Flexible Intramedullary Rodscrew Locking for Torque-Stable Fixation
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Solution Overview
Problem
Existing bone fracture fixation devices struggle with flexibility during implantation and rigidity during healing, as well as stability under load and torque, particularly in complex bone structures like the pelvis.
Innovation Solution
A rodscrew with a flexible configuration that can bend through a curved intramedullary pathway and transition to a rigid configuration for fracture fixation, featuring internal cables and beads with tabs and pockets for torque resistance, allowing for a shape-locking mechanism to maintain alignment and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rodscrew is made rigid to provide stable fixation, then it can support loads and maintain alignment, but it cannot be easily implanted through curved pathways
Solution Approach 1:
The rodscrew employs a dynamic configuration system with multiple cables that can transition between a flexible state during implantation and a rigid locked state during fixation. The cables are arranged in a flexible configuration allowing the rodscrew to bend and conform to curved intramedullary pathways during insertion, then transition to a rigid configuration to provide stable load support and maintain alignment during the fracture-healing process.
2Ease of operation
If the rodscrew is made flexible for easy implantation through curved pathways, then it can be easily inserted, but it cannot withstand the torque and loads during fracture healing
Solution Approach 1:
The rodscrew utilizes parameter changes in its cable configuration to transition between operational states. During implantation, the cables are in a flexible configuration allowing the rodscrew to be easily inserted through curved pathways. After implantation, the cables are locked into a rigid configuration that enables the rodscrew to withstand significant torque and loads during fracture healing, thus changing the mechanical parameters of the device based on operational requirements.
3Reliability
If the rodscrew uses multiple cables to increase stability, then it can withstand higher torques, but the device complexity increases
Solution Approach 1:
The rodscrew divides its cable system into multiple discrete cable elements that can independently configure and lock. Each cable segment can be individually managed and locked at specific points along the rodscrew body, allowing the system to achieve high torque resistance through distributed cable segments rather than requiring a single complex cable system. This segmentation enables modular stability while managing overall system complexity.
Data Source
AI summary
An embodiment of a body bead for a bone fracture fixation device, such as a rodscrew, includes at least one pocket and at least one tab. Each of the at least one pocket is configured to engage a respective one of at least one tab of an adjacent body bead and to withstand, without being significantly deformed, a torque of at least three N·m while rotating with the adjacent body bead. And each of the at least one tab is configured to engage a respective one of at least one pocket of another adjacent body bead and to withstand, without being significantly deformed, a torque of at least three N·m while rotating with the other adjacent body bead.