Spinal Cage Expansion Apparatus with Cam Mechanism
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Solution Overview
Problem
Current spinal surgery expansion apparatuses lack the ability to adjust the intervertebral distance precisely in the vertical axis, necessitating non-customizable cage sizes that do not accommodate individual anatomical variations, and lack easy access and positioning mechanisms.
Innovation Solution
An expansion apparatus with a rotating body, a moving edge with 'cam' geometry, and protrusions that allows the operator to apply a rotational force to expand the cage in a preferred amount, adjusting the intervertebral distance by moving the movable part of the cage in the vertical axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed-size cages are used based on average vertebral distances, then manufacturing is simplified, but adaptability to individual patient anatomy is reduced
Solution Approach 1:
The cage incorporates an expandable mechanism that transforms it from a fixed-size component to a dynamic, adjustable structure. The cage can be compressed to a smaller insertion size and then expanded in-situ to various final dimensions, allowing a single cage design to adapt to different patient anatomies while maintaining manufacturing simplicity.
Solution Approach 2:
The cage design allows change in the physical parameter of size/dimension after implantation. By incorporating expandable elements that can be actuated post-insertion, the cage transitions from a single fixed dimension to multiple possible dimensions, enabling customization to individual patient needs without requiring multiple cage sizes to be manufactured.
2Adaptability or versatility
If expandable cages are used to accommodate different patient anatomies, then adaptability is improved, but device complexity increases
Solution Approach 1:
The cage is divided into multiple expandable segments or struts that can be independently actuated. This segmentation allows the complexity to be distributed across multiple simple, identical components rather than one complex monolithic structure, making the expandable mechanism more manageable and reliable.
Solution Approach 2:
The expandable cage employs a nested configuration where internal expandable elements are contained within the outer cage structure during insertion. Once positioned, these nested elements are deployed outward to achieve the final expanded configuration, allowing the complex expanded structure to be delivered through a simpler insertion form factor.
3Ease of operation
If a cam-based expansion mechanism is used, then ease of operation is improved, but access to the cage becomes more difficult
Solution Approach 1:
A cam-based mechanism serves as an intermediary between the simple rotational input from the surgeon and the complex multi-directional expansion movements required. The cam geometry translates easy rotational motion into the desired linear and radial expansion motions of the cage, maintaining ease of operation while managing the complexity of the expansion action.
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 of intervertebral distance, facilitates easy access and positioning of the expandable cage, and allows for customizable fit between vertebrae, addressing the limitations of existing technologies by providing a mechanism for adjusting the cage height during surgery.
Implementation Method 1
The body is provided thereon with two protrusions. The operator places the expansion apparatus in the space of the cage located between the vertebrae and applies a rotational force on the body such that the expandable cage will expand between the vertebrae in a preferred amount. The body rotates upon the applied force. With the rotation of the body, the moving edge disposed in the cage contacts with an extension comprised by the cage and makes the movable part of the cage move in vertical axis
Data Source
AI summary
An expansion apparatus is used in spinal surgery, and which opens the expandable cage located between the vertebrae during the operation in a preferred amount, and thus adjusts the distance between the vertebrae as desired.