KR20060069451A - Biocompatible porous ti-ni material - Google Patents

Abstract

This invention relates to a porous nickelide of titanium (TiNi) material also comprising oxygen, that is biomechanically and biochemically compatible and is intended primarily for use in the biomedical fields for implantation and interfacing with living tissues. The material has a porous structure defined by morphological, mechanical and surface properties to conform well to adjacent bone to which the TiNi material is designed to bind. The material is further distinguished by a complete lack of nickel enriched secondary phases. These phases may leach nickel into the body which could result in complications associated with nickel toxicity. The mechanical properties and surface characteristics achieved confirm the biofunctionality of the invention.

Description

BIOCOMPATIBLE POROUS TI-NI MATERIAL}

The present invention relates primarily to porous titanium nickel nitride (TiNi) materials for use in implantation bordering living tissue in the biomedical field. The present invention has morphological features and mechanical properties that match well with adjacent bones.

Bones are a major component of the human musculoskeletal system. There are two main types of bones: trabecular bones and cortical bones.

The scalloped bone or spongy bone is the internal net of scalloped bones (thin crutch). Residual bone has an elastic modulus of about 1 GPa and a porosity range of 30 to 90%.

Cortical bone is the dense crust of the bone, also known as dense bone. Its porosity ranges from 5% to 30% while the modulus of elasticity is about 18 Gpa.

Bone fractures occur when a bone is loaded and destroyed. Compression fractures are the most common in proximal bone. Bending fractures and torsional fractures are most common in cortical bones. Implanting metal or ceramic implants into fractured or diseased areas causes complex bone stress conditions. Distractions and depressions due to the destruction of the "plant-bone" interface are important determinants of the success of medical treatment. Congruence between the mechanical properties of the implant and the mechanical properties of the bone is required by itself.

The use of a porous surface for the biological attachment of the implant through the internal proliferation of the bone greatly improves the fixation of the implant implant to the bone. However, the release of nickel ions from the Ni-rich precipitates present into the body fluid upon contact with the body fluid, due to the fairly large surface area of the porous TiNi material, has become important mainly due to the relative toxicity of nickel and nickel salts [Assad M. , Chernyshov A., et al. J. Biomed +. Mater. V. 64B, 2, 2003, pp. 121-129].

Summary of the Invention

It is an object of the present invention to provide porous TiNi materials with improved biomechanical and biochemical compatibility with bone while maintaining the required porosity and maximizing the pore fraction in the range of 50 to 500 μm to allow for more efficient bone integration.

It is a further object of the present invention to remove the nickel rich second phase from the porous TiNi material.

According to one embodiment of the present invention, there is provided a TiNi substrate comprising interconnected crutches, each said crutch having an outer surface and an inner region, the substrate having an atomic ratio of Ni: Ti varying from 0.96: 1 to 1.13: 1 Having a maximum oxygen concentration of 10 atomic%, with the remainder being Ni and Ti, wherein the Ni concentration is limited to a maximum of 53 atomic%); Complex precipitates interspersed in the substrate; And a biomechanically and biochemically suitable porous titanium nickel nitride (TiNi) material comprising a plurality of interconnected pores defined by the substrate, wherein the pores have a pore size distribution as given below:

Pore size (㎛) percent <50 μm <5% 50 to 500 μm > 75% > 500 μm Remainder

The material has a substrate with varying 35-80% open porosity and mechanical properties suitable for surgical implantation, and the substrate lacks a Ni-rich second phase.

1 shows a transverse macrostructure (sample A) of porous TiNi material;

2 shows a longitudinal macrostructure (sample A) of porous TiNi material;

3 shows the microstructure of the porous TiNi material (Sample A);

4 shows a typical “stress-strain” curve (sample A) under compression test conditions;

5 shows the microstructure of the porous TiNi material (sample B);

6 shows the microstructure (sample C) 1500X of the porous TiNi material;

FIG. 7 shows a back scattered electron SEM micrograph 500X for a Ni-rich second phase and a Ti-rich second phase around Sample A;

FIG. 8 shows a back scattered electron SEM micrograph 3000X for the Ni-rich second phase and Ti-rich second phase around Sample A. FIG.

