Cervical Plate Screw Locking Mechanism Prevents Loosening

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Solution Overview

Problem

Spinal fixation devices face issues such as screw loosening due to unwanted rotation and axial movement, leading to instability and complications in bone fusion procedures, which can result in non-union, fracture, and neurological injuries.

Innovation Solution

A cervical plate fusion system with a resilient member and toothed wheel mechanism that prevents screw counter-rotation and axial backing out by using a beveled shoulder and fins to secure the screw in place, eliminating the need for welding or additional fixtures, thereby enhancing stability and ease of assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional fixation devices are used, then bone alignment and stabilization can be achieved, but screw loosening occurs due to unwanted rotation and axial movement under repetitive loads

Engineering Contradiction:

Improvefixation stabilityVSAvoidscrew position stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The resilient member is designed to be compressible along the longitudinal axis of the plate, allowing it to dynamically adapt to load changes. When compressive forces are applied to the plate, the resilient member compresses accordingly, maintaining constant pressure on the screw to prevent both rotation and axial movement, thereby preventing screw loosening under repetitive physiological loads

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system preemptively counteracts the harmful effects of screw loosening through multiple mechanisms: the resilient member pre-compresses to prevent axial backing out, the fin-groove interface pre-prevents counter-rotation, and the overall design anticipates repetitive loading conditions that would otherwise cause screw failure

Inventive Principle:

Principle #9Preliminary anti-action

2Stability of the object's composition

If additional fixtures or welding are used to prevent screw loosening, then screw position stability improves, but device complexity increases

Engineering Contradiction:

Improvescrew position stabilityVSAvoidfixation system complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Multiple anti-loosening functions are merged into a single integrated resilient member: axial compression to prevent backing out, rotational prevention through the fin-groove mechanism, and load distribution. This consolidation eliminates the need for separate fixtures, welds, or additional components, reducing device complexity while maintaining screw position stability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The resilient member serves multiple functions simultaneously: it acts as a spring to prevent axial movement, provides a mechanical interface for rotational prevention, distributes loads across the plate-screw-bone interface, and maintains constant compressive force. This multi-functionality eliminates the need for multiple specialized components

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9119681B2Spinal plate and locking screw devices, methods, and systems

Publication Date: 2015.09.01 GENESYS SPINE

AI summary

An embodiment of the invention provides for a system, such as a cervical plate fusion system, that has mechanisms for preventing bone screws from backing out of the plate. The system prevents both counter-rotation of the screw and axial backing out of the screw. Other embodiments are described herein.