Orthopedic Cable Pulling Device with Worm-Gear Reel Control

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Solution Overview

Problem

Existing cable bone transport systems face issues with instability, complexity, and complications from external components, such as rollers and unprotected cable ends, which can lead to soft tissue damage and misalignment during bone transport.

Innovation Solution

A cable pulling device using a mechanical transmission with a reel and worm gear mechanism to incrementally pull a cable through the transport bone segment, ensuring stability and minimizing external components by attaching the cable to the transport bone segment via the intermedullary canal and redirecting it through a fulcrum pin, with a locking mechanism to prevent accidental release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional cable bone transport systems use external rollers and unprotected cable ends, then the cable can be redirected and pulled, but soft tissue damage and system instability occur

Engineering Contradiction:
Improvesoft tissue damageVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent removes the harmful external rollers from the system and replaces them with an intramedullary cable routing system. The cable is inserted through the medullary canal of the bone and secured internally, eliminating the need for external rollers that cause soft tissue damage. This extraction of harmful components while maintaining the core cable-pulling function resolves the contradiction between reducing soft tissue damage and maintaining system functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The cable is nested within the medullary canal of the bone, utilizing the existing bone structure as a protective conduit. The cable routing system is integrated within the bone's internal architecture rather than being external, which protects the cable ends and eliminates the need for external protective components. This nesting approach reduces both soft tissue damage and overall system complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Stability of the object's composition

If oblique wires are used to stabilize the transport bone segment, then fixation stability is achieved, but multiple long longitudinal cuts through soft tissues are produced

Engineering Contradiction:
Improvefixation stabilityVSAvoidsoft tissue damage
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful oblique wires that cause multiple longitudinal cuts through soft tissues and replaces them with a cable system routed through the medullary canal. The cable enters through a single entry point and is secured internally, eliminating the need for multiple wire insertions that damage soft tissue. This maintains fixation stability while dramatically reducing soft tissue trauma.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If threaded rods and rollers are used for gradual cable pulling, then bone transport is achieved, but the process becomes very complicated and space is occupied on external supports

Engineering Contradiction:
Improvebone transport capabilityVSAvoidtransport mechanism complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent removes the complex external threaded rods and rollers from the bone transport mechanism. Instead, a simple cable is routed through the medullary canal and secured to the transport bone segment. The cable is pulled directly through the bone's internal canal, eliminating the need for external mechanical assemblies. This maintains bone transport capability while dramatically simplifying the overall system and freeing up space on external supports.

Inventive Principle:
Principle #2Taking out (Extraction)

4Device complexity

If cable ends are left unprotected between external supports, then the system remains simple, but the cable can be damaged from the outside

Engineering Contradiction:
Improvesystem simplicityVSAvoidcable stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The cable ends are nested within the medullary canal and secured internally to the bone structure. The cable routing system utilizes the bone's internal architecture as protection, eliminating the need for external protective components. This nested configuration maintains system simplicity while significantly improving cable reliability by preventing external damage.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 system provides stable and controlled bone transport with minimal soft tissue penetration, reducing complications and simplifying the transportation process by using a cable pulling device with a worm gear mechanism for incremental, controlled movement.

Implementation Method 1

A cable pulling device using a mechanical transmission with a reel and worm gear mechanism to incrementally pull a cable through the transport bone segment

Methodology Applied
Scientific EffectWorm gear mechanism: Worm Drive

Implementation Method 2

a reel rotatable about said main body, for winding up a cable to be secured to a transport bone segment, thus moving said transport bone segment towards said fixed bone segment

Methodology Applied
Scientific EffectMechanical transmission: Mechanical Advantage

Implementation Method 3

with a locking mechanism to prevent accidental release

Methodology Applied
Scientific EffectLocking mechanism: Ratchet

Data Source

PatentEP4452103B1Orthopedic cable bone transport device and bone transport system comprising said device
Publication Date: 2025.10.29 ORTHOFIX SRL
  • EP4452103B1 patent drawingFigure 1
  • EP4452103B1 patent drawingFigure 2
  • EP4452103B1 patent drawingFigure 3

AI summary

The present invention relates to a cable pulling device (1) for orthopedic bone transport, comprising: a main body (2); a worm gear mechanism (4) disposed in the main body (2), and a reel (8) set into rotation by the worm gear mechanism (4) and meant to wind up a cable which is secured to a transport bone segment.