The present invention relates to novel biocompatible porous TiNi materials having limited biochemical and biomechanical properties suitable for the creation of interfaces with adjacent bones upon implantation.

Various objects can be created in accordance with the present invention. One particularly preferred product group is suitable for medical transplantation. Porous TiNi implants of the present invention have properties similar to those of bone and produce properties suitable for bioactivity and allow the material to be compatible with living tissue.

The nature of the implant

Maximization of percent pore in the range from -50 to 500 μm;

Porosity in harmony with the properties of the surrounding bone;

Mechanical properties capable of withstanding the complex loading conditions present in the human body; And

Importantly

Surface properties that minimize the release of nickel ions by reducing the amount of -Ni-rich second phase to substantially zero

It includes.

The following guidelines for the design of porous TiNi materials with suitable biomechanical compatibility were formulated by analyzing the mechanical properties of bone tissue under various physiological conditions.

Under normal physiological conditions (small deformations):

The transplanted material must match the elastic modulus of the bone to prevent large stress shielding at the "plant-bone" interface;

The actual yield strain / stress value of the implanted material under tension and compression should be greater than the value that the striatum bone considers as the required performance under cyclic loading.

Under higher or extreme conditions (high strain):

The material of the transplant should have a greater final strength than the surrounding bone;

The material should exhibit good viscoelasticity and impact resilience to minimize the energy absorbed by the bones. This requires the maximization of energy absorption properties for the implanted material.

Some properties of the scaffold bone at small strains are shown in Table 1, where E is the modulus of elasticity, σ _y is the yield strength, and ε _y is the maximum elastic strain.

Yield Properties ± Standard Deviation of Barebones at Different Anatomical Sites Anatomical site Load method 0.02 to 0.24% strain E, Gpa σ _y , MPa ε _y ,% spine pressure 0.32 ± 0.13 2.11 ± 0.97 0.85 ± 0.06 kidney 0.32 ± 0.13 1.83 ± 0.68 0.78 ± 0.05 Proximal tibia pressure 1.06 ± 0.60 6.25 ± 3.45 0.80 ± 0.05 kidney 0.87 ± 0.65 4.38 ± 3.19 0.72 ± 0.04 spin pressure 0.56 ± 0.28 3.37 ± 1.91 0.78 ± 0.05 kidney 0.52 ± 0.29 2.58 ± 1.30 0.71 ± 0.06 Cow tibia pressure 0.7-2.3 20.64 ± 0.59 1.09 ± 0.12 kidney 1.1-1.5 14.36 ± 0.33 0.78 ± 0.04

[Reference to Table 1: Morgan E.F., Yeh O.C., et al. Nonlinear Response of Residual Bone Bone at Small Variation. J. Biomech. Eng., V. 123, February 2001, pp. 1-9; And Keaveny, T.M., Wachtel, E.F., Ford, C.M., and Hayes, W.C., "The difference between elongation and compressive strength of bovine tibial sinus bones varies with modulus", J. Biomech., Vol. 27, 1994, pp. 1137-1146].

The mechanical properties of the stout and cortical bones under extreme conditions and high deformation are shown in Table 2:

Mechanical Properties of Bones for Predicting Fractures Bone Type (Deformation vs. Destruction) Load type Modulus, GPa Final strength, MPa Cortical Bone (2%) pressure 15.1-19.7 156-212 kidney 11.4-19.1 107-146 Residual Bone (<75%) pressure 0.1-3 1.5-50 kidney 0.2-5 3-20

[Reference to Table 2: Neibur G.L. "Computer Investigation of Multi-Axis Breakage in Pillar Bones", Ph.D. Thesis. The University of California, Berkely, USA; Guo E. Mechanical properties of cortical bones and spongy bone tissue. In: Cowin SC, Eds. Bone Mechanics handbook. Boca Raton, FL: CRC Press LLC, 2001; Moroi H.H., Okimoto K., Moroi R., and Terada Y. Int. J. Prosthodont, 6 :, 1993, pp. 564-572; Frankel V.H., Nordin M. "Basic Biomechanics of the Skeletal System", Philadelphia, Lea & Febiger, 1980].

