Variable Angle Bone Fastener With Interrupted Threads
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Solution Overview
Problem
Existing orthopedic plating systems lack operational simplicity and versatility in securing bones at variable angles, often resulting in suboptimal engagement and potential tissue damage during bone fixation procedures.
Innovation Solution
A bone fixation assembly featuring a bone fastener with circumferentially interrupted external threads and angled slots allows for controlled angled-threading, enabling secure fixation at variable angles without additional components, effectively clearing tissue and preventing cross-threading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional plating systems with fixed orientation screws are used, then bone fixation stability is improved, but surgical versatility and ease of operation deteriorate due to inability to accommodate variable angle requirements
Solution Approach 1:
The screw head incorporates a dynamic angled-threading mechanism with circumferentially interrupted threads that allow the screw to engage the plate at variable angles (0-15 degrees of offset) while maintaining stable fixation. This dynamic capability enables the same hardware to adapt to different anatomical configurations without compromising fixation stability.
Solution Approach 2:
The invention changes the thread geometry parameter by introducing circumferentially interrupted threads with specific lead angles and pitch configurations. This parameter modification enables controlled angled-threading that accommodates variable angle requirements while maintaining adequate engagement and fixation stability.
2Reliability
If conventional plating systems with additional locking components are used, then bone fixation reliability is improved, but device complexity and ease of operation worsen due to multiple components and assembly steps
Solution Approach 1:
The invention merges the locking mechanism and variable angle capability into the screw head itself through circumferentially interrupted threads. This integration eliminates the need for separate locking rings or complex multi-component systems, reducing device complexity while maintaining fixation reliability through the self-locking angled-threading mechanism.
Solution Approach 2:
The circumferentially interrupted threads provide self-locking functionality through their geometric configuration. As the screw is inserted at an angle, the thread geometry automatically prevents backout and secures the fixation without requiring additional locking components or complex assembly procedures, thereby simplifying the overall device.
3Ease of manufacture
If conventional plating systems force aligned threading are used, then manufacturing simplicity is improved, but tissue damage and engagement quality worsen due to cross-threading and soft tissue interference
Solution Approach 1:
The circumferentially interrupted threads are pre-configured with specific lead angles and pitch variations that anticipate and accommodate variable angle insertion. This preliminary geometric configuration guides the screw along the correct insertion path, preventing cross-threading and soft tissue interference before they can occur, while maintaining manufacturing simplicity through standardized thread cutting processes.
Solution Approach 2:
The circumferentially interrupted threads act as an intermediary mechanism between the screw and the bone/plate interface. This intermediate thread structure mediates the engagement process by providing a controlled threading path that prevents direct cross-threading contact and reduces soft tissue damage, while the threads themselves can be manufactured using conventional machining methods.
4Adaptability or versatility
If variable angle capability is added to plating systems through additional components, then surgical versatility is improved, but ease of operation and device complexity worsen
Solution Approach 1:
The screw head incorporates a dynamic angled-threading mechanism with circumferentially interrupted threads that allow the screw to engage the plate at variable angles (0-15 degrees of offset) while maintaining stable fixation. This dynamic capability enables the same hardware to adapt to different anatomical configurations without compromising fixation stability.
Solution Approach 2:
The circumferentially interrupted thread design provides multi-functionality by combining variable angle engagement capability with self-locking functionality in a single component. This universal design allows the same screw to be used for both aligned and angled fixation requirements, eliminating the need for separate specialized components and simplifying the surgical toolkit.
Data Source
AI summary
A bone fixation assembly and associated method. The bone fixation assembly includes a bone fastener having a shaft for engaging a bone, and a head connected to the shaft. The shaft defines a longitudinal first axis. The bone fastener also includes a plurality of external thread windings defining an outer surface of the head. The external thread windings are circumferentially interrupted by at least one slot defined on the outer surface. The slot is inclined at an angle relative to the first axis.