RU2262550C2 - Method of memorizing two forms in article made from memorized-shape-effect alloy and articles made by this method - Google Patents

Abstract

FIELD: metallurgy; methods of memorizing geometric forms in articles made from memorized-shape-effect materials which are secured to another member and are later removed from this member.

SUBSTANCE: method of memorizing two forms of articles made from memorized-shape-effect materials is used for making human implants. Method includes imparting first form to article by deformation of initial form at first temperature, imparting second form to article by deformation at second temperature; second form (30C) imparted to article is intermediate between initial form (30A) and first form (30B) or second form (13') obtained through deformation of initial form (11) in direction opposite to deformation of first form (12).

EFFECT: enhanced efficiency.

9 cl, 5 dwg

Description

The present invention relates to a method for storing two geometric states of an article obtained from an alloy with a shape memory effect. It relates to applications of this method for products intended to be attached to another element and later to remove it from this element. It also relates to applications of this method for products in medicine, dentistry, veterinary medicine or similar fields.

Form memory alloys are already known. The effect of shape memorization is that the material that was deformed at the first temperature will return to its original shape when it returns to the second temperature. This effect occurs due to thermoelastic conversion between the austenite solid phase and the martensite phase, which is also solid.

This effect may have different known alloys.

The use of such alloys with such an effect in medicine is also known, in particular for the manufacture of fittings for bone elements or clamps. In particular, reference can be made to patent FR-A-2700464, which describes the use of such a memory effect material.

It should be noted that the use of the present invention in medicine is described in this application for illustration only.

The use of alloys with the effect of shape memory in medicine is usually limited to attaching the product to the element and does not allow subsequent removal of the specified product from the element. For example, with regard to human implants, the use of alloys with a memory effect currently facilitates their installation, but in no way affects their removal, which, in addition, is not considered.

An object of the present invention is to propose a method for processing an article with a memory effect so that this effect is possible first for applying said article to an element and then for removing said article from said element. Therefore, the aim of the present invention is to propose a method of storing not one geometric state, as described in the prior art, but two geometric states of the product obtained from an alloy with the effect of shape memory.

For this purpose, the method corresponding to the present invention provides

(a) teaching said alloy to adopt a first geometric state by acting on said article to bring it into said first state and leaving it in said first state at a first temperature, then

(b) teaching said alloy to adopt a second geometric state by acting on said article to bring it into said second state and leaving it in said second state at a second temperature.

If the product in question is an implant intended for placement in the body, then the installation of this implant is carried out by bringing it into one of two geometric states by exposure to the necessary heat so that it reaches a temperature corresponding to this state. Its removal is carried out by bringing it into another geometric state by exposure to the necessary heat so that it reaches a temperature corresponding to this other state.

It should be noted that the geometric state for the installation corresponds to the state in which the implant acts on the element, for example, on another implant, another component or part of the body, so as to fix itself to it. As for the geometric state for removal, it corresponds to the state in which the specified implant returns to its original state before installation or to a similar state.

Therefore, the fact that the implant is obtained from an alloy trained to have two different geometric states makes it possible to install it in one of the states and remove it in another state.

The alloy used is, for example, a nickel or titanium alloy or a composite material reinforced with said alloy.

For example, the highest of the two temperatures in question is a temperature ranging from + 37 ° C to + 55 ° C, while the lowest temperature is from + 30 ° C to -30 ° C.

If the present invention is used in medicine, the highest temperature can be achieved with a diathermy knife, and the lowest temperature can be achieved with physiological serum, a cryoextractor, and so on.

In accordance with another feature of the present invention, said method comprises finishing a specified product after teaching said alloy to adopt a first geometric state, but before learning said alloy to adopt a second geometric state. Such finishing may consist of polishing the specified product, for example, by sandblasting.

To prevent nickel, which may be contained in said alloy with a shape memory effect, from entering into contact with the human body, such finishing may include applying a thin protective layer, for example, 1-5 microns thick.

Such a layer can be obtained from one of the following materials:

nickel carbide

aluminium oxide,

titanium carbonitride,

molybdenum bisulfide,

triple alloy of nickel, titanium and aluminum,

chromium nitride

amorphous diamond

titanium carbide

titanium nitride and so on.

Such a protective layer is, for example, a layer obtained by nitriding the surface of the specified product at low temperature. This can be accomplished by ion bombardment or vapor deposition.