Many important properties define what makes porous TiNi implants compatible with natural bone and biomechanically. At typical functional strain levels, these properties are as follows: a) modulus of elasticity, b) maximum elastic strain and c) yield strength. Under significant inelastic strain conditions up to and including the break point, the property is d) final strength, e) maximum strain versus break, f) viscoelasticity and g) energy that can be absorbed before fracture.

The modulus of elasticity defines the stress shielding effect at the "bone-graft" interface, where the stress shielding compensates for the difference in elastic properties of adjacent bones and implants with the formation of fibrous tissue at the "bone-graft" interface. To induce the reaction of the organism. Maximum elastic strain refers to the predictable performance of the material under actual in vivo conditions and circulating loads. Yield strength can be directly related to the energy dissipation mechanism. Final strength is the maximum load a material can bear before breaking. Maximum strain versus destruction is self-evident. Viscoelasticity refers to slow relaxation, tight relaxation, stress relaxation, or a combination thereof. The energy absorbed before fracture is obtained from the total area under the “stress-strain” curve 30 (FIG. 4) and therefore varies with both final stress and final strain. Although not mentioned above, greater porosity is desirable because it maximizes energy absorption due to wave scattering.

The present invention relates to a porous titanium nickel nitride (TiNi) material which is biomechanically and biochemically suitable and intended to be used in the biomedical field primarily for implantation as a surgical implant. The material can be used wherever bone attachment is required and is particularly useful for cervical implants, lumbar fixation devices, spinal substitutes, artificial discs and tibial cup substitutes (in the buttocks).

Porous TiNi products with stress plateaus under compression test conditions without oblique fracture are porous TiNi materials that have maximum energy absorption before fracture and consequently improved impact relieving properties.

Table 3 shows the optimal combination of mechanical properties under compressive load for the porous TiNi material explored in biomedical use, making the material biomechanically suitable for the bone tissues to which it is linked.

Mechanical Properties of Preferred Embodiments of Porous TiNi Materials Mechanical properties Selection criteria Optimal value a) Modulus, GPa Elasticity of bone 0.1-3.0 b) Elastic deformation% Exceeding the yield strain of the bone > 2 c) Yield strength, MPa Bone Yield Stress Excess 1.5-50 d) Final strength, MPa Final strength of bone 50-250 e) Maximum strain versus break,% Maximum value for bone 75 or less f) Viscoelastic Stress Plane in Strain-Stress Curves - g) Energy absorbed before destruction No incline fractures under pressure maximum

Biomechanical suitability is defined as the absence of stress shielding at the "plant-bone" boundary.

In the present invention, control over the properties of the porous TiNi material is obtained through the distribution or arrangement of oxygen content throughout the substrate of the TiNi. This can be accomplished by any number of means, including air removal, purging with inert gas in the reactor mold, and raw material selection.

The method of making the TiNi material may be a self-expanding high temperature synthesis (SHS) reaction or other method, for example sintering. In SHS, expansion is done according to a process understood by the skilled person. This includes gradual combustion using the heat of the exothermic reaction released during the reaction of nickel and titanium.

Small deviations from the required stoichiometric ratios in the raw material mixture prior to the SHS reaction can significantly increase the formation of the second phase and adversely affect the mechanical properties of the TiNi material, including shape memory and superelastic properties (Lopez HF, Salinas A., Calderon H., Metallurgical and Materials Transactions AV32A, March 2001, pp. 717-729). The appearance of the Ni-rich second phase can increase the release of Ni ions. The recoverable strain is strongly influenced by the Ni content, thermodynamic treatment, and the conversion sequence exhibited by the alloy during thermal cycling. Several important features help to define the quality of the product, ie premix the Ti and Ni raw materials into a very homogeneous mixture; The reproducibility of the properties must be high; Control of technical parameters during manufacturing should be reliable. This applies particularly to biomedical implants that are designed to match the properties of adjacent bones to achieve the necessary bioactivity and promote an efficient healing response.

