Bone Fixation Bridge Member with Shape Memory Tines
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Solution Overview
Problem
Conventional bone fixation devices made from shape memory effect materials, such as nitinol, are limited in their ability to stabilize multiple bone fragments at a single location, particularly in complex fractures like those found in the wrist or ankle, where multiple bones need to be brought together.
Innovation Solution
A bone fixation apparatus featuring a bridge member with multiple tines that are configured to move inward toward a central portion, utilizing a shape memory effect material that changes geometry with temperature, allowing for the stabilization of three or more bone pieces by applying force as it transitions from a higher to a lower temperature state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional bone staples with two prongs are used, then simple fracture lines can be stabilized, but complex fractures with multiple bone fragments cannot be effectively stabilized
Solution Approach 1:
The bridge member is segmented into multiple tines (at least three) that can be independently inserted into different bone fragments. Each tine acts as an independent anchoring element, allowing the device to stabilize multiple fracture sites simultaneously while maintaining a relatively simple overall structure.
Solution Approach 2:
The bone fixation apparatus is designed with multiple tines that can accommodate various fracture configurations. The same basic structure can be used for different numbers of bone fragments by adjusting which tines are inserted, making the device universally applicable to both simple and complex fractures without requiring multiple specialized devices.
2Adaptability or versatility
If the bridge member is designed with curved sides to pull tines inward, then multiple bone pieces can be brought together, but the manufacturing precision requirements increase
Solution Approach 1:
The bridge member utilizes shape memory effect material properties where geometric parameters (curve radii) change with temperature. The curved sides have different radii in different material states (martensitic vs. austenitic), allowing the same structure to provide both easy insertion at low temperature and effective compression at body temperature without requiring extremely precise manufacturing tolerances.
Solution Approach 2:
The shape memory effect material undergoes phase transition between martensitic and austenitic states based on temperature. In the martensitic state (lower temperature), the material is softer and the curves have smaller radii, facilitating insertion. Upon heating to body temperature, the material transitions to austenitic state, the curves expand to larger radii, and the structure generates inward forces to compress the bone fragments together.
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 apparatus effectively stabilizes complex fractures by applying force to multiple bone fragments, allowing for proper healing while providing visibility of the fracture site for monitoring through its open center design, suitable for various orthopedic applications including wrist and ankle fusions.
Implementation Method 1
The present invention relates to a bone fixation apparatus and a method for manufacturing such an apparatus that includes a bridge member having at least three tines extending outwardly therefrom... The tines are configured for insertion into bone pieces, and the bridge member is specifically configured to pull the tines inward toward a central portion of the bridge member... when the device transitions from the second material state, where the side curves have a larger radius, to the first material state, forces applied to the tines from each of the adjacent pairs of sides, moves the tines toward each other
Data Source
AI summary
A bone fixation apparatus comprising a shape memory effect material includes a bridge member having at least three sides and an open center portion. Each of the bridge member sides defines a curve having a respective first radius when the shape memory effect material is in a first state, and a respective second radius larger than a corresponding first radius when the shape memory effect material is in a second state. Elongate members are connected to, and extend outwardly from, the bridge member. Each of the elongate members are connected to the bridge member at an approximate intersection of a respective two of the sides, such that each elongate member is subject to a force from each of two intersecting sides, and moves toward the open center portion of the bridge member when the shape memory effect material changes from the second state to the first state.