Expandable Cervical Interbody Wedge Screw Mechanism
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Solution Overview
Problem
Conventional expandable implants for the cervical spine in ACDF procedures are limited in adjusting lordosis and sagittal alignment due to cumbersome mechanical mechanisms and fixed lordotic angles, making them unsuitable for optimal alignment and fusion.
Innovation Solution
An expandable implant system with hingedly coupled superior and inferior endplates, featuring a locking mechanism and an external surgical tool for adjusting the implant's angle and expansion, allowing for customizable lordosis and sagittal alignment through a wedge and screw mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional mechanical mechanisms are used to separate endplates, then the implant can be expanded, but the mechanism becomes cumbersome and requires a large footprint
Solution Approach 1:
The patent extracts the expansion function from a complex mechanical mechanism and implements it through a simple screw thread system. The screw thread directly converts rotational motion into linear separation of the endplates, eliminating the need for cumbersome mechanical components while maintaining the expansion capability and maximizing internal volume for bone grafting.
Solution Approach 2:
The patent replaces complex mechanical separation mechanisms with a threaded screw system. Instead of using cam locks, lever systems, or hydraulic mechanisms, the invention uses a simple screw thread that directly engages with the endplates to achieve controlled separation and expansion, significantly reducing device complexity.
2Adaptability or versatility
If fixed lordotic angle implants are used, then manufacturing is simplified, but the ability to optimize spinal alignment is limited
Solution Approach 1:
The patent implements a dynamic adjustment system where the lordotic angle can be modified after implant insertion. The screw mechanism allows the superior and inferior endplates to be separated and repositioned at different angles, enabling post-operative optimization of spinal alignment without requiring a complex pre-set adjustable mechanism.
Solution Approach 2:
The implant is segmented into a superior endplate, an inferior endplate, and a connecting body with a screw mechanism. This segmentation allows independent positioning of each endplate relative to the other, enabling adjustment of lordotic and sagittal alignment while keeping each component relatively simple in design.
3Area of stationary object
If a reduced footprint implant is used for ACDF, then anatomical disruption is minimized, but the expansion mechanism becomes more difficult to implement
Solution Approach 1:
The screw mechanism is designed to be self-contained within the implant body, requiring no external tools or complex instrumentation for operation. The surgeon can directly manipulate the screw to expand the implant after insertion, making the system easy to operate despite the reduced footprint, and the mechanism serves itself without requiring additional mechanical components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise adjustment and secure fixation of the implant at a desired angle, optimizing spinal alignment and fusion while minimizing anatomical disruption, with a reduced footprint for easier insertion and expanded internal volume for bone grafting.
Implementation Method 1
the wedge pin and groove are configured to prevent overexpansion of the implant and to maintain an angular position of the superior endplate relative to the inferior endplate
Implementation Method 2
the superior endplate and the inferior endplate are pivotally connected; the inferior endplate may include a hinge member
Implementation Method 3
the superior endplate may include an arcuate channel, a ramp having an inclined surface coaxially in line with a support frame
Data Source
AI summary
A system including an implant and a tool for inserting and expanding the medical implant and locking the implant in place is disclosed. The medical 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 implant may include a wedge disposed between the superior and inferior endplates that is configured to slide across a channel on inferior endplate and along an inclined groove on superior endplate. In at least some embodiments, an expansion screw is operative coupled to the threaded portion of the wedge that when expansion screw is rotated, the wedge is translated thereby expanding the implant.