DE102014103962A1 - Feumurkomponente a hip joint prosthesis and method for producing a femoral component of a hip joint prosthesis - Google Patents

Abstract

The invention relates to a femoral component (20) of a hip joint prosthesis made of a forged titanium alloy, with a shaft (21) intended for cementless anchoring in the femur of a human or animal, which in a proximal shaft region (24) has a porous, metallic, by sintering and / or Fusion produced surface (25). The proximal shank region (24) of the shank (21) is provided with an outer surface (28) which has been made to measure and which has metal structures (31) which have been sintered and / or fused by means of a laser beam, web-shaped and / or band-shaped and / or undercut or undercuts. is made of titanium or of a titanium alloy, which define outwardly open pores (32) to support femoral growth and / or osseointegration. The invention also relates to a method for producing a femoral component of a hip joint prosthesis.

Description

The invention relates to a femoral component of a forged hip joint prosthesis with a distal shaft end and a proximal shaft end intended for cementless anchoring in the femur of a human or animal, which in a, preferably proximal, shaft region a porous, metallic, by sintering and / or fusing surface to promote femur construction and osseointegration, or bone growth of the femur and femur or femur engagement. The invention also relates to a method for producing a cementless implantable or to be implanted femoral component of a hip joint prosthesis.

Hip joint prostheses are also known as hip endoprostheses. These have acetabular components and femoral or femoral components, which are also referred to as femoral components. The femoral components can be distinguished in hip-joint prostheses which can be implanted or implanted by means of a cement, which are also referred to as cemented components, and in cementless implantable or hip-joint prostheses which are also referred to as cement-free components. The invention relates to cementless implantable or to be implanted Hüftschäfte. Such Hüftschäfte are made of metal and can be produced in particular by casting or forging, in particular by drop forging. Because of their particular mechanical and biocompatible properties and because of their minimal weight at the same time, femoral components or shanks of hip joint prostheses made of a titanium alloy are particularly preferred.

Usually, forged blanks are made over measure, descaled by cleaning jets and then brought by a machining production, in particular by milling, on close to final dimensions or to measure. The cutting achieves rather smooth surfaces with a comparatively small roughness in the range of a few micrometers.

In order to achieve a permanent fixation in the femur or in the thighbone, a very good primary stability is required, in particular in the cementless implanted hip joint prostheses. In order to support the bone cultivation and the osseointegration or to promote bone growth of the femur and the femur engagement, in particular in a proximal shaft region of the shaft or in a region in which a bone attachment to the implant is desired, surface roughness, preferably in the form of a porous outer surface, be provided. In this context, one can also speak of textured areas. There the bone should grow in as early and well as possible so that the patient can load the implant as soon as possible.

Various methods for producing such porous surfaces have become known. Among these methods, in particular the so-called plasma spraying process or the application of metal short fibers of titanium compressed metal fiber fabrics have become known. Sintered porous coatings of metal particles are also used. Such methods or implants made therewith are for example from the DE 35 27 136 A1 , of the U.S. Patent 3,906,550 and the U.S. Patent 3,605,123 known.

From the DE 696 30 933 T2 For example, there have been known metal casting shanks of hip joint prostheses produced by casting into molds, which are made with pockets or depressions of about 1 mm depth to form a shallow pelvis or shed, the porous surface texture in the shed being achieved by placing metal beads or metal grains in the sheath Tray and heating of the assembly is made to weld or melt the beads or grains to the recessed surface of the Metallgußschafts.

Optimum pore size, porosity and biocompatibility of the porous surfaces support bone attachment and osseointegration, which is required for long-term stability of the implants.

It is an object of the invention to provide a femoral component of a hip joint prosthesis of the type mentioned in the introduction, which permits improved bone cultivation and improved osseointegration and which offers advantageous possibilities for pore-limiting metal structures which after bone ingrowth into the bone tissue Pores can not only absorb shear forces along the shaft, but can also safely absorb tensile or bending forces. It is a further object of the invention to provide a method which offers particularly flexible and expanded possibilities for producing a porous surface structure femoral component of a hip joint prosthesis, which has the aforementioned advantages.

