Cannulated Screw-Cable Locking for Patella Fracture Fixation
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Solution Overview
Problem
Current Cable-pin systems for patella fractures face challenges such as displacement and loss of fixation during screw reinsertion, requiring open reduction and hindering early recovery due to the need for hollow drill reaming and guide pin withdrawal, leading to instability and potential failure of cerclage.
Innovation Solution
A cannulated screw-cable locking system comprising a cannulated screw with internal and external threads, a fastening screw connected to the cannulated screw, and a traction cable, allowing guide pin insertion through the screw's cavity without reaming, providing stable fixation and eliminating the need for open reduction by securing the traction cable to the cannulated screw post-reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid screw is used in the Cable-pin system, then the screw provides compression function and prevents backing out, but the hole must be reamed with a hollow drill and the guide pin must be withdrawn, causing displacement of fracture reduction and loss of cerclage
Solution Approach 1:
The guide pin is nested inside the hollow cannulated screw during insertion. The hollow structure of the cannulated screw allows the guide pin to be positioned within its cavity before final fixation, eliminating the need for separate guide pin removal and hole reaming operations.
Solution Approach 2:
The cannulated screw serves multiple functions: it acts as both the fixation screw and the guide pin holder. The hollow cavity of the cannulated screw functions as the guide pin channel, combining the guidance function and fixation function into a single component.
2Ease of manufacture
If the guide pin is withdrawn after reduction, then the screw can be inserted, but the fracture reduction may be displaced and the cerclage may fail
Solution Approach 1:
The guide pin is inserted through the hollow cannulated screw before the screw is fully fixed. This preliminary guidance ensures accurate positioning of the fracture reduction before the screw is tightened, preventing displacement during the fixation process.
Solution Approach 2:
The hollow cannulated screw acts as an intermediary structure that maintains the fracture reduction position while allowing guide pin insertion. It serves as a temporary framework that prevents cerclage failure during the surgical process.
3Manufacturing precision
If open reduction is required for simple patellar fracture, then the fracture can be reduced, but the recovery time is extended and early recovery is hindered
Solution Approach 1:
The cannulated screw with hollow cavity serves as a self-contained fixation system that provides both guidance and fixation functions. This self-service design eliminates the need for separate open reduction procedures, allowing minimally invasive fixation that promotes early recovery.
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 system enhances surgical success and recovery by maintaining stability and preventing screw loosening or sliding, allowing for early recovery without the need for open reduction and reducing the risk of fixation failure.
Implementation Method 1
a tail end of the fastening screw is threadedly connected to the cannulated screw through the internal threads
Data Source
AI summary
A cannulated screw-cable locking system for patella fracture is provided, relating to the technology field of medical devices. The cannulated screw-cable locking system for patella fracture includes a cannulated screw, a fastening screw, and a traction cable. A head end of the cannulated screw is provided with internal threads, and a tail end of the cannulated screw is provided with external threads. The tail end of the fastening screw is threadedly connected to the cannulated screw through the internal threads. The head end of the fastening screw is fixedly connected to the traction cable.