Cervical Spine Fixation Device with Movable Cover and Asymmetric Profile
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Solution Overview
Problem
Cervical vertebra fixation devices face challenges in achieving effective screw insertion and fixation while minimizing side effects such as adjacent segment degeneration, where existing devices often result in inadequate coverage of the bone and increased risk of screw escape.
Innovation Solution
A cervical vertebra fixation device with a body having three or more openings for screw insertion, where the first end is designed with a convex profile and portions removed to reduce bone coverage, and a movable cover to prevent screw escape, allowing for angled screw placement and increased fixation force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the body of the fixation device covers a large area of the bone, then screw fixation force is improved, but adjacent segment degeneration is increased
Solution Approach 1:
The device applies local quality by creating a convex profile at the first end that concentrates screw fixation force at specific localized areas rather than distributing it uniformly across the entire bone surface. This allows strong fixation where needed while leaving adjacent segments uncovered to maintain their natural motion and prevent degeneration.
Solution Approach 2:
The convex profile segments the bone coverage into distinct zones: a covered zone at the first end for screw fixation and an uncovered zone at the second end to preserve adjacent segment function. This segmentation allows the device to fulfill its fixation purpose while minimizing harmful effects on adjacent segments.
2Reliability
If the cover is fixed to the body, then screw escape prevention is improved, but screw insertion difficulty is increased
Solution Approach 1:
The cover is designed with dynamic characteristics, being movable relative to the body during screw insertion. This allows the cover to be positioned out of the way during insertion operations and then moved into place to prevent screw escape, providing both ease of operation and reliability.
Solution Approach 2:
The cover is positioned and secured to the body before final screw insertion. This preliminary action ensures that the cover is in place to prevent screw escape, while the movable design allows it to be temporarily displaced during the insertion process itself.
3Ease of manufacture
If the first end is flat, then manufacturing simplicity is improved, but adjacent segment degeneration prevention is worsened
Solution Approach 1:
The device employs asymmetry by making the first end convex while the second end remains flat. This asymmetric design allows the first end to prevent adjacent segment degeneration through its profile, while the second end maintains manufacturing simplicity with a flat surface.
Data Source
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AI summary
Disclosed are a cervical vertebra fixation device using a plurality of screws characterized by comprising: a body having a length extending across at least two bones and including a first end and a second end opposite to the first end; and three or more openings formed in the body for receiving the plurality of screws, wherein the first end has a profile with at least a portion of the body being removed with respect to the horizontal line perpendicular to the length direction to prevent adjacent segment degeneration, and a cervical vertebra fixation device using at least one screw, comprising: a body fixed into a bone; at least one opening formed in the body for receiving the at least one screw; a cover for preventing any escape of the screws inserted; and a cover screw, wherein the cover is movable with respect to the body to allow the insertion of screws while the cover is coupled to the body.