Acetabular Prosthesis with Barbed Stakes and Porous Metal
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Solution Overview
Problem
Conventional acetabular prostheses face challenges in initial fixation and wear resistance, particularly in younger patients, where mechanical fixation methods are undesirable and existing materials do not adequately mimic natural bone, leading to potential loosening and revision operations.
Innovation Solution
The acetabular cup prosthesis features a plurality of barbed stakes that are integral with the prosthesis, allowing for initial fixation by being difficult to extract and providing stability, combined with a multi-layered structure of polyaryletherketone and porous metal layers for enhanced osteointegration and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal shells are used for acetabular cups, then strength and durability are improved, but the risk of damage or deformation during insertion increases
Solution Approach 1:
The patent employs a composite structure combining a metal shell with a polyethylene liner. The metal shell provides the necessary strength and durability, while the polyethylene liner reduces friction and wear during insertion and use, preventing damage to the metal shell and reducing the force required for insertion.
2Ease of operation
If cement is used to fix the acetabular cup, then ease of insertion is improved, but long-term stability and osteointegration worsen
Solution Approach 1:
The metal shell is designed with a porous outer surface that allows bone ingrowth and osteointegration. This porous structure provides long-term stability and secure fixation without requiring cement, while still allowing for relatively easy insertion compared to solid metal shells.
3Reliability
If polyethylene liners are used, then wear resistance is improved compared to natural cartilage, but wear and loosening still occur over time
Solution Approach 1:
The patent uses a composite material system with the polyethylene liner providing low-friction articulation surface that reduces wear compared to natural cartilage. The metal shell with porous surface provides structural support and osteointegration, together extending the service life of the prosthesis by addressing both wear resistance and long-term fixation.
4Reliability
If screws are used to secure the cup shell, then fixation stability is improved, but mechanical disruption and complexity increase
Solution Approach 1:
The metal shell features a porous outer surface structure that enables direct bone ingrowth and osteointegration. This eliminates the need for screws or other mechanical fixation devices, reducing device complexity while maintaining fixation stability through biological bonding between the bone and porous metal surface.
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 barbed stakes ensure secure initial fixation without mechanical disruption, while the multi-layered structure offers improved wear resistance and osteointegration, reducing the need for revision operations and enhancing the prosthesis's longevity.
Implementation Method 1
a metal shell for insertion into the pelvic cavity... Often the metal shells have outer surfaces or coatings which encourage bone to grow into them over time
Implementation Method 2
The acetabular cup prosthesis features a plurality of barbed stakes that are integral with the prosthesis, allowing for initial fixation by being difficult to extract and providing stability
Implementation Method 3
The acetabular cup prosthesis features a plurality of barbed stakes that are integral with the prosthesis, allowing for initial fixation by being difficult to extract and providing stability, combined with a multi-layered structure of polyaryletherketone and porous metal layers for enhanced osteointegration and wear resistance
Data Source
Figure 1~2
Figure 3a~4
Figure 5~6
AI summary
A prosthesis comprising a plastics body and a plurality of barbed stakes extending from a bone- facing surface of said body; said stakes being sized and located to provide fixation on impaction