It was noted that the effect of such nitriding at low temperature, in addition to protecting the human body, should enhance the memory of the alloy in the hot and cold state (approx. Per.) At the highest and lowest temperatures).

In addition, it shortens and, therefore, simplifies the polishing of the product, since a very good surface condition is obtained more quickly. He also prepares parts that are exposed to friction or load.

The present invention can be applied in any field of technology to the extent that two geometric states of the product are required. In particular, this applies to applications with products intended to be secured by tightening to the element and removing from it later. Further in this application will be described the use of the present invention in medicine, which should be considered as an illustration, for example, to obtain human implants.

Examples of the application of the method corresponding to the present invention are described below with reference to the accompanying drawings.

Figure 1 is a view illustrating the method corresponding to the present invention, for example, a clamp.

Figa-d are views illustrating the method corresponding to the present invention, for example, a pin.

FIG. 3 is an isometric view illustrating a socket with which the method of the present invention can be used.

Figa-c are views illustrating the method corresponding to the present invention, for example, an anchor plug.

5 is a view of a femoral stem using a storage method in accordance with the present invention.

The use of human implants will first be discussed with reference to FIG. 1, wherein such implants are clamps for orthopedic use or for healing injuries, which are used either to keep the ligaments together or to connect the bone (for example, epiphyseal clamps). They can also be clamps used in the treatment of the spine. They can also be ligature brackets for medical or surgical use.

The following describes a method for producing a clamp in accordance with the present invention. Such a clamp is obtained from a wire 10, obtained, for example, from an alloy of nickel and titanium, preferably in a stoichiometric ratio close to unity, which is then molded to give it a p-shape 11 with two branches 11a and 11b connected together by a central inner part 11c. This is the so-called initial form of clamping.

Then, forces are applied to the branches 11a and 11b, respectively, so that they are brought closer to each other. Thus, the first geometric state is obtained. This technological operation is carried out at a temperature T1, which is, for example, in the range from a temperature of 37 ° C to a temperature of 55 ° C, for example, at a temperature of 40 ° C. This process step is carried out, for example, in a vice or using a matrix 20 having a complementary shape with respect to the desired shape. Now we can say that the clamp is trained to accept its first state for memorization.

After that, you can finish the clamp in its state 12. It can be polished, for example, by sandblasting, or low-temperature coating, for example, by deposition or nitriding from the gas phase. This stage in figure 1 is indicated as stage N.

After such a finishing treatment, a force is applied to the branches of the clamp so as to transfer them to a second geometric state, different from the first geometric state 12. Depending on the intended application, this may be state 13, in which the clamp returns to its original state 11, in which it the branches 11a and 11b are parallel or additionally to the state 13 ', in which the branches of the clamp diverge in the direction from each other. This technological operation is carried out at a temperature of T2, for example, in the range from a temperature of -30 ° C to a temperature of + 30 ° C, for example, at a temperature of 5 ° C. It is, for example, carried out using a roller or using a punch 21 or 21 'of the corresponding complementary form relative to the desired shape corresponding to the second geometric state.

In practical use cases of clamps, to ensure ease of removal of the clamp, state 13 is preferred over state 13 '.

The following is a description of how to use this type of clamp. During installation, the clamp is positioned in place and heated so that it reaches temperature T1. Since this is a high temperature, for example, a diathermy knife can be used. Then the clamp will take its geometric state 12, in which two branches are brought closer to each other. After that, the clamp retains its state. In this state, the clamp is fixed on its support, for example, on the bone, and cannot be dismantled without additional action.

To remove the clamp, heat is acted upon in such a way that it reaches a temperature in the temperature region T2, so that it then assumes its geometric state 13, in which its branches are again parallel. Then the clamp can be removed by removing it in a direction parallel to its branches. This temperature is the low temperature that can be achieved by feeding physiological serum.

The shapes corresponding to the geometric states 12 and 13 or 13 ′ are determined at the time they are entered into the memory, and can therefore be selected to be suitable for the clamp in question.

It should be noted that in the above clamp example and in accordance with embodiments of the present invention, the temperature T1 may be the lowest, for example, between -30 ° C and the temperature + 30 ° C, and the temperature T2 may be the highest, for example between temperature + 37 ° С and temperature + 55 ° С.

Another application of the method of the present invention is described with reference to FIGS. 2a-d and relates to the pin 30, which is mainly used to connect the bone. The pin 30 essentially consists of a tube open on one side surface through a longitudinal slot 31. Its lower end 32 has the shape of a trocar to facilitate installation in a cavity formed for this purpose.

