Planetary-Gear Rotary Surgical Tool for Fibrous Tissue Protection
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Solution Overview
Problem
Existing surgical tools with rotary cutters face issues when encountering fibrous tissues like muscle and nerves, leading to damage, and oscillating tools have mechanisms that do not operate smoothly due to inefficient oscillation mechanisms.
Innovation Solution
A surgical tool with a drive transmission utilizing a planetary gear set, where the ring gear is fixed and the pinion gear revolves about the motor's axis, coupled via an input crank, forming a Cardan mechanism, translating motion to a cutter shaft through a follower and sector gear for smooth oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rotary cutter is used to modify tissue, then cutting efficiency is improved, but fibrous tissue wraps around the cutter and causes damage
Solution Approach 1:
The patent applies dynamic motion by transitioning from simple rotation to oscillating rotation. The cutter shaft performs reciprocating oscillations superimposed on its rotation, creating a complex dynamic motion pattern that prevents fibrous tissue from wrapping around the cutter while maintaining cutting efficiency on hard tissues.
Solution Approach 2:
The patent implements periodic action through the oscillating motion of the cutter. The cutter shaft executes periodic reciprocating movements during rotation, creating intervals of reverse motion that prevent continuous wrapping of soft tissues while maintaining effective cutting action on bone and cartilage.
2Object-affected harmful factors
If an oscillation mechanism is added to the rotary cutter, then damage to fibrous tissue is reduced, but the mechanism does not operate smoothly
Solution Approach 1:
The patent uses a follower as an intermediary element between the drive transmission and the cutter shaft. The follower converts the oscillating motion from the planetary gear set into smooth reciprocating motion of the cutter shaft, acting as a mediator that ensures smooth operation while achieving the desired oscillating cutting action.
Solution Approach 2:
The patent replaces traditional oscillation mechanisms with a planetary gear set that incorporates an oscillating drive. This substitution provides a more compact and smoother operating mechanism compared to conventional oscillation systems, eliminating the operational issues of prior art oscillating tools.
3Ease of operation
If a planetary gear set is used for oscillation, then smooth oscillation is achieved, but device complexity increases
Solution Approach 1:
The planetary gear set serves multiple functions simultaneously: it provides speed reduction, generates oscillating motion, and transmits power to the cutter shaft. This multi-functionality reduces the need for separate mechanisms, thereby limiting the increase in overall device complexity despite the sophisticated motion control achieved.
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 solution provides smooth oscillation of the cutter, reducing the risk of damage to fibrous tissues and enhancing cutting efficiency in modifying hard tissues like bone, cartilage, and discs.
Implementation Method 1
a drive transmission configured between the motor and the shaft to effect oscillating rotary movement of the shaft and cutter, utilizing a planetary gear set operably connected to the motor with the ring gear of the planetary gear set being fixed against rotation
Implementation Method 2
whereby the planetary gear set and input crank are operably coupled to an output driver connected to the pinion gear of the planetary gear set with a portion of the pinion gear having a motion path that is substantially linear, forming a Cardan mechanism
Data Source
AI summary
A surgical tool with a housing, and a cutter support shaft operably connected to a motor to effect rotation of the shaft with a drive transmission configured between the motor and the shaft to effect oscillating rotary movement of the shaft and cutter is disclosed.