The present invention is a biocompatible porous TiNi material that is compatible with the properties and properties of adjacent bone tissue and has an optimal combination of properties and properties without a Ni-rich second phase. “None” is understood herein as a concentration level that cannot be detected by SEM (scanning electron microscopy) or TEM (transmission electron microscopy) analysis. The TiNi material thus lacks a Ni-rich second phase and substantially reduces the likelihood that the second phase leaks nickel into the human body (such a leak can cause complications associated with nickel toxicity). The SEM apparatus used was JEOL JSM-840 coupled to an ultra-thin window (UTW) energy dissipation X-ray spectrometer (EDS). The TEM used was Philips CM-30 300 kv.

The present invention is explained with reference to the following examples.

Example  1. Sample A

Sample A represents the porous TiNi material obtained by the SHS technique. Its combination of form and mechanical properties is within the optimum ranges shown in Table 3.

Sample A has a porosity in the range of 63 ± 1.2%. 1 and 2 show two-dimensional (2D) macrostructures of the synthesized porous material in the transverse and longitudinal directions, respectively. The porous material comprises a TiNi substrate (skeleton of interconnected shoring), lighter regions 10 and darker apertures 20 regions. The confined aperture includes "open" and "closed" pores. 3 shows “open” pores 20 defined as interconnected pores forming a continuous network. The percentage of “open” pores reflects the volume that is most likely to promote bone ingrowth. The percentage of “closed” pores 24 is related to the volume of the pores that are less likely to promote any bone ingrowth in the product because the pores are too small or not presumably interconnected. Table 4 shows the data regarding the pore size distribution.

Pore Variable, Sample A Pore distribution Statistics on open pore dimensions, μm Size, μm percent, % at least 4-27 <50 1-2 maximum 689-1013 50-500 93-97 Average 192-225 > 500 2-5 Standard Deviation 91-119

The properties of the solid object (the crutch) of the TiNi substrate of Sample A are shown in Table 5.

Solid object of TiNi substrate, sample A statistics Area, (A) μm ² Convex Peripheral Length (CP) μm Density (4πA / CP ² ) at least: 6.8-7.0 8.0-8.2 0.02-0.14 maximum: 547876-1071025 4165-5918 One Average: 6946-13151 173-309 0.71-0.79 Standard Deviation: 36774-52875 386-520 0.19-0.24

The properties of the crutch (or solid object) are defined as follows:

The statistically measured area A of the crutch is proportional to the final strength and stiffness of the porous material when all other factors are equal;

The convex peripheral length (CP) of the crutch is the indirect peripheral length of the surface area in contact with adjacent tissue;

The density of each shoring (4πA / (CP) ² ) in the TiNi substrate provides indirect information about the processing conditions. Rounder shoring may indicate greater liquid phase involvement during the SHS reaction. Fully rounded solid objects have a density value of one.

The fine structure of the said TiNi shoring is shown in FIG. At 200 times magnification, the details of the TiNi substrate 10 can be clearly identified. Precipitate 22 is a Ti-rich second phase. Smoother substrate surface and lower visible Ti-rich second phase amounts lead to better uniformity of the sample.

The TiNi substrate of Sample A has a local content of Ti-rich second phase in the range of 6-11%. The Ti-rich precipitate has an average diameter of 2 to 4 μm, with a maximum outer diameter of 27 to 96 μm (Table 6).

Sediment Properties of Sample A Ti-rich sediment, distribution Metrics for Ti-enriched precipitate dimensions, μm Size, μm percent, % at least 0.6-1 maximum 27-96 <10 95 Average 2-4 > 10 5 Standard Deviation 2-4

In FIG. 3, the presence of Ti-rich phases 22 in the form of “stains” is observed. The shape of the Ti-rich second phase is undesirable because it can form nuclei of cracks along the Ti-rich "stain extension". However, the oxygen content in the Ti-rich phase in the range of 2.3 to 3.4 atomic percent (Table 7) leads to desirable values of the mechanical properties found in Table 3.

