Microdebrider Interface Bushing for Stable Rotating Blades
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Solution Overview
Problem
Existing microdebriders, such as the Medtronic Straightshot®, face instability issues due to varying blade angles and rotational positions, particularly when cutting dense tissue or bone, which affects the stability and reliability of the interface between the middle and outer tubes, especially when using navigation systems.
Innovation Solution
A stabilizing interface is introduced through a bushing seated between the shoulder of the middle tube and the inner lip of the outer tube, enhancing the stability of the interface between the concentric tubes, allowing for 360° rotation of the cutting window without repositioning the outer tube, and incorporating a rotating wheel for selective orientation of the cutting window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the blade angle of the middle tube and inner tube varies from 12 to 120 degrees, then the device can handle different tissue types and cutting requirements, but the tube interface stability deteriorates due to varying rotational forces and stress distribution
Solution Approach 1:
A bushing is introduced as an intermediary component between the middle tube and outer tube. This bushing acts as a mediator that absorbs and distributes the varying rotational forces and stresses generated by different blade angles (12-120 degrees), preventing direct stress concentration at the tube interface. The bushing maintains stable electrical and mechanical connection regardless of the blade angle configuration.
2Productivity
If the inner tube rotates at high rpms to cut dense tissue or bone, then the cutting efficiency and productivity improve, but the tube interface stability deteriorates due to increased centrifugal forces and vibration
Solution Approach 1:
The bushing serves as a pre-positioned cushioning element between the rotating inner tube and the stationary outer tube. Before high-speed rotation encounters dense tissue or bone, the bushing is already in place to absorb centrifugal forces, reduce vibration, and prevent stress concentration at the tube interface, thereby maintaining stability during high-productivity cutting operations.
3Adaptability or versatility
If the middle tube and inner tube extend several centimeters from the distal end to accommodate various blade angles, then the adaptability improves, but the device complexity increases due to additional interface requirements for navigation system compatibility
Solution Approach 1:
The bushing serves multiple functions simultaneously: it maintains mechanical stability of the tube interface, provides electrical connection for navigation system compatibility, and accommodates various blade angles (12-120 degrees). This multi-functional design reduces overall device complexity by consolidating multiple requirements into a single component rather than requiring separate solutions for each function.
Data Source
AI summary
A device for removing tissue or bone includes a housing having an outer tube defining an inner lip. A middle tube is supported within the outer tube and includes an opening having teeth at a distal end thereof and a shoulder defined around an outer surface thereof proximate the opening. An inner tube is disposed within the middle tube and includes an opening having teeth at a distal end thereof in registration with the opening in the middle tube. The inner tube couples to a power source and rotates relative to the middle tube such that the teeth cooperate to cut tissue or bone disposed in a cutting window between the openings. A bushing is disposed atop the middle tube against the shoulder, such that, upon assembly, the bushing seats between the shoulder of the middle tube and the inner lip of the outer tube to provide stability therebetween.