Porous Titanium Implant with Interconnected Pores for Bone Ingrowth
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Solution Overview
Problem
Current titanium-based prosthetic materials face challenges in osseointegration and bone resorption due to modulus mismatch with human bone, and existing surface treatments like thermal spraying and microsphere deposition have drawbacks such as rough surfaces and risk of detachment, leading to mechanical stress and potential fracture.
Innovation Solution
A method involving the use of titanium powder with specific size distribution and mixing with NaCl, followed by sintering and bioactive surface treatment to create interconnected pores greater than 150 micrometers, enhancing osseointegration and fatigue strength, and converting the surface to a bioactive layer through sodium titanate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the modulus of rigidity of the prosthesis is reduced to match bone modulus, then bone resorption is reduced and implant lifespan is improved, but the mechanical strength and load-bearing capacity of the prosthesis deteriorates
Solution Approach 1:
The patent employs a composite structure combining a solid metallic core (providing mechanical strength) with a porous outer layer (providing bone ingrowth and reduced modulus). This composite architecture allows the prosthesis to simultaneously achieve high mechanical strength for load-bearing and low effective modulus for stress matching with bone, thereby resolving the contradiction between strength and reliability.
Solution Approach 2:
The patent utilizes porous titanium or titanium alloys with controlled porosity (30-70%) to reduce the effective modulus of rigidity closer to that of bone (0.5-30 GPa). The porous structure allows bone ingrowth and reduces stress shielding while maintaining sufficient mechanical properties through optimized pore size (100-500 μm) and distribution, thus improving implant lifespan without compromising strength.
2Reliability
If thermal spraying is used to create surface roughness for bone anchoring, then bone grip is improved, but the surface roughness lacks actual intercommunication and only grips cavities and crests
Solution Approach 1:
The patent creates a truly porous surface structure with interconnected pores (100-500 μm) through powder metallurgy or electrolytic deposition, allowing actual bone tissue ingrowth and intercommunication throughout the surface layer. This differs from thermal spraying by providing continuous pore networks rather than isolated cavities, enabling deep bone anchoring with proper mechanical interlocking and biological integration.
Solution Approach 2:
The patent applies different surface characteristics to different regions: the core maintains smooth or minimally treated surfaces for structural integrity, while the outer layer features controlled porosity and surface roughness (Ra 1-10 μm) optimized for bone anchoring. This local differentiation allows simultaneous optimization of mechanical strength and bone integration without compromising either function.
3Reliability
If microsphere deposition is used for coating, then biocompatible coating is achieved, but there is risk of microsphere detachment and prosthesis fracturing due to fatigue and sharp edges from welding
Solution Approach 1:
The patent replaces microsphere coatings with an integrated porous titanium layer formed through powder metallurgy or electrolytic deposition. This monolithic porous structure eliminates the interface between coating and substrate that causes microsphere detachment, while maintaining biocompatibility through titanium's inherent properties and osteoconductive porous architecture, thus removing the source of fatigue failures and sharp edges.
Solution Approach 2:
The patent creates a composite structure where the porous titanium layer is metallurgically bonded to the solid core, forming a unified material system rather than a coated structure. This integration eliminates weak interfaces and stress concentration points from welding or adhesive bonding, preventing fatigue-induced detachment and fracture while maintaining biocompatibility.
4Strength
If fine powder is used for powder metallurgy, then mechanical properties are maintained, but density gradients and shape distortions occur during sintering requiring expensive green machining
Solution Approach 1:
The patent optimizes powder characteristics (grain size 10-50 μm, specific surface area 0.5-2.0 m²/g, controlled moisture content) and sintering parameters (temperature 900-1100°C, pressure 5-20 MPa, atmosphere control) to achieve uniform densification without severe shape distortions. This parameter optimization reduces the need for post-sintering green machining while maintaining mechanical properties, simplifying the manufacturing process.
Solution Approach 2:
The patent performs preliminary blending and granulation of powders with binders to create uniformly sized green pellets or shapes before sintering. This pre-forming step ensures uniform density distribution and minimizes shape distortions during sintering, eliminating the need for expensive green machining operations while preserving mechanical properties through controlled densification.
5Reliability
If porosity is increased to reduce modulus of rigidity, then bone resorption is reduced, but the interconnection between pores remains insufficient for vascularization and efficient bone growth
Solution Approach 1:
The patent employs porous titanium with specifically controlled pore characteristics: porosity 30-70%, pore size 100-500 μm, and interconnected pore networks with channel diameters >10 μm. This optimized porous structure simultaneously achieves reduced effective modulus for stress matching, sufficient surface area for bone attachment, and adequate interconnection for vascularization and bone ingrowth, resolving the contradiction between porosity benefits and interconnection requirements.
Solution Approach 2:
The patent creates spatial variation in pore size and connectivity: larger interconnected pores (100-500 μm) near the surface for bone ingrowth and vascularization, transitioning to smaller pores deeper in the structure for mechanical strength. This gradient pore architecture optimizes both bone resorption prevention through surface porosity and structural integrity through controlled internal pore distribution.
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 method achieves improved osseointegration, reduced bone resorption, and stable mechanical properties, including increased modulus of elasticity and fatigue resistance, with a bioactive surface that promotes bone attachment and growth, ensuring long-term implant stability and patient quality of life.
Implementation Method 1
The mixture is then sintered under vacuum at a temperature between 900°C and 1100°C and at a pressure between 5 and 20 MPa
Implementation Method 2
sintered under vacuum at a temperature between 900°C and 1100°C
Implementation Method 3
The sintered compact is then subjected to acid treatment to remove the NaCl
Implementation Method 4
converting the surface to a bioactive layer through sodium titanate formation
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The present invention relates to a method for obtaining a porous titanium part, characterized in that the starting titanium powder is pure, with a mean particle size of 200 micrometers, a flow rate of 93s and an apparent density of 1.0 g/cm3. Said powder is mixed at a proportion of 34% titanium by weight with NaCl with a particle size between 300 and 600 micrometers and at least 50% by weight. As a result of these parameters, the resulting material has optimal osseointegration, biocompatibility and strength for biomedical applications.