Self-Locking Tether Clamping Assembly for Spinal Fixation
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Solution Overview
Problem
Current spinal fixation technologies require additional locking elements or steps to secure tethers around anatomical features, which can complicate surgical procedures and increase the risk of loosening or size changes in the tether loop.
Innovation Solution
A tether clamping assembly with inner and outer coupling pieces that utilize a wedge lock mechanism and friction differential between surfaces to self-lock the tether in place without additional locking features, allowing the tether to move in one direction while preventing movement in the opposite direction, thereby stabilizing the anatomical feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional locking elements are used to secure tethers, then the reliability of tether fixation is improved, but the device complexity and surgical procedure complexity increase
Solution Approach 1:
The tether clamping assembly utilizes the tether itself to provide the locking mechanism. The asymmetric friction surfaces create a self-locking action where the tether's own tension and movement generate the friction differential needed to secure it in place, eliminating the need for separate locking elements.
Solution Approach 2:
The invention changes the friction parameter by creating asymmetric friction surfaces with different coefficients of friction. This parameter change enables the tether to self-lock through friction differential, where one surface provides higher friction than the opposing surface, creating a mechanical lock without additional components.
2Reliability
If additional locking steps are implemented, then the reliability of tether fixation is improved, but the ease of operation deteriorates
Solution Approach 1:
The locking mechanism is self-executing through the surgical workflow. As the tether is threaded through the passage and tensioned, the asymmetric friction surfaces automatically engage and lock the tether in place without requiring additional manual locking steps or specialized instruments.
Solution Approach 2:
The asymmetric friction surfaces are pre-configured during manufacturing, with the higher friction surface positioned to engage first as the tether is inserted. This preliminary arrangement ensures that the locking action occurs automatically during the threading process, eliminating the need for post-installation locking steps.
3Reliability
If traditional locking mechanisms are used, then the reliability of tether fixation is improved, but the risk of loosening increases
Solution Approach 1:
The invention fundamentally changes the friction parameter by creating asymmetric friction surfaces. The higher friction surface is positioned to engage the tether first, creating a mechanical lock that resists loosening forces. This parameter change transforms the interaction from symmetric (equal friction both ways) to asymmetric (unequal friction creating lock).
Solution Approach 2:
The invention converts the potential harm of friction (which could allow sliding and loosening) into a beneficial locking mechanism. By strategically positioning surfaces with different friction coefficients, the friction that could cause unwanted movement is instead harnessed to create a secure, anti-loosening lock.
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 solution enables secure and stable fixation of tethers around spinal features or other anatomical structures without additional locking elements, reducing surgical complexity and the risk of loosening, while allowing for easy adjustment and readjustment of the tether loop.
Implementation Method 1
One or both passages may be configured to provide for a wedge lock of the tether therein. This may be provided, for example, by providing opposing surfaces defining the passage(s), which surfaces may be part of inner and outer surfaces of an outer and inner coupling piece of the assembly, respectively, that are tapered in the same direction relative to a central axis of the tether clamping assembly
Implementation Method 2
the first surface comprises a surface roughness greater than a surface roughness of the second surface, and wherein the first passage is configured such that the tether can be clamped in between the first surface and the second surface so as to allow the tether to move through the first passage in a first direction and lock the tether in place so as to at least substantially prevent the tether from moving through the first passage in a second direction opposite from the first direction
Data Source
AI summary
Tether clamping assemblies, such as clamping assemblies used to clamp a tether about a spinal feature to assist in spinal fixation, and related methods and systems. In some embodiments, the assembly may comprise a tether configured to engage a bone or other anatomical feature, an inner coupling piece, and an outer coupling piece. A first passage may be at least partially defined by an inner surface of the outer coupling piece and an outer surface of the inner coupling piece. The first passage may be configured such that the tether can be clamped in between the inner surface and the outer surface to allow the tether to move through the first passage in a first direction and lock the tether in place. The inner and outer surfaces preferably differ in surface roughness to facilitate automatic or self-locking of the tether in the assembly.