Spinal Interbody Locking Plate and Pawl Mechanism
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Solution Overview
Problem
Existing expandable intervertebral spinal fusion devices collapse under patient weight, hindering bone fusion and stability in spinal surgery due to lack of a locking mechanism to prevent displacement.
Innovation Solution
A stand-alone expandable interbody spinal fusion device with a locking mechanism comprising a plate and pawl system that engages through-bores and teeth to prevent the superior component from reversing direction, ensuring the device remains expanded and stable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an expandable intervertebral spinal fusion device is used to provide immediate stability and support bone fusion, then the device can be inserted in a compressed state and expanded to restore disc space height, but the device collapses under patient weight due to lack of a locking mechanism
Solution Approach 1:
The device is divided into superior and inferior components that can be independently positioned and locked relative to each other. The locking mechanism segments the stabilization function from the expansion function, allowing the device to be inserted in a compressed state, expanded to restore disc space height, and then locked to prevent collapse under patient weight.
Solution Approach 2:
The locking mechanism is pre-configured with engagement features (teeth and pawls) that are initially disengaged to allow expansion. After the device is expanded to the desired disc space height, the locking mechanism is activated to prevent collapse. This preliminary configuration allows the device to be inserted in a compressed state and then locked after expansion.
2Reliability
If a locking mechanism is added to prevent device collapse, then the device can maintain its expanded state and provide spinal stability, but the device complexity increases
Solution Approach 1:
The locking mechanism is integrated into the superior and inferior components of the device, merging the locking function with the existing structural elements. The teeth are formed on the superior component and the pawls on the inferior component, eliminating the need for separate locking assemblies and reducing overall device complexity.
Solution Approach 2:
The locking mechanism is designed to be self-activating through the expansion process itself. As the superior component is displaced relative to the inferior component during expansion, the pawls automatically engage with the teeth to lock the device in its expanded state. This self-service approach eliminates the need for additional actuators or complex control systems.
Data Source
AI summary
A stand-alone expandable interbody spinal fusion device, including a superior component, an inferior component, an expansion mechanism operatively arranged to displace the superior component in a first direction relative to the inferior component about a first hinge, and a locking mechanism. The locking mechanism including a plate operatively arranged to pivot about a second hinge, the plate further including a first through-bore and a first plurality of teeth, a pawl operatively arranged to pivot about a third hinge, the pawl further including a second through-bore, and a post operatively arranged to pass through the second and third through-bores such that after the superior component is displaced in the first direction, the locking mechanism prevents displacement of the superior component in a second direction, opposite the first direction.