Bone Anchor with Polymer Sleeve for Iliosacral Screw Guidance
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Solution Overview
Problem
Existing bone anchors for triangular iliosacral osteosynthesis require oversized screws, leading to practical limitations and potential anatomical and structural issues during implantation and fixation.
Innovation Solution
A bone anchor design featuring an ilium screw with a slot-shaped through-opening and a sleeve element made of polymer material, allowing the iliosacral screw to be guided through and securely fixed, with a smaller outer diameter and a form-fitting engagement to prevent displacement during screwing, enhancing implantability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ilium screw and iliosacral screw are designed with large outer diameters to accommodate the through-opening for passing the iliosacral screw, then the structural strength and stability are improved, but the implantability and anatomical compatibility deteriorate due to oversized dimensions
Solution Approach 1:
The iliosacral screw is nested through the through-opening of the ilium screw, with the sleeve element positioned within the through-opening to provide form-fit engagement. This nesting arrangement allows the iliosacral screw to pass through the ilium screw without requiring oversized dimensions, as the sleeve element provides the necessary engagement mechanism within the constrained space of the through-opening.
Solution Approach 2:
The sleeve element acts as an intermediary component between the ilium screw and the iliosacral screw. It is inserted into the through-opening of the ilium screw and provides form-fit engagement for the iliosacral screw, enabling secure fixation without requiring the ilium screw to have a large outer diameter. The sleeve element mediates the interaction between the two screws, allowing compact design while maintaining structural integrity.
2Ease of operation
If the through-opening in the ilium screw is made large enough to accommodate the iliosacral screw, then the iliosacral screw can be passed through easily, but the outer diameter of the ilium screw must be increased, causing anatomical and structural issues
Solution Approach 1:
The iliosacral screw is nested through the through-opening of the ilium screw, with the sleeve element positioned within the through-opening to provide form-fit engagement. This nesting arrangement allows the iliosacral screw to pass through the ilium screw without requiring oversized dimensions, as the sleeve element provides the necessary engagement mechanism within the constrained space of the through-opening.
Solution Approach 2:
The sleeve element acts as an intermediary component between the ilium screw and the iliosacral screw. It is inserted into the through-opening of the ilium screw and provides form-fit engagement for the iliosacral screw, enabling secure fixation without requiring the ilium screw to have a large outer diameter. The sleeve element mediates the interaction between the two screws, allowing compact design while maintaining structural integrity.
3Ease of manufacture
If the sleeve element is held only frictionally in the through-opening, then the insertion process is simple, but the stability and reliability of fixation deteriorate during screwing operations
Solution Approach 1:
The sleeve element is preliminarily inserted into the through-opening of the ilium screw before the iliosacral screw is screwed in. This preliminary insertion positions the sleeve element in advance to provide the necessary form-fit engagement, ensuring that when the iliosacral screw is screwed in, the sleeve element is already in place to prevent displacement and provide stable fixation.
Solution Approach 2:
The sleeve element is made of polymer material, which provides both frictional engagement and form-fit engagement properties. The polymer material allows for easy insertion through friction while also providing reliable mechanical interlocking through form-fit engagement with the through-opening, combining the benefits of simple insertion with stable fixation.
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 effective treatment of sacral fractures with improved implantability and stability, allowing for secure fixation of the iliosacral screw to the ilium screw, reducing the risk of sleeve element displacement during screwing and accommodating anatomical constraints.
Implementation Method 1
a sleeve element having a shape complementary to the shape of the through-opening and made of a polymer material is inserted into the through-opening and is then held in the through-opening frictionally and additionally in a form-fitting manner
Data Source
AI summary
The invention relates to a bone anchor for triangular iliosacral osteosynthesis. The bone anchor includes an ilium screw having a first longitudinal direction and an iliosacral screw having a second longitudinal direction. The ilium screw, in a thread-free portion, has a preferably elongated-hole-like through-opening transversely to the first longitudinal direction, and the iliosacral screw has such a smaller outer diameter in relation to the ilium screw that the iliosacral screw can be guided through the through-opening and can be screwed proceeding from the ilium into the sacrum, through the ilium screw.