Expandable Cervical Interbody Implant With Recessed Breakoff Screw
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Solution Overview
Problem
Conventional interbody implants for the cervical spine often have a large footprint and cumbersome mechanical mechanisms, and breakoff screws lack a recessed fracture surface, potentially damaging adjacent tissues.
Innovation Solution
An expandable interbody implant with hingedly connected superior and inferior endplates, a locking element, and a breakoff screw with a recessed fracture surface, allowing for external adjustment and secure insertion into the disc space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional mechanical mechanisms are used to separate endplates, then the implant provides structural support, but the footprint becomes large and the mechanism becomes cumbersome
Solution Approach 1:
The implant is divided into separate components including endplates, a body, and a locking mechanism that can be inserted and expanded separately within the disc space, reducing the initial footprint while maintaining structural support capabilities
Solution Approach 2:
The implant transitions from a compressed low-profile state during insertion to an expanded state after placement, allowing the structure to adapt its configuration based on the surgical phase, thereby minimizing footprint during insertion while providing adequate support when deployed
2Reliability
If breakoff screws are used for insertion, then secure fixation is achieved, but exposed fracture surfaces may damage adjacent soft tissues
Solution Approach 1:
The fracture surface that could potentially cause tissue damage is converted into a beneficial recessed feature that protects surrounding soft tissues while still providing the necessary mechanical breakoff function for secure fixation
Solution Approach 2:
The recessed fracture surface is designed in advance to prevent the sharp edges of the broken screw from contacting and damaging adjacent soft tissues, eliminating the harmful effect before it can occur
3Area of stationary object
If a compact design is used for cervical spine procedures, then the implant suits small disc spaces, but the mechanical locking mechanism must be simplified
Solution Approach 1:
The locking function is extracted from a complex mechanical system and simplified to a breakoff screw mechanism that provides adequate locking capability for cervical applications while minimizing the overall implant footprint
Solution Approach 2:
The locking mechanism parameters are optimized for cervical spine applications by using a breakoff screw design that provides sufficient fixation strength while reducing the complexity and size compared to thoracic/lumbar mechanisms
Data Source
AI summary
An expandable implant may include an expandable body defined by a superior endplate and an inferior endplate that are hingedly coupled and may be expanded and lordosed. The superior endplate may include a first core having a distal engagement surface and the inferior endplate may include a second core having a proximal engagement surface and a threaded screw aperture. The implant may include a threaded breakoff screw disposed in the threaded screw aperture and movable between a locked position and an unlocked position, for example. In the locked position, the threaded locking screw may urge the distal engagement surface of the first core into direct contact with the proximal engagement surface of the second core. When broken, the breakoff screw may comprise a recessed fracture surface.