The object related to the device is in particular solved by the features of claim 1 and the task related to the method is in particular solved by the features of claim 7.

Accordingly, the invention relates in particular to a cementless implantable or cementless femoral component of a forged titanium alloy having a distal shaft end and a proximal shaft end intended for cementless anchoring in the femur of a human or animal, which is in one, preferably proximal Shank region has a porous, metallic, by sintering and / or by fusing surface for supporting femur cultivation and osseointegration or to promote bone growth of the femur and an engagement of the femur or with the femur, wherein a shaft portion of the shaft, in particular the proximal shaft region of the shaft is provided with an outer surface produced under dimension, which has metal structures a sintered and / or fused, rib-shaped and / or band-shaped and / or undercut or undercut Titanium or titanium alloy is provided to limit the externally open pores to support the femoral culture and / or osseointegration or to promote bone growth of the femur and an intervention of the femur or with the femur.

According to a very particularly preferred embodiment it can be provided that the outer surface produced under measure with sintered by means of a laser beam or by laser sintering and / or molten, web-shaped and / or band-shaped and / or undercut or undercut metal structures of titanium or of a titanium alloy is provided, which limit the pores open to the outside. This creates flexible and new opportunities for even better hip joint prostheses for the benefit of the affected patients. This is especially true when the sintered metal structures are undercut or have undercuts. Because then, after ingrowth of the bone into the undercuts or into the undercut areas of the metal structures, form-fitting connections between the bone and the implant can be formed in such a way that tensile forces, but in particular bending forces, acting perpendicular to the respective outer surface of the implant are effectively transferred can. This achieves a particularly good and long-term secure fixation of the implant in the bone or femur.

According to a development, it can be provided that the metal structures, seen in a plan view, are arcuate and / or letter-shaped and / or V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F -shaped and / or L-shaped and / or T-shaped and / or T-shaped and / or star-shaped and / or X-shaped and / or annular over the outer surface produced under dimension or that the metal structures, in a plan view considered, arcuate and / or letter-shaped and / or V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T-shaped and / or star-shaped and / or X-shaped and / or annular.

Alternatively or additionally, it may be provided that the metal structures, viewed in a sectional plane running parallel or tangentially to the outer surface of the shaft produced under dimension, have an arcuate and / or letter-shaped, in particular V-shaped and / or U-shaped and / or S -shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T-shaped and / or X-shaped, and / or a star-shaped and / or an annular cross-section exhibit.

Alternatively or additionally, it may be provided that, in a sectional plane running transversely or perpendicular to the outer surface produced under dimension, the metal structures have a rectangular and / or oblong and / or elongated and / or concave and / or V-shaped and / or U-shaped and / or T-shaped and / or T-shaped and / or mushroom-shaped and / or conical and / or biconical cross-section. Preferably, when the metal structures have a tapered cross-section, they are formed with wall portions that taper toward the outer surface made to dimension. Preferably, when the metal structures have a double-cone-shaped cross-section, they are formed with two conical wall parts, which taper conically in the direction of each other.

Alternatively or additionally, it may be provided that the, preferably proximal, shaft portion of the shaft is provided with a recess formed, for example, as a pocket or a pocket, which is partially or fully bounded by a recess edge of the shaft and that of the lower produced outer surface having recess bottom of the shaft is limited.

The invention also relates in particular to a method for producing the femoral component, in particular according to one of claims 1 to 6, or for producing a femoral component of a hip joint prosthesis made of a titanium alloy, which has a cementless anchorage in the femur of a human or animal, a distal shaft end and a Proximal shank end containing shaft of a forged stock material, either from a one shaft or a shank-containing blank of the femoral component is produced by forging, preferably hot forging, in particular swaging, whereby in a, preferably proximal, shank region of the forged stem the forged stem material is partially, preferably machined, for example by milling to a degree to form an outer surface is removed, after which applied to the outer surface, a metal powder, preferably in the form of one or more layers of titanium or a titanium alloy and simultaneously or subsequently by means of a laser beam or by laser sintering, preferably at ambient pressure or at non-elevated pressures, in particular free from elevated pressures, so sintered onto the outer surface of the shaft and / or is melted into the outer surface of the shaft or with the outside fused to the outside surface of the stem, there are titanium or titanium alloy metal structures, open to the outside, to support femurs and / or osseointegration or to promote bone growth of the femur and femur or femur engagement form.

