CH704518B1 - Method for producing an implant having at least one area with a surface structure, implant produced by the method and apparatus for carrying out the method. - Google Patents

Abstract

The present invention relates to a method for producing an implant having at least one region with a surface structure, wherein depressions (4) are embossed onto the implant surface in a first step. In a second step, material is removed between the depressions (4) by mechanical processing, in particular by milling or turning, with rows of structural elements (6) separated from one another by the depressions (4). Furthermore, the present invention relates to an implant having at least one region with a surface structure which consists of structure elements (6) arranged in spaced-apart rows. The structural elements (6) are separated from each other by depressions (4), which are produced by material deformation. Further, the invention relates to an apparatus for producing a semi-finished Gelenkpfannen with a structured surface.

Description

Description: The present invention relates to a method for producing an implant with at least one area with a surface structure. Furthermore, the present invention relates to an implant produced by this method and a device for carrying out the method.

[0002] A large number of surface structures are known for better anchoring of implants, in particular endoprostheses in bones. These range from roughened surfaces to equipping the surface with complex structural elements.

In particular in the field of hip prostheses, it is advantageous if the implant parts, especially the acetabular cup attached in the hip bone, can be anchored in the bone in a manner that is resistant to tearing and rotation. While a group of acetabular cups is anchored by screws, a second group is attached using bone cement.

In order to increase the pull-out behavior and the torsional strength of an acetabular cup fastened by means of bone cement, the surface of such pans is usually provided with structural elements. These structural elements evenly distribute occurring forces and thus prevent the joint socket from rotating or even tearing out.

[0005] With this in mind, various structural elements for joint pans have been developed. For example, EP 0 186 471 shows a knee joint prosthesis with sawtooth-like grooves which are arranged transversely to the direction of insertion, the stability in the direction of the grooves being reduced. Another alternative provides barb-like pins on the prosthesis, which penetrate into the femoral stump in the direction of insertion.

A general requirement for anchoring surfaces of this type is that they should have a structure that is conducive to ingrowth and that on the other hand they should be economically producible.

DE 2 914 513 shows anchoring surfaces which are provided with wart-like projections and depressions in order to improve the ingrowth of bones. No information is given on the generation and the absolute dimensions of this structure. In the relative geometric relationships, rounded shapes are proposed that only allow a limited primary anchoring.

A further structure is proposed in EP 0 381 351, in which a type of rimmed anchoring surface with flattened protruding pyramids is produced on a hip joint shell on a bulge projecting outwards by obliquely running and circumferentially offset punctures which intersect in the circumferential direction becomes. Here too the primary anchorage is limited, i.e. very much dependent on the preload in the bone cavity or on the undersize of the bone cavity in the area of the equator.

[0009] EP 1 648 350 describes an acetabular cup which is provided in the equatorial region with a thread which consists of thread regions which are separated from one another by inclined grooves. When manufacturing the surface structure, the inclined grooves are first milled out of the implant body and then the thread is turned.

A major disadvantage of the structures described is that they are manufactured by machining processes. However, the production of very fine, non-symmetrical or staggered structures is very complex or even impossible with such methods.

[0011] EP 0 639 356 further proposes to provide the surface of a joint socket with ribs which are essentially perpendicular to the direction of insertion of the socket and which are provided with trenches running parallel to the direction of insertion by means of a pressing tool. At the edges of the trenches, the ribs form shoulder sections, the tips of which are bent against the direction of insertion by the pressing process. This creates a barb structure that additionally anchors the socket.

Due to the pressing process used, only straight trenches can be produced. It is not possible to equip an implant surface with staggered trenches.

The object of the invention is to circumvent the disadvantages of the known manufacturing methods and in particular to create a manufacturing method for an implant, which makes it possible to provide a structured surface with fine, asymmetrical or mutually offset structural elements. This object is achieved with a method according to claim 1.

