EP3077017A1

EP3077017A1 - Implants

Info

Publication number: EP3077017A1
Application number: EP14843176.0A
Authority: EP
Inventors: Heinrich Wecker; Alfons Kelnberger; Frank Ziermann
Original assignee: Ceramtec GmbH
Current assignee: Ceramtec GmbH
Priority date: 2013-12-05
Filing date: 2014-12-05
Publication date: 2016-10-12
Also published as: CA2932377A1; US20160367374A1; WO2015082078A1

Abstract

The present invention relates to implants, methods for the production thereof and the use thereof.

Description

implants

The present invention relates to implants, processes for their preparation and their use.

Implants for the partial renewal of joint surfaces are known and are implanted when irreparable cartilage damage, e.g. due to osteoarthritis of various joints in the human body and lead to impairments. If, for example, joint surfaces are damaged or destroyed by signs of wear, illness or injury, and if neither conservative non-operative treatment methods nor joint-preserving surgeries promise a cure, the implantation of a partial denture usually becomes necessary. These partial endoprosthetic implants are understood as a treatment concept in patients for whom the total arthroplasty is too massive a procedure or because of their active lifestyle is out of the question. In this way, to increase the mobility and quality of life in everyday life, work and leisure on the one hand, the pain in the affected joint eliminated or reduced in the long term and on the other the maximum possible mobility of this joint to be restored.

In contrast to total endoprostheses only a part of the articulation surface is renewed. The necessary interventions can usually be minimally invasive.

Nevertheless, the potential of a revision for a total endoprosthesis remains intact. It can be done later. Elderly patients may also benefit from this, e.g. reject a total joint replacement due to the higher morbidity.

Commercially, such prosthetic components are offered for hip, knee, shoulder and small joints, based on metallic materials such as titanium or cobalt

CONFIRMATION COPY Chromium, where the function of these implants is divided into two parts. Examples of such components are shown in Figure 1.

They usually have a tribologically stressed part, which serves as an articulation surface, and an osseointegrating part, which grows into the bone tissue and ensures a secure anchorage.

The disadvantages associated with the metallic solutions are known:

• Metallic abrasion and the resulting negative effects on the human organism

• Artifacts in imaging in medical diagnostics

• aging effects and long-term behavior (fatigue, corrosion, release of metallic ions that can be toxic)

As a general problem, an increasing risk of infection during surgery has become increasingly common.

In addition to these metallic solutions, a so-called osteochondral implant based on human cartilage and bone tissue is known and can be implanted minimally invasively into the damaged areas (Figure 1 d). Disadvantages of such implants are the high degree of wear, the low strengths, the aging effects and an insufficient long-term behavior.

The object of the present invention was to provide implants that do not have the disadvantages of the known solutions.

The implants according to the invention should in particular have the following properties: The implant according to the invention should securely grow together with the bone tissue of the joint after implantation and ensure a sufficiently high anchoring and stability.

The implant according to the invention should, after implantation, together with the rest of the joint surface, constitute a unit which, from a tribological point of view, is compact and securely and permanently in operative connection with the articulation partner.

The implant according to the invention should function safely, durably and wear during articulation against a natural cartilage surface

The implant of the invention should ideally be designed to promote and promote the formation of new, natural cartilage tissue

The implant according to the invention should not cause any damage to health during its residence in the human body. In particular it should

o produce no harmful particles of abrasion

o in interaction with the articulation partner, in particular with the natural cartilage tissue, this does not cause lasting damage o are not damaged or destroyed by the biomechanical conditions

o do not provide conditions favorable to infection-causing bacteria.

The problem underlying the invention is achieved by implants having the features of the main claim. Preferred embodiments can be found in the subclaims.

The invention relates to ceramic-polymer composite-based implants. In principle, the implant according to the invention consists of three different functional units (hereinafter also called layers):

• The first unit is an osseointegrating ceramic-based unit that forms a biologically active compound with underlying bone tissue beneath the cartilage.

The second unit is also a ceramic-based unit that communicates with the first and serves primarily as a substrate for the third unit. This can also be tribologically stressed in the case of wear of the third unit and serve as articulation surface.

The third unit is a polymer-based unit, preferably based on PVA or hydrogels, which is in firm association with the second unit and primarily ensures the tribological function in articulation with the natural cartilage. A hydrogel is a water-containing, but water-insoluble polymer whose molecules are chemically, e.g. By covalent or ionic bonds, or physically, e.g. B. by looping the polymer chains are linked to a three-dimensional network.

The osseointegrative first unit has a ceramic with porous portions and open-pore, interconnecting structure. It can be prepared in a conventional manner, for example via

• Molding process

• Frozen direct foam process

• foaming processes

• Pore forming processes based on organic pore formers These structures should be optimally adapted to the biological processes of osteogenesis and vascularization and ensure optimal osseoconductive properties.