According to a particularly preferred embodiment, provision may be made for a first powder layer of titanium powder or titanium alloy or titanium alloy to be applied to the outer surface of the shaft, which is simultaneously or subsequently sintered onto the outer surface of the shaft by means of a laser beam and / or the outer surface of the stem is fused or fused with the outer surface of the stem to form elevational metal structures over the outer surface, after which at least one further powder layer of one or the titanium or titanium alloy metal powder is applied to the metal structures at the same time or subsequently sintered onto the metal structures by means of a laser beam and / or melted into the metal structures or fused to the metal structures such that the metal structures opening outward open pores from titanium or from the titanium alloy.

According to a particularly preferred embodiment, it can be provided that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam or by laser sintering such that the metal structures are web-shaped and / or band-shaped and / or undercut or Have undercuts.

Alternatively or additionally, it may be provided that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam or by laser sintering such that the metal structures, seen in a plan view, arcuate and / or a letter-shaped and / or V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T-shaped and / or star-shaped and or extend X-shaped and / or annular over the outer surface.

Alternatively or additionally, it can be provided that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam or laser sintering such that the metal structures, viewed in a direction parallel or tangent to the outer surface cutting plane, an arcuate and / or a letter-shaped and / or a V-shaped and / or a U-shaped and / or an S-shaped and / or an F-shaped and / or an F-shaped and / or an L-shaped and / or a T-shaped and / or have a T-shaped and / or a star-shaped and / or an X-shaped and / or an annular cross-section.

Alternatively or additionally, it may be provided that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam or laser sintering such that the metal structures in a transverse or perpendicular to the outer surface extending cutting plane considered a rectangular and / or elongate and / or elongate and / or concave and / or V-shaped and / or U-shaped and / or T-shaped and / or T-shaped and / or mushroom-shaped and / or conical and / or biconical cross-section.

Alternatively or additionally, it may be provided that the forged shaft material in the, preferably proximal, shaft portion of the shaft to form a, for example as a pocket or a pocket formed, recess, preferably machined, for example, by milling, which partially or completely from a recess edge of the forged shaft is limited and which is bounded by a recess having the outer surface of the shaft, after which the metal powder of titanium or titanium alloy on the outer surface or on the metal structures of the recess by means of a laser beam or sintered by laser sintering and / or is melted into the outer surface of the recess or in the arranged in the recess metal structures.

It is understood that the above features and measures may be combined as desired within the scope of the invention.

Further features, advantages and aspects of the invention will become apparent from the claims and the drawings and from the following description part, in which a preferred embodiment of the invention with reference to figures.

Show it:

1 a perspective view of a femoral component of a hip joint prosthesis with metal surface structures schematically shown in the proximal shaft region;

2 a greatly enlarged section of the metal surface structures in a plan view;

3 a section of metal surface structures in a perpendicular to an outer surface produced by material removal of a recess of the shaft of the hip joint prosthesis, greatly enlarged cross-section.

The 1 shows a femoral component 20 a hip joint prosthesis. This includes a shaft as an essential component 21 , This has a distal shaft end 22 and a proximal shaft end 23 on. The shaft 21 is at its proximal end 23 insoluble or detachable with a neck 26 Mistake. At the neck 26 is a spherical head 27 releasably or permanently attached. The usually smooth, preferably polished, head 27 forms a surface of a hip joint. The head 27 may rotate in an unillustrated hip gap, which is the acetabular component of the hip joint prosthesis. The shaft 21 serves for cementless anchoring in a femur or femur, not shown, of a human or animal. At least the shaft 21 , if necessary, the neck 26 , is made by forging of a titanium alloy.

