Shape Memory Alloy Spinal Rods for Misaligned Screw Fixation
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Solution Overview
Problem
Conventional spinal fixation apparatuses face challenges in aligning pedicle screws and rods, leading to difficulties in connecting them securely, especially when the screws are not in a straight line, which complicates surgery and may result in instability and increased costs due to non-standardized rod shapes and high complexity in assembly.
Innovation Solution
The use of shape memory alloy rods and transverse links that can deform at specific temperatures, allowing for flexible alignment and secure connection to pedicle screws, even when they are not perfectly aligned, and providing elastic support to maintain spinal correction with reduced parts and simplified installation procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rigid rods and transverse links are used for spinal fixation, then the structural strength is maintained, but the alignment precision and ease of connection deteriorate when pedicle screws are not perfectly aligned
Solution Approach 1:
The rod and transverse link are made from shape memory alloy that changes its physical state (phase transformation) in response to temperature changes. This allows the rod to be pre-deformed at lower temperatures for easy insertion and connection, then automatically returns to its memorized shape at body temperature to provide rigid fixation, resolving the contradiction between ease of connection and structural strength
Solution Approach 2:
The rod transitions from a flexible, deformable state during installation to a rigid, shape-memory state during fixation. This dynamic property allows the same component to provide both ease of operation during surgery and reliable structural support after implantation
2Adaptability or versatility
If non-standardized rod shapes are used to accommodate individual spinal curvatures, then the adaptability improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
A single standardized rod design with shape memory alloy properties can accommodate various spinal curvatures through its temperature-induced shape transformation. The rod is pre-deformed to match individual patient anatomy during installation, then automatically returns to its memorized shape, eliminating the need for multiple standardized rod shapes while maintaining adaptability
Solution Approach 2:
The rod automatically adapts to the patient's spinal curvature through its shape memory properties without requiring manual adjustment or pre-forming by the surgeon. The rod self-adjusts to the memorized shape after insertion, reducing surgical complexity and eliminating the need for multiple customized rod designs
3Manufacturing precision
If multiple surgical steps are used for rod connection and alignment, then the connection precision can be improved, but the surgical time and operational complexity increase
Solution Approach 1:
The rod is pre-deformed at lower temperatures before surgery to match the patient's spinal anatomy, and the shape memory properties are activated during or after implantation. This preliminary preparation eliminates the need for complex intraoperative adjustment procedures while maintaining connection precision
Solution Approach 2:
The traditional mechanical process of manual rod bending and shaping during surgery is replaced by the shape memory alloy's automatic shape transformation. This substitution eliminates time-consuming manual deformation steps while ensuring precise anatomical alignment through the material's inherent memory function
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 easy and secure connection of rods to pedicle screws, reduces the number of surgical steps, and provides flexible support to maintain spinal alignment, thereby simplifying surgery and reducing complications and costs.
Implementation Method 1
The use of shape memory alloy rods and transverse links that can deform at specific temperatures, allowing for flexible alignment and secure connection to pedicle screws
Implementation Method 2
providing elastic support to maintain spinal correction with reduced parts and simplified installation procedures
Data Source
AI summary
The present invention relates to a spinal fixation apparatus having a segment flexible rod for connecting pedicle screws and a transverse link for spacing out the rods, which are made from a shape memory alloy, thereby easily and simply connecting the rods and the pedicle screws. According to the present invention, it can easily and simply fit the rods to the misaligned pedicle screw, even if it may be a failure of alignment of the pedicle screws in surgery. Also, it can easily set up the transverse link on a pair of the longitudinal rods, even if the longitudinal rods are declined or are not in parallel.