Spinal Rod Biasing Coil and Ratchet for Progressive Curvature Correction
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Solution Overview
Problem
Current surgical treatments for scoliosis, such as long fusion rods with pedicle screws, often fail to perfectly correct spinal deformity and are prone to failure, leading to suboptimal clinical outcomes.
Innovation Solution
A spinal device with a movable rod and a biasing mechanism comprising partial coils and a ratchet mechanism, allowing controlled protrusion and retraction, coupled with polyaxial-joint attachments for spinal fixation, to apply an urging force and adjust spinal curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a long fusion rod is used to force the deformed spine into a healthier position, then spinal deformity correction is achieved, but the treatment results in severe shortcomings including imperfect correction, lifelong fusion, and high failure rates
Solution Approach 1:
The spinal rod system is divided into modular segments including a housing, a movable rod with ratchet mechanism, and separate biasing devices. This segmentation allows each component to perform its specific function independently, improving reliability while reducing overall system complexity compared to a single long fusion rod.
Solution Approach 2:
The rod is made movable within the housing through a ratchet mechanism, allowing dynamic adjustment of rod protrusion. This dynamic capability enables progressive spinal correction and maintains flexibility, avoiding the rigidity of traditional long fusion rods while improving correction effectiveness.
2Adaptability or versatility
If a movable rod with ratchet mechanism is used to allow controlled protrusion and retraction, then spinal curvature adjustment is improved, but the device complexity increases due to additional mechanisms
Solution Approach 1:
The ratchet mechanism is contained within the housing as a separate module from the rod itself. This segmentation isolates the complexity of the adjustment mechanism, allowing the rod to remain simple while gaining adaptability through controlled movement capabilities.
Solution Approach 2:
The housing acts as an intermediary between the rod and the external environment, containing the ratchet mechanism and providing controlled interaction. This mediator allows the rod to be adjustable without exposing the full complexity of the ratchet mechanism, balancing adaptability with simplicity.
3Force
If a biasing device with partial coils is mounted on the rod, then the ability to apply urging force and maintain correction is enhanced, but the device complexity increases due to additional components
Solution Approach 1:
The biasing device is segmented into partial coils rather than a continuous spring, with each coil section providing localized force application. This segmentation reduces material usage and complexity while maintaining the essential force-generating function needed for spinal correction.
Solution Approach 2:
Instead of using a full 360-degree coil spring, partial coils subtending less than 360° are employed. This partial action provides sufficient urging force for spinal correction while reducing the complexity and size of the biasing device compared to a complete circular spring.
4Reliability
If axial fixation of the biasing device second end is used to determine pretension, then the reliability of force application is improved, but the ease of operation decreases due to fixation requirements
Solution Approach 1:
The axial fixation of the biasing device second end establishes pretension in advance during installation. This preliminary action ensures reliable force application from the start, while the fixation mechanism is designed to be set once during installation, minimizing ongoing operational complexity.
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
Enhances the ability to correct spinal deformity more effectively and maintain correction over time, reducing the risk of failure and improving clinical outcomes.
Implementation Method 1
a biasing device, mounted on the rod, which includes a series of connected partial coils
Data Source
Figure 1~4
AI summary
A spinal device includes a rod which has a first end disposed in a housing and a second end which protrudes out of the housing through an aperture and which is movable to protrude more out of the housing or less out of the housing. A biasing device, mounted on the rod, includes a series of connected at-least partial coils. A first end of the biasing device is arranged to abut against the housing and a second end of the biasing device, opposite to the first end, is affixed to the rod.