Expandable Reamer With Retractable Blade for Controlled Bone Removal
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Solution Overview
Problem
Existing procedures for removing diseased bone areas, such as in Avascular Necrosis of the hip, are invasive and require improved methods for efficient and controlled bone removal.
Innovation Solution
An expandable reamer with a movable cutting blade that can be incrementally advanced radially outward from a tube to create a socket in bone, utilizing a clutch assembly and deflection pin for precise control, and optionally using nitinol wires with shape memory for enhanced flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cutting blade is exposed to remove diseased bone, then bone removal effectiveness is improved, but tissue damage increases
Solution Approach 1:
The cutting blade is designed to be movable between a retracted position (concealed inside the tube) and an extended cutting position. This dynamic configuration allows the blade to be exposed only when needed for bone removal, minimizing tissue damage during insertion and positioning, while enabling effective bone removal when the blade is extended to the cutting position.
Solution Approach 2:
The surgical device is divided into separate functional components: a protective tube that can be moved independently from the cutting blade. This segmentation allows the tube to protect the blade during navigation through tissue, while the blade can be extended independently when bone removal is required, thus separating the protective function from the cutting function.
2Object-affected harmful factors
If the cutting blade is concealed inside the tube, then tissue damage is reduced, but bone removal capability is limited
Solution Approach 1:
The cutting blade transitions from a concealed state inside the tube to an extended cutting position when bone removal is needed. This dynamic extension allows the device to maintain low tissue damage during insertion while achieving full bone removal capability when the blade is positioned radially outward from the tube.
Solution Approach 2:
The cutting blade is nested within the tube during the insertion and positioning phases, allowing the tube to protect the blade and minimize tissue damage. When bone removal is required, the blade is extended from its nested position to perform the cutting function, thus combining protection and functionality in a nested configuration.
3Manufacturing precision
If the cutting blade is incrementally advanced radially outward, then socket creation precision is improved, but device complexity increases
Solution Approach 1:
The cutting blade is designed to be incrementally advanceable from a retracted position to an extended cutting position. This incremental movement capability allows precise control over the blade's exposure, enabling accurate socket creation by advancing the blade only to the necessary extent rather than full exposure, thus improving precision while managing complexity through controlled motion.
Solution Approach 2:
The tube is positioned and secured in the bone tunnel before the cutting blade is advanced to its cutting position. This preliminary positioning allows the tube to serve as a guide and support structure, ensuring that when the blade is advanced, it does so along a predetermined path, thereby improving socket creation precision without requiring complex guidance mechanisms during the cutting phase.
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 expandable reamer allows for minimally invasive removal of diseased bone with controlled socket creation, reducing tissue damage and enabling efficient backfilling with biologics.
Implementation Method 1
the cutting blade includes nitinol wires having a shape memory
Data Source
AI summary
A surgical device may include a tube and a cutting blade movable between a first position in which the cutting blade is concealed inside the tube and a second position in which the cutting blade is exposed through a sidewall of the tube.