Expandable Spinal Cage with Rack Mechanism for Height Adjustment
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Solution Overview
Problem
Current spinal surgical devices lack effective mechanisms for adjusting and securing expandable cages between vertebrae to promote spinal fusion, particularly in variable anatomical spaces, which can lead to inadequate support and fusion outcomes.
Innovation Solution
An expandable cage apparatus comprising first and second supporting members that move relative to each other, with an expansion member maintaining their position, and a tool for adjusting and securing the cage using a driver and rack mechanism, allowing for customizable height adjustment and fixation between vertebrae.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-size spinal cage is used, then the device structure is simple, but it cannot accommodate variable anatomical spaces between vertebrae
Solution Approach 1:
The spinal cage is designed with expandable features, allowing it to change size dynamically. The cage includes expansion mechanisms such as movable panels or telescoping structures that enable adjustment of the cage dimensions to match varying anatomical spaces between vertebrae, transforming a static structure into an adaptable one.
Solution Approach 2:
The cage is divided into multiple segments or panels that can move independently relative to each other. This segmentation allows the cage to expand or contract by moving the panels apart or together, providing adaptability to different spinal dimensions while maintaining structural integrity through the modular design.
2Adaptability or versatility
If an expandable cage mechanism is added, then adaptability to anatomical spaces is improved, but the device complexity increases
Solution Approach 1:
The expansion mechanism is nested within the cage structure itself, with movable panels or telescoping elements integrated into the cage walls. This nesting approach allows the expansion mechanism to be compact when not in use and eliminates the need for separate external expansion devices, reducing overall system complexity.
Solution Approach 2:
A simple intermediary component such as a compression spring, elastic element, or mechanical latch is used to mediate the expansion and locking functions. These intermediary elements provide the necessary mechanical advantage and locking capability without requiring complex actuation systems, maintaining device simplicity while enabling expandability.
3Measurement precision
If manual adjustment of cage position is used, then the device structure is simple, but surgical time and precision are reduced
Solution Approach 1:
The cage is pre-adjusted to specific dimensions and configurations before surgery. Multiple pre-sized cage options or pre-configured expansion settings are provided, allowing the surgical team to select and install the appropriate cage size without requiring complex intraoperative adjustments, thereby reducing surgical time while maintaining positioning precision.
Solution Approach 2:
Manual mechanical adjustment is replaced with self-adjusting or automatically positioning mechanisms. For example, the cage may include self-locking features, elastic memory components, or interface geometries that automatically align and secure the cage in the correct position upon insertion, eliminating the need for time-consuming manual positioning while ensuring precise placement.
Data Source
AI summary
An apparatus supports the spine between vertebrae and promotes spinal fusion. The apparatus generally includes a first supporting member, a second support member, and an expansion member. The first support member has a first longitudinal passage extending therethrough, a first supporting end configured to engage tissue, and a rack configured to engage a tool. The second supporting member contains a second longitudinal passage extending therethrough and a second supporting end configured to engage tissue. The second longitudinal passage is dimensioned to receive at least a portion of the first supporting member. The first and second supporting members are configured to move with respect to each other. The expansion member is removably positioned between the first and second supporting members and is adapted to maintain the first and second supporting members in a fixed relative position.