Double-Joint Rod Bending Pliers for One-Handed Spinal Rod Shaping

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Solution Overview

Problem

Existing medical rod bending pliers require a large opening angle for the handles, necessitating a two-handed operation, which is unergonomic and can lead to contamination during spinal surgery.

Innovation Solution

Designing the rod bending pliers as double-joint pliers with a boom supported on a first joint and extending to a scissor hinge, allowing the handles to be gripped with one hand while maintaining the desired travel of the bending rollers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the rod bending pliers use a single joint mechanism with large travel path for bending rollers, then the bending angle is sufficient, but the opening angle of handles becomes too large requiring two-handed operation

Engineering Contradiction:
Improvebending angleVSAvoidhandle opening angle
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The single joint mechanism is divided into two joints: a first joint connecting handles to intermediate links, and a second joint connecting intermediate links to bending rollers. This segmentation allows independent optimization of handle opening angle and bending roller travel path, resolving the contradiction between sufficient bending angle and manageable handle opening angle for one-handed operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The mechanism transitions from a planar single-joint rocker motion to a spatial double-joint mechanism with intermediate links. This dimensional change enables the handles to move through a smaller angular range while the bending rollers achieve the necessary travel distance through the compounded motion of both joints

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Length of moving object

If the handles are operated with two hands to achieve sufficient opening angle, then the bending roller travel is adequate, but the operation becomes unergonomic and risks contamination

Engineering Contradiction:
Improvebending roller travel pathVSAvoidergonomics and sterility
Core Design Contradiction:
Length of moving objectVSEase of operation

Solution Approach 1:

By segmenting the mechanism into two joints with intermediate links, the patent enables sufficient bending roller travel path while reducing the handle opening angle to a range suitable for one-handed operation. This eliminates the need for two-handed operation and associated ergonomic issues and contamination risks

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Intermediate links act as mediators between the handles and bending rollers. These intermediate links transmit and transform the motion from the handles, allowing the bending rollers to achieve adequate travel path while the handles maintain a compact opening angle for one-handed operation

Inventive Principle:
Principle #24Intermediary (Mediator)

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 one-handed operation of the pliers, reducing the risk of contamination and improving ergonomics, while maintaining the necessary bending radius and angle of the rod.

Implementation Method 1

a first (pivoting) joint / hinge on which the handles are arranged so that they can pivot relative to one another in the manner of a seesaw

Methodology Applied
Scientific EffectPivoting joint mechanism: Hinge

Implementation Method 2

the two jaws pivot apart. The bending rollers follow a circular path toward the gripping jaws

Methodology Applied
Scientific EffectCircular motion mechanism: Hinge

Implementation Method 3

When the pair of handles is pressed together, the bending rollers pivot around the joint/hinge so that the bending rollers move apart and backwards towards the handles. When the bar rests against the central support surface, the bar is bent by the circular movement of the bending rollers

Methodology Applied
Scientific EffectMechanical force: Mechanical Force

Implementation Method 4

The pivot arms/jaw parts are coupled together in their central areas by means of a joint/connecting pin in a scissor-like manner

Methodology Applied
Scientific EffectScissor mechanism: Four-Bar Linkage

Data Source

PatentEP4563107A1Medical rod bending pliers with double joint
Publication Date: 2025.06.04 AESCULAP AG
  • EP4563107A1 patent drawingFigure 1~2
  • EP4563107A1 patent drawingFigure 3~4
  • EP4563107A1 patent drawingFigure 5~8

AI summary

The present disclosure relates to medical rod bending pliers (1) with compressible handles (2) that can be pivoted about a first joint (6), and pivoting arms (4) that can be moved in opposite directions when the handles (2) are moved. Each pivoting arm (4) has a bending roller (10) that can be moved with the pivoting arm (4) and is prepared and designed to bend a rod, in particular a spinal implant, that is inserted into the rod bending pliers (1). The pivoting arms (4) are each movably connected to the respective handles (2) by a second joint (8).