Vertebral Fixation Separator Mitigates Torsional Forces

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Solution Overview

Problem

Existing vertebral fixation systems face instability due to excessive torque applied during installation, which can lead to loosening of pedicle screws and compromise the long-term stability of the fusion, causing potential disassembly of the vertebral fixation system.

Innovation Solution

The vertebral fixation system incorporates a separator device that is placed between the anchor device and the cross member, providing a larger surface area for securing the cross member, thereby reducing the transfer of torsional forces and maintaining the integrity of the installed system by distributing the force to the rod member, thus preventing loosening of the anchor devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multi-step installation process is used to fix vertebrae with pedicle screws and rods, then the fixation can be achieved, but excessive torque applied during installation may cause screws to loosen and reduce long-term stability

Engineering Contradiction:

Improvelong-term stability of fixation systemVSAvoidexcessive torque causing screw loosening

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A separator component is introduced between the cross member and the pedicle screw head. This separator acts as a mediator that prevents direct contact and torque transfer between the cross member and the screw, thereby protecting the screw from loosening while still allowing the fixation system to function. The separator absorbs the harmful torsional forces before they can reach the anchor device.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the cross member is secured directly to the anchor device head, then the fixation structure is simplified, but torsional forces are directly transferred causing anchor device loosening

Engineering Contradiction:

Improvefixation system structureVSAvoidanchor device stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The separator serves as an intermediary element placed between the cross member and the anchor device head. It breaks the direct force transmission path, allowing the cross member to be secured to the system while preventing harmful torsional forces from reaching the anchor device. This maintains both structural functionality and component stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The fixation system is segmented into distinct functional components: the anchor device for bone fixation, the separator for torque mitigation, and the cross member for structural connection. This segmentation allows each component to perform its specific function optimally without interfering negatively with other components.

Inventive Principle:

Principle #1Segmentation

3Reliability

If a separator device is added between the anchor device and cross member, then torsional force transfer is reduced, but the device complexity increases

Engineering Contradiction:

Improveresistance to torque-induced looseningVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The separator is a simple intermediary component that provides torque mitigation functionality. By introducing this single specialized element, the system achieves better reliability against torque-induced loosening without requiring complex mechanisms or multiple additional components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8920475B1Vertebral fixation system including torque mitigation

Publication Date: 2014.12.30 HIGHRIDGE MEDICAL LLC

AI summary

Various spinal fixation assemblies are presented that include a separator installable in relation to a coupler attached to the head of an anchor device, and disposable between the head of the anchor device and a cross member. The separators may be implemented in a variety of forms.