The shaft 21 points in a proximal shaft area 24 who in 1 is schematically illustrated by a cross-hatching, a porous, metallic, produced by laser sintering by means of a laser beam, not shown, surface 25 on. The proximal shaft area 24 of the shaft 21 is with a by, preferably machined, removal of forged stock material on undersized outer surface 28 a recess 29 Mistake. The recess 29 can be groove-shaped. The recess 29 may be annular, preferably continuous, about the longitudinal axis of the shaft 21 extend around. But it is also possible that the recess is formed as a bag or as a compartment. The recess 29 can be partially or fully from a recess edge 30.1 . 30.2 of the shaft 21 be limited. The outer surface 28 is with metal structures sintered on and / or fused thereto 31 ; 31.1 to 31.7 made of titanium or a titanium alloy. The metal structures 31 ; 31.1 to 31.7 limit or form outward open pores 32 to support femoral growth and osseointegration or to promote bone growth of the femur and femoral or femoral interventions. The sintered metal structures 31 ; 31.1 to 31.7 can be designed web-shaped and / or band-shaped. In particular, the sintered metal structures 31.3 to 31.7 Having undercuts or be undercut formed.

The 2 shows in a plan view a greatly enlarged section of inventive or inventively produced metal structures 31 , As can be seen, the sintered metal structures 31 arcuate and / or letter-shaped, for example V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T -shaped and / or X-shaped, and / or star-shaped and / or ring-shaped extend over the outer surface made under measure or can the metal structures 31 arcuate and letter-shaped, for example V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T-shaped , and / or be formed star-shaped and / or X-shaped and / or annular. The metal structures 31 may be similar to a coral structure or may be the surface 25 have a rough surface finish similar to a coral structure. Due to the rough and large surface of the metal structures 31 can be achieved in the implant very good bone growth and a very good osseointegration.

The 3 shows a section of inventive or inventively prepared metal structures 31 ; 31.1 to 31.7 in a perpendicular to the outer surface produced by material removal 28 the recess 29 of the shaft 21 the hip joint prosthesis extending, greatly enlarged cross-section. There are the following metal structures from left to right 31 shown: a web-shaped, elongated metal structure 31.1 with a rectangular cross-section; a web-shaped, elongated metal structure 31.2 with a wavy or caterpillar-shaped cross section; an undercut, T-shaped metal structure 31.3 ; an undercut, T or mushroom-shaped metal structure 31.4 ; an undercut, double conical metal structure 31.5 with two facing each other tapered conical structural parts; an undercut, conical metal structure 31.7 moving towards the outside surface 28 the recess 29 rejuvenated; an undercut, a concave cross section and a cross section similar to a concave lens having metal structure 31.7 ,

The in the 3 shown in cross section recess 29 is designed to be open to the outside. It is designed groove-shaped. The recess 29 is laterally bounded by Ausnehmungsränder 30.1 . 30.2 of the shaft 21 and is further limited by a between the Ausnehmungsrändern 30.1 . 30.2 extending recess bottom 30.3 , The recess floor 30.3 indicates the outer surface made under measure 28 on or is limited by this. By sintering or melting the metal structures 31 ; 31.1 to 31.7 are these with the the outer surface 28 having recess bottom 30.3 the recess 29 at least partially or completely merged.

For making the femoral component 20 The hip joint prosthesis can be used according to the invention as follows:
Either one may start from a forged titanium alloy stem for a femoral component of a hip joint prosthesis, or first a stem containing a stem for or for a femoral component of a hip joint prosthesis may be made by forging a titanium alloy. As a forging method, hot forging and drop forging can be preferably used.

Subsequently, first in one or in the proximal shaft region 24 of the forged shaft 21 the forged shaft material partially, preferably machined, for example, by milling, removed to below measure, wherein or after which an outer surface is formed.

Following this is on the outer surface formed by the material removal 28 of the shaft 21 a first powder layer, not shown, of a metal powder of titanium or of a titanium alloy is applied.

Simultaneously or subsequently, the metal powder of this first powder layer by means of a laser beam not shown or by laser sintering at ambient pressure, ie free of elevated pressures, at the elevated temperature by the laser beam, on the outer surface 28 of the shaft 21 sintered and / or in the outer surface 28 of the shaft 21 melted down, leaving it over the outside surface 28 form uplifting first metal structures.

