DE20121411U1 - Tool used for magnetic resonance operations and/or investigations on humans and animals comprises working section made from metallic base material made from aluminum, aluminum alloy, aluminum compound and/or their mixtures - Google Patents

Abstract

A tool comprises a working section (2) made from a metallic base material made from aluminum, an aluminum alloy, an aluminum compound and/or their mixtures. Preferred Features: The whole tool is made from the base material. The base material is made from at least 98 wt.% aluminum. The base material is covered with a barrier layer which is impermeable to aluminum, aluminum ions and/or bodily fluids. The working section is marked with a magnetic resonance visible material, preferably made from a metalloid or precious metal or heavy metal.

Description

Surgical tool

The present invention relates to a surgical tool according to the preamble of claim 1 and to an implant according to the preamble of claim 8.

The term "surgical tool" is primarily understood to mean a device or instrument that is used during an operation and/or examination, particularly on the human or animal body, i.e. in particular is inserted and/or used, for example, to influence body tissue. In a broader sense, however, this also includes other instruments, devices and aids that are used during operations and/or examinations and in particular come into contact with the respective body.

The term "working section" is understood here to mean at least a part of the surgical tool that is essential for the intended function of the surgical tool and/or is primarily in contact with or penetrates the body to be operated on and/or examined. In particular, this is a relatively small part in the area of the respective surgical or examination site. The surgical tool can therefore, for example, have further sections or parts, such as a handle or the like, that also come into contact with or penetrate the body.

The term "implant" is understood here in the narrower sense to mean an element that can be inserted into the body of an animal or a human at least temporarily and that can, for example, perform therapeutic, support and/or joint functions, such as temporary implants, for example so-called "seeds", or stents for tumor treatment or therapy, tracheal stents, etc. In the broader sense, however, this also includes elements or the like that can be brought into contact with the body from the outside and/or in particular temporarily.

Implants in the form of stents are used, for example, to support dilated vessels. These tubular inserts are inserted

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narrowed vessels and then expanded radially so that the stents support the vessel walls on the inside.

When operating, examining and/or implanting, a determination of the position and/or function of the surgical tool and/or the implant based on magnetic resonance is increasingly used - particularly with a view to making interventions as minimally invasive as possible. For example, a so-called magnetic resonance tomograph is used for this purpose. Magnetic resonance - referred to here as MR for short - is therefore used here in particular to map spatial relationships in a body, for example the position of tissues, organs, surgical tools and/or implants, whereby a relatively strong magnetic field is applied and substances and materials can be distinguished due to the different magnetic properties. Operations and/or examinations in which MR is used as a support, for example for control functions, or for guidance, for example for the correct positioning of an implant, are also referred to here for short as "MR-guided and/or -based".

In order to be able to use MR, it is necessary to use MR-compatible materials for surgical instruments or their working sections and for implants. When using a conventional material such as stainless steel, such artifacts (misrepresentations) arise that mean that MR does not provide any or only insufficient (image or spatial) resolution.

Plastics and special Nikkei titanium alloys have so far been used as MR-compatible materials. The properties of the available plastics are not very satisfactory in terms of compatibility, mechanical properties and costs. The very special nickel titanium alloys are expensive and require very difficult and therefore costly processing.

The present invention is based on the object of specifying a surgical tool and an implant which are suitable for MR-guided or -based operations and/or examinations, in particular on the human and/or animal body, wherein the surgical tool and the implant

can be produced easily and cost-effectively with very good mechanical properties.

The above object is achieved by a surgical tool according to claim 1 or an implant according to claim 8. Advantageous further developments are the subject of the subclaims.

A basic idea of the invention is to use aluminum or an aluminum compound that preferably consists primarily of aluminum or an aluminum alloy or mixtures thereof as the base material or main component. Tests have shown that aluminum is surprisingly invisible or almost invisible in an MRI scanner. When using MRI, the artifacts that are otherwise generally present with metals do not occur.

The artifacts mentioned occur particularly in ferromagnetic materials. Aluminium is often used for alloys for transformer cores, i.e. for highly ferromagnetic alloys. It is therefore all the more surprising that aluminium is suitable for the use of MR and is even particularly MR compatible.

