Variable Angle Orthopedic Locking Insert Mechanism
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Solution Overview
Problem
Existing orthopedic implant systems lack the ability to securely fixate screws or pegs at variable angles, limiting their adaptability to different bone structures and orientations, particularly in small bones and areas like the clavicles, pelvis, and spine.
Innovation Solution
A variable angle locking mechanism that includes a biocompatible locking insert with a smooth, hexagonal central opening and an annular flange, allowing screws or pegs to be inserted at angles up to 15° by deforming the insert's material to accommodate the screw head, with tapered threads for enhanced locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed angle locking screw is used in a threaded hole, then the fixation angle is predetermined and simple to manufacture, but the adaptability to different bone orientations is limited
Solution Approach 1:
The locking mechanism is divided into separate functional components: a plate with threaded holes, removable locking inserts with specific thread configurations, and locking screws. This segmentation allows the locking insert to be independently designed with variable angle capability while keeping the plate design relatively simple.
Solution Approach 2:
The locking insert acts as an intermediary component between the plate and the locking screw. It mediates the angle variation by providing different thread configurations that allow the locking screw to engage at different angles relative to the plate, thus enabling adaptability without requiring complex integrated design.
2Adaptability or versatility
If a variable angle locking mechanism is implemented, then the adaptability to different bone orientations is improved, but the device complexity increases
Solution Approach 1:
The locking insert is designed to provide multiple functions: it can be configured with different thread angles to accommodate various bone orientations, and the same basic component structure can be used across different plate designs. This multi-functionality reduces the need for entirely different components for each angle requirement.
Solution Approach 2:
The thread configuration of the locking insert is varied by changing parameters such as thread angle and pitch. By adjusting these parameters, the locking mechanism can accommodate different insertion angles (e.g., 0°, 15°, 30°) while maintaining the same basic component geometry and assembly procedure.
3Adaptability or versatility
If the locking insert material is made deformable to accommodate screw head, then the variable angle fixation is achieved, but the structural rigidity may be compromised
Solution Approach 1:
The locking insert is designed with localized deformability only in the specific region where the screw head engages. The bulk of the insert structure and the plate itself maintain their original rigid properties. This localized approach allows angle adjustment where needed while preserving overall structural integrity.
Solution Approach 2:
The locking mechanism utilizes materials with different properties: the plate and locking screw are made from rigid, high-strength materials, while the locking insert may incorporate materials with some degree of deformability to accommodate angle variations. This composite material approach allows both flexibility for angle adjustment and rigidity for load-bearing.
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
Enables secure fixation of bones or bone segments at variable angles, providing a rigid construct and improving the surgeon's options for fixation in various orthopedic applications by allowing flexible angle adjustment and secure locking.
Implementation Method 1
The locking insert is made from a biocompatible material that can be deformed by the threads of the fixator head, (i.e. a screw or peg,) so that the fixator is inserted through the locking insert and into the adjacent bone to the point where the proximal head threads interact with the internal opening of the locking insert to cause the material to flow and accept the head of the fixator at any angle
Data Source
AI summary
A locking mechanism assembly to allow locking of a fastener in an orthopedic implant having its axis at a variable angle relative to the axis of threaded through opening in the implant. The assembly includes a locking insert, having threads which mates with the threads of the through opening and which includes a smooth opening that forms a torque driving recess and an annular flange. A fixator has a head portion with external threads of a harder material than that which forms the through opening so that the threads of the fixator will deform the insert to lock the fixator in a desired position relative to the plate.