Variable Angle Locking Screw With Wedge Mechanism
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Solution Overview
Problem
Existing surgical fasteners lack the ability to securely orient and lock screws at various angular and rotational positions relative to a substrate, particularly in non-planar materials like bone, which can lead to instability and complications during surgical procedures.
Innovation Solution
A locking screw assembly comprising a plate material with a semispherical through hole, washers with specific dimensions and configurations, and a screw with a threaded head and shaft, allowing for angular and rotational adjustment and secure locking through a mechanism involving washers and a screw head that engages threads on the washers to maintain orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional fixed-angle screw is used, then the device complexity is low, but the adaptability to various angular positions is poor
Solution Approach 1:
The fastening system is divided into separate functional components: a plate with through-holes, washers with specific geometric features, and a screw. The washers are segmented into first and second washers that can be positioned independently within the through-hole, allowing angular adjustment while maintaining structural simplicity.
Solution Approach 2:
The system transitions from a fixed-angle configuration to a dynamic, adjustable-angle configuration. The washers can rotate and reposition within the through-hole to achieve different angular orientations, and the locking mechanism transforms the dynamic adjusted position into a stable locked state.
2Stability of the object's composition
If a locking mechanism is added to secure angular position, then the stability is improved, but the ease of operation deteriorates
Solution Approach 1:
The washers are designed with geometric features that enable them to self-lock into position. When the washers are rotated to the desired angular orientation, their interaction with the through-hole walls and each other creates a self-retaining configuration that maintains the angular position without requiring additional locking components or complex procedures.
3Reliability
If multiple washers with specific dimensions are used, then the reliability of angular locking is improved, but the device complexity increases
Solution Approach 1:
The washers serve multiple functions simultaneously: they guide the screw, enable angular adjustment through rotation, provide locking through their geometric interaction with the through-hole, and maintain the angular position. This multi-functionality reduces the need for separate components for each function, thereby improving reliability without proportionally increasing complexity.
4Adaptability or versatility
If a semispherical through-hole is used, then the adaptability to non-planar substrates is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The through-hole is formed with a semispherical geometry that can accommodate variations in substrate surface topology. The curved geometry of the semispherical hole allows it to conform to non-planar surfaces such as bone, providing adaptability while the standardized semispherical shape can be manufactured with consistent precision using conventional machining or forming processes.
Data Source
AI summary
A variable angle locking screw assembly that includes a plate material, a screw, and a washer at least partially located within the plate material, the washer and screw cooperating to create a wedge locking the screw in one of a plurality of axial and rotational positions, where the locked position may be undone and adjusted by manipulation of at least one of the screw and washer.