Spinal Implant Sliding Rod for Growth-Adaptive Correction
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Solution Overview
Problem
Current treatments for scoliosis, which involve implanting a high-stiffness rod to correct spinal curvature, often result in reduced spinal flexibility, impaired growth, and the need for re-operations due to decreasing corrective force over time as the spine grows, and do not effectively prevent vertebrae fusion.
Innovation Solution
An implantation system with an elongated element featuring a resilient U-shaped or helically shaped portion, allowing for sliding bone fixation elements that maintain or increase corrective force action as the spine grows, preventing vertebrae fusion and enhancing spinal flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high-stiffness rod is implanted to correct spinal curvature, then the corrective force action is strong initially, but the spinal flexibility is reduced and vertebrae fusion occurs
Solution Approach 1:
The rod transitions from a static high-stiffness structure to a dynamic system where the rod can slide within the anchoring elements. This sliding capability allows the rod to adjust its position as the spine grows, maintaining corrective force while permitting controlled spinal movement and flexibility.
Solution Approach 2:
The system changes the effective stiffness parameter over time. Initially, the rod provides high corrective force with limited movement. As the spine grows and the rod slides within the anchoring elements, the system allows increased spinal flexibility while maintaining adequate corrective force through the sliding mechanism.
2Stability of the object's composition
If a high-stiffness rod is implanted to secure corrected curvature, then the implant provides initial stability, but the corrective force decreases over time as the spine grows
Solution Approach 1:
The rod is designed to slide within the anchoring elements as the spine grows. This dynamic sliding mechanism allows the rod to maintain tension and corrective force over time, compensating for spinal growth and preventing the loss of corrective force that occurs with fixed-position implants.
Solution Approach 2:
The rod automatically adjusts its position within the anchoring elements in response to spinal growth. This self-adjusting mechanism maintains corrective force without requiring external intervention or reoperation, allowing the implant to serve itself throughout the growth period.
3Reliability
If a high-stiffness rod is used to stabilize the spine, then fusion of vertebrae is stimulated, but spinal flexibility and natural growth are impaired
Solution Approach 1:
The sliding mechanism allows the rod to move relative to the anchoring elements as the spine grows. This dynamic capability permits natural spinal growth and flexibility while the rod maintains stabilization through its sliding tension, avoiding the complete immobilization caused by fixed high-stiffness rods.
Solution Approach 2:
The system allows changes in spinal length and flexibility parameters over time as the patient grows. The rod's sliding capability enables these parameter changes while maintaining adequate stabilization force, adapting the system's mechanical properties to the changing physiological requirements.
4Ease of operation
If the rod stiffness is reduced to improve flexibility, then spinal flexibility increases, but the corrective force action decreases
Solution Approach 1:
The rod can be made of lower stiffness material since the sliding mechanism within the anchoring elements provides the necessary corrective force. The dynamic sliding action generates tension that compensates for the reduced material stiffness, allowing both flexibility and adequate corrective force.
Solution Approach 2:
The sliding mechanism acts as an intermediary between the rod and the anchoring elements. This intermediary mechanism amplifies the corrective force through the sliding tension, allowing a lower-stiffness rod to achieve the same corrective effect as a higher-stiffness fixed rod while providing greater flexibility.
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 system maintains spinal flexibility and natural growth while ensuring the effectiveness of the corrective treatment over time, reducing the need for re-operations by automatically adjusting the corrective force in response to spinal growth, thereby providing long-term stability and reliability.
Implementation Method 1
the elongated element has bending resilience and/or torsional resilience for resiliently applying in mounted condition of the implantation system corrective bending and/or torsional force action to said spinal column
Implementation Method 2
said sliding and contacting connection is present between the second bone fixation element and the elongated element for guiding the second bone fixation element relative to the elongated element
Data Source
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AI summary
An implantation system for treatment of a defective curvature of the spinal column comprises an elongated element (2), a first bone fixation element (31) being fixedly attached to said elongated element, a second bone fixation element (32, 33), and guiding structure (45, 50) through which the second bone fixation element is slidably and contactingly connected to the elongated element. The elongated element has bending resilience and/or torsional resilience for applying corrective force action to the spinal column. A special arrangement of the guiding structure (45, 50) provides automatical adjustment of the corrective force action in dependence of growth of the spinal column. The system allows for good flexibility of the spine and for a natural healthy growth of the spine, while it avoids re-operations and implant adjustments.