Faceted Bone Screw Thread Design Reduces Insertion Torque
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Solution Overview
Problem
Existing orthopedic screws face issues such as bone splitting during insertion due to high torque requirements and potential loosening post-installation, which can lead to mis-setting and require additional procedures.
Innovation Solution
The development of a faceted bone screw with varying thread depths and angles, featuring transverse facets on the leading and trailing edges, reduces friction and enhances osteointegration, thereby lowering insertion torque and preventing screw backout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional bone screws are used for insertion into bone, then the screw can provide fixation, but high torque is required which causes bone splitting
Solution Approach 1:
The thread form is segmented into multiple facets (first facet, second facet, third facet) along the thread engagement surface. Each facet creates a separate stress distribution zone, dividing the concentrated insertion force into multiple directional components. This segmentation allows the screw to penetrate bone with lower torque while maintaining fixation strength, as the facets progressively engage the bone structure rather than relying on a single high-stress thread interface.
Solution Approach 2:
The facet configuration creates an asymmetric thread geometry where the engagement surface is divided into inclined planes at different orientations. This asymmetric design allows the screw to cut through bone more efficiently by creating a self-drilling effect, where the facets sequentially remove bone material and engage the surrounding structure. The asymmetry in facet angles optimizes the balance between insertion torque and pull-out strength, reducing the risk of bone splitting while maintaining secure fixation.
2Stability of the object's composition
If conventional bone screws are used for fixation, then the screw can secure bone positioning, but the screw may loosen or back out after installation
Solution Approach 1:
The facet structure performs preliminary bone engagement and compaction during the insertion process itself. As the screw advances, the facets progressively engage and compact the bone around the thread form, creating a pre-formed engagement zone. This preliminary action ensures that when the screw is fully inserted, the bone is already optimized for maximum thread engagement, preventing future loosening and ensuring long-term retention without requiring additional procedures.
3Speed
If high torque is applied during screw insertion, then proper penetration can be achieved, but the risk of bone splitting increases
Solution Approach 1:
The facet configuration creates a dynamic engagement process during insertion. As the screw rotates and advances, the facets sequentially engage the bone at different depths and angles, creating a progressive penetration effect. This dynamic engagement allows the screw to adapt to varying bone densities during insertion, maintaining optimal torque levels throughout the process. The facets act as progressive cutting elements that remove bone material efficiently, enabling proper penetration without requiring excessively high torque that would cause bone splitting.
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 faceted design reduces the torque required for screw insertion by up to 50% and improves osteointegration, minimizing bone splitting and screw loosening, while allowing for easier removal.
Implementation Method 1
The faceted bone screw of the present principles will operate to reduce the friction between the screw and the bone, thereby reducing the torque required to drive the screw and/or threaded pins into the bone
Implementation Method 2
The faceted bone screw of the present principles will also reduce the likelihood of bone screws and threaded pins backing out of the bone due to improved osteointegration between the faceted threaded portion of the implanted device and the bone
Data Source
Figure 1~2A
Figure 2B
Figure 3A
AI summary
A faceted bone screw and a method for manufacturing the same includes a screw thread configuration having facets that are incorporated into one or more of the leading edge, trailing edge or root of the thread. The facets are generally made up of a plurality of transitioning peaks and valleys which vary the depth of the thread and are disposed in one or more locations throughout the threaded portion of the bone screw. The facets operate to reduce the torque required to drive the bone screw into bone, while at the same time operate to assist in anchoring the bone screw within the bone once inserted therein, and thereby reduce the possibility for the screw backing out after insertion.