Mixed Material Bone Screw with Composite Ends
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Solution Overview
Problem
Bone screws often experience stripping of the insertion feature during or after procedures, making them unusable for further advancement or removal, and there is a need for a composite screw that can serve different purposes at its ends while being inexpensive, safe, and easy to use.
Innovation Solution
A bone screw composed of multiple materials, where the distal end is made of a biocompatible material for osteointegration and the proximal end is made of a stronger, stiffer material to resist torsional loads and prevent stripping, with a cannulated design for delivering bone cement or substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bone screw is made from a single biocompatible material, then osteointegration is enhanced, but the insertion feature becomes prone to stripping under torsional loads
Solution Approach 1:
The bone screw is constructed as a composite device with the insertion feature made from a first material (e.g., titanium alloy or cobalt chrome) that provides high torsional strength and resistance to stripping, while the distal engagement feature is made from a second biocompatible material (e.g., titanium) that promotes osteointegration. This composite construction allows each portion to be optimized for its specific function without compromise.
2Strength
If a bone screw is made from a stronger, stiffer material, then resistance to stripping is improved, but osteointegration is reduced
Solution Approach 1:
The bone screw applies local quality by using different materials for different portions of the device. The proximal insertion feature uses a stronger, stiffer material optimized for mechanical strength and torsional resistance, while the distal engagement feature uses a more biocompatible material optimized for osteointegration. This localized material selection allows each portion to have the specific properties needed for its function.
3Adaptability or versatility
If a single material is used for the entire bone screw, then manufacturing is simplified, but the screw cannot optimally serve different functions at its ends
Solution Approach 1:
The bone screw is constructed as a composite device with the insertion feature made from a first material (e.g., titanium alloy or cobalt chrome) that provides high torsional strength and resistance to stripping, while the distal engagement feature is made from a second biocompatible material (e.g., titanium) that promotes osteointegration. This composite construction allows each portion to be optimized for its specific function without compromise.
Solution Approach 2:
The bone screw is divided into distinct portions with different material compositions. The proximal portion (insertion feature) and distal portion (engagement feature) are segmented into different materials, allowing each to be optimized for its specific function. This segmentation may be achieved through separate manufacturing and assembly or through additive manufacturing with material transitions.
Data Source
AI summary
The present invention relates to a mixed material bone screw. The bone screw comprises a distal end made of a biocompatible material and a proximal end made from a stronger material to resist stripping of the bone screw during its insertion or removal from a bone. In another embodiment, the mixed material bone screw is cannulated, wherein the bone screw has a bore forming a central channel connected to a plurality of sideward channels for delivering bone cement or other substances into the bone surrounding the bone screw.