Torque Limiting Ratcheting Handle for Medical Instruments

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Solution Overview

Problem

Current disposable handles for surgical instruments are expensive and require constant reseating during use, leading to inefficiencies and potential mistakes, as they lack a mechanism to effectively limit torque in one direction while allowing maximal torque in the opposite direction.

Innovation Solution

A handle with a ratchet mechanism that allows for clockwise and counterclockwise ratcheting, featuring a ratchet shifter, tool connector, torque coupler, and rear power housing, which limits torque in one direction and enables maximal torque in the opposite direction, allowing for quick disconnect and reduced steps in the installation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a normal screwdriver device is used, then the surgeon can seat the driver and turn the screw, but the surgeon must constantly reseat the driver to turn the screw again, which slows down the operation and could cause mistakes

Engineering Contradiction:

Improveinstallation speedVSAvoidoperation continuity

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The ratchet mechanism allows the driver to remain seated while enabling bidirectional rotation. The ratchet teeth engage to permit rotation in one direction (seating the screw) while preventing reverse rotation, allowing the surgeon to continuously operate the driver without reseating it multiple times

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The drive shaft is segmented into multiple functional zones: a ratchet-resistant portion that engages with ratchet teeth, a smooth portion for continuous rotation, and a driver engagement portion. This segmentation allows different rotational behaviors in different sections, enabling the driver to stay seated while allowing controlled bidirectional movement

Inventive Principle:

Principle #1Segmentation

2Strength

If torque is limited too low to prevent damage, then the screw or driver is protected, but the initial mechanical implant stability is reduced

Engineering Contradiction:

Improvemechanical implant stabilityVSAvoidtorque damage risk

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The ratchet mechanism changes the torque parameter dynamically during operation. During screw insertion, the ratchet teeth engage to limit maximum torque and prevent over-tightening damage. During screw removal or adjustment, the ratchet allows free rotation without torque limitation, enabling the surgeon to achieve optimal stability without risking damage

Inventive Principle:

Principle #35Parameter changes

3Productivity

If a ratchet mechanism is added to allow bidirectional rotation, then the installation process is simplified and speed is improved, but the device complexity increases

Engineering Contradiction:

Improveinstallation speedVSAvoidhandle mechanism complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The ratchet mechanism is nested within the existing handle structure. The ratchet teeth are integrated into the drive shaft itself, and the ratchet-resistant portion is built into the mounting post. This nested design adds functionality without significantly increasing overall device complexity or size

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The ratchet mechanism serves multiple functions: it limits torque during screw insertion, enables bidirectional rotation for easier operation, and allows the driver to remain seated during continuous operation. This multi-functionality justifies the added complexity by providing several benefits from a single integrated mechanism

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 handle simplifies the surgical process by allowing surgeons to seat the driver once and spin freely in both directions, reducing the installation steps and improving efficiency, while protecting instruments from torsional overload.

Implementation Method 1

The ratchet shifter includes a proximal end, a distal end and a body defining a through-hole. The mounting post includes a forward ratchet hinge and a rear ratchet hinge. In the first position, the forward ratchet hinge engages the plurality of teeth of the forward portion to allow ratcheting in a first direction and maximum torque in a second direction.

Methodology Applied

Scientific EffectRatchet mechanism: Ratchet

Implementation Method 2

The torque coupler is slidably and rotatably coupled to the mounting post of the tool connector. The outer surface of the torque coupler includes a plurality of fingers extending radially outward from the outer surface. During rotation of the rear power housing in a first direction, the plurality of fingers slidably engage the plurality of teeth to limit the applied torque of the torque coupler and the tool connector from the rear power housing.

Methodology Applied

Scientific EffectTorque limitation through mechanical engagement: Mechanical Force

Data Source

PatentUS11944502B2Torque limiting ratcheting handle for medical instrument

Publication Date: 2024.04.02 MEDARTIS AG

AI summary

A torque limiting ratcheting handle for a medical instrument is provided that includes a ratchet shifter, a tool connector, a torque coupler, and a rear power housing. The handle provides clockwise and counterclockwise ratcheting and limits the amount of torque in one direction while allowing for maximal torque in the opposite direction. In one aspect, the ratcheting handle may include a drive shaft removeably connected to a power tool or, alternatively, to a handle grip for manual manipulation.