Typical characteristics of such a structure are pore diameters in the order of 100 to 1000 μητι, especially between 300 and 700 pm.

Open porosities are on the order of between 50% and 90%, preferably between 60% and 80%. The moduli of elasticity should be on the order of 5 to 50 GPa, ideally in the range of human bone, to provide a beneficial mechanical stimulus for bone formation.

In addition, these structures can be coated with osseoinductive coatings of any kind in a conventional manner, so that the effect of osseointegration is enhanced.

Examples of such coatings useful in the invention are

• Bioglass, especially the composition 45S5

• Hydroxylapatite coatings of all kinds, including nanostructured and biomimetic layers

Phosphating layers, in particular covalently bound, monolayer phosphatings

• Metallic coatings, in particular based on tantalum or titanium

The second unit has a relatively dense ceramic, which is characterized in particular by its high hardness and strength. It is firmly connected to the first unit and structured on the side facing the third unit so that it represents an optimum substrate surface for the third unit. The connection to the first unit can be made for example by applying a slurry in the green state and then cosintering, or depending on the method for producing the first unit in one piece.

Of particular importance is the structure of the side facing the third, polymer-based unit. This side must ensure not only a tight positive or non-positive connection, but also a flow apart during the biomechanical load of the third unit or the lowest possible shear loads. In particular, it should be avoided that internal cracks or other damage to the crosslinked polymer occur.

In particular, care must be taken when structuring that no sharp edges arise.

In accordance with the invention, structures are generally provided which increase the surface and thus ensure a good connection between the second and the third unit, for example via adhesion forces or else via medically suitable adhesives. For example, defined depressions in the surface, which could look like a golf ball structure, or also undercut or drop-shaped depressions in the range of a few μm up to mm, which provide optimal hold for the polymer materials of the third unit, and for self-stabilization or self-fixing, are suitable axial load or also web-like structures. ,

It is particularly advantageous if the strength of the connection between the second and third unit increases under load. According to the invention this is achieved by correspondingly shaped structures on the ceramic second unit.

Ideally, the structure of the second unit facing the third unit has very little microroughness in the range of a few μm, which can be achieved by blending or polishing, or at least those areas of the structure resulting from eventual abrasion of the third unit exposed. Thus, even in the event of destruction or abrasion of the third unit, optimal articulation of the ceramic surface of the second unit with the cartilage can be ensured.

The structuring of the ceramic of the second unit can be carried out by means of injection molding processes (ceramic injection molding, low pressure injection molding) or other molding technologies, including mechanical processing in the green state or by laser processing or ultrasonically assisted mechanical processing in the sintered state, or even spark erosion or chemical etching.

The ceramic material of the first and the second unit is preferably an oxide ceramic from the class of aluminum oxides or zirconium oxides, for example zirconium-reinforced aluminum oxide or yttrium-stabilized zirconium oxide, but also all variants thereof or composites with the general designations ZTA (Zirconia toughened alumina) or ATZ (Alumina toughened zirconia).

Non-oxide ceramics, such as e.g. Materials based on S13N4.

All of the listed materials have extremely good tribological properties due to their chemical composition, hardness and strength, are highly tolerant to injury during implantation and more than meet biomechanical requirements.

In addition, they are highly bioinert without further functionalization and inhibit the proliferation of bacteria.

Also advantageous are all further developments of these materials, for example, extremely damage tolerant materials such as rare earth-stabilized dispersoid ceramics of zirconium oxide with proportions of aluminates. For the third unit, three-dimensionally linked polymers have proven to be particularly suitable polymers which, in addition to their mechanical properties, in particular with regard to stiffness and shear resilience, also withstand the biomechanical loads and which are similar to those of natural cartilage material.

Polymers also have the advantage that they can be loaded with functional groups with which the physical properties can be selectively adjusted.

In particular, hydrogels can be used as carriers of biologically active substances which can produce antibacterial or chondrogenetic action. These biologically active substances favor the in vivo development of endogenous cartilage material.

In this context, synthetic alginates are often used in combination with human stem cells in order to promote the development of endogenous cartilage tissue. This approach could also be integrated into the third unit.

It is very advantageous if the internal structure of the polymers, in particular of the hydrogels, is designed so that cartilage formation is promoted under mechanical pressure loading and corresponding loading with chondrogenetic substances. These mechanisms also act in natural cartilage, which relies on mechanical stimuli.

The firm connection between the second and third unit can be done by positive or non-positive joining processes, but it is also conceivable - especially in undercut structures - to melt the polymers or generally apply in the liquid phase.

The thickness of the polymer or hydrogel layer provided according to the invention depends greatly on the properties of the polymer. It can be micro or Nanocoats on the second unit or thick layers up to a few mm applied or joined.

