bone screws may incorporate alternating notches and ridges into the head of the screw. The notches and ridges may interface with a set screw, thereby preventing rotation and loosening of the screw.