Bone Fixation Device with Parallel Guide Rails
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Solution Overview
Problem
Existing bone fixation devices face challenges in providing rigid stabilization against shear stresses and bending, while also allowing for controlled loading and mechanical stimulation of fractures, particularly in long bones with comminuted zones or critical size defects, and are often bulky or prone to infection.
Innovation Solution
A bone fixation device featuring parallel guide rails and compressible resilient members that allow for uniaxial motion and predeterminable load sharing between the bone and implant, with adjustable screw angles and axial compression, using a configuration of plates and guide rails that prevent rotation and provide optimal visibility for imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If external fixation devices are used to allow interfragmentary movement for accelerated bone healing, then bone formation is enhanced, but the device becomes bulky and hinders patient daily life
Solution Approach 1:
The guide rails are inserted into hollow cylindrical members of the plates, creating a nested structure where the rails move within the plate bodies. This nesting approach allows the dynamic fixation function to be integrated within the compact plate structure rather than requiring external bulky components.
Solution Approach 2:
The invention transitions from external fixation to internal fixation by embedding the dynamic mechanism within the bone plate structure itself. The guide rails provide uniaxial motion capability within the three-dimensional plate structure, eliminating the need for external bulky fixation devices.
2Stability of the object's composition
If rigid stabilization is provided against shear stresses and bending, then fracture fixation stability is improved, but controlled loading and mechanical stimulation of the fracture are reduced
Solution Approach 1:
The plate structure is segmented into multiple functional components: hollow cylindrical members, guide rails, and compressible resilient members. This segmentation allows different parts to perform specialized functions - the guide rails provide rigid guidance for uniaxial motion while the resilient members provide controlled compression, achieving both stability and adaptability.
Solution Approach 2:
The guide rails are configured to slide within the hollow cylindrical members, providing uniaxial motion capability. This dynamic mechanism allows controlled movement and loading along the longitudinal axis while maintaining stability against shear stresses and bending through the parallel arrangement and structural constraints.
3Stability of the object's composition
If parallel guide rails are used to prevent rotation and provide shear stability, then fracture fixation stability is improved, but device complexity increases
Solution Approach 1:
The guide rails serve multiple functions simultaneously: they provide uniaxial motion guidance, prevent rotation about any axis, resist shear stresses, and work in conjunction with the compressible resilient members to enable controlled loading. This multi-functionality reduces the need for separate components for each function.
Solution Approach 2:
The guide rails are merged with the hollow cylindrical members of the plates, with the rails inserted into and sliding within the cylindrical members. This merging integrates the motion guidance function directly into the plate structure, reducing overall device complexity while maintaining stability.
4Object-affected harmful factors
If internal fixation is used to reduce infection risk, then patient safety is improved, but the ability to provide dynamic fixation for accelerated healing is reduced
Solution Approach 1:
The internal fixation device incorporates dynamic elements through the guide rails that can slide within the hollow cylindrical members. This allows the internally fixed device to provide controlled uniaxial motion and mechanical stimulation for accelerated bone healing while maintaining the infection reduction benefits of internal fixation.
Solution Approach 2:
The dynamic mechanism is nested within the internal plate structure, with guide rails inserted into hollow cylindrical members. This nested configuration enables dynamic fixation functionality to be integrated into the internal fixation device, providing both infection protection and accelerated healing capabilities.
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 device achieves high stability against shear stresses, accelerates bone healing through dynamic fixation, and allows for controlled load distribution, reducing infection risk and improving patient mobility with a more compact design.
Implementation Method 1
a compressible resilient member (16) arranged between said first and second plate
Implementation Method 2
a first and a second guide rail (13, 14) arranged parallel with respect to a longitudinal axis (2) such uniaxially slideably connecting said first and second plate (3, 4)
Data Source
Figure 1~2
AI summary
A bone fixation device (1) for internal fixation of bone fragments with a longitudinal axis (2) and comprising: A) a first and a second plate (3, 4) each having a lower surface (5), an upper surface (6), two lateral surfaces (22, 23), a front surface (7) axially intermediate between said first and second plate (3, 4), an axially terminal surface (8) and at least one screw hole (17) extending from said upper surface (6) to said lower surface (5) and intended to receive a bone screw; B) a first and a second guide rail (13, 14) arranged parallel with respect to said longitudinal axis (2) and uniaxially slideably connecting said first and second plate (3, 4); and C) at least one resilient member (15, 16) arranged between said first and second plate (3, 4) acting as a compression spring.