Multi-Material Orthopedic Screw Reduces Tissue Inflammation
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Solution Overview
Problem
Conventional orthopedic screws made of single metallic materials cause inflammation and delay healing due to stiffness and sharp threads, and their removal can be painful and cause discomfort.
Innovation Solution
A multi-material orthopedic screw with a softer outer part and a rigid inner part, where the outer part is bio-inert or bio-absorbable and resorbs after healing, reducing inflammation and facilitating easy removal, while the inner part provides structural stability and can be easily retracted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional orthopedic screws are made of single metallic material, then structural strength is ensured, but inflammation and tissue irritation occur due to stiffness and sharp threads
Solution Approach 1:
The orthopedic screw is constructed as a composite device with an outer part made of softer material (such as polyethylene, polypropylene, or other biocompatible polymers) and an inner part made of rigid metallic material. This composite structure allows the outer softer surface to reduce inflammation and tissue irritation while the inner rigid core maintains structural strength and stability for fracture fixation.
Solution Approach 2:
Different parts of the screw are assigned different material properties: the outer surface is made softer to interact gently with bone tissue and reduce inflammation, while the inner core maintains high rigidity for mechanical strength. This local differentiation of material properties resolves the contradiction between strength and tissue compatibility.
2Reliability
If conventional metallic screws are used, then fracture fixation is achieved, but removal causes pain and discomfort
Solution Approach 1:
The composite structure with a softer outer material layer reduces the harmful effects during removal. The softer outer material causes less trauma to surrounding tissues during extraction, while the inner rigid core maintains fixation reliability during the healing period.
3Stability of the object's composition
If stiff metallic screws are used, then structural stability is provided, but puncture risk increases during accidental falls
Solution Approach 1:
The softer outer material layer acts as a protective cushion that reduces the risk of puncture and trauma to surrounding tissues during accidental falls or impact, while the inner rigid core maintains structural stability for fracture fixation.
4Ease of manufacture
If single material screws are used, then manufacturing is simple, but bio-absorbability and easy removal are compromised
Solution Approach 1:
The screw combines different materials with complementary properties: the outer part can be made of bio-absorbable or easily removable material while the inner part provides structural integrity. This composite approach enables both easy removal/bio-absorbability and maintains manufacturing feasibility through established composite manufacturing techniques.
Data Source
AI summary
An orthopedic screw is provided which includes an outer part having a tip, a head, threads disposed on an outer surface of the outer part between the tip and the head, and a longitudinal cavity with an opening in the head. The orthopedic screw further includes an inner part enclosed by the outer part and is removable from the outer part via the opening of the head. The outer part is made of a material softer than a material of the inner part to ensure shock absorption when the orthopedic screw is in inserted state into a bone of a human body.