Aluminium has several advantages. It is inexpensive and easy to work with, so that the proposed surgical tool and the proposed implant can be manufactured inexpensively. It has good mechanical properties, in particular high resilience and strength and sufficient elasticity. Like most metals, it is a metal that is very temperature-resistant, so that sterilization at elevated temperatures is possible without any problems. It is not an organic compound, so that a large number of different elements or ions cannot dissolve from the proposed base material in the body with undesirable or unknown consequences.

With regard to MR compatibility, it may be sufficient if only one working section, for example a cannula, a cutting edge, a hook, a clamp, a holder or the like, which is directly connected to the respective operating

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tion site consists at least essentially of the proposed base material. Preferably, however, the entire surgical tool is made at least essentially of the proposed base material.

Alternatively, however, the base material can also only form a covering or coating of another carrier material, in which case the implant/surgical tool or its working section can essentially consist of the carrier material, i.e. another material.

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According to a particularly preferred embodiment, the base material, possibly the entire surgical tool or implant, is covered with a barrier layer at least in surface areas that are free and/or accessible to body fluids or tissue. The barrier layer is preferably designed to be tight or impermeable to aluminum, aluminum ions and/or body fluids. This prevents aluminum ions, which are suspected of being harmful, from dissolving in the body.

A preferred development provides that the working section or the surgical tool and/or the implant is marked with an MR-visible substance. "Marking" is to be understood here as meaning that the substance is provided in a sufficient quantity, either at specific points or distributed, to make the implant or at least the working section or the entire surgical tool visible for MR, without causing undesirable artifacts (misrepresentations or covering of other areas) in MR.

The MR-visible substance, such as a precious metal, heavy metal or even iron, can be added directly to the base material in a suitable amount, whereby the aluminum can be "contaminated" with an appropriate amount for marking, for example. It cannot be referred to as an aluminum alloy, since the amount of substance to be added to the aluminum is too small.

Preferably, however, the MR-visible substance for marking is not directly integrated into the base material, but rather provided in or on the barrier layer. For example, the MR-visible substance can be integrated in the barrier layer material

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contained and/or absorbed by cavities formed in the barrier layer.

Further properties, features, aspects and advantages of the present invention are explained in more detail below for two embodiments with reference to the drawing, It shows

Fig. 1 is a schematic representation of a proposed opera

tion tool;

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Fig. 2 a schematic representation of a proposed implant

in the form of a stent;

Fig. 3 a partial representation of the schematic structure of the

surgical tool or implant; and

Fig. 4 is a further enlarged, schematic representation of a possible

layer structure according to Fig. 3.

Fig. 1 shows a proposed surgical tool 1 in the sense explained at the beginning. The example shown is a forceps-like instrument or tool. As already explained, however, this can be any type of instrument, technical aid or tool for examinations and/or operations on the human or animal body.

The surgical tool 1 preferably has at least one working section 2, in this case two working sections 2. The working sections 2 here form pincer-like gripping, holding and/or cutting elements. However, the term "working section" is not limited to a single part; rather, it can also refer to a plurality of parts on the one hand or to a section or region of a one-piece part on the other.

As already explained, the working section 2 is in particular the front or relevant area of the surgical tool 1, which and/or

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whose surroundings should be invisible through MR or visible when appropriately marked.

Fig. 2 shows a perspective view of a proposed implant 3 in the form of a stent, which has been greatly simplified for illustrative purposes. In the example shown, the implant 3 forms a grid-like, tubular body. For alternative forms, functions and applications of the implant 3, please refer to the definition at the beginning.

&iacgr;&ogr; Fig. 3 shows an enlarged section of the proposed material structure in a representation that is not to scale. This material structure is intended at least for the working sections 2 of the surgical tool 1 or, if necessary, for the entire surgical tool 1. This material structure is also intended for the proposed implant 3. For the sake of simplicity, reference is made below only to the implant 3, even if the corresponding statements apply to at least one working section 2 of the surgical tool 1, several working sections 2 of the surgical tool 1 or the entire surgical tool 1.

