Half-Pipe Cannula With Flexible-Rigid Instrument Passage

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Solution Overview

Problem

Existing cannulas used in minimally invasive surgeries face challenges such as tipping over during instrument insertion, difficulty in passing non-standard objects, and requiring additional instrumentation for insertion, which affects procedural efficiency and complexity.

Innovation Solution

A half pipe cannula design featuring a flexible portion and a rigid portion, allowing instruments with larger diameters to pass through by radial expansion, and enabling insertion without additional tools, combining stability with ease of use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid cannula is used to provide stability during surgery, then the cannula resists tipping over, but it cannot allow instruments with larger diameters to pass through

Engineering Contradiction:

Improvecannula stabilityVSAvoidinstrument passage capability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The cannula transitions from a static rigid structure to a dynamic structure that can change its properties. The memory wire provides a base shape that the cannula returns to after deformation, allowing it to dynamically adapt between a compressed insertion state and an expanded stable state during instrument passage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cannula's physical parameters (shape, rigidity) are changed temporarily during insertion and then restored. The application of force during insertion deforms the cannula to accommodate larger instruments, after which the memory wire restores the original shape, maintaining stability for subsequent use.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a fully flexible cannula is used to allow large instruments to pass through, then non-standard objects can be inserted, but the cannula requires additional instrumentation for insertion and is difficult to insert through portals

Engineering Contradiction:

Improvenon-standard object passageVSAvoidinsertion ease

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

Different portions of the cannula have different properties. The distal portion contains the memory wire for self-insertion capability, while the proximal portion can be manipulated by the operator. This local differentiation allows the cannula to be both easy to insert and capable of passing non-standard objects.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cannula inserts itself through the portal using the memory wire's elastic recovery force, eliminating the need for additional insertion instruments. The operator simply needs to apply initial force to deform the cannula, after which it self-inserts and stabilizes.

Inventive Principle:

Principle #25Self-service

3Stability of the object's composition

If a rigid cannula with a large moment arm is used to prevent tipping, then stability is improved, but the cannula tips over when instruments are inserted through it

Engineering Contradiction:

Improvecannula stabilityVSAvoidtipping during insertion

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The cannula's rigidity is dynamic rather than static. During instrument insertion, the cannula temporarily deforms to accommodate the instrument, then returns to its stable shape. This dynamic behavior prevents the tipping that occurs with rigid cannulas while maintaining stability afterward.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cannula combines materials with different properties: a memory wire (nitinol or similar) that provides elastic recovery and a outer layer that provides structural support. This composite structure allows the cannula to be both stable and resistant to tipping during instrument passage.

Inventive Principle:

Principle #40Composite materials

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 half pipe cannula stabilizes during insertion, facilitates passage of non-standard instruments, and reduces the need for additional instrumentation, enhancing surgical efficiency and reducing procedural time.

Implementation Method 1

a flexible portion (e.g., made from a memory wire such as nitinol) and a rigid portion

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20250302503A1Half pipe cannula and methods of manufacturing and using half pipe cannula

Publication Date: 2025.10.02 HYBRID CANNULA

AI summary

A half pipe cannula has a first portion and a second portion. The first portion, which includes a proximal end and an elongated tab along the length of the first portion, can be formed from a first material with a selected rigidity. The second portion, which includes a proximal end, a cannulated passage, and a distal end, can be formed from a second material with a selected flexibility. The second portion of the half pipe cannula partially or fully overlaps the elongated tab of the first portion of the half pipe cannula. The second portion of the half pipe cannula has surface features such as a thread or bumper feature. Each portion of the half pipe cannula may have one or more flanges on either end or both ends. The second portion of the half pipe cannula can be made of a flexible material such as thermoplastic elastomer.