Flexible Spinal Driver With Malleable Core For Challenging Angles

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Solution Overview

Problem

Current flexible bone screw drivers with straight shafts in their resting configuration require significant soft tissue retraction and overcome spring forces during screw insertion, leading to potential screw disengagement at challenging approach angles, especially near the chin or sternum during spinal procedures.

Innovation Solution

A flexible bone screw driver with a malleable core rod and interlocking segments allows for a perfectly in-line handle position, maintaining torque transmission and flexibility, reducing tissue retraction and overcoming natural straight configuration forces, enabling easier screw insertion and secure attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a straight-shaft instrument is used to insert screws through the cage, then the instrument can maintain a stable structure and transmit torque effectively, but it produces challenging approach angles when operating near the patient's chin or sternum

Engineering Contradiction:

Improveapproach angleVSAvoidinstrument structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The instrument shaft is divided into multiple interlocking segments that can flex relative to each other, allowing the distal tip to reach challenging angles while the proximal handle remains stable for torque transmission

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The instrument transitions from a static straight shaft to a dynamic flexible shaft that can adapt its configuration, bending at the interlocking segments to navigate around anatomical structures while maintaining operational stability

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If a flexible inserter instrument with interlocking segments is used to achieve flexibility, then the handle can be positioned off-axis from the screw trajectory, but the spring force of the flex segment must be overcome and may cause screw disengagement

Engineering Contradiction:

Improvehandle positioningVSAvoidscrew retention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The drill guide is pre-positioned in the cage before screw insertion, establishing the correct trajectory in advance. The flexible shaft is then configured to match this pre-established path, allowing smooth insertion without overcoming spring forces that would disengage the screw

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The drill guide acts as an intermediary that defines the screw trajectory and guides the flexible shaft, mediating between the off-axis handle position and the on-axis screw insertion path

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the flexible shaft is straight in its resting configuration, then the instrument structure is simple, but significant soft tissue retraction is required to engage the tip into the drill guide

Engineering Contradiction:

Improveshaft configurationVSAvoidsoft tissue retraction

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The shaft is given a pre-bent curved configuration that matches the natural anatomy and drill guide trajectory, eliminating the need to retract soft tissue to accommodate a straight shaft while maintaining structural simplicity

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 flexible driver facilitates precise screw placement with reduced tissue retraction and improved torque transmission, enhancing surgical efficiency and reducing the risk of screw disengagement at difficult angles.

Implementation Method 1

a flexible shaft comprising a plurality of interlocking segments carried on a flexible core rod

Methodology Applied

Scientific EffectMalleability: Plasticity

Implementation Method 2

The flexible shaft allows a screwdriver handle to be perfectly in-line with the cage inserter if desired, while still taking advantage of the tactile feel and torque transmission of the flex segment in its bent position

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

an intermediate shaft comprising: i) a plurality of interlocking segments, each segment having a throughhole

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 4

The flexible shaft allows a screwdriver handle to be perfectly in-line with the cage inserter if desired, while still taking advantage of the tactile feel and torque transmission of the flex segment

Methodology Applied

Scientific EffectMechanical coupling: Mechanical Force

Data Source

PatentUS11045210B2Flexible spinal driver or drill with a malleable core, and/or fixed core radius

Publication Date: 2021.06.29 DEPUY SYNTHES PROD INC

AI summary

The improvement is a spinal instrument (preferably, a bone screw driver) having a flexible shaft comprising a plurality of interlocking segments carried on a malleable core rod. The flexible shaft allows a screwdriver handle to be perfectly in-line with the cage inserter if desired, while still taking advantage of the tactile feel and torque transmission of the flex segment in its bent position. Accordingly, a surgeon can limit the amount of retraction and keep the driver handle close to the inserter without having to overcome the forces of the flexible segments' natural straight configuration.