The implant 3 preferably consists at least essentially of a base material 4 indicated in Fig. 3. In particular, Fig. 3 shows only a partial section into the material of the implant 3.

The base material 4 is preferably covered by a barrier layer 5 on its surface, at least in surface areas 6 that are free and/or accessible to body fluids or tissue.

The base material 4 consists at least essentially of aluminum, an aluminum compound, an aluminum alloy and/or mixtures thereof. In particular of relatively pure aluminum. The base material 4 preferably consists of at least 95% by mass, preferably 97 or 98% by mass, of aluminum, in particular a corresponding aluminum alloy.

This results in the already mentioned MR compatibility of the base material 4.

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The optionally provided barrier layer 5 is relatively thin and preferably amorphous. This results in good or sufficient flexibility. This is particularly important when the implant 3 is designed as a stent in order to avoid detachment of the barrier layer 5 during the radial expansion of the stent inside a vessel, as is usually provided.

Preferably, the barrier layer 5 is at least substantially uniformly thick. In particular, the average thickness is 10 to 200 nm, preferably 20 to 100 nm and in particular about 50 nm.

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The barrier layer 5 is preferably impermeable to the base material 4, ions formed therefrom and/or body fluids or other substances produced by the body. In this way, an unwanted dissolution of the base material 4 in the body can be prevented.

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The base material 4 is preferably plasma-coated to form the barrier layer 5, i.e. the barrier layer 5 is applied using a plasma process. The material to be applied, preferably silicon here, is evaporated in a vacuum, for example, and reacts with the addition of oxygen on the surface of the implant 3 to form a firmly adhering oxide layer that is predominantly amorphous and thus flexible.

As an example of the coating options, in particular the application of a silicon dioxide layer, reference is made to US 4,917,786, US 5,096,558, US 5,565,248 and US 5,662,741, the content of which is hereby mentioned as a supplementary disclosure. However, the application is not limited to pure plasma processes. Rather, other processes, in particular plasma-assisted processes, such as the plasma-assisted PVD process or the plasma-assisted CVD process, can also be used, as disclosed in the article "Character roles" by Volker Buck and Horst Ehrich, Essener Unikate, Materialwissenschaft, Volume 13, Universität GH Essen / Wissenschaftsverlag, ISSN 0944-6060, page 42 following. The aforementioned journal is mentioned in full as a supplementary disclosure with regard to coating processes and usable materials, including usable biocompatible materials.

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Preferably, the barrier layer 5 consists at least essentially of a semi-metal oxide, in particular silicon dioxide. Silicon dioxide, as the most common inorganic compound, has excellent biocompatibility, i.e. it is optimally tolerated by the body. Silicon dioxide can also be used to form a sufficiently dense or impermeable barrier layer 5.

The preferably provided amorphous formation also achieves sufficient flexibility and adhesion to the base material 4 or the surface areas 6 to be covered

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Due to the relatively small thickness of the barrier layer 5, it is possible to use virtually any material for the barrier layer 5, at least not one that is MR compatible. Due to the small total amount required to form the barrier layer 5, an overall sufficient MR compatibility is maintained. If necessary, the barrier layer 5 can simultaneously represent a desired "marking" of the implant 3, i.e. ensure that the implant 3 is still visible using MR - for example, in an MRI scan, which is not the case when using only high-grade aluminum.

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Alternatively, the barrier layer 5 can also consist of other materials, in particular at least essentially of aluminum oxide or titanium dioxide. A design made of aluminum oxide is suitable because the base material 4 - at least if it is aluminum - only needs to be oxidized on its surface. This is done in particular by electrolytic oxidation (anodization), whereby a sufficiently dense or impermeable barrier layer 5 with the desired properties - sufficient flexibility, amorphous structure - can be achieved.

In the following, a further development or design variant for the MR-visible marking of the implant 3 is explained in more detail using the partial magnification according to Fig. 4.

