Bone Undercut Tool with Segmented Cutting Sleeve
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Solution Overview
Problem
Existing tools for generating undercuts in bones are complex and difficult to handle, especially for bores with small diameters, often requiring excessive force that can lead to bone fractures.
Innovation Solution
A tool comprising a core with a stamp and a cutting sleeve, where the stamp has a run-on bevel and the cutting sleeve has pivotable segments with cutting edges, allowing for the creation of an undercut in a bone without applying great force, facilitating easy insertion and effective tissue removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing tools with complex structures are used to generate undercuts, then the undercut generation capability is achieved, but the device complexity increases and handling becomes difficult
Solution Approach 1:
The cutting sleeve is divided into multiple segments that can pivot independently relative to the shaft. This segmentation allows the cutting edges to be distributed around the circumference, enabling effective undercut generation while maintaining a simpler overall tool structure that is easier to handle.
Solution Approach 2:
The cutting sleeve with its segments is nested around the central shaft, creating a compact tool structure. When the segments are in the retracted position, the tool has a small profile for easy insertion into bores. When activated, the segments pivot outward to perform the cutting function, providing both simplicity and effectiveness.
2Strength
If excessive force is applied to achieve secure hold in the bone, then the anchoring strength is improved, but the risk of bone fracture increases
Solution Approach 1:
The tool creates an undercut cavity in the bone before the bone anchor is inserted. This preliminary action of shaping the bone cavity with expanded cutting edges allows the bone anchor to engage mechanically with the undercut, providing secure anchoring through form fit rather than requiring excessive insertion force that could fracture the bone.
Solution Approach 2:
The undercut cavity acts as an intermediary structure between the bone and the bone anchor. Instead of directly forcing the bone anchor into the bone which could cause fractures, the undercut serves as a mechanical intermediary that provides engagement surfaces, distributing forces and reducing the risk of bone fracture while maintaining anchoring strength.
3Productivity
If the cutting elements are always exposed, then the undercut generation efficiency is improved, but the difficulty of insertion into small diameter bores increases
Solution Approach 1:
The cutting sleeve segments are designed to be dynamically movable between a retracted position (for easy insertion into small diameter bores) and an expanded position (for effective undercut generation). This dynamic capability allows the tool to adapt its profile during the procedure, achieving both easy insertion and efficient undercut creation.
Solution Approach 2:
The cutting edges are locally deployed only when and where needed - the segments pivot outward at the cutting location to engage the bone tissue. The rest of the tool maintains a compact profile for insertion. This localized activation of cutting functionality provides both insertion ease and cutting efficiency without requiring the entire tool to be large or complex.
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 tool enables simple, quick, and low-risk generation of undercuts in bones, allowing for secure anchoring of bone anchors with a form fit, reducing the risk of bone fractures and improving handling and safety during the procedure.
Implementation Method 1
When the cutting sleeve is pushed onto the run-on bevel, the segment is pivoted by means of a hinge to a second position in which it protrudes from the outer contour of the cutting sleeve
Implementation Method 2
The cutting edge can cut into tissue that surrounds the tool circumferentially. By rotation of the cutting sleeve about its longitudinal axis, the cutting edge can be moved in a tangential direction with respect to the cutting edge
Data Source
AI summary
A tool according to the invention for generating an undercut in a bone including a core with a shaft and a stamp mounted on a distal end of the shaft, wherein the stamp, in a transition area to the shaft, has a run-on bevel ascending in the distal direction, and a cutting sleeve which is arranged to be longitudinally movable on the shaft and of which the distal end is formed by at least one segment that can be spread open when pushed onto the run-on bevel, wherein the at least one segment has at least one laterally arranged cutting edge. The invention also relates to a method for generating an undercut in a bone.