Chemical Composition of Porous TiNi Materials at Different Locations Re: Sample A Inner area of crutch Outer surface of the crutch Ti, atomic% Ni, atomic% O, atomic% Ti, atomic% Ni, atomic% O, atomic% TiNi Substrate 49.4 49.0-49.4 1.2-1.7 45.9-47.7 47.2-49.5 3.2-6.9 Ti-rich phase 64.4-64.8 32.2-32.9 2.3-3.4 51.7-54.2 28.0-30.2 17.8-18.1 Ni-rich phase ^** - - - - ^** Footnote: Ni-rich phases were detected to a depth of 1625 μm at the outer periphery of the porous rod

With reference to the data provided in Table 7, the maximum oxygen content in the substrate was found on the outer surface of the crutch. The oxygen value was recorded at 6.9 atomic%, which corresponds to 2.16 weight% (the oxygen content was obtained by the Electronic Probe Micro Analysis (EPMA) technique).

Using chemical corrosion, the Ni-rich precipitate 52 was detected primarily at the periphery of the porous TiNi product (FIG. 8). Ni-rich region 50 can be seen clearly in FIG. 7. The composite precipitate in the substrate comprises the Ti-rich second phase and the Ni-rich second phase that is readily visible (22). The Ni-rich second phase is also found throughout the substrate, albeit to a much lesser extent. The predominance of the Ni-rich second phase at the boundary of the TiNi product is due to the separation and heat loss of the initial components at the interface surrounding the mold. The depth of the Ni-rich second phase can characterize the range of non-equilibrium solidification conditions that lead to the formation of the phase. The maximum depth of the Ni-rich second phase controls the depth of machining required to eliminate the unnecessary formation. In the case of Sample A, the Ni-rich second phase was detected at the periphery of the cylindrical rod at a penetration distance of 1625 μm or less. In order to ensure the absence of the enormous Ni-rich second phase in the final product, at least 2 mm of the porous TiNi was machined at its periphery. Sample A still contained a small amount of Ni-rich second phase in the substrate after processing, which could not be accurately quantified.

Using the ASTM E8-96a method, porous TiNi samples of the present invention and prior art samples (Chernyshov A., Leroux M., et al., Influence of Porous TiNi Forms on Mechanical Properties. Proceedings "Advanced Materials for Biomedical Applications" , MetSoc'2002, 41-th Annual Conference, August 11-14, 2002, Montreal, pp. 109-119). Tables 8-10 show significant improvements in compression, tension and fatigue test properties for materials of the prior art.

Compression test data Property Sample A Prior art [2002] Modulus, GPa 0.5-0.76 0.8-2.1 Yield strength 0.2%, MPa 39.0-46.0 10.6-33.9 Elastic deformation,% 6.1-8.0 1.8-5.8 Final strength, MPa 201-224 34-85 Deformation versus destruction,% 49.0-54.1 11.0-36.9

Tension test data Property Sample A Prior art [2002] Modulus, GPa 0.27-1.05 0.68-0.99 Yield strength 0.2%, MPa 6.7-11.3 9.4-14.4 Elastic deformation,% 1.0-3.9 1.5-2.7 Final strength, MPa 12.9-22.3 13.8-16.6 Deformation versus destruction,% 5.2-9.1 2.4-3.7

Fatigue Test Data Load, N (max) Fatigue Life @ 5 Hz, Cycle Sample A U.S. Patent 5,986,169 2500 5,000,000 5,000,000 3000 5,000,000 Failed at 688,032 3500 5,000,000 Failed

A typical “stress-strain” curve 30 for Sample A under compression test conditions is shown in FIG. 4. 4 also shows a 0.2% deformation curve 32, shown in dotted lines; A straight correction curve 34 (solid line); The flexion point or stress plateau 36 is shown.

Sample A once again shows a significant difference from the aspect of the prior art material (Chernyshov A., Leroux M., et al., Supra). The prior art material exhibited oblique fractures under compression test conditions. On the other hand, for Sample A, there was no oblique fracture even at strains greater than 49% and the stress plateau 36 was recorded. The A sample is characterized by a higher final strength than the cortical bone, demonstrating maximum energy absorption and improved impact relieving before fracture. These morphological and mechanical properties lead us to conclude that Sample A has improved bioactivity compared to what was previously observed for porous TiNi materials.