In the embodiment shown in Fig. 4, cavities 7 are formed in the barrier layer 5 - for example by appropriate anodization, in particular

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when using aluminum oxide as the material for the barrier layer 5 - to accommodate an MR-visible substance 8.

The MR-visible substance 8 can be formed, for example, by a metal, in particular a noble metal or a heavy metal. If required, the substance 8 can be bound to walls 10 of the cavities 7 via schematically indicated binding partners 9.

In the example shown, the cavities 7 are open to the outside or surface 11 of the barrier layer 5, i.e. they have openings 12. If necessary, the openings 12 or the surface 11 can be covered by a covering layer 13, for example made of gold.

When forming cavities 7 in the barrier layer 5, these preferably do not extend through the entire thickness of the barrier layer S in order to maintain the blocking effect or barrier effect of the barrier layer 5, i.e. to ensure the desired impermeability.

As already explained, the MR-visible substance 8 can also be embedded in the base material 4 and/or the barrier layer 5 in another way if required, and can possibly be mixed with the respective material.

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Claims (14)

1. Surgical tool ( 1 ) for MR-guided or -based operations and/or examinations, in particular on the human and/or animal body, with a working section ( 2 ) which consists at least substantially of a metallic base material ( 4 ), characterized in that the base material ( 4 ) consists of aluminum, an aluminum compound, an aluminum alloy and/or mixtures thereof. 2. Surgical tool according to claim 1, characterized in that the entire surgical tool ( 1 ) consists at least essentially of the base material ( 4 ). 3. Surgical tool according to claim 1 or 2, characterized in that the base material ( 4 ) consists of at least 97 mass%, preferably 98 mass%, of aluminum. 4. Surgical tool according to one of the preceding claims, characterized in that at least the base material ( 4 ) is covered with a barrier layer (S) which is preferably impermeable to aluminum, aluminum ions and/or body fluids, at least in surface areas ( 6 ) which are free and/or accessible to body fluids or tissue. 5. Surgical tool according to claim 4, characterized in that the barrier layer ( 5 ) is amorphous and/or consists at least substantially of an inorganic oxide, in particular aluminum oxide, titanium dioxide and/or silicon dioxide. 6. Surgical tool according to one of the preceding claims, characterized in that the working section ( 2 ) is marked with an MR-visible substance ( 8 ) which in particular contains or consists of a semi-metal or metal, preferably a precious metal or heavy metal. 7. Surgical tool according to claim 4 or 5 and according to claim 6, characterized in that the MR-visible substance ( 8 ) is or can be embedded in the barrier layer ( 5 ), in particular in cavities ( 7 ) preferably formed by electrolytic oxidation. 8. Implant ( 3 ) for MR-guided or -based operations and/or examinations, wherein the implant ( 3 ) consists at least substantially of a metallic base material ( 4 ), characterized in that the base material ( 4 ) consists of aluminum, an aluminum compound, an aluminum alloy and/or mixtures thereof. 9. Implant according to claim 8, characterized in that the base material ( 4 ) consists of at least 97 mass%, preferably 98 mass%, of aluminum. 10. Implant according to claim 8 or 9, characterized in that the base material ( 4 ) is covered with a barrier layer ( 5 ) which is preferably impermeable to aluminum, aluminum ions and/or body fluids, at least in surface areas ( 6 ) which are free and/or accessible to body fluids or tissue. 11. Implant according to claim 10, characterized in that the barrier layer ( 5 ) is amorphous and/or consists at least essentially of an inorganic oxide, in particular aluminum oxide, titanium dioxide and/or silicon dioxide. 12. Implant according to one of claims 8 to 11, characterized in that the implant ( 3 ) is marked with an MR-visible substance ( 8 ) which in particular contains or consists of a semi-metal or metal, preferably a noble metal or heavy metal. 13. Implant according to claim 10 or 11 and according to claim 12, characterized in that the MR-visible substance ( 8 ) is or can be embedded in the barrier layer ( 5 ), in particular in cavities ( 7 ) preferably formed by electrolytic oxidation. 14. Implant according to one of claims 8 to 13, characterized in that the implant ( 3 ) is designed as a stent.