[0014] The method according to the invention comprises the following steps:

- Presentation of an implant body;

Embossing a plurality of depressions, preferably arranged in rows, on a surface section of the implant base body; and

- Removal of material between the rows of depressions in such a way that raised structural elements are formed on the surface section, which are delimited by the depressions and by the removed locations.

[0015] The method according to the invention can be used to produce implants with at least one area with a surface structure. Alternatively, several areas of an implant with a surface structure

CH 704 518 B1 doors. Several or all areas can be provided with the same structure. Alternatively, however, the method according to the invention can also be used to provide several areas with different surface structures.

[0016] In the method according to the invention, an implant base body is initially presented. The basic implant body is understood to mean both already manufactured implants and semi-finished implant products which are to be additionally equipped with at least one area with a surface structure, or also blanks which are to be formed into an implant. The implants are preferably endoprostheses. The method according to the invention particularly preferably provides acetabular cups, in particular acetabular cups, with at least one area with a surface structure. Furthermore, the method according to the invention can also be applied to other implants, such as knee prostheses, intramedullary nails, femoral or humeral stem prostheses, dental prostheses or the like.

In the next step, depressions are embossed in the implant body. These depressions have a defined geometric spatial shape and are introduced into the material by means of a manufacturing process. The arrangement and the shape of the depressions can be determined depending on the surface structure to be produced. However, the depressions are preferably arranged regularly, particularly preferably in individual, spaced-apart rows. The rows can run parallel to each other or at a certain angle. The distance between the rows can also be varied, depending on the surface structure to be produced. In the case of round or dome-shaped implant base bodies, the depressions can also be arranged in a spiral or helical shape around the implant base body.

The recesses can be shaped differently depending on the intended design of the surface structure. The depressions are preferably designed as cuboids, pyramids, tetrahedra, wedges, cylinders, cones, truncated cones and / or in the form of an acute-angled saddle roof. In principle, however, the depressions can also be in the form of any polyhedron.

[0019] The dimensions of the depressions can also vary depending on the configuration of the surface structure. The depressions on the implant surface preferably have a maximum edge length. a maximum diameter of 0.1 mm to 3 mm, particularly preferably from 1 mm to 2 mm. In addition, the depressions have a maximum depth of 0.1 mm to 3 mm, particularly preferably 0.5 mm to 2 mm, to the surface of the implant base body.

Notches, troughs or the like are also understood as “recesses” in the sense of the application.

Preferably, the depressions are impressed by pressing at least one patrix onto the implant base body. This method step preferably takes place without prior heating of the implant base body in the sense of cold forming. Depending on the material used, the embossing can also be carried out under the influence of heat.

The embossing of the depressions is preferably carried out in a single or multi-axis press.

After the depressions are embossed into the implant base body, material is removed in a further step between the rows of depressions. This creates individual rows of structural elements separated from one another by the depressions and the removed material.

The combination of embossing and material removal can produce very fine symmetrical as well as asymmetrical or mutually offset surface structures which cannot be produced or can only be produced with a great deal of time by pure machining of the basic implant body.

The removal of material between the rows is preferably carried out by a machining manufacturing process. Material is particularly preferably removed by turning or milling. Alternatively, other manufacturing processes can also be used, such as electrochemical machining (ECM) or electroeroding.

[0026] The basic implant body is preferably formed by deep drawing before the depressions are impressed. As a result, joint pans can be produced using the method according to the invention.

Particularly preferably, the deep-drawing of the main implant body and the embossing of the depressions are carried out sequentially, the main implant body remaining in the same clamping. Since the basic implant body does not have to be reclamped between the two processing steps, the manufacture of an implant with a structured surface is accelerated and simplified.

The embossing of the depressions is preferably carried out by laterally rolling embossing elements on the implant base body. Alternatively, the indentations can also be stamped using linearly closing jaws.

Another object of the invention is to provide an implant with an improved surface structure. This object is achieved with an implant according to claim 9.