Example  2. Sample B

Sample B represents a porous TiNi material with similar morphological and mechanical properties as observed for Sample A. In FIG. 5, the Ti-rich second phase 22 can see a smaller and similar chemical composition distribution (Table 11).

Chemical Composition of Porous TiNi Materials at Different Locations (Sample B) Re: Sample B Inner area of crutch Outer surface of the crutch Ti, atomic% Ni, atomic% O, atomic% Ti, atomic% Ni, atomic% O, atomic% TiNi Substrate 48.3-49.0 49.1-50.0 1.7-1.9 45.8-51.7 44.6-50.7 0.4-9.4 Ti-rich phase 56.2-57.5 29.1-29.5 13.0-14.6 51.8-61.8 21.7-43.2 5.9-25.6 Ni-rich phase - - - -

Sample B was prepared by the same SHS technique as used for Sample A except for further annealing under an argon atmosphere. Annealing was carried out at 1000 ° C. for 60 minutes, more preferably at 1100 ° C. for 45 minutes. Sample B exhibited a more uniform chemical composition and a complete absence of the Ni-rich second phase in the substrate, due to the annealing step. Higher oxygen content and lower Ni content on the TiNi shoring surface are desirable results. In general, higher oxygen content on the surface improves the corrosion resistance (biochemical compatibility) of the TiNi material.

By lowering the Ni-rich second phase to substantially zero, the likelihood of leakage of nickel from the implant is close to zero while maintaining the bioactivity of the product. The material is identified by the complete lack of a nickel rich phase. The phase can leak nickel in vivo and cause complications associated with nickel toxicity.

Example  3. Sample C

Sample C was prepared in the same manner as Sample B, but the raw Ti powder used had a higher oxygen content. Sample C has a total porosity of 65 to 68.0%. The pore parameters of Sample C are shown in Table 12.

Pore Variable, Sample C Pore distribution Statistics on pore dimensions, μm Size, μm percent, % at least 5-29 <50 1-2 maximum 915-1752 50-500 78-86 Average 294-369 > 500 13-20 Standard Deviation 145-245

The TiNi substrate had a topical content of Ti-rich second phase in an amount of 14.35%.

Sample C represents a porous TiNi material that satisfies the optimal combination of mechanical properties shown in Table 13. Sample C furthermore has a smaller and rounder Ti-rich precipitate 44 and chemical component distribution shown in FIG. 6 (FIG. 13).

Chemical Composition of Porous TiNi Materials at Different Locations Re: Sample C Inner area of crutch Outer surface of the crutch Ti, atomic% Ni, atomic% O, atomic% Ti, atomic% Ni, atomic% O, atomic% TiNi Substrate 46.1-46.3 51.5-52.0 1.9-2.2 - - - Ti-rich phase 55.0-55.6 28.0-29.0 15.4-16.9 46.3-54.2 24.5-37.3 13.8-23.2 Ni-rich phase - - - -

The TiNi substrate of Sample C shown in FIG. 6 represents a martensite substrate having localized austenite needle-shaped regions 40 and regions of martensite phases 42 found therebetween.

Example  4. Sample D

The effect of the supplied oxygen content on the mechanical properties of the porous TiNi material contribution test was tested. A porous TiNi material was prepared having an oxygen content of 4.6 atomic% (1.4 wt%) evenly distributed within the crutch inner region. The resulting mechanical properties were substantially inferior to the optimal combination of values (Table 3) and the final strength was less than 10 MPa. In addition, the effect of the surface oxygen content on the Ni: Ti ratio was confirmed and shown in Table 14.

