Adjustable Intervertebral Spacer with Cam and Ramp Mechanism
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Solution Overview
Problem
Existing technologies face challenges in providing stable support for the spinal column, particularly in addressing weaknesses caused by degenerative diseases, tumors, fractures, and dislocations, where traditional spacers may not adequately adjust to maintain optimal spinal alignment and stability.
Innovation Solution
The development of an adjustable intervertebral spacer with first and second endplates, cams, slides, a threaded shaft, and a nut mechanism that allows for the relative movement of cams and ramps to increase the spacer's height, providing customizable support between adjacent vertebrae.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional fixed-height spacer is used, then the implantation procedure is simple, but the spacer cannot adequately adjust to maintain optimal spinal alignment and stability
Solution Approach 1:
The spacer transitions from a static fixed-height design to a dynamic adjustable-height design. The mechanism includes a threaded rod that can be rotated to change the distance between the first and second endplates, allowing the spacer to adapt to different spinal alignment requirements while maintaining structural integrity
Solution Approach 2:
The spacer is divided into multiple functional segments: first and second endplates for bone engagement, cams for force transmission, ramps for height adjustment, and a threaded rod mechanism for controlled expansion. This segmentation allows each component to perform its specific function while contributing to the overall adjustability
2Manufacturing precision
If multiple spacers of different heights are prepared, then optimal spinal alignment can be achieved, but the number of implants and tissue disruption increases
Solution Approach 1:
Instead of using multiple static spacers of different heights, a single dynamic spacer is used that can be adjusted intraoperatively to any required height. The threaded rod mechanism allows precise control of the spacer height, eliminating the need to prepare and implant multiple spacers of different sizes
Solution Approach 2:
The spacer height parameter can be continuously changed during implantation by rotating the threaded rod. This allows the same physical spacer to provide multiple height configurations, replacing the need for multiple spacers with different fixed dimensions
3Ease of operation
If an adjustable mechanism is added to the spacer, then spinal alignment can be optimized, but the device complexity and implantation time increase
Solution Approach 1:
The adjustable mechanism allows real-time modification of spacer height during implantation. The threaded rod can be rotated with a simple tool to expand or compress the spacer, enabling quick adjustments without requiring complex procedures or multiple surgical steps
Solution Approach 2:
The spacer mechanism is designed to be self-adjusting through the threaded rod system. Once the spacer is inserted between the vertebrae, the height can be modified by rotating the threaded rod, which automatically drives the cams and ramps to change the endplate distance without requiring additional components or complex operations
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
This adjustable spacer effectively enhances spinal stability and alignment by allowing for precise adjustment of the spacer's height, reducing the need for multiple spacers and minimizing tissue disruption during implantation, while promoting bone fusion and maintaining disc height.
Implementation Method 1
a threaded shaft having a second hinge portion cooperative with the first hinge portion to connect the shaft to the second slide and to enable the shaft to form a changeable angle with respect to the second slide; a nut threadably engaged with the shaft, the nut forming an interference with the angled portion of the first slide when the nut is threadably advanced upon the shaft, thereby driving the first slide with respect to the second slide
Implementation Method 2
at least two cams each having an inclined cam surface, the cams positioned on a side opposite to the bone engaging surface; first and second slides, each having at least two ramps each having an inclined surface and each engaged with an inclined cam surface of a cam of an endplate
Implementation Method 3
each having at least two ramps each having an inclined surface and each engaged with an inclined cam surface of a cam of an endplate
Implementation Method 4
a threaded shaft having a second hinge portion cooperative with the first hinge portion to connect the shaft to the second slide and to enable the shaft to form a changeable angle with respect to the second slide
Data Source
AI summary
A joint spacer has first and second endplates, with each having a bone engaging surface, and at least two cams with an inclined cam surface positioned on an opposite side. First and second slides, each having ramps with an inclined surface are engaged with the cams of the endplate. The first slide has an angled portion at an end, and the second slide has a hinge portion. A threaded shaft has a hinge portion connected to the slide hinge portion, connecting the shaft to the slide, enabling the shaft to pivot. A nut is threaded to the shaft, and can contact and interfere with the angled portion of the first slide to drive the first slide with respect to the second slide. This results in engagement of the cams and ramps to drive the endplates apart to increase the spacer height.