Progressive Metallic Spring for Vertebral Stabilization
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Solution Overview
Problem
Existing vertebral stabilization devices either require complex manufacturing processes or use biocompatible materials with linear spring characteristics, limiting their ability to provide adequate elastic yielding and damping, and often result in overload of posterior elements under high compressive forces.
Innovation Solution
A device featuring a single metallic spring element with progressive spring characteristics, constructed as a helical spring with varying coil pitch or cross-sectional areas, or a meander-shaped spring with different spring coils and restraining means, allowing for continuous elastic deformation and fixation to bone anchoring means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single metallic spring element with progressive spring characteristics is used, then elastic yielding and damping at small compressive forces is improved, but manufacturing complexity increases due to varying coil pitch or cross-sectional areas
Solution Approach 1:
The spring element features varying coil pitch or cross-sectional areas at different locations along its length, creating local quality variations that produce progressive spring characteristics. This allows different sections of the spring to have different stiffness properties, enabling elastic yielding at small forces while maintaining structural integrity at high loads.
Solution Approach 2:
The spring design incorporates continuous parameter changes in coil pitch or cross-sectional area along the spring length, transforming a uniform spring into a progressive spring. This parameter variation enables the spring to provide appropriate elastic response across a wide range of compressive forces without requiring multiple discrete spring elements.
2Ease of manufacture
If biocompatible materials with linear spring characteristics are used, then manufacturing is simplified, but adequate elastic yielding and damping at small compressive forces is limited
Solution Approach 1:
Rather than using a uniform linear spring, the invention applies local quality variations through changing coil pitch or cross-sectional area along the spring length. This allows the spring to provide enhanced elastic yielding and damping at small forces while maintaining biocompatibility and manufacturability of the single-element structure.
3Ease of manufacture
If conventional helical springs with uniform characteristics are used, then manufacturing is easier, but overload of posterior elements occurs under high compressive forces
Solution Approach 1:
The spring incorporates continuous parameter changes in coil pitch or cross-sectional area that create progressive spring characteristics. This ensures that under high compressive forces, the spring provides adequate support without allowing excessive compression that would overload the posterior elements, while still being manufacturable as a single element.
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 sufficient elastic yielding and damping at low compressive forces, maintaining spinal column mobility while preventing overload under high loads, with continuous progressive spring characteristics achieved using a single biocompatible material like titanium.
Implementation Method 1
a single spring element made from a metallic material and that has progressive spring characteristics under compressive forces
Implementation Method 2
sufficient elastic yielding and damping at small compressive forces
Data Source
AI summary
A device for elastically stabilizing vertebral bodies includes at least two bone anchoring means, each having a central axis and a head segment. The device also includes elastic means that can be joined to the head segments of two adjacent bone anchoring means in such a manner that the longitudinal axis of the elastic means extends transversely to the central axes of the bone anchoring means. Under compressive loads, the elastic means has a progressive spring characteristic. The elastic means is manufactured from a metallic material and has a plurality of spring coils, of which at least two spring coils have a geometric dimension which is different from the other spring coils.