Spinal Surgery Bone Anchor Tool with Gear-Driven Torque Isolation

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Solution Overview

Problem

Existing tools for bone anchors, particularly in spinal surgery, face challenges with high tightening torques that can deform flexible rods and require difficult two-handed handling, making them unsuitable for materials like polycarbonate urethane and complicating the fixation process.

Innovation Solution

A tool with a gear unit-driven screw driver mechanism that reduces manually applied tightening torque by transferring force directly through the locking element and counter-holding portion, allowing for smooth operation and minimizing load on the rod, featuring an exchangeable tip portion and torque limiting options.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a counter-holding portion is used to hold the receiving portion during tightening, then the tightening torque can be applied, but the rod becomes loaded and deformed

Engineering Contradiction:

Improvetightening torqueVSAvoidrod deformation

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The invention extracts the counter-holding function from the rod-bearing path. The counter-holding portion engages the receiving portion directly, separating the torque application path from the rod support path. This allows the rod to remain unloaded during tightening while still providing necessary counter-holding force.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The receiving portion acts as an intermediary element between the bone anchor and the rod. By engaging the receiving portion directly with the counter-holding portion, the system transfers torque without transmitting it through the rod, preventing rod deformation while maintaining anchoring stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high tightening torque is applied to secure the locking element, then secure fixation is achieved, but two-handed handling becomes difficult

Engineering Contradiction:

Improvefixation securityVSAvoidhandling difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The tool is segmented into distinct functional portions: a drive shaft for torque application, a counter-holding portion for securing the receiving portion, and a tip portion for engaging the locking element. This segmentation allows each component to be optimized independently, with the counter-holding portion providing stable engagement without requiring two-handed operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The counter-holding portion replicates the engagement interface of the receiving portion, creating a complementary fit that provides secure holding without requiring additional support hands. The geometric copying of the engagement surfaces enables single-handed operation while maintaining fixation security.

Inventive Principle:

Principle #26Copying

3Device complexity

If the tip portion is fixed, then the tool structure is simple, but it cannot accommodate different locking elements

Engineering Contradiction:

Improvetool structureVSAvoidcompatibility with different locking elements

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The tip portion is designed as a dynamic, interchangeable component rather than a fixed structure. This allows the tool to adapt to different locking element geometries by simply changing the tip portion, maintaining overall tool simplicity while achieving versatility through modular replacement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The main tool body is designed with universal compatibility, accommodating various locking elements through interchangeable tip portions. The standardized interface between the main body and tip portion enables single tool to perform multiple functions with different locking element types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 tool enables efficient and controlled tightening of bone anchors with reduced manual effort, minimizing deformation of flexible rods and facilitating easier handling by isolating the tightening load from the bone, thus ensuring secure fixation without damaging the rods.

Implementation Method 1

a mechanism to apply torque to the tip portion, wherein the mechanism to apply torque includes a drive shaft and a driven shaft coupled by a gear unit

Methodology Applied

Scientific EffectGear mechanism: Gear

Implementation Method 2

A tool with a gear unit-driven screw driver mechanism that reduces manually applied tightening torque by transferring force directly through the locking element and counter-holding portion

Methodology Applied

Scientific EffectMechanical advantage: Mechanical Advantage

Data Source

PatentUS9149308B2Tool for use with a bone anchor, in particular for spinal surgery

Publication Date: 2015.10.06 BIEDERMANN TECH GMBH & CO KG

AI summary

A tool is provided for use with a bone anchor, wherein the bone anchor has an anchoring section and a receiving portion for receiving a rod to be connected to the anchoring section and a locking element, the tool comprising a tip portion for engaging the locking element; a mechanism to apply torque to the tip portion comprising a drive shaft and a driven shaft coupled by a gear unit, where the drive shaft has a different axis than the driven shaft, and where the driven shaft comprises an engagement portion configured to connect the driven shaft to the gear unit; and a counter-holding portion for engaging the receiving part, wherein the counter-holding portion is rotatable with respect to the tip portion.