Adjustable-Length Slotted Cannula for Arthroscopic Instrument Access

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Solution Overview

Problem

Existing cannulas used in arthroscopic surgery are prone to damage from instruments with large or sharp distal tips, limiting their suitability for subsequent instrument insertion during the same procedure.

Innovation Solution

A slotted cannula with a semi-circular body, outward bend, and fold lines perpendicular to the longitudinal axis, made from polymers like polyacrylate or polycarbonate, allowing adjustable length and flexibility for accommodating various instruments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a traditional solid cannula is used, then it provides structural strength, but it is damaged by instruments with large or sharp distal tips

Engineering Contradiction:

Improvecannula structural strengthVSAvoidcannula resistance to instrument damage

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The cannula is designed with a slot running through its structure, transforming it from a rigid solid tube into a flexible slotted structure. This slot allows the cannula to flex and deform elastically when instruments with large or sharp distal tips are inserted or extracted, preventing the cutting damage that would occur with a rigid solid cannula while maintaining sufficient structural integrity during use

Inventive Principle:

Principle #30Flexible shells and thin films

2Adaptability or versatility

If multiple cannulas are used to accommodate different instruments, then instrument compatibility is improved, but device complexity increases

Engineering Contradiction:

Improveinstrument compatibilityVSAvoidnumber of cannulas required

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The slotted cannula design creates a universal interface that can accommodate instruments of varying sizes and configurations through its flexible slot structure. The slot allows the cannula to adapt to different instrument shapes without requiring multiple specialized cannulas, thereby simplifying the overall device system while maintaining broad instrument compatibility

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If the cannula length is fixed, then manufacturing is simplified, but adaptability to different surgical needs is reduced

Engineering Contradiction:

Improvecannula manufacturing simplicityVSAvoidoperable length adjustment

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The cannula incorporates fold lines that divide its structure into segments, allowing it to be bent or broken at these predetermined locations to adjust the operable length. This segmentation enables a single manufactured cannula to be customized to different length requirements during surgery, providing adaptability without requiring multiple pre-manufactured length variants

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250255645A1Slotted canulla for arthroscopic surgery

Publication Date: 2025.08.14 SMITH & NEPHEW INC

AI summary

A slotted cannula for surgical procedures is disclosed. The slotted cannula has an elongated semi-circular body comprising a cavity extending along a longitudinal axis of the semi-circular body, the cavity having an open distal end and an open proximate end and an integrally formed outward bend extending curvilinear from the cavity on the proximate end and at least one fold line across the width of the cannula, perpendicular to the longitudinal axis. The cannula can be bent or broken along the at least one fold line to adjust the operable length of the cannula during a surgical procedure.