Multi-Layered Prosthetic Element with Porosity Gradient
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Solution Overview
Problem
Current prosthetic elements, such as tibial fillers, face issues with structural rigidity and bone cement leakage, leading to instability and potential complications in joint replacement surgeries, especially when dealing with bone deficiencies or cortical bone damage.
Innovation Solution
A multi-layered prosthetic element with a central body of truncated conical shape, comprising an outer and inner trabecular metal portion and an intermediate non-porous metal portion, which are integrally connected to resist stresses and prevent bone cement leakage, while promoting bone growth and regrowth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trabecular metal structure is used to promote bone growth, then osseointegration is improved, but structural rigidity and resistance to stresses deteriorate
Solution Approach 1:
The prosthetic element applies local quality by having different portions with different porosity characteristics. The outer and inner portions have trabecular metal structure with porosity to promote bone growth, while the intermediate portion has reduced porosity (below 30%) to provide structural rigidity. This spatial variation in material properties resolves the contradiction between osseointegration and structural strength.
Solution Approach 2:
The prosthetic element uses composite material structure by combining trabecular metal material with controlled porosity gradients. The intermediate portion has porosity specifically controlled to be between 10-30%, creating a composite structure that exhibits both bone-conductive properties and enhanced mechanical strength, resolving the contradiction between biocompatibility and structural integrity.
2Reliability
If bone cement is used to fix the joint element, then anchoring is improved, but bone cement leakage through porous structure causes instability
Solution Approach 1:
The intermediate portion acts as an intermediary barrier between the outer and inner trabecular portions. Its reduced porosity (below 30%) creates a barrier that prevents bone cement from leaking through the porous structure, while still allowing the cement to anchor the joint element securely. This intermediary layer resolves the contradiction between anchoring stability and cement leakage prevention.
3Reliability
If the bone structure has deficiencies or cortical damage, then implantation stability deteriorates, but additional strengthening elements increase device complexity
Solution Approach 1:
The prosthetic element is segmented into three distinct portions: outer trabecular portion, intermediate portion with reduced porosity, and inner trabecular portion. This segmentation allows each portion to fulfill specific functions (bone integration, structural support, stress resistance) within a single integrated component, providing enhanced stability for compromised bone structures without requiring multiple separate implant components.
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 multi-layered prosthetic element provides enhanced structural rigidity to withstand major stresses, effectively replaces the cortical portion of a bone, prevents bone cement leakage, and facilitates bone regrowth, ensuring stable and reliable implantation with improved mechanical resistance and osseointegration.
Implementation Method 1
facilitates bone regrowth, ensuring stable and reliable implantation with improved mechanical resistance and osseointegration
Implementation Method 2
The intermediate portion is configured to mechanically resist to stresses transmitted to the inner portion on one side and to the outer portion on the other side
Implementation Method 3
an intermediate portion made of metal material without significant porosity... prevents bone cement leakage
Data Source
AI summary
A multi-layered prosthetic element comprises a central body (1; 1′) of a substantially truncated conical shape and having a through axial cavity (2; 2′) open at both ends which gives the central body (1; 1′) a ring-shaped cross-section. The central body (1, 1′) comprises an outer portion (110; 110′), made of trabecular metal material, an inner portion (130; 130′), made of trabecular metal material, and an intermediate portion (120; 120′) made of metal material without significant porosity. The outer portion (110; 110′) and the inner portion (130; 130′) are integrally connected to the intermediate portion (120; 120′). The intermediate portion (120; 120′) is configured to mechanically resist to stresses transmitted to the inner portion (130; 130′) on one side and to the outer portion (110; 110′) on the other side.