Cannulated Bone Anchor Geometry to Prevent Bone Cement Leakage
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Solution Overview
Problem
Existing bone anchors face challenges in maintaining anchoring stability due to insufficient bone quality in conditions like osteoporosis, and there is a risk of bone cement leakage during minimally invasive procedures, which complicates the surgical treatment of compression fractures.
Innovation Solution
A one-piece bone anchor design with a fully penetrating cannulation opening and a hollow chamber featuring transition zones that act as fluidic diodes, allowing controlled release of bone cement into the surrounding tissue while preventing leakage, manufactured via additive manufacturing or conventional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a through-hole cannulation opening is used for minimally invasive insertion, then the bone anchor can be guided over a guide wire, but bone cement may spread outside the bone causing serious complications
Solution Approach 1:
The cannulation opening is segmented into multiple sections: a first section with a first diameter, a second section with a second diameter smaller than the first, and a third section with a third diameter. This segmentation creates controlled flow resistance zones that prevent cement leakage while maintaining guidability.
Solution Approach 2:
Different sections of the cannulation opening have different diameters to provide different functions: the first section allows guide wire passage, the second section creates flow resistance to prevent leakage, and the third section allows cement injection. This local quality variation resolves the contradiction between ease of operation and prevention of harmful effects.
2Object-affected harmful factors
If a mini-plug is used to close the distal end to prevent cement leakage, then cement leakage is prevented, but an extra component is required and handling safety against accidental loss must be ensured
Solution Approach 1:
The bone anchor integrates the cannulation opening structure directly into the shaft, eliminating the need for a separate mini-plug component. The multi-section cannulation opening itself provides the leakage prevention function through its geometric design, merging the structural and functional requirements into a single integrated component.
Solution Approach 2:
The cannulation opening's geometric structure automatically prevents cement leakage through its flow resistance zones without requiring additional active components or user intervention. The structure serves its own leakage prevention function through its design, eliminating the need for separate plugs or closure mechanisms.
3Productivity
If the injection cannula is removed immediately after injection, then application time is reduced and material savings are achieved, but bone cement can leak out of the bone anchor from the back
Solution Approach 1:
The cannulation opening is designed with flow resistance zones that create preliminary counter-action against cement backflow. The geometric constraints and pressure differentials are built into the structure before cement injection, preventing leakage even when the injection cannula is removed immediately after injection.
Solution Approach 2:
The cannulation opening uses parameter changes in diameter across different sections to control fluid flow characteristics. The transition from larger to smaller diameters creates increasing flow resistance that prevents cement leakage, allowing rapid application without compromising prevention of harmful effects.
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 design ensures stable anchoring and minimizes bone cement leakage, facilitating faster application and reducing material waste by eliminating the need for multiple injection cannulas.
Implementation Method 1
transition zones that act as fluidic diodes, allowing controlled release of bone cement into the surrounding tissue while preventing leakage
Implementation Method 2
allowing controlled release of bone cement into the surrounding tissue
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The invention relates to a bone anchor (10) for fixing bone components and bone fragments, which bone anchor consists of a shank (13), a neck zone (12) and a head (11) located in the proximal direction (10), and a tip (14) located in the distal direction (102), wherein the bone anchor (10) has a mainly cylindrically shaped cavity (40), which extends along the central axis (103), wherein the cavity (40) adjoins a transition zone (30) located proximally (101) from a central plane (106), characterized in that the transition zone (30) has, at least in sections, an internal diameter (d30) and the cavity (40) has, at least in sections, an opening diameter (d40), and the opening diameter of the cavity (d40) is greater than the internal diameter (d30) of the proximal transition zone (30).