Directional Reamer With Flexible Shaft For Intramedullary Canal Shaping
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Solution Overview
Problem
Current intramedullary nailing techniques struggle with shaping complex or asymmetric medullary canals in bones, often requiring invasive procedures or complete changes in treatment protocols for fractures with non-unions or irregular geometries.
Innovation Solution
A system comprising a directional reamer with a flexible drive shaft and a follower sleeve, where the reaming plunger engages the collar of the follower sleeve to deflect the cutting head, allowing for selective shaping of the medullary canal by varying the degree of deflection, enabling precise reaming within the bone's anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional reamers are used for intramedullary nailing, then the medullary canal can be enlarged, but selective shaping of the canal is not possible for complex or asymmetric bone geometries
Solution Approach 1:
The reamer system is divided into separate functional components: a flexible drive shaft for navigation, a cutting head for bone removal, and a follower sleeve for directional control. This segmentation allows each component to be optimized independently while providing selective shaping capability through their coordinated interaction.
Solution Approach 2:
The cutting head is designed to be deflectable relative to the drive shaft, allowing dynamic adjustment of the reaming direction. The follower sleeve can be positioned at different locations along the drive shaft to control the degree of deflection, enabling selective shaping of the medullary canal according to complex bone geometries.
2Manufacturing precision
If the medullary canal is enlarged with standard reamers, then a smooth hollow tube is created, but the bone thickness cannot be selectively retained on thinner sides
Solution Approach 1:
The follower sleeve acts as an intermediary component between the drive shaft and the cutting head, providing directional control and deflection. By positioning the follower sleeve at different locations, the operator can precisely control the reaming path to selectively shape the canal while preserving bone thickness on thinner sides.
Solution Approach 2:
The deflectable cutting head allows different regions of the medullary canal to be reamed with different characteristics. The cutting head can be deflected toward thicker bone regions to remove more material or kept straight to preserve bone on thinner sides, enabling local adaptation to the specific bone geometry being treated.
3Adaptability or versatility
If directional reaming is implemented with a deflectable cutting head, then selective canal shaping is enabled, but the system complexity increases
Solution Approach 1:
The drive shaft is constructed as a flexible structure that can bend and deflect while maintaining structural integrity. This flexibility allows the cutting head to be directed at various angles without requiring complex mechanical articulation mechanisms, achieving directional control through material properties rather than mechanical complexity.
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
Enables precise and controlled reaming of medullary canals, accommodating complex bone geometries, reducing the need for invasive procedures and allowing for targeted bone grafting, thereby improving fracture fixation outcomes.
Implementation Method 1
the collar defines a first sloped surface and the reaming plunger defines a second sloped surface that engages the first sloped surface such that, when the reaming plunger is advanced along the channel, the second sloped surface slides along the first sloped surface causing the reaming plunger to move outward within the channel of the follower sleeve
Implementation Method 2
the outer surface of the collar engages the inner surface of a bony canal such that it does not slip rotationally during reaming
Data Source
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AI summary
A system for intramedullary preparations comprises a directional reamer including a flexible drive shaft having a proximal end and a distal end, and a cutting head operably connected to the distal end of the flexible drive shaft. The system further includes a means of displacing the distal end of the flexible drive shaft and deflecting the cutting head to selectively shape a medullary canal in a bone. A follower sleeve is also include in the system and has a proximal end and a distal end in the form of a collar, with the follower sleeve being configured to accept the flexible drive shaft. The system additionally includes a reaming plunger that extends through the follower sleeve and is positioned adjacent to the flexible drive shaft such that the reaming plunger engages the collar of the follower sleeve to deflect the cutting head.