With regard to the topographic design of the articulating surface, it can also be extremely advantageous if it is adapted to the anatomical and patient-specific circumstances, which can be ensured in the manufacturing process via suitable CAD CAM methods.

In addition, a perfect biomechanical and surgical fit of the implant is extremely advantageous, which can be ensured by a suitable procedure with appropriate and possibly individualized instruments.

The implants according to the invention are preferably used for the renewal of joint surfaces in the human body, for example joint surfaces from the shoulder, hip, knee and foot area. The implants according to the invention are suitable as joint surfaces for local cartilage defects, as partial joint replacement but also as full endoprostheses. They are particularly suitable for articulations against natural cartilage surfaces, so-called hemiprostheses, for example as shoulder hemiprosthesis, also called humeral head prosthesis. This is a partial replacement of the shoulder joint, which preserves the natural shoulder socket (glenoid) and replaces only the humeral head with an endoprosthesis.

In summary, the present invention accordingly relates to:

• Ceramic-polymer composite-based implants.

Implants according to item 1, characterized in that they contain three different functional layers.

Implants according to item 1 or 2, characterized in that the first layer is ceramic based. Implants according to one or more of the preceding points, characterized in that the second layer is also ceramic based and is bonded to the first layer.

Implants according to one or more of the preceding points, characterized in that the third layer is a polymer-based and is firmly bonded to the second layer.

Implants according to one or more of the preceding points, characterized in that the first layer has an osseointegrating property.

Implants according to one or more of the preceding points, characterized in that the second layer serves primarily as a substrate for the third layer.

Implants according to one or more of the preceding points, characterized in that the third layer primarily ensures the tribological function in the articulation with the natural cartilage.

Implants according to one or more of the preceding points, characterized in that the first layer contains a ceramic with porous portions.

Implants according to one or more of the preceding points, characterized in that the first layer contains a ceramic with porous portions and open-pore, interconnecting structure.

Implants according to one or more of the preceding points, characterized in that the first layer has pore diameters in the order of between 100 and 1000 μm, preferably between 300 and 700 μm.

Implants according to one or more of the preceding points, characterized in that the first layer has open porosities in the Magnitude between 50% and 90%, preferably between 60% and 80%.

Implants according to one or more of the preceding points, characterized in that the elastic moduli of the first layer are of the order of magnitude of between 5 and 50 GPa, preferably in the range of the human bone.

Implants according to one or more of the preceding points, characterized in that the first layer is coated with osseoinduktiven coatings.

Implants according to one or more of the preceding points, characterized in that the first layer is coated with osseoinduktiven coatings, wherein the layer is selected from Biogläsern, hydroxyapatite coatings, phosphating layers, and / or metallic coatings.

Implants according to one or more of the preceding points, characterized in that the first layer is coated with osseoinduktiven coatings, wherein the layer is selected from Biogläsern, preferably from the Bioglas the composition 45S5, from hydroxyapatite coatings, preferably from nanostructured and biomimetic acting hydroxyapatite , from phosphating layers, in particular from covalently bonded, monolayer phosphatings and / or metallic coatings, in particular from metallic coatings, based on tantalum or titanium.

Implants according to one or more of the preceding points, characterized in that the second layer comprises a relatively dense ceramic.

Implants according to one or more of the preceding points, characterized in that the second layer has high hardness and strength. Implants according to one or more of the preceding points, characterized in that the second layer has a side facing the third layer, which is structured such that it represents an optimal substrate surface for the third unit.

Implants according to one or more of the preceding points, characterized in that the second layer has a side facing the third layer, which is structured such that it represents an optimal substrate surface for the third layer, the fixed positive or non-positive connection and a Flow apart during the biomechanical loading of the third layer or to ensure the lowest possible shear stress.

Implants according to one or more of the preceding points, characterized in that the second layer has structures which increase the surface.

Implants according to one or more of the preceding points, characterized in that the second layer structures which increase the surface, preferably defined depressions in the surface (golf ball structure), undercut or drop-shaped depressions in the range of a few pm to mm or web-like structures having.

Implants according to one or more of the preceding points, characterized in that the second layer has a side facing the third layer, which has a very low micro-roughness in the range of a few pm.

Implants according to one or more of the preceding points, characterized in that the ceramic material of the first and the second layer contains an oxide ceramic of the class of aluminum oxides or zirconium oxides or a non-oxide ceramic, for example materials based on SiaN-j. Implants according to one or more of the preceding points, characterized in that the third layer contains three-dimensionally linked polymers.

Implants according to one or more of the preceding points, characterized in that the third layer contains hydrogels.

Implants according to one or more of the preceding points, characterized in that the third layer contains three-dimensionally linked polymers, wherein the internal structure of the polymers, in particular the internal structure of the hydrogels, is designed such that under mechanical pressure loading and corresponding loading with chondrogenetic substances Cartilage formation is promoted.

