Magnesium Bone Anchor Hardness for Osteosynthesis Fixation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing osteosynthesis systems face challenges in achieving a secure and stable fixation of bone plates and bone anchors, particularly due to high loosening torque and material deformation issues.
Innovation Solution
The use of magnesium alloys for both the bone plate and bone anchor, with the bone anchor having a higher hardness than the bone plate, allows for a form-fitting and/or frictional connection that reduces material deformation and enhances stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threads of the anchor head and bone plate are made non-complementary to achieve form-fitting connection, then loosening torque increases and unintentional loosening is avoided, but material deformation occurs during connection
Solution Approach 1:
The patent applies different hardness levels to different components: the bone anchor is made with higher hardness magnesium alloy (HV 80-120) while the bone plate uses lower hardness magnesium alloy (HV 40-80). This local differentiation allows the anchor to cut into the plate during threading, creating form-fitting connection with high loosening torque while controlling deformation to occur in the plate rather than the anchor
Solution Approach 2:
The patent changes the hardness parameter of the magnesium alloys used in the anchor and plate. By adjusting the alloy composition and heat treatment parameters, the anchor achieves higher hardness than the plate, enabling deliberate material deformation during connection that secures the form-fitting interface while maintaining connection reliability
2Reliability
If different titanium alloys with different hardness are used for connection partners, then deliberate material deformation is achieved for secure fixation, but device complexity increases due to multiple material types
Solution Approach 1:
The patent uses the same base material (magnesium alloy) for both the bone anchor and bone plate, differing only in hardness level achieved through composition adjustments and heat treatment. This homogeneous material selection simplifies the device by eliminating the need for multiple dissimilar materials like different titanium grades, while still achieving the required differential hardness for secure fixation
3Reliability
If magnesium alloys with different hardness are used for bone anchor and bone plate, then form-fitting connection is achieved with high loosening torque, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific hardness ranges for the magnesium alloys: anchor hardness of HV 80-120 and plate hardness of HV 40-80. These parameter specifications enable controlled material deformation during connection while providing clear manufacturing targets that balance connection reliability with manufacturability
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
This approach results in a secure and stable fixation with a high loosening torque, effectively preventing unintentional loosening while allowing for deliberate deformation of the material for secure anchoring.
Implementation Method 1
the material of one of the connection partners is deformed. This results in a high loosening torque for the threaded connection
Implementation Method 2
The fixation can be achieved by an interaction of threads of the anchor head and of the bone plate... by forming a form-fitting and/or frictional connection
Data Source
AI summary
An osteosynthesis system includes at least one bone plate (2), which has at least one receiving opening (8), and a bone anchor (3), which has an anchor head, the anchor head being designed to be fixed in the receiving opening by forming a form-fitting and/or frictional connection with the bone plate (2). The bone plate (2), at least in a portion including the receiving opening, and the bone anchor (3), at least in a portion including the anchor head, are each made of a magnesium alloy, the magnesium alloy of the bone anchor (3) having a different hardness to the magnesium alloy of the bone plate (2).