Rotatable Ultrasonic Surgical Cutting Implement
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Solution Overview
Problem
Current ultrasonic surgical instruments face challenges with temperature rise due to frictional heating during bone and tissue interaction, and they often leak under the fluid pressure in arthroscopic surgeries, leading to tissue damage and inadequate sealing.
Innovation Solution
The development of an ultrasonic surgical instrument with a cutting implement that is selectively rotatable within a hollow sheath, allowing for both cutting and ultrasonic positioning, and featuring enhanced sealing arrangements to prevent fluid leakage in aqueous environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ultrasonic energy is applied to cut tissue, then cutting precision and smooth surfaces are improved, but temperature rise due to frictional heating increases causing tissue damage
Solution Approach 1:
The cutting implement is divided into distinct functional zones: a cutting surface for mechanical cutting and an ultrasonic surface for ultrasonic tissue interaction. This segmentation allows each surface to perform its specific function optimally without the negative effects of the other, enabling precise cutting with minimal thermal damage to surrounding tissue.
Solution Approach 2:
Different regions of the cutting implement are given different properties: the cutting surface is designed for mechanical cutting action while the ultrasonic surface is optimized for ultrasonic energy transmission. This local differentiation enables the instrument to provide both mechanical cutting precision and ultrasonic coagulation/sealing capabilities at different locations on the same implement.
2Device complexity
If conventional seals are used in ultrasonic instruments, then device simplicity is maintained, but fluid leakage occurs under arthroscopic pressure
Solution Approach 1:
The sealing system employs a nested structure with an inner seal positioned within the hollow sheath and an outer seal positioned externally. This nested arrangement provides redundant sealing, where the inner seal prevents leakage into the hollow sheath and the outer seal prevents leakage to the external environment, ensuring reliability under high arthroscopic fluid pressure.
Solution Approach 2:
The sealing arrangement is designed with pre-compression and redundant sealing elements that are activated before failure can occur. The nested seals provide a backup system that engages if the primary seal is compromised, cushioning against the high fluid pressures encountered in arthroscopic surgery and preventing catastrophic leakage.
3Productivity
If a rotary cutting implement is used, then cutting speed and productivity are improved, but frictional heating at the bone/tissue interface increases
Solution Approach 1:
The rotary cutting implement incorporates periodic ultrasonic activation that alternates with mechanical rotation. This periodic action allows brief intervals of ultrasonic tissue interaction that reduce continuous frictional contact, thereby maintaining cutting speed while reducing cumulative frictional heating at the bone/tissue interface.
Solution Approach 2:
The invention replaces pure mechanical cutting with a hybrid system that incorporates ultrasonic energy. The ultrasonic surface partially substitutes mechanical cutting action with ultrasonic vibration, reducing direct mechanical friction between the rotating implement and tissue, thus maintaining productivity while reducing frictional heating.
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 instrument provides increased cutting precision, minimizes tissue damage, and maintains effective sealing under fluid pressure, addressing the issues of frictional heating and leakage in arthroscopic surgeries.
Implementation Method 1
applying ultrasonic motion to the cutting implement
Implementation Method 2
temperature rise in bone and adjacent tissue due to frictional heating at the bone/tissue interface
Data Source
AI summary
In one general aspect, various embodiments are directed to methods for treating tissue within an aqueous environment. Various methods may include introducing a cutting implement of a surgical instrument into the aqueous environment. The cutting implement may have at least one cutting surface thereon and at least one ultrasonic portion thereon and be selectively rotatable within a hollow sheath. The methods may include rotating or rotatably oscillating the cutting implement within the hollow sheath for tissue cutting purposes. The cutting implement may also be retained in a position wherein the ultrasonic portion of the cutting implement may be applied to tissue and then have ultrasonic motion applied thereto.