Asymmetric Hexagonal Rod Insertion Device for Spine Surgery
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Solution Overview
Problem
In minimally invasive spine surgery, existing rod insertion devices face challenges in efficiently managing reduced available space and achieving strong, versatile connections with rods, particularly for curved rods used in treating kyphosis or lordosis, while also allowing for easy orientation and repositioning.
Innovation Solution
A rod insertion device with a slim design featuring a hexagonal connection portion that engages rods in specific positions, allowing for form-fit rotation and easy reorientation, and enabling connection with various rods of different diameters and shapes, including curved ones, facilitating precise placement and repositioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the rod insertion device is designed with a slim profile to accommodate reduced available space in minimally invasive surgery, then the device can be inserted through small incisions, but the connection strength and stability with the rod may be compromised
Solution Approach 1:
The connection portion is designed with an asymmetric hexagonal cross-section where the maximum height (in the vertical direction) is greater than the maximum width (in the horizontal direction). This asymmetric geometry allows the device to maintain a slim horizontal profile for minimally invasive insertion while providing sufficient vertical engagement depth to achieve strong connection strength with the rod.
2Adaptability or versatility
If the rod insertion device allows for rotation and repositioning of the rod to treat curved spine conditions, then the versatility and adaptability improve, but the device complexity increases
Solution Approach 1:
The hexagonal connection portion serves multiple functions: it provides form-fit engagement to prevent rotation, allows controlled rotation when needed for positioning curved rods, enables repositioning by disengagement and re-engagement, and maintains structural strength. This single geometric feature integrates several functions that would otherwise require separate mechanisms.
3Manufacturing precision
If the connection portion is designed with a polygonal cross-section for form-fit engagement, then the manufacturing precision and engagement accuracy improve, but the ease of manufacture decreases
Solution Approach 1:
The hexagonal cross-section with specific asymmetric dimensions (maximum height greater than maximum width) provides precise form-fit engagement to control rod orientation and prevent unwanted rotation. Despite the asymmetric geometry requiring precise manufacturing, the hexagonal shape can be efficiently produced using standard machining or forming processes, balancing precision requirements with manufacturing feasibility.
Data Source
AI summary
A system for spine surgery includes a rod with a longitudinal axis and a connection portion, and a rod insertion device including a rod holding member with a central axis and a rod engagement portion, wherein at least part of a shape of the rod engagement portion substantially matches at least part of a shape of the connection portion to engage the connection portion in a fixed manner at more than one distinct rotational orientation around the longitudinal axis. When the connection portion is engaged with the rod engagement portion, when viewed in a plane perpendicular to the longitudinal axis, a cross-section of the connection portion has a maximum height measured in a direction of the central axis of the rod holding member that is greater than a maximum width of the connection portion measured in a direction transverse to the longitudinal axis.