Spinal Rod Manipulator Lateral Force Application

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Solution Overview

Problem

Conventional rod persuader instruments face challenges in aligning spinal fixation rods due to non-linear arrangements of implants, limited visibility, and difficulty in applying force when the rod receiver body has a short profile length, leading to incomplete insertion and obstruction during set screw introduction.

Innovation Solution

A rod manipulator instrument with a gripping section and lever body that engages the spinal implant on one side, allowing force application to the rod outside the receiver body, maintaining visibility and enabling complete insertion without obstructing the top opening, using a pivoting mechanism and clamping extensions to secure the rod in place.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a rod persuader instrument attaches over the top of a rod receiver body to apply downward force, then sufficient force can be applied to position the rod in the saddle, but the instrument visually obstructs the opening in the saddle and limits visibility

Engineering Contradiction:

Improvedownward force on rodVSAvoidvisibility of saddle opening

Core Design Contradiction:

ForceVSIllumination intensity

Solution Approach 1:

Instead of applying force from above the rod receiver body, the instrument applies force from the side by engaging the rod externally. The lever body with rod carrier positions laterally against the rod, and pivoting motion applies downward force without obstructing the top opening, thus maintaining visibility while achieving the required force application.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The instrument transitions from a vertical engagement approach (attaching over the top) to a lateral engagement approach (engaging from the side). By positioning the rod carrier and gripping section in a lateral configuration, the instrument applies force through side engagement, eliminating visual obstruction of the saddle opening while maintaining effective force transmission to the rod.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Force

If a rod persuader instrument attaches over the top of a rod receiver body, then force can be applied to advance the rod, but there is limited surface area for gripping when the rod receiver body has a short profile length

Engineering Contradiction:

Improveforce to advance rodVSAvoidsurface area for gripping

Core Design Contradiction:

ForceVSArea of stationary object

Solution Approach 1:

Rather than gripping the top surface of the rod receiver body, the instrument engages the rod itself from the side. The rod carrier and gripping section contact the external surface of the rod, providing ample gripping area independent of the rod receiver body's profile length, thus enabling effective force application even when the receiver body is short.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The instrument uses the rod itself as an intermediary engagement point rather than directly gripping the rod receiver body. By engaging the rod externally through the rod carrier and gripping section, the instrument bypasses the limitation of short profile length on the receiver body, providing sufficient surface area for gripping and force application.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If conventional rod persuader instruments are used to align spinal fixation rods with non-linear implant arrangements, then rod insertion can be attempted, but incomplete insertion occurs and set screw introduction is obstructed

Engineering Contradiction:

Improverod alignment and insertionVSAvoidcomplete insertion and set screw introduction

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

Instead of pushing the rod from above through the saddle opening, the instrument engages the rod from the side and uses pivoting motion to guide it into the channel. This side-engagement approach allows the rod to be advanced completely into the channel without obstruction, and the top opening remains clear for set screw introduction, thus improving both ease of operation and reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The instrument employs a pivoting mechanism where the lever body rotates relative to the gripping section to apply controlled downward and forward force on the rod. This dynamic motion allows the rod to be guided smoothly into the non-linear channel arrangement, ensuring complete insertion while maintaining the top opening clear for subsequent set screw placement.

Inventive Principle:

Principle #15Dynamics

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 precise alignment and complete insertion of spinal fixation rods into receiver bodies with improved visibility and ease of use, reducing the risk of incomplete insertion and facilitating the introduction of set screws.

Implementation Method 1

The lever body is pivotally attached to the gripping section

Methodology Applied

Scientific EffectLever: Lever

Implementation Method 2

A rod manipulator instrument with a gripping section and lever body that engages the spinal implant on one side, allowing force application to the rod outside the receiver body

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentUS8211111B2Spinal rod manipulator instrument

Publication Date: 2012.07.03 AESCULAP IMPLANT SYSTEMS LLC

AI summary

An instrument for manipulating a spinal fixation rod includes a gripping section for engaging a spinal implant and a lever body pivotally attached to the gripping section. A rod carrier extends from one side of the lever body and is adapted to push a spinal fixation rod downwardly into the spinal implant.