Artificial Joint Stem Coating with Segmented Bone Adhesion
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Solution Overview
Problem
Existing artificial joint stems face challenges in controlling both antimicrobial properties and adherence to bone, often resulting in excessive adhesion that complicates removal after surgery.
Innovation Solution
The artificial joint stem features a coating film with a calcium phosphate-based material and an antimicrobial agent, applied to a rough surface with strategically placed recessed portions such as holes and grooves, allowing for controlled adherence and reduced bacterial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating with bone-binding agent and antimicrobial metal agent is applied to the entire surface, then antimicrobial properties are improved, but adherence to bone becomes excessive and removal becomes difficult
Solution Approach 1:
The coating surface is segmented into multiple regions with different properties: a first region with high bone-binding capability (containing bone-binding agent) and a second region with low bone-binding capability (without bone-binding agent or with reduced concentration). This segmentation allows the implant to have both strong antimicrobial properties in the coated region and controlled adherence in the non-coated or low-binding region, enabling easier removal when necessary.
Solution Approach 2:
Different regions of the coating surface are given different local qualities: the first region contains a bone-binding agent (such as calcium phosphate) that provides strong bone adherence, while the second region either lacks the bone-binding agent or has it in reduced concentration, providing weaker adherence. This local differentiation resolves the contradiction by allowing strong bonding where needed while maintaining ease of removal in other areas.
2Reliability
If a coating film is applied to cover the rough surface, then antimicrobial properties are improved, but bone adherence becomes excessive
Solution Approach 1:
The coating film is segmented into a first region containing a bone-binding agent that provides strong bone adherence and a second region that lacks the bone-binding agent or has reduced concentration, providing weaker adherence. This segmentation allows the implant to achieve both antimicrobial protection and controlled bone adherence strength.
Solution Approach 2:
The coating is designed as a composite structure where the first region contains both the bone-binding agent (such as calcium phosphate) and antimicrobial metal agent, while the second region contains primarily the antimicrobial metal agent or has reduced concentrations of both. This composite approach allows simultaneous achievement of antimicrobial properties and controlled bone adherence.
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
This design effectively balances antimicrobial properties with controlled bone adherence, reducing the risk of excessive adhesion and facilitating easier removal when necessary.
Implementation Method 1
a coating film with a calcium phosphate-based material and an antimicrobial agent
Implementation Method 2
applied to a rough surface with strategically placed recessed portions such as holes and grooves
Data Source
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AI summary
In the present disclosure, an artificial joint stem includes a base having an outer surface including a rough surface, and a coating film disposed on the rough surface of the base and containing a calcium phosphate-based material and an antimicrobial agent. The rough surface includes an exposed region exposed from the coating film.