3D-Printed Cervical Implant With Rotating Screw Lock
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Solution Overview
Problem
Existing intervertebral implants face issues such as screw trajectories directing screws into vertebrae at shallow angles, requiring separate components for assembly, and locking mechanisms that can become disengaged over time.
Innovation Solution
A monolithic intervertebral implant with a locking element that is integrated through additive manufacturing, featuring rotatable and secure fastener openings and a locking mechanism that prevents backout, allowing for single-step assembly and enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional separate components are used for cage assembly, then manufacturing flexibility is maintained, but assembly complexity increases and single-step assembly is not achieved
Solution Approach 1:
The locking element and cage are merged into a single monolithic structure formed by additive manufacturing. The locking element is integrated within the cage body, eliminating the need for separate assembly steps while maintaining manufacturing flexibility through digital design and 3D printing processes.
Solution Approach 2:
The monolithic implant structure serves multiple functions simultaneously: the cage body provides intervertebral support and spacing, while the integrated locking element provides screw retention. This multi-functionality is achieved through a single manufactured component that combines both structural and locking functions.
2Ease of operation
If locking mechanism is exposed on one side of the cage, then access for operation is improved, but reliability decreases due to risk of disengagement
Solution Approach 1:
The locking element is nested within the cage body, with only the necessary operational portions exposed. The locking mechanism is housed inside the monolithic structure, protecting it from disengagement while maintaining access for screw insertion and locking operations through strategically positioned openings.
Solution Approach 2:
The locking element is extracted as a separate functional component within the monolithic structure, allowing it to be positioned and oriented optimally for both operation and retention. The locking element can rotate between operational positions and secured positions, providing both ease of operation and reliability.
3Ease of operation
If screw openings provide straight trajectory, then ease of screw insertion is improved, but screw engagement quality deteriorates due to shallow angle
Solution Approach 1:
The screw openings are designed with asymmetric trajectories that angle downward toward the corners of the vertebra. This asymmetric geometry optimizes screw engagement by directing screws into the densest bone regions, improving pull-out strength while maintaining ease of insertion through the monolithic structure's integrated design.
Data Source
AI summary
In one embodiment, an intervertebral implant includes a body and a locking element. The body includes a leading surface and a trailing surface opposite the leading surface. The body also includes first and second bone fastener passageways through the implant body and a cavity in between the first and second passageways. The cavity includes a trailing wall that separates the cavity from the trailing surface. The locking element is disposed in the cavity such that part of the locking element is visible through an access opening in the trailing wall so that the locking element may be rotated from outside of the implant. In a first rotational position, a first part of the locking element is located within one of the first and second passageways and in a second rotational position, the first part of the locking element is inside the body covered by the trailing wall.