Expandable Cannula Structure for Low-Force Port Upsizing
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Solution Overview
Problem
Existing minimally invasive surgical ports, particularly those with fixed diameters, face issues such as high insertion forces, risk of injury, loss of pneumoperitoneum, and inefficiencies in upsizing, leading to complications and increased surgical time, especially in scenarios requiring larger instruments or in obese patients.
Innovation Solution
A cannula device with a vertical expansion mechanism using elongate rigid members that create an internal conical taper, allowing for controlled and less forceful insertion of larger members through a smaller cannula, facilitated by a vertical application of force on an internal housing or a resistive member, enabling a one-step expansion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a larger diameter port is inserted directly, then the instrument size is adequate, but the insertion force is high and risk of injury increases
Solution Approach 1:
The port device transitions from a collapsed low-profile state during insertion to an expanded operational state after insertion. The elongate members are configured to move from a compressed configuration to an expanded configuration, dynamically changing the port diameter to match the instrument size while maintaining low insertion forces
Solution Approach 2:
The port device is inserted in a collapsed state where the elongate members are nested within each other, allowing the larger diameter port to pass through tissue with minimal force. Once inserted, the members expand outward to create the larger working diameter, effectively nesting the insertion profile within the operational profile
2Force
If a smaller diameter port is used, then insertion force is low, but upsizing requires removing the port and inserting a larger one, causing loss of pneumoperitoneum
Solution Approach 1:
The port device allows dynamic upsizing by further expanding the elongate members to larger diameters without removal. The mechanism can transition from a small initial diameter to larger diameters as needed, maintaining continuous pneumoperitoneum and surgical field of view throughout the procedure
Solution Approach 2:
The single port device serves multiple functions: it provides initial access with a small diameter, maintains pneumoperitoneum, and allows upsizing to accommodate various instrument sizes. This multi-functional design eliminates the need for separate ports of different sizes
3Reliability
If threads are added to improve fixation, then the port stability increases, but insertion force and defect size increase
Solution Approach 1:
External expansion elements are provided on the outer surface of the elongate members at the distal end, creating localized fixation features only where needed for tissue engagement. This allows improved fixation without requiring threads along the entire length of the members, reducing overall insertion force and tissue defect size
4Force
If bladed tips are used to reduce insertion force, then the port can cut through tissue easier, but the risk of puncturing internal organs increases
Solution Approach 1:
The distal tips of the elongate members are configured with localized cutting edges or bladed portions only at the very tip, while the main body of the members remains smooth and non-cutting. This allows the tip to initiate tissue penetration with reduced force while the larger diameter main body provides safety margins to prevent deep organ puncture
Data Source
AI summary
Cannula devices, systems, and methods are provided for introducing one or more instruments into a patient's body to perform a procedure. In one example, the cannula device includes first and second housings defining a throughbore, and a plurality of elongate members extending distally from the housings, the elongate members cooperatively defining a passage axially aligned with the throughbore between proximal ends and distal tips of the elongate members. The first housing is moveable in an axial direction with respect to the second housing to cause the proximal ends of the elongate members to move outwardly to increase a size of the passage and, optionally, may taper when expanded. Optionally, one or more secondary devices, e.g., an obturator with a sharpened tip, or an obturator and tubular access device may be provided that may be inserted through the throughbore into the passage before expansion of the passage.