Cranial Flap Fixation Tool with Over-Torque Protection

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Solution Overview

Problem

The existing cranial flap fixation devices lack a mechanism for the surgeon to intuitively determine if the upper disc is properly tightened, leading to potential damage from excessive torque or instability due to insufficient clamping force, which complicates high-intensity craniotomy procedures.

Innovation Solution

The installation tool is designed with a two-section structure and an over-torque protection mechanism that sets a threshold value, preventing further torque transmission when the clamping force reaches its limit, ensuring consistent and safe clamping forces across multiple cranial flaps by switching between driving and failure states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the doctor applies larger torque to ensure stable clamping, then the stability of clamping is improved, but the cranial flap may be damaged or the upper disc becomes difficult to remove

Engineering Contradiction:
Improvestability of clampingVSAvoiddamage to cranial flap
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs feedback through the torque limiting mechanism that automatically senses when the applied torque reaches the predetermined threshold and stops further torque transmission. This feedback system eliminates the need for doctor's subjective estimation and automatically prevents over-tightening that could damage the cranial flap while ensuring sufficient clamping stability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the parameter of torque from an uncontrolled variable dependent on doctor's experience to a controlled parameter with a predetermined maximum value. By setting a specific torque threshold in the torque limiting mechanism, the system transforms the ambiguous tightening process into a quantifiable and controllable operation, ensuring consistent clamping force without exceeding safe limits.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the doctor tightens multiple cranial flap fixation devices rapidly during high-intensity craniotomy, then the surgical efficiency is improved, but the torque applied to each device becomes inconsistent

Engineering Contradiction:
Improvesurgical efficiencyVSAvoidconsistency of torque
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The torque limiting mechanism performs the function of torque control automatically without requiring the doctor's attention or skill in estimation. Each fixation device self-regulates the torque at the predetermined threshold, allowing the doctor to rapidly tighten multiple devices with consistent results regardless of individual variation in applied force.

Inventive Principle:
Principle #25Self-service

3Device complexity

If no torque limiting mechanism is provided, then the device structure is simple, but the doctor cannot estimate whether the upper disc is tightened properly

Engineering Contradiction:
Improvestructure of installation toolVSAvoidinformation on tightening status
Core Design Contradiction:
Device complexityVSLoss of information

Solution Approach 1:

The torque limiting mechanism provides automatic feedback by physically stopping torque transmission when the threshold is reached. This mechanical feedback replaces the lost information about tightening status that would otherwise require doctor's subjective estimation, clearly indicating when proper tightness is achieved without adding significant structural complexity.

Inventive Principle:
Principle #23Feedback

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 eliminates the need for surgeons to estimate torque, ensuring precise and consistent clamping forces, improving surgical efficiency and safety while protecting the cranial flap from damage, and allowing for customization based on flap hardness.

Implementation Method 1

an over torque protection mechanism comprising a thin column fixed on the bottom surface of the driving part; the loading part includes a groove with an upward opening, the groove and the bottom surface of the driving part form a closed accommodating cavity, and a baffle is disposed in the groove; the loading part is driven to rotate through the cooperation of the thin column and the baffle

Methodology Applied
Scientific EffectTorque transmission: Torque

Implementation Method 2

When the torque of the driving part acting on the thin column is larger than the threshold value, the thin column will be broken and/or the thin column will fall off from the bottom surface of the driving part

Methodology Applied
Scientific EffectFracture mechanics: Fracture Mechanics

Data Source

PatentEP3932345B1Cranial bone flap fixation device, and installation tool therefore
Publication Date: 2023.10.04 CHENGDU MEDART MEDICAL SCI CO LTD
  • EP3932345B1 patent drawingFigure 1~2
  • EP3932345B1 patent drawingFigure 3~4
  • EP3932345B1 patent drawingFigure 5~6

AI summary

A fixing device and an installation tool and a fixing method of the cranial flap, wherein the installation tool comprises a driving part, a loading part and an over torque protection mechanism disposed between the driving part and the loading part, the driving part drives the loading part to rotate by the over torque protection mechanism, the loading part is used for tightening the cranial flap fixation device, when the torque of the driving part acting on the over torque protection mechanism is larger than the threshold value, the over torque protection mechanism will be separated from the driving part and/or the loading part. The present invention not only effectively improves the installation and disassembly efficiency of the installation tool, but also eliminates hidden safety hazards caused by uncertainties caused by human factors in the tightening process, significantly improves the safety of the installation process, and effectively protects the cranial flap.