Acetabular Cup with Differentiated Elasticity for Bone Preservation
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Solution Overview
Problem
Conventional hip prosthesis cotyles with uniform rigidity lead to bone density loss in the acetabulum due to their greater rigidity compared to surrounding bone, causing damage and necessitating improved fixation methods without compromising mechanical performance.
Innovation Solution
A cotyle with differentiated elasticity along its surface, featuring a grid-like structure of ribs and holes connected by a porous mesh, manufactured using EBM or SLM technology on titanium alloy, providing varying flexibility from the base to the polar summit, allowing for enhanced osseointegration and mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cotyle is made with high rigidity to ensure mechanical performance, then the mechanical strength is improved, but bone density loss occurs in the acetabulum due to the rigidity mismatch
Solution Approach 1:
The cotyle incorporates regions with different elastic moduli: a first region with higher elasticity (E1) and a second region with lower elasticity (E2), where E1 > E2. This local differentiation allows the cotyle to match the mechanical properties of surrounding bone tissue in critical areas, reducing stress shielding and preventing bone density loss while maintaining overall structural strength.
Solution Approach 2:
The cotyle is constructed as a composite structure combining materials or regions with different elastic moduli. This composite approach enables the device to simultaneously achieve high mechanical strength in load-bearing areas and bone-compatible flexibility in osseointegration zones, resolving the contradiction between strength and bone preservation.
2Strength
If the cotyle is made with high rigidity to ensure primary fixation, then the mechanical coupling is improved, but the osseointegration is compromised due to inadequate bone adherence
Solution Approach 1:
The cotyle features a first region optimized for primary fixation with higher elasticity and a second region optimized for osseointegration with lower elasticity. This local differentiation ensures that each region performs its specific function effectively: the first region provides mechanical coupling while the second region facilitates bone adherence through matched mechanical properties.
Solution Approach 2:
The cotyle is divided into functionally distinct segments: a first region for mechanical fixation and a second region for biological integration. This segmentation allows independent optimization of each region's properties, enabling simultaneous achievement of strong primary fixation and reliable osseointegration without compromise.
3Ease of manufacture
If the cotyle has uniform elasticity throughout, then the manufacturing is simplified, but bone damage occurs due to rigidity mismatch with surrounding tissue
Solution Approach 1:
The cotyle implements local quality variation with distinct first and second regions having different elastic moduli. This approach balances manufacturing feasibility with biological compatibility, allowing the device to be produced using established techniques while preventing bone damage through localized mechanical property matching.
Data Source
AI summary
An acetabular cup for a hip prosthesis, which includes a cotyle body provided with a number of holes for the passage of fixing screws. T holes are connected to each other by a number of ribs which define a grid.