Spinal Fixation Device With Pivot Inhibitor

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Solution Overview

Problem

Current spinal fixation devices lack directional control over the angle between the fastening and receiving portions, limiting the precision and flexibility in manipulating the spine during surgical corrections of spinal deformities.

Innovation Solution

A spinal fixation device with a dual-layered housing system and a pivot inhibitor that allows selective rotation and pivoting of the screw, inhibiting pivoting in specific directions to control the angle, enabling precise alignment and stabilization of the spinal rod.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a multi-axial or poly-axial head portion is used to allow one or more degrees of freedom between fastening and receiving portions, then the precision of placement and flexibility in assembling the rod construct is improved, but the device loses directional control over the angle between fastening and receiving portions

Engineering Contradiction:

Improveflexibility in assembling rod constructVSAvoiddirectional control over angle

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The device employs a dynamic locking mechanism that transitions from an unlocked state (allowing multi-axial movement and flexibility during assembly) to a locked state (providing rigid directional control and angle maintenance). The poly-axial head portion can pivot freely during insertion, then is locked into a specific angular position to provide precise directional control when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The device changes its degrees of freedom parameter dynamically - during the assembly phase, it allows one or more degrees of freedom for flexibility, then transitions to a fixed angular position with zero degrees of freedom when locked, thereby providing directional control. This parameter change resolves the contradiction between flexibility during assembly and precision after assembly.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a larger maximum angle between fastening and receiving portions is provided for one position, then adaptability is improved, but the device complexity increases due to position-dependent angle limitations

Engineering Contradiction:

Improvemaximum angle between fastening and receiving portionsVSAvoidposition-dependent angle limitations

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The poly-axial head portion serves multiple functions: it allows flexible positioning during assembly, provides large maximum angles when needed, and maintains locked angular positions for stability. This single component handles both the adaptability requirement (large angles) and the simplicity requirement (no position-dependent limitations) by being universally applicable across different assembly scenarios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11589903B2Spinal fixation device

Publication Date: 2023.02.28 VB SPINE LLC

AI summary

A spinal fixation device includes an inner housing, an outer housing, a screw, and a pivot inhibitor. The outer housing is circumferentially disposed around at least a portion of the inner housing, wherein the outer and inner housings are translatable relative to one another to cause transitioning of the spinal fixation device between a locked configuration and an unlocked configuration. The screw including a screw head pivotably coupled to a lower portion of the inner housing and a shaft extending from the screw head. The pivot inhibitor is coupled to one of the inner housing or screw, such that pivoting of the inner housing about the screw head is inhibited in a direction of the pivot inhibitor.