[0030] The implant is preferably produced by the method according to the invention. The surface structure of the implant according to the invention has individual structural elements, which are characterized by material impressions and mate

CH 704 518 B1 rial deductions are limited. By means of material impressions, very fine as well as asymmetrical or staggered structural elements can be produced, which cannot be produced by purely machining or only with great expenditure of time.

[0031] The rows with the structural elements can be arranged parallel to one another. Alternatively, individual rows or all rows can be arranged at an angle to at least one of their adjacent rows. In the case of round or dome-shaped implants, the rows can also be designed as at least one spiral or helix that rotates one or more times around the implant.

The wells can be arranged in a row at the same distance from each other. Alternatively, however, the depressions can also be arranged in a row at different distances from one another. The distances between the wells can be the same on all rows. Alternatively, the spacing between the wells on one row may be different from the spacing of the wells of an adjacent row.

The depressions which separate the structural elements from one another in a row are preferably offset relative to one another with respect to the depressions which separate the structural elements from one another in a row. The staggered arrangement of the depressions makes it possible to create surface structures that simplify the insertion of the implant into bones or that better distribute the forces that occur on the surrounding bones.

The depressions in a row are preferably arranged in the middle between two depressions in an adjacent row. This results in a surface structure that enables the implant to be well anchored in bone. In addition, forces acting on the implant are optimally distributed to the surrounding bone tissue.

The structural elements defined by the depressions on the individual rows are preferably shaped as cuboids, pyramids, tetrahedra, wedges and / or in the form of any polyhedra. The structural elements are particularly preferably in the form of an acute-angled saddle roof. The shape of the structural elements depends on the shape of the rows and the recesses. By choosing the appropriate shape, a variety of shapes of structural elements can be created. The structural elements preferably have a width of 0.5 mm to 3 mm. All structural elements preferably have the same width. Alternatively, the width of the structural elements of different rows can be different. Alternatively, the width of individual structural elements can vary in a row.

[0036] The implant is preferably an articular socket, the structural elements preferably being arranged in an area close to the equator. Alternatively, however, the structural elements can also be arranged on the entire surface. The joint socket particularly preferably has a large number of parallel rows which run essentially at right angles to the direction in which the joint socket is inserted into the bone. Alternatively, the rows can also be arranged in the form of a thread that winds several times around the pan or in the form of spirals.

Preferably, depressions of adjacent rows are arranged offset to one another in the direction of the rows, the distance by which the depressions are offset increasing from one row to the next.

[0038] This allows the structural elements to be arranged in certain geometric patterns on the surface of the socket. The distance by which the depressions are arranged offset from one another particularly preferably increases from row to row in such a way that the structural elements run along a helical or circular arc-shaped line over several rows. Such an arrangement of the structural elements allows a joint socket to be easily inserted into the bone by a slight rotation.

Another object of the present invention is to provide a device which enables a quick and efficient production of an acetabular cup with at least one area with a surface structure. This object is achieved with a device according to claim 16.

[0040] The device according to the invention comprises an opening for a socket base body and a press ram. The opening is arranged between at least two embossing elements which are pivotally mounted in the embossing direction. The base of the socket can be pressed into the opening using the press ram.

The embossing elements are designed as patrices of the structure to be imprinted on the base of the joint socket and can be pivoted in the embossing direction from a first, open position to a second, closed position. The embossing elements are designed and arranged in such a way that, in the first, open position, an opening remains between them which is suitable for receiving the base of the socket. Pressing in the base of the joint socket causes the embossing elements to pivot into the second, closed position.

In this closed position, the dimensions of the opening correspond to the dimensions of the surface of the base of the socket. However, the protruding contours of the structure to be stamped on the embossed elements protrude into the opening. The structure is thereby impressed into the surface of the base of the socket. The presence of at least two swiveling embossing elements leads to an increase in the embossing force due to the toggle action. Four to twelve embossing elements are particularly preferably arranged under the receptacle in the embossing direction.