2b shows a circular arc of a pin 30 in its initial state 30A before training. 2c, pin 30 is shown in its first geometric state 30B after training at temperature T1. The circle arc, which represents the cross section of the pin 30, is open relative to the initial state 30A. 2d, pin 30 is shown in its second geometric state 30C after training at temperature T2. The circle arc, which represents the cross section of the pin 30, is slightly closed relative to the previous geometric state 30B, but open relative to the initial state 30A.

A section in the form of a simple arc of a circle is given as an example. It should be obvious that it can take the form of more complex configurations.

After the last stage described above, an additional stage may follow, in which the pin 30 returns to its original state. This stage is realized mechanically at room temperature.

The following describes how to use this type of pin 30. The surgeon makes a hole in the bone, for example, using a bur, so that a pin 30 can be installed in it in its original state. The diameter of the hole is slightly larger than the outer diameter of the pin 30, so that it can be inserted.

Once inserted, the pin 30 is heated to a temperature T1. Then, the pin 30 itself is positioned in its first geometric state 30B, in which it itself wedges itself against the side wall of the hole made in the bone. After that, he retains this form during the processing time and cannot be dismantled without taking an additional action.

On the day of its removal, it is heated so that it reaches a temperature of T2. After that, he contracts and transfers himself to his second geometric state 30C.

It should be noted that its degree of closure in the second geometric state 30C is slightly larger than in its first geometric state 30B, but less than in its initial state 30A, which means that it does not destroy the spongy tissue that grew inside the pin during processing .

In addition to the fact that when applying the method corresponding to the present invention, it becomes possible to dismantle the implanted pin 30, in this case, an advantage is provided due to the use of material with dual memory, which facilitates the installation of the pin compared with the prior art, in which it is fixed by a screw the installation of which requires the use of a fluorescent screen for monitoring, which, as a rule, is a source of harmful or even dangerous radiation. Install and uninstall operations are also simplified.

In the same way as in the case of a tubular configuration having a slot extending in the longitudinal direction, as described above, rivets commonly used for fixing plates, ligaments and so on can also be made. Their use is substantially similar to that of the pin 30 described above with reference to FIG. 2a.

Similarly, the components of the femoral shaft can also be made.

It should be obvious that only one part of the pin or rivet can be provided with a side slot or even with several side slots.

Figure 3 illustrates a socket 40, usually intended, firstly, for installing the spherical head of the prosthesis, for example, the femoral part, and, secondly, for fixing itself in the corresponding connecting cavity.

Such a socket 40 has a hollow crater-shaped recess, which is essentially hemispherical and open on the side surface by a slot 41 of width e. In the manufacturing process, width e has the original value e _ini . During the first training at temperature T1, the nest is prompted to accept its first geometric state, in which the width e has the value e ₁ . For example, this value of e _{1 is} greater than the value of e _ini .

During the second training at temperature T2, the nest is prompted to accept its second geometric state, in which the width e has a value of e ₂ , which can be, for example, slightly less than the value of e ₁ , but greater than the initial value of e _ini for the same reason as for the pin 30 described above.

The following describes how to use the specified jack. As mentioned above, the socket is installed in the connecting cavity and then exposed to heat so that it reaches a temperature T1. After that, it assumes its first geometric state, in which the width of the slot 41 has a value of e ₁ , so that it fastens itself against the walls of the connecting cavity. If the temperature T1 is high, then heating can be provided by a diathermy knife.

When installed in place, the socket remains fixed.

To remove it, the nest is exposed to heat so that it reaches a temperature T2 at which it assumes a second geometric state with a width e _{2 of the} slot 41. This value of width e is slightly less than the value e _{1 of the} first geometric state, which prevents damage to the grown tissue when the nest is removed. .

Said dual memory slot, in addition to the advantages of the method of the present invention, provides easier and faster installation than the sockets of the prior art that require screws or cementing. In addition, when using screws, their friction with respect to the central polyethylene inner part of the socket was a source of significant wear.

It should be noted that the slot 40 may be provided with one such slot (or more), such as slot 41.

The present invention may also be applicable with implants for a metatarsophalangeal prosthesis.

It is also applicable for lumbar wiring designed to align the vertebrae, which is shaped into a dual-memory material and trained to have two separate geometric states: one for applying wire wiring between the vertebrae and the other for removing it.

