Bone Screw Fastener With 3D Surface Pattern
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Solution Overview
Problem
Bone screws tend to loosen over time due to the nature of their helical threads, which can lead to reduced pull-out forces and instability in bone fixation, necessitating additional anti-backout features, and existing surface treatments do not effectively enhance bone ingrowth.
Innovation Solution
A bone screw with a 3-dimensional pattern on its external surfaces, mimicking marine mammal bone structures, such as whales or dolphins, to enhance resistance to thread loosening and promote bone growth, using titanium or stainless steel materials and manufacturing techniques like laser technology to create a continuous network of voids or ridges that mimic trabecular bone structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If helical threads are used in bone screws, then the screw can be easily inserted into bone, but the screw tends to loosen over time
Solution Approach 1:
The patent applies different surface characteristics to different regions of the screw. The thread flanks have a smooth, polished finish to facilitate easy insertion, while the thread crests and shank surfaces have a textured, porous pattern to prevent loosening and promote bone ingrowth. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The screw surface is segmented into distinct functional zones: smooth thread flanks for insertion, textured thread crests for locking, and porous shank surfaces for bone integration. This segmentation allows each zone to perform its specific function optimally, preventing loosening while maintaining ease of insertion.
2Reliability
If anti-backout features are added to prevent loosening, then screw stability improves, but device complexity increases
Solution Approach 1:
The patent merges the anti-backout function with the bone ingrowth function into a single integrated surface pattern. The textured, porous structure that promotes bone growth also provides mechanical interlocking to prevent loosening, eliminating the need for separate anti-backout features and reducing device complexity.
Solution Approach 2:
The textured surface pattern serves multiple functions simultaneously: it promotes bone ingrowth, provides mechanical locking to prevent loosening, and maintains screw stability. This multi-functionality eliminates the need for additional dedicated anti-backout features, simplifying the overall device design.
3Reliability
If surface patterning is applied to enhance bone ingrowth, then bone formation improves, but manufacturing complexity increases
Solution Approach 1:
The patent replaces complex multi-step mechanical surface treatment processes with a single laser patterning step. The laser creates the textured, porous surface pattern directly on the screw, simplifying manufacturing while achieving superior bone ingrowth compared to traditional mechanical methods.
Solution Approach 2:
The patent uses laser parameters (power, speed, scan pattern) to control the surface pattern characteristics. By adjusting these parameters, the desired porous structure is created efficiently in a single pass, simplifying manufacturing while optimizing bone ingrowth potential.
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 3-dimensional pattern significantly reduces the likelihood of screw loosening and enhances bone ingrowth, potentially eliminating the need for additional anti-backout mechanisms by providing a stable interface with the bone, facilitating faster and more secure integration.
Implementation Method 1
surface patterning... greatly enhanced bone formation... continuous network of voids creates regions of enhanced osteoinductivity to enhance rapid new bone growth
Implementation Method 2
The creation of these patterns can be accomplished employing laser technology. This manufacturing ability allows the machining to occur on difficult to reach surfaces and angles.
Data Source
AI summary
An improved bone screw for humans or mammals is a bone screw having exposed surfaces along a shank and threads extending from the shank with one or more selected portions of the exposed surfaces having a 3-dimensional pattern. The pattern provides enhanced resistance to thread loosening when affixed to bone. The exposed surface is on exterior portions of the threads or portions of the shank or both. The one or more selected portions of the exposed portions having a bone formation enhancing 3-dimensional patterns are in the external exposed thread surfaces or in the exposed shank surfaces or both.