Tapered Cannula Fixation Assembly for Spinal Screw Insertion
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Solution Overview
Problem
Current spinal fixation systems face challenges in efficiently inserting screws into vertebrae without breaching the bone, which can lead to nerve damage and require additional surgeries for screw redirection, increasing time and labor and risking vertebral body damage.
Innovation Solution
A fixation assembly comprising a tapered cannula and a post secured with a snap ring, allowing for axial fixation and rotation, which limits distal movement and prevents breaching by facilitating secure insertion into osseous tissue while protecting spinal nerves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a screw is inserted into the vertebral body to fix the spine, then spinal stabilization is achieved, but the screw may breach the vertebral body and damage spinal nerves
Solution Approach 1:
The patent introduces a guide cannula as an intermediary tool that is inserted into the vertebral body first to establish a safe insertion path. The guide cannula serves as a mediator between the screw and the vertebral body, allowing the screw to be inserted along a pre-defined trajectory that avoids nerve damage while maintaining fixation reliability
Solution Approach 2:
The guide cannula is inserted and positioned in advance before the screw insertion. This preliminary action creates a protective tunnel or pathway within the vertebral body that guides the subsequent screw insertion, preventing the screw from breaching the vertebral body and damaging nerves while ensuring proper fixation
2Object-affected harmful factors
If the screw breaches the vertebral body and redirection is required, then nerve protection is achieved, but additional surgery time and labor are required
Solution Approach 1:
The guide cannula is inserted and positioned in advance before the screw insertion. This preliminary action creates a protective tunnel or pathway within the vertebral body that guides the subsequent screw insertion, preventing the screw from breaching the vertebral body and damaging nerves while ensuring proper fixation
Solution Approach 2:
The guide cannula provides real-time feedback during screw insertion by physically guiding the screw along a safe trajectory. The cannula acts as a feedback mechanism that prevents deviation from the correct path, eliminating the need for post-breach redirection surgery and reducing overall surgical time
3Object-affected harmful factors
If redirection of the screw is performed to protect nerves, then nerve damage is prevented, but vertebral body integrity is compromised
Solution Approach 1:
The guide cannula serves as a mediator that protects the vertebral body integrity during screw insertion. By providing a pre-defined insertion pathway, the cannula ensures the screw enters the vertebral body through optimal entry points, preventing breaches that would require redirection and compromise bone structure
Solution Approach 2:
The guide cannula is inserted and positioned in advance before the screw insertion. This preliminary action creates a protective tunnel or pathway within the vertebral body that guides the subsequent screw insertion, preventing the screw from breaching the vertebral body and damaging nerves while ensuring proper fixation
Data Source
AI summary
A fixation assembly includes a tapered cannula, a post, and a snap ring. The snap ring is attachable to the post and the tapered cannula. The snap ring is configured to maintain the tapered cannula axially fixed in relation to the post such that the tapered cannula and the post are rotatable relative to each other.