Injection-Molded Surgical Instrument Guide for Thin-Wall Cannulas
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Solution Overview
Problem
Existing instrument guides for minimally invasive surgery, particularly those designed for single port access, face challenges in achieving sufficient length and thin walls while being suitable for injection molding, which is necessary to minimize incision size and eliminate the need for sterilization.
Innovation Solution
The design of an instrument guide with a thick solid central core and strategically thickened radial walls, combined with carefully designed channels for insufflation gas, allows for injection molding while maintaining structural integrity and minimizing incision size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the walls of the instrument guide are made thin to minimize incision size, then the cannula inner diameter can be reduced, but the guide length must be limited because plastic material hardens quickly within thin walls during injection molding
Solution Approach 1:
The instrument guide employs varying wall thicknesses in different regions. The distal portion has thinner walls to minimize incision size, while the proximal portion has thicker walls to accommodate the full length of plastic material flow during injection molding. This local variation in thickness allows the guide to achieve both sufficient length and small cannula diameter.
Solution Approach 2:
The invention transitions from a uniform thickness design to a graduated thickness profile along the length of the instrument guide. By varying the thickness dimension along the longitudinal axis, the design accommodates both the length requirements and the injection molding constraints that limit thin wall length.
2Area of stationary object
If the walls of the instrument guide are made thin to minimize incision size, then the cannula inner diameter can be reduced, but the guide length must be limited due to plastic material hardening
Solution Approach 1:
The instrument guide employs varying wall thicknesses in different regions. The distal portion has thinner walls to minimize incision size, while the proximal portion has thicker walls to accommodate the full length of plastic material flow during injection molding. This local variation in thickness allows the guide to achieve both sufficient length and small cannula diameter.
3Area of stationary object
If the walls of the instrument guide are made thin to minimize incision size, then the cannula inner diameter can be reduced, but surface irregularities and deformations occur during injection molding
Solution Approach 1:
The instrument guide employs varying wall thicknesses in different regions. The distal portion has thinner walls to minimize incision size, while the proximal portion has thicker walls to accommodate the full length of plastic material flow during injection molding. This local variation in thickness allows the guide to achieve both sufficient length and small cannula diameter.
Data Source
AI summary
An instrument guide is removably inserted into a proximal portion of a cannula and extends to a distal end of the cannula to guide and support multiple surgical instruments within the cannula. The instrument guide is designed to be manufactured by injection molding of plastic material. The instrument guide includes a tube and several radial walls connected to the tube to form passageways within the tube. The radial walls are joined to a core where they intersect. The tube and radial walls have substantially the same wall thickness and the core has a minimum diameter that is substantially larger than the wall thickness to facilitate delivery of plastic material. Portions of the tube and radial walls are thinner than the general wall and rib thickness to form guideways that support surgical instruments within the passageways. Channels may be formed on an outside of the tube to deliver insufflation gas.