External Fixation Rod with Telescopic and Threaded Adjustment

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Solution Overview

Problem

Existing external fixation devices lack a connection rod mechanism that allows for both rapid and gradual adjustments in length, particularly when connecting non-parallel rings, which can complicate bone realignment and stabilization procedures.

Innovation Solution

The external fixation connection rod features a telescopic housing with a sliding adjustment sleeve and a threaded elongated member, enabling rapid length adjustments through sleeve translation and gradual adjustments via a rotating adjustment mechanism, allowing secure attachment to non-parallel fixator rings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a traditional threaded or telescopic rod is used to connect non-parallel rings, then the device can maintain structural simplicity, but the ability to perform both rapid and gradual adjustments is limited

Engineering Contradiction:
Improveadjustment capabilityVSAvoidrod mechanism complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The connection rod is divided into multiple functional segments: a telescopic housing for rapid adjustment, an inner sleeve for intermediate adjustment, and a threaded elongated member for gradual precision adjustment. Each segment handles a different aspect of length modification, allowing the system to achieve both rapid and gradual adjustments while maintaining manageable complexity through functional decomposition.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a nested structure where the inner sleeve is disposed within the telescopic housing, and the threaded elongated member is disposed within the inner sleeve. This nesting arrangement allows multiple adjustment mechanisms to coexist in a compact configuration, enabling both rapid and gradual adjustments without significantly increasing the overall device footprint or complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Measurement precision

If a single adjustment mechanism is used, then the device structure remains simple, but the precision and control over length adjustment are insufficient

Engineering Contradiction:
Improvelength adjustment precisionVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Different segments of the connection rod are assigned different adjustment qualities: the telescopic housing provides rapid coarse adjustment capability, the inner sleeve offers intermediate adjustment, and the threaded elongated member delivers fine precision adjustment. This local differentiation of adjustment quality across the rod structure enables multi-level precision control while keeping each individual mechanism relatively simple.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The adjustment system transitions from static to dynamic control by incorporating multiple movable components. The telescopic housing can rapidly change length, the inner sleeve provides intermediate positioning, and the threaded member enables precise incremental adjustments. This dynamic multi-stage adjustment process allows the system to adapt to different precision requirements during bone realignment procedures.

Inventive Principle:
Principle #15Dynamics

3Speed

If rapid adjustment is prioritized, then the ability to perform acute corrections is improved, but the ability to perform gradual controlled changes is reduced

Engineering Contradiction:
Improveadjustment speedVSAvoidcontrolled adjustment ease
Core Design Contradiction:
SpeedVSEase of operation

Solution Approach 1:

The adjustment process is divided into periodic stages: rapid telescopic adjustment for acute corrections, followed by intermediate sleeve adjustment, and finally gradual threaded adjustment for precise controlled changes. This periodic multi-stage action allows the system to switch between different adjustment speeds and control levels as needed, accommodating both rapid acute corrections and gradual controlled changes in a systematic manner.

Inventive Principle:
Principle #19Periodic action

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

This solution enables precise and efficient length adjustments of the connection rod, facilitating rapid acute corrections and gradual, controlled changes, thereby enhancing the stability and alignment of bone segments during surgical procedures.

Implementation Method 1

an externally threaded elongated member threadably coupled within the second rotating member of the adjustment mechanism; wherein when the adjustment mechanism is rotated about the inner sleeve and the elongated member, the elongated member is translated within the axial bore defined in the inner sleeve during gradual adjustment

Methodology Applied
Scientific EffectThreaded coupling: Screw

Data Source

PatentEP2919683B1External fixation connection rod for rapid and gradual adjustment
Publication Date: 2017.11.29 TEXAS SCOTTISH RITE HOSPITAL FOR CHILDREN
  • EP2919683B1 patent drawingFigure 1~2
  • EP2919683B1 patent drawingFigure 3~4
  • EP2919683B1 patent drawingFigure 5~6

AI summary

An external fixation connection rod that allows for rapid and gradual length adjustment. In some embodiments, the fixation connection rod includes an inner sleeve received within a telescopic rod to allow for rapid adjustment of an overall length of the fixation connection rod. In some embodiments, the fixation connection rod includes an adjustment mechanism to allow for gradual adjustment of the overall length of the fixation connection rod by lengthening or shortening a threaded elongated member within the inner sleeve, and the adjustment mechanism includes a first rotation member, a second rotation member, and a spring. Distal translation of the first rotation member relative to the second rotation member allows the adjustment mechanism to move from a first, locked position to a second, unlocked position, allowing the first rotation member and the second rotation member to rotate about the inner sleeve and the threaded elongated member during gradual adjustment.