One-Handed Cannula Locking Mechanism for Surgical Instruments
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Solution Overview
Problem
Conventional low profile, small cannula systems are costly due to the use of multiple components, require cumbersome two-handed operation for unlocking, and lack effective retention features and ergonomic design, leading to undesirable movement during surgery.
Innovation Solution
A low profile, small cannula system with fewer components, an ergonomic locking mechanism that allows one-handed operation, cannula retention features, and a multi-grip handle designed to reduce manufacturing costs and minimize movement during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional locking mechanisms are used to secure the trocar to the cannula, then the trocar is prevented from rotating and translating relative to the cannula, but two hands are required to unlock the trocar from the cannula making the operation cumbersome
Solution Approach 1:
The locking mechanism is inverted so that the default state is locked and the user must actively disengage it. The spring-biased locking arm automatically engages with the cam feature on the cannula, requiring only a single transverse force to disengage rather than two coordinated forces.
Solution Approach 2:
The complex two-handed unlocking operation is extracted and replaced with a simple single-handed transverse force mechanism. The locking arm is designed to be disengaged by applying force in one direction only, removing the need for simultaneous axial and transverse forces.
2Ease of operation
If a smooth cannula surface is used, then placement of the cannula through the body wall is easy and safe, but the cannula lacks desired retention characteristics once placed
Solution Approach 1:
The cannula surface is designed with different local qualities: the distal portion maintains a smooth surface for easy insertion through tissue, while the proximal portion incorporates retention features such as knurling or ridges that provide friction and prevent accidental dislodgement after placement.
3Reliability
If conventional valves and insufflation ports are integrated with the cannula housing, then they control insufflation fluid passage, but they obstruct use and manipulation of the cannula system especially when multiple cannula systems are employed
Solution Approach 1:
The valves and insufflation ports are repositioned from the lateral surface of the cannula housing to the proximal end of the handle assembly. This spatial reconfiguration allows multiple cannula systems to be positioned adjacent to each other without their control valves interfering with each other's manipulation.
4Manufacturing precision
If conventional cannula systems use nine to fourteen components, then precision and desired features are achieved, but manufacturing costs are driven up
Solution Approach 1:
Multiple separate components are merged into integrated assemblies. The handle assembly combines the valve mechanism, insufflation port, and locking mechanism into a single integrated unit. The cannula assembly integrates the sealing surface and retention features directly into the cannula body, reducing the total component count from nine to fourteen parts to fewer than nine parts while maintaining precision.
Data Source
AI summary
A medical instrument includes a handle, a trocar in communication with the handle, and a cannula in communication with the trocar and the handle. The cannula is engaged (locked) with the handle when linearly displaced proximally towards the handle and, the cannula is disengaged (unlocked) from the handle when linearly displaced distally away from the handle. The cannula is linearly reciprocated, between the locked position and the unlocked position, along a linear travel path defined parallel to a longitudinal axis of the trocar such that the cannula is prohibited and permitted to articulate about the longitudinal axis of the trocar, and relative to the handle, respectively. Advantageously, the cannula is locked and unlocked from the trocar by without requiring an external force exerted generally transverse to trocar and/or cannula, thereby permitting a user to lock/unlock the cannula, relative to the trocar, with one hand.