Effect of Oxygen Content on the Ni: Ti Ratio External chemical composition of the crutch Ni: Ti ratio O, atomic% Ti, atomic% Ni, atomic% 3.3 47.2 49.5 1.05: 1 4.6 47.7 47.6 0.99: 1 6.9 45.9 47.2 1.03: 1 9.4 60.7 29.9 0.49: 1 11.2 51.2 37.5 0.73: 1 14.3 53.4 32.3 0.60: 1 20.8 51.8 27.4 0.53: 1

As shown in Table 14, the maximum content of oxygen that allows the formation of titanium nickelide is 10 atomic percent. Higher oxygen levels on the surface of the TiNi crutch lead to substantial redistribution of the Ni: Ti ratio, resulting in the presence of the Ti-rich second phase. Elevated oxygen content and Ti-rich second phase are preferred for the surface of TiNi crutch in view of the required biochemical compatibility and corrosion resistance. It should be noted that Ni: Ti ratios other than 0.96: 1 to 1.13: 1 substantially reduced the mechanical properties between the TiNi metals.

Surprisingly, the maximum oxygen content of 10 atomic percent on the outer surface of the crutch maintains the material while maintaining the optimal combination of mechanical properties of the nickelide substrate of titanium.

Example  5.

In order to extend the possible shape range of the porous TiNi material, the porous TiNi embodiments disclosed in Examples 1-4 above were ground in powder form. The powder was sieved to a particle size range of about 100 to 500 micrometers and consequently sintered at a temperature below the melting point of titanium nickelide. The resulting porous TiNi material had desirable biochemical, biomechanical properties and corrosion resistance, indicating a wider possible means of making for porous NiTi products.

Changes and changes may be made by those skilled in the art without departing from the spirit and scope of the invention. The examples of the above embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

Claims (12)

Substrates of TiNi including interconnected crutches, each said crutch having an outer and inner region, said substrate having an atomic ratio of Ni: Ti varying from 0.96: 1 to 1.13: 1 and having a maximum oxygen concentration of 10 atomic percent And the remainder are Ni and Ti, wherein the Ni concentration is limited to at most 53 atomic percent); Complex precipitates interspersed in the substrate; And A plurality of interconnected pores defined by the substrate, the pores having a pore size distribution given as follows: Pore size (㎛) percent <50 μm <5% 50 to 500 μm > 75% > 500 μm Remainder Biomechanically and biochemically suitable porous titanium nickel nitride (TiNi) material comprising a, having a substrate having an open porosity that varies from 35 to 80% and a mechanical property suitable for surgical implantation, A material free of Ni-rich second phases in the substrate. The material of claim 1 wherein the substrate has an atomic ratio of Ni: Ti that varies from 0.99: 1 to 1.04: 1 and comprises a maximum oxygen concentration of 2.2 atomic percent in the interior region, with the remainder being Ni and Ti. The composite precipitate of claim 1 or 2, wherein the composite precipitate comprises a Ti-rich second phase comprising oxygen limited to a maximum of 28 atomic percent, the remainder being Ni and Ti, and the atomic ratio of Ni: Ti is from 0.37: 1 to A substance that changes to 0.95: 1. 4. The material of claim 3, wherein the Ti-rich second phase comprises 2.0 to 17.0 atomic percent oxygen, the remainder is Ni and Ti, and the atomic ratio of Ni: Ti varies from 0.49: 1 to 0.53: 1. The material according to claim 3 or 4, wherein the Ti-rich second phase comprises 2.3 to 3.4 atomic percent oxygen. The material according to claim 3, wherein the Ti-rich second phase has an outer shape of the spheroid and an average diameter of 10 μm. The material according to claim 1, wherein the complex precipitate in the substrate is limited to less than 15% by volume. 8. The material of any of claims 1 to 7, wherein the substrate comprises martensite and austenite. The method according to any one of claims 1 to 8, The mechanical properties of the substrate Modulus of elasticity under compression of 0.2 to 3.0 GPa; Maximum elastic strain of greater than 2%; Final strength of 50 to 250 MPa; Up to 75% strain versus fracture; And Yield strength of 1.5 to 50 MPa Substances containing. Use of a material as defined in claim 1 in the manufacture of a surgical implant. Use according to claim 10, wherein the surgical implant is selected from the group consisting of cervical implants, lumbar fixation devices, spinal substitutes, artificial discs, and tibial cup substitutes (buttocks). Surgical implants made of a material as defined in claim 1.

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