CH 704 518 B1 The embossing elements are preferably interchangeable. As a result, a large number of different surface structures can be produced with a single device.

In a further embodiment, a drawing die is additionally arranged in the pressing direction before the recording. As a result, a blank made of flat material can first be formed into a joint socket base body in the same pressing operation and then pressed onto the embossing elements. This enables a particularly quick and efficient production of joint socket semi-finished products.

The device according to the invention is preferably used in a method according to the invention for producing an acetabular implant. Through modifications, such a device can also be used for processing other implants, such as femoral shaft implants, knee prostheses or the like.

[0046] Further aspects and details of the present inventions can be found in the following description of examples and figures. Show it:

1a-1c: a schematic representation of the method according to the invention;

2 shows a view of a surface profile obtained by the method according to the invention;

3a-3c: an embodiment of a device according to the invention in a sectional view; and

4: an acetabular cup produced by the method according to the invention.

1 shows a schematic representation of the method according to the invention in a cut perspective. 1 a shows the first step. In this case, a plurality of depressions 4 are impressed on an implant base body 1. 1b shows the semifinished product 3 obtained after the first step. The depressions 4, which were embossed in the first process step, are arranged in rows. In the second process step, 4 material is removed between the rows of depressions, preferably with a turning or milling tool. The structured surface 9 produced by the method shown can be seen in FIG. 1c. The structured surface 9 comprises several rows of structural elements 6 separated from one another by depressions 4. The individual rows of the structural elements 6 are spaced apart from one another by grooves 7. The grooves 7 were created by the material removal in the second process step, while the depressions 4 were embossed in the first process step.

2 shows a view of a surface profile 8 obtained by the method according to the invention on a curved surface. This surface profile can be arranged, for example, on an acetabular cup or a femoral shaft. The depressions 4, which separate the structural elements 6 of one row from one another, are arranged offset with respect to the depressions 4, which separate the structural elements 6 of an adjacent row from one another. In the example shown, the depressions 4 of adjacent rows are each offset such that they lie in the middle between two depressions 4 of an adjacent row. Alternatively, however, the depressions 4 of adjacent rows can also be arranged offset from one another by a greater or a smaller distance.

3 shows a preferred embodiment of a device 10 according to the invention. The device 10 has a deep-drawing die 14 on which a blank 13 made of flat material can be placed. Furthermore, the device 10 has a press stamp 12. First, the blank 13 is pressed by the press stamp 12 through the deep-drawing die. The blank 13 deforms into an implant base body 11. The blank 13 is particularly preferably formed into a spherical socket. In a further step, the basic implant body 11 is embossed. The basic implant body 11 can remain clamped in the same clamping. The clamped main implant body can be moved to this step of the method. In this step, the implant base body 11 is pressed into an opening 15, in which at least two embossing elements 16 are present. The embossing elements 16 are arranged so that they can pivot about the axes of rotation 17 in the pressing direction. The embossing elements 16 are arranged and designed such that the implant base body 11 can be inserted into the opening 15 in a suitable manner. The implant base body 11 is pressed into the opening 15 by the press ram 12. This leads to the contact of the implant base body 11 with the protruding contours 19 of the structure to be impressed, which protrude slightly into the opening 15. By further pressing in the implant base body 11, the embossing elements 16 pivot in the pressing direction into a second position. The protruding contours 19 are pressed into the implant base body 11. Two embossing elements 16 are preferably arranged on opposite sides of the opening 15, as a result of which the embossing pressure of the embossing elements 16 is increased by the toggle action. Four to twelve embossing elements 16 are preferably arranged in the device 10, these particularly preferably completely encompassing the main implant body 11. After the embossing step has taken place, the semi-finished implant product 18 can be ejected from the device, for example by means of ejection means (not shown). In a further step, which is shown in FIG. 3d, material is removed between the rows of depressions 4 formed by the embossing by means of a turning or milling tool. A large number of raised structural elements 6 thus arise between the depressions 4 and the grooves 7 obtained by material removal.