Subsequently, at least one further powder layer of one or of the metal powder made of titanium or of one or the titanium alloy is applied to the first metal structures.

At the same time or subsequently, the metal powder of this further powder layer is sintered onto the first metal structures and / or melted into the metal structures by means of a laser beam, which is not shown, or by means of laser sintering at ambient pressure, ie, free of elevated pressures, at temperatures greatly increased by the laser beam pores open to the outside 32 limiting metal structures 31 ; 31.1 to 31.7 of titanium or of the titanium alloy, extending over said outer surface 28 of the shaft 21 rise.

In this case, the metal powder by means of the laser beam or by means of laser sintering in such a manner on the said recessed or made under measure outer surface 28 of the shaft 21 or sintered on the first metal structures and / or with the outer surface 28 or fused with the first metal structures, in particular metal structures 31 ; 31.1 to 31.7 be formed, as exemplified in the 2 and 3 are shown.

LIST OF REFERENCE NUMBERS

20

 Femoral / acetabular prosthesis

21

 shaft

22

 distal shaft end

23

 proximal shaft end

24

 proximal shaft area

25

 surface

26

 neck

27

 head

28

 outer surface

29

 recess

30.1

 recess edge

30.2

 recess edge

30.3

 recess bottom

31

 metal structure

31.1

 metal structure

31.2

 metal structure

31.3

 metal structure

31.4

 metal structure

31.5

 metal structure

31.7

 metal structure

31.7

 metal structure

32

 pore

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3527136 A1 [0005]
• US 3906550 [0005]
• US 3605123 [0005]
• DE 69630933 T2 [0006]

Claims (13)

