Flexible Spinal Rod with Dynamic Curvature for Load Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spinal implant systems struggle to effectively mimic the natural load-bearing and dynamic characteristics of the spine, particularly in supporting a full range of anatomical loads during flexion, extension, and lateral bending, while providing adequate fixation and sharing loads with anterior portions of the vertebrae.
Innovation Solution
A flexible spinal rod system comprising a retainer and a flexible shaft, where the retainer and shaft are designed to change curvature in response to physiological loads, allowing for non-linear load distribution and movement, with features such as adjustable curvature, materials like PEEK and Nitinol, and dampening elements to mimic natural spinal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid fixation system is used to stabilize spinal joints, then joint stability is improved, but natural spinal motion and load-bearing characteristics are lost
Solution Approach 1:
The spinal rod is designed with dynamic flexibility to allow motion and deformation under physiological loads. The rod can bend and articulate to accommodate natural spinal movements during flexion, extension, and lateral bending while still providing stabilization, thus resolving the contradiction between joint stability and natural spinal motion.
Solution Approach 2:
The rod's mechanical properties are optimized to change its stiffness and flexibility parameters in response to applied loads. The rod exhibits non-linear load distribution characteristics that allow it to adapt its rigidity dynamically, providing stability when needed while permitting natural motion under physiological conditions.
2Strength
If pedicle screws are used for fixation, then anchorage strength is improved, but the system fails to share loads with anterior portions of the spine
Solution Approach 1:
The flexible rod creates a dynamic load-sharing system that redistributes forces between anterior and posterior spinal structures. As the rod articulates and deforms under load, it naturally transfers portions of the mechanical load to anterior spinal elements, enabling physiological load sharing while maintaining strong pedicle screw anchorage.
Solution Approach 2:
The flexible rod acts as an intermediary mechanical element between the pedicle screws and the anterior spinal structures. Through its articulated motion and deformation, it mediates force transmission, allowing loads to be shared with anterior portions of the spine without compromising the anchorage strength of the pedicle screw fixation.
3Adaptability or versatility
If a flexible rod is used to mimic natural spinal characteristics, then load distribution is improved, but fixation stability may be compromised
Solution Approach 1:
The rod's mechanical parameters are specifically engineered to provide optimal load distribution across different spinal segments. By controlling the rod's flexibility, curvature, and material properties, the system achieves physiological load distribution patterns while maintaining sufficient fixation stability through the pedicle screw connections.
Solution Approach 2:
The flexible rod provides dynamic load distribution that adapts to varying physiological conditions and motion phases. The rod's ability to articulate and deform allows it to distribute loads more naturally across the spinal construct while the rigid pedicle screw anchors maintain fixation stability, resolving the contradiction between flexibility and stability.
4Force
If the rod is made rigid to support full ranges of motion, then load-bearing capacity is improved, but the system cannot share loads with anterior spine structures
Solution Approach 1:
The rod exhibits dynamic mechanical behavior that allows it to bear full ranges of motion loads while simultaneously sharing loads with anterior spine structures. Through articulated motion and controlled deformation, the rod transfers a portion of the applied loads to anterior spinal elements, achieving both high load-bearing capacity and physiological load sharing.
Solution Approach 2:
The flexible rod serves as a mechanical intermediary that couples the pedicle screw fixation system with the anterior spinal structures. Its articulated design enables it to transmit and distribute forces, allowing the rigidly fixed posterior elements to share loads with the more compliant anterior spine during full ranges of motion.
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
The flexible spinal rod system enables more accurate tracking of spinal motion and load distribution, sharing loads with anterior vertebrae and providing a non-linear force/displacement profile that closely mimics natural spinal resistance, enhancing the range of motion and load-bearing capabilities.
Implementation Method 1
The flexible shaft of some embodiments is configured to bend to change curvature along at least a portion of a length of the flexible shaft in response to normal physiological loads
Implementation Method 2
with features such as adjustable curvature, materials like PEEK and Nitinol, and dampening elements to mimic natural spinal resistance
Data Source
AI summary
Embodiments of the invention include a spinal construct for stabilizing a segment of a spinal column with a flexible spinal rod having one or more flexible components that articulate longitudinally and change curvature along at least a portion of their length in response to normal physiological loads.