4 shows an embodiment of a socket 21 produced by the method according to the invention. The socket is designed as a spherical cap. In the area near the equator, the socket has a surface

CH 704 518 B1 structure, which consists of structural elements 6. The structural elements 6 are arranged in several rows spaced apart by grooves 7. The structural elements 6 are separated from one another by depressions 4, the depressions 4 in one row being arranged offset with respect to the depressions 4 in an adjacent row. The depressions 4 are offset from one another from row to row in such a way that the depressions 4 in one row are offset by half the distance between the depressions 4 in an adjacent row. In the region near the pole, the joint socket 21 has no structural elements 6. For better insertion of the socket, several longitudinal grooves 23 are arranged in the area of the structural elements 6.

Claims (17)

claims 1. A method for producing an implant with at least one area with a surface structure comprising the steps: - Submission of an implant base body (1); - embossing a plurality of depressions (4), preferably arranged in rows, on a surface section of the implant base body (1); and - Removal of material between the rows of depressions in such a way that raised structural elements are formed on the surface section, which are delimited by the depressions and by the removed locations. 2. The method according to claim 1, characterized in that the embossing of the depressions (4) takes place in a press (2). 3. The method according to any one of claims 1 or 2, characterized in that the removal of the material is carried out by a machining manufacturing process. 4. The method according to any one of claims 1 to 3, characterized in that the removal of the material is carried out by an electroerosive or electrochemical method. 5. The method according to any one of claims 1 to 4, characterized in that the implant base body (1) is deformed by deep drawing before the depressions (4) are impressed. 6. The method according to claim 5, characterized in that the deep-drawing of the implant body (1) and the embossing of the depressions (4) are carried out sequentially in the same clamping. 7. The method according to any one of claims 1 to 6, characterized in that the embossing of the depressions (4) is carried out by lateral rolling of the embossing elements (16) on the implant base body (1). 8. The method according to any one of claims 1 to 6, characterized in that the impressions of the depressions (4) are carried out by linearly closing jaws. 9. Implant with at least one area with a surface structure, produced by a method according to one of claims 1 to 8, characterized in that the individual structural elements (6) are limited by material impressions and material removals. 10. The implant as claimed in claim 9, characterized in that the depressions (4) which separate the structural elements (6) from one another in a row are arranged offset with respect to one another with respect to the depressions (4) which separate the structural elements from one another in a row are. 11. Implant according to one of claims 9 or 10, characterized in that the depressions (4) of a row are each arranged in the middle between two depressions (4) of an adjacent row. 12. Implant according to one of claims 9 to 11, characterized in that the structural elements (6) are shaped as cuboids, pyramids, tetrahedra, wedges, polyhedra or in the form of an acute-angled gable roof. 13. Implant according to one of claims 9 to 12, characterized in that the implant is an articular socket (21) and the structural elements (6) are arranged in an area close to the equator. 14. Implant according to claim 13, characterized in that the rows are arranged parallel to one another and run essentially at right angles to the direction of insertion of the implant. 15. Implant according to claim 14, characterized in that the distance by which the depressions (4) are arranged offset from one another increases from row to row in such a way that the structural elements (6) over several rows along a helical or circular arc-shaped line run. 16. A device for producing a joint socket semi-finished product (18) with depressions (4), comprising: - An opening (15) for receiving a socket base body (11); and - A press ram (12), wherein the base of the joint socket (11) can be pressed into the opening (15) by the press ram (12), characterized in that the opening (15) between at least two stamping elements (16) designed as patrons, which are pivotally mounted in the embossing direction, is arranged. 17. The apparatus according to claim 16, characterized in that the device (1) comprises four to twelve embossing elements (16) designed as patrices. CH 704 518 B1

CH 704 518 B1

CH 704 518 B1