Use of the implants according to one or more of the preceding points for the renewal of joint surfaces in the human body, for example joint surfaces of the shoulder, hip, knee and foot area.

Use of the implants according to one or more of the preceding points as joint surfaces for local cartilage defects, as partial joint replacement but also as full endoprostheses.

Use of the implants according to one or more of the preceding points in articulations against natural cartilage surfaces.

Claims

Patent claims

1. Ceramic-polymer composite based implant.

2. Implant according to claim 1, characterized in that it contains three different functional layers.

3. Implant according to claim 1 or 2, characterized in that the first layer is ceramic based.

4. Implant according to one or more of the preceding claims, characterized in that the second layer is also ceramic-based and is connected to the first layer.

5. Implant according to one or more of the preceding claims, characterized in that the third layer is polymer-based and is firmly connected to the second layer.

6. Implant according to one or more of the preceding claims, characterized in that the first layer has an osseointegrating property.

7. Implant according to one or more of the preceding claims, characterized in that the second layer primarily serves as a substrate for the third layer.

8. Implant according to one or more of the preceding claims, characterized in that the third layer primarily ensures the tribological function in the articulation with the natural cartilage.

9. Implant according to one or more of the preceding claims, characterized in that the first layer contains a ceramic with porous components.

10. Implant according to one or more of the preceding claims, characterized in that the first layer contains a ceramic with porous components and an open-pored, interconnecting structure.

11. Implant according to one or more of the preceding claims, characterized in that the first layer has pore diameters in the order of magnitude between 100 and 1000 pm, preferably between 300 and 700 pm.

12. Implant according to one or more of the preceding claims, characterized in that the first layer has open porosities in the order of between 50% and 90%, preferably between 60% and 80%.

13. Implant according to one or more of the preceding claims, characterized in that the elasticity moduli of the first layer are in the order of magnitude between 5 and 50 GPa, preferably in the range of human bone.

14. Implant according to one or more of the preceding claims, characterized in that the first layer is coated with osseoinductive coatings.

15. Implant according to one or more of the preceding claims, characterized in that the first layer is coated with osseoinductive coatings, the layer being selected from bioglasses, hydroxyapatite coatings, phosphating layers, and / or metallic coatings.

16. Implant according to one or more of the preceding claims, characterized in that the first layer is coated with osseoinductive coatings, the layer being selected from bioglasses, preferably from the bioglass of the composition 45S5, from hydroxyapatite coatings, preferably from nanostructured and biomimetic hydroxyapatite layers

Phosphating layers, in particular from covalently bonded, monolayer phosphating and/or metallic coatings, in particular from metallic coatings based on tantalum or titanium. 7. Implant according to one or more of the preceding claims, characterized in that the second layer has a relatively dense ceramic.

18. Implant according to one or more of the preceding claims, characterized in that the second layer has high hardness and strength.

19. Implant according to one or more of the preceding claims, characterized in that the second layer has a side facing the third layer, which is structured so that it represents an optimal substrate surface for the third unit.

20. Implant according to one or more of the preceding claims, characterized in that the second layer has a side facing the third layer, which is structured so that it represents an optimal substrate surface for the third layer, which has a firm positive or non-positive connection and ensures that the third layer flows apart during the biomechanical loading or that the shear loads are as low as possible.

21. Implant according to one or more of the preceding claims, characterized in that the second layer has structures that increase the surface.

22. Implant according to one or more of the preceding claims, characterized in that the second layer has structures that increase the surface, preferably defined depressions in the surface, (golf ball structure), undercut or teardrop-shaped depressions in the range of a few pm to mm or bar-like structures.

23. Implant according to one or more of the preceding claims, characterized in that the second layer has a side facing the third layer which has a very low micro-roughness in the range of a few pm.

24. Implant according to one or more of the preceding claims, characterized in that the ceramic material of the first and second layers contains an oxide ceramic from the class of aluminum oxides or zirconium oxides or a non-oxide ceramic, for example materials based on S13N4.

25. Implant according to one or more of the preceding claims, characterized in that the third layer contains three-dimensionally linked polymers.

26. Implant according to one or more of the preceding claims, characterized in that the third layer contains hydrogels.

27. Implant according to one or more of the preceding claims, characterized in that the third layer contains three-dimensionally linked polymers, the internal structure of the polymers, in particular the internal structure of the hydrogels, being designed in such a way that under mechanical pressure load and corresponding loading with chondrogenetic Substances promote cartilage formation.

28. Use of the implant according to one or more of the preceding claims for the renewal of joint surfaces in the human body, for example joint surfaces in the shoulder, hip, knee and foot areas.

29. Use of the implant according to one or more of the preceding claims as joint surfaces for local cartilage defects, as partial joint replacements but also as full endoprostheses.

30. Use of the implant according to one or more of the preceding claims for articulations against natural cartilage surfaces.