The present invention may also be applicable to an anchor plug of a prosthesis, for example, a knee prosthesis, which is illustrated in FIGS. 4a-c. The plug 50 has a substantially cylindrical shape and is surrounded by a hemispherical cup 51 designed to set the end of the prosthesis. It should be noted that this cup 51 can be provided with a prosthesis attachment system, for example, a bayonet or other fitting.

In the cylindrical part of the plug 50, petals 52 are cut, which are integral with the housing 53 of the plug through their flexible bases 54. Therefore, each petal can be bent outward relative to its base 54.

Fig. 4b shows a top view of a plug 50, the petals of which are curved outward. This state of the plug 50 is the first geometric state and corresponds to the state that will be given during installation of the plug by heating the plug so that it reaches a temperature close to the temperature T1.

As shown in FIG. 4c, the plug 50 has its petals 52 diverted along the axis of the plug 50. This state of the plug 50 is its second geometric state and corresponds to the state that will be given during removal of the plug by exposure to the necessary heat to reach a temperature close to the temperature T2.

Now will be described another application of the present invention with reference to figure 5, which illustrates the device of the femoral rod component. This device consists of a flat rod 60, one end of which enters in a known manner in the centering cylinder 61 either directly or by means of a sleeve, to fit in the sphere intended to form the head of the femoral prosthesis. This device also includes a module 62 provided for fitting and closing the rod 60. In the illustrated embodiment, this module 62 comprises two side walls 62a and 62b connected together by a central inner part 62c.

The module 62 is made of a material with a shape memory function and, in accordance with the method of the present invention, undergoes double training. In the initial state, the walls 62a and 62b are parallel to each other, and the distance d that separates them has a value d _ini , which is slightly larger than the thickness of the rod 60, so that the specified module 62 can be mounted on top of the specified rod 60. This geometric state corresponds to the installation and fixing the module 62 by a simple tightening on the rod 60, the installation of which is carried out at a temperature T1. In the second geometric state, the side walls 62a and 62b are essentially parallel to each other, and the distance d, therefore, is equal to the initial value d _ini and corresponds to the removal of the module 62 from the rod 60, which is carried out at a temperature T2.

Claims (9)

1. A method of storing two forms of an alloy product with a shape memory effect, comprising giving the first shape to the product by deforming the original shape at the first temperature, giving the second shape to the product by deforming at the second temperature, characterized in that the product is given the second shape (30C), which is intermediate between the original (30A) and the first (30B), or the second form (13 ^/ ), obtained by deformation of the original form (11) in the opposite direction to the deformation of the first form (12). 2. The method according to claim 1, characterized in that an alloy with a shape memory effect uses an alloy of nickel and titanium in a stoichiometric ratio close to unity, or a composite material reinforced with the specified alloy. 3. The method according to claim 1 or 2, characterized in that the highest of the two temperatures during deformation is a temperature in the range from +37 to + 55 ° C, and the lowest temperature is in the range from +30 to -30 ° C. 4. The method according to any one of claims 1 to 3, characterized in that after giving the product the first form, the product is finished. 5. The method according to claim 4, characterized in that, as a finishing treatment, polishing of the specified product is carried out, for example, by sandblasting. 6. The method according to claim 4, characterized in that as a finishing treatment, a thin protective layer is deposited at a low temperature of one of the following materials: nickel carbide, titanium carbide, titanium nitride, aluminum oxide, molybdenum bisulfide, titanium carbonitride, nickel triple alloy , titanium and aluminum, chromium nitride, diamond in an amorphous state. 7. The product, which is a human implant, characterized in that it is made in the form of a clamp and contains two branches parallel to each other in the original form and connected by the central inner part, the two branches are brought together relative to each other in the first form, and in the second form of the branch divorced in a direction from each other, while the product is obtained by the method according to any one of claims 1 to 6. 8. The product, which is a human implant, characterized in that it is made in the form of a tube open on one side surface through at least one longitudinal slot, and the tube is more open in the first form than in the original form, and less open in the second form in relation to the first form, while the product is obtained by the method according to any one of claims 1 to 6. 9. The product, which is a human implant, characterized in that it is made in the form of a socket formed by a hemispherical hollow cup with at least one slot provided, and the slot is more open in the first form than in the second form, and the product is obtained by the method according to any one of claims 1 to 6.

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