Retracting Cannula for Arthroscopic Workspace Expansion

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Solution Overview

Problem

Current arthroscopic surgical procedures face limitations in maintaining a sufficient workspace within joints, particularly for larger osteochondral cores, as the size of the workspace restricted by fluid pressure is insufficient for performing open procedures.

Innovation Solution

A retracting cannula system comprising an outer cannula with a threaded surface to engage soft tissue and an inner cannula with a curved distal end for sealing the bone surface, allowing for distraction and locking of the soft tissue to create a larger surgical workspace, enabling arthroscopic osteochondral transplantation procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If fluid pressure is used to maintain arthroscopic workspace, then the workspace is maintained without mechanical support, but the workspace size is restricted and insufficient for larger osteochondral cores

Engineering Contradiction:

Improveworkspace sizeVSAvoidapplicability to larger cores

Core Design Contradiction:

Area of stationary objectVSAdaptability or versatility

Solution Approach 1:

The retracting cannula acts as an intermediary mechanical device between the surgical site and the external environment. It provides direct mechanical distraction and stabilization of soft tissue, enabling larger osteochondral core harvesting and implantation procedures that cannot be performed with fluid pressure alone.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention extracts the soft tissue from the immediate surgical workspace by retracting it laterally with the cannula. This creates a clear, enlarged workspace that accommodates larger osteochondral cores and harvesting instruments, separating the tissue of interest from the operational field.

Inventive Principle:

Principle #2Taking out (Extraction)

2Area of stationary object

If open procedures are used for larger osteochondral cores, then sufficient workspace is available, but the benefits of arthroscopic procedures (rapid recovery) are lost

Engineering Contradiction:

Improveworkspace sizeVSAvoidrecovery time

Core Design Contradiction:

Area of stationary objectVSLoss of time

Solution Approach 1:

The invention merges the advantages of both open and arthroscopic procedures. It combines the large workspace capability of open procedures with the minimally invasive nature of arthroscopic surgery. The retracting cannula enables adequate exposure for large core procedures while maintaining small incisions and rapid recovery benefits.

Inventive Principle:

Principle #5Merging (Combining)

3Area of stationary object

If soft tissue is distracted to create workspace, then larger cores can be accommodated, but tissue stability is compromised

Engineering Contradiction:

Improveworkspace sizeVSAvoidtissue stability

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The retracting cannula provides dynamic tissue distraction and stabilization. The device can be adjusted and repositioned to maintain optimal workspace while adapting to tissue movement during the surgical procedure, ensuring both workspace maintenance and tissue stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The soft tissue is distracted and stabilized by the retracting cannula before the osteochondral core harvesting and implantation procedures begin. This preliminary tissue preparation creates a stable, enlarged workspace that remains maintained throughout the subsequent surgical steps.

Inventive Principle:

Principle #10Preliminary action

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 retracting cannula effectively expands the arthroscopic workspace, allowing for the successful performance of osteochondral transplantation surgeries by maintaining tissue distraction and providing a stable environment for surgical instruments, overcoming the size limitations of traditional arthroscopic procedures.

Implementation Method 1

an outer cannula with a threaded outer surface for engaging the soft tissue to be distracted

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

an inner cannula with a curved distal end for contacting and sealing the bone surface of a joint

Methodology Applied

Scientific EffectPhysical contact sealing:

Implementation Method 3

further relative movement between the inner cannula and the outer cannula causes the soft tissue to distract from the articular surface

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentUS8328716B2Retracting cannula

Publication Date: 2012.12.11 ARTHREX INC

AI summary

A retracting two-piece cannula for distracting soft tissue from bone (e.g., the articular surface of a knee) to provide a surgical workspace for osteochondral repair. After inserting an outer cannula provided with a threaded outer surface into an incision (preferably widened by one or more dilators), the outer cannula is rotated to engage the threaded outer surface with the soft tissue to be distracted. An inner cannula is then inserted into the outer cannula and advanced until it contacts the articular surface. Further relative movement between the inner and outer cannulas causes the outer cannula to be drawn away from the articular surface, thereby retracting the soft tissue and establishing the workspace. The inner and outer cannula are then locked together to maintain the workspace, and an osteochondral core may be introduced through the inner cannula.