Zonal Trabecular Tibial Plateau for Uniform Bone Ingrowth
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Solution Overview
Problem
Existing uni-compartmental knee prostheses face issues such as bone cement syndrome, coating failure, uneven coating thickness, stress shielding, and non-uniform fixation due to mechanical differences in bone tissue regions, leading to potential loosening and reduced long-term stability.
Innovation Solution
A zonal trabecular uni-compartmental tibial plateau made of zirconium-niobium alloy with an oxidation layer, prepared through 3D printing and subsequent heat treatment, featuring varying trabecular structures and an oxygen-rich transition layer to enhance mechanical properties and biocompatibility, reducing stress shielding and improving fixation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bone cement fixation is used for uni-compartmental knee prosthesis, then the prosthesis can be easily fixed, but it causes bone cement syndrome including fragmentation, thermal burn, and infection
Solution Approach 1:
The invention extracts and removes the bone cement component from the fixation system, replacing it with a direct biological fixation method using a porous coating structure that allows bone ingrowth, thereby eliminating bone cement syndrome while maintaining fixation capability
Solution Approach 2:
The invention introduces a porous coating layer as an intermediary between the prosthesis and bone tissue, facilitating direct biological bonding without requiring bone cement, thus resolving the harmful effects of bone cement while preserving easy fixation
2Reliability
If double coating (titanium micropore & HA coating) is used for biological fixation, then bone ingrowth is promoted, but coating falling off and uneven coating thickness occur
Solution Approach 1:
The invention segments the coating into a controlled porous structure with specific pore sizes (30-200 μm) and porosity (60-80%), creating a uniform single-layer porous coating that eliminates the interface problems between multiple coating layers while maintaining bone ingrowth capability
Solution Approach 2:
The invention changes the coating parameters by controlling pore size (30-200 μm), porosity (60-80%), and thickness (0.5-2 mm) to achieve optimal bone ingrowth while ensuring coating uniformity and preventing coating failure
3Strength
If solid structure prosthesis with high elastic modulus is used, then mechanical strength is sufficient, but stress shielding occurs leading to prosthesis loosening
Solution Approach 1:
The invention uses a porous coating structure with controlled porosity (60-80%) on the prosthesis surface, which reduces the effective elastic modulus to match bone tissue better, thereby reducing stress shielding while maintaining overall structural strength through the porous architecture
Solution Approach 2:
The invention creates a composite structure combining the solid prosthesis body with a porous coating layer, where the porous layer acts as a transition zone that reduces stress shielding effects while the solid body provides necessary mechanical strength
4Reliability
If uniform trabecular structure is used in 3D printed prosthesis, then stress shielding is reduced, but non-uniform fixation occurs due to mechanical differences in different bone regions
Solution Approach 1:
The invention applies local quality by creating zonal trabecular structures with different pore sizes and porosity in different regions of the prosthesis, matching the mechanical properties to the specific bone quality at each location (weight-bearing vs. non-weight-bearing areas), thereby achieving both stress shielding reduction and uniform fixation
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 zonal trabecular design enhances initial and long-term stability by minimizing fretting wear, stress shielding, and promoting uniform bone ingrowth, with improved mechanical properties and biocompatibility, reducing the risk of prosthesis loosening.
Implementation Method 1
Zirconium-niobium alloy can react with N, C, O or other elements to form a hard ceramic layer on the surface
Implementation Method 2
3D printing technology, as an additive manufacturing technology, breaks through the manufacturing process-oriented product design concepts
Implementation Method 3
putting the first intermediate product into a Sinter-HIP furnace, heating to 1250° C.-1400° C. under inert gas protection
Data Source
AI summary
The present invention discloses a zonal trabecular uni-compartmental tibial plateau containing zirconium-niobium alloy on oxidation layer and preparation method, including following steps: using zirconium niobium alloy powder as raw material, conducting a 3D printing for one-piece molding to obtain an intermediate product of the uni-compartmental tibial plateau, performing hot isostatic pressing and cryogenic oxidation to obtain the uni-compartmental tibial plateau; the lower surface of the semi-tibial plateau support and the surface of the keel plate are both provided with a bone trabeculae; the zonal trabecular uni-compartmental tibial plateau adopts the structure of arranging step distributed bone trabeculaes which can reduce the fretting wear of the interface between the prosthesis and the bone, and reduce the stress shielding effect of the prosthesis on the bone tissue, homogenize the stress of the tibial plateau bone tissue, and improve the initial stability and long-term stability of the uni-compartmental tibial plateau.