Femoral component ( 20 ) of a forged hip joint prosthesis made of a titanium alloy, with a distal shaft end ( 22 ) and a proximal shaft end ( 23 ), intended for cementless anchoring in the femur of a human or animal ( 21 ) located in a proximal shaft region ( 24 ) a porous, metallic surface produced by sintering and / or fusing ( 25 ) for supporting a femur cultivation and an osseointegration, characterized in that a proximal shaft region ( 24 ) of the shaft ( 21 ) with an outer surface ( 28 ) provided with sintered and / or fused, web-shaped and / or band-shaped and / or undercut or undercuts metal structures ( 31 ; 31.1 to 31.7 ) is made of titanium or a titanium alloy, the pores open to the outside ( 32 ) to support femur production and / or osseointegration. Femoral component of a hip joint prosthesis according to claim 1, characterized in that the outer surface ( 28 ) with metal structures sintered and / or fused by means of a laser beam, web-shaped and / or strip-shaped and / or undercut or undercuts ( 31 ; 31.1 to 31.7 ) is made of titanium or of a titanium alloy, which the pores ( 32 ) to support femur production and / or osseointegration. Femoral component of a hip joint prosthesis according to claim 1 or 2, characterized in that the metal structures ( 31 ; 31.1 to 31.7 ), viewed in a plan view, arcuate and / or letter-shaped and / or V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T-shaped and / or star-shaped and / or X-shaped and / or annular over the undersized outer surface ( 28 ). Femoral component of a hip joint prosthesis according to one of the preceding claims, characterized in that the metal structures ( 31 ; 31.1 to 31.7 ), in a parallel or tangential to the outer surface ( 28 ), an arcuate and / or a letter-shaped and / or a V-shaped and / or a U-shaped and / or an S-shaped and / or an F-shaped and / or an F-shaped and / or have an L-shaped and / or a T-shaped and / or a T-shaped and / or a star-shaped and / or an X-shaped and / or an annular cross-section. Femoral component of a hip joint prosthesis according to one of the preceding claims, characterized in that the metal structures ( 31 ; 31.1 to 31.7 ) in a transverse or perpendicular to the outer surface ( 28 ) considered a rectangular and / or elongated and / or elongated and / or concave and / or V-shaped and / or U-shaped and / or and / or T-shaped and / or T-shaped and / or mushroom-shaped and or have conical and / or biconical cross-section. Femoral component of a hip joint prosthesis according to one of the preceding claims, characterized in that the proximal shaft region ( 24 ) of the shaft ( 21 ) with a recess ( 29 ), which is partially or completely covered by a recess edge ( 30.1 . 30.2 ) of the shaft ( 21 ) and that of an outer surface ( 28 ) having recess bottom ( 30.3 ) of the shaft ( 21 ) is limited. Method for producing the femoral component according to one of the preceding claims or for producing a femoral component ( 20 ) of a titanium alloy acetabular prosthesis having a distal end (a) intended for cementless anchoring in the femur of a human or animal ( 22 ) and a proximal shaft end ( 23 ) shank ( 21 ) from a forged stem material, either starting from a forged blunt of the femoral component containing a stem, or a blunt containing the stem of the femoral component is made by forging, after which in a proximal stem area (Fig. 24 ) of the shaft ( 21 ) the forged shaft material is partially reduced in dimension to form an outer surface ( 28 ) is ablated, after which on the outer surface ( 28 ) of the shaft ( 21 ) applied to a metal powder of titanium or of a titanium alloy and at the same time or subsequently by means of a laser beam to the outer surface ( 28 ) of the shaft ( 21 ) sintered and / or in the outer surface ( 28 ) of the shaft ( 21 ) is melted down, that outwardly open pores ( 32 ) delimiting metal structures ( 31 ; 31.1 to 31.7 ) of titanium or of a titanium alloy in support of one or the femur growing and one or osseointegration. Method according to claim 7, characterized in that on the outer surface ( 28 ) of the shaft ( 21 ) a first powder layer of one or of the metal powder of titanium or of one or the titanium alloy is applied to the outer surface simultaneously or subsequently by means of a laser beam ( 28 ) of the shaft ( 21 ) sintered and / or in the outer surface ( 28 ) of the shaft ( 21 ) is melted down, so that there over the outer surface ( 28 Forming elevating metal structures, after which at least one further powder layer of one or the metal powder of titanium or of one or the titanium alloy is applied to the metal structures, which is simultaneously or subsequently sintered onto the metal structures by means of a laser beam and / or fused into the metal structures the outwardly open pores bounding metal structures ( 31 ; 31.1 to 31.7 ) of titanium or of the titanium alloy. A method according to claim 7 or 8, characterized in that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam in such a way that the metal structures ( 31 ; 31.1 to 31.7 ) are web-shaped and / or band-shaped and / or undercut or have undercuts. Method according to one of claims 7 to 9, characterized in that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam such that the metal structures, ( 31 ; 31.1 to 31.7 ), viewed in a plan view, arcuate and / or a letter-shaped and / or V-shaped and / or U-shaped and / or S-shaped and / or F-shaped and / or F-shaped and / or L-shaped and / or T-shaped and / or T-shaped and / or star-shaped and / or X-shaped and / or annular over the outer surface ( 28 ). Method according to one of claims 7 to 10, characterized in that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam in such a way that the metal structures ( 31 ; 31.1 to 31.7 ), in a parallel or tangential to the outer surface ( 28 ), an arcuate and / or a letter-shaped and / or a V-shaped and / or a U-shaped and / or an S-shaped and / or an F-shaped and / or an F-shaped and / or have an L-shaped and / or a T-shaped and / or a T-shaped and / or a star-shaped and / or an X-shaped and / or an annular cross-section. Method according to one of claims 7 to 11, characterized in that the metal powder of titanium or of the titanium alloy is sintered and / or melted by means of a laser beam in such a way that the metal structures ( 31 ; 31.1 to 31.7 ) in a transverse or perpendicular to the outer surface ( 28 ) extending sectional plane considered a rectangular and / or elongated and / or elongated and / or concave and / or V-shaped and / or U-shaped and / or T-shaped and / or T-shaped and / or mushroom-shaped and / or conical and / or have a double-cone-shaped cross-section. Method according to one of claims 7 to 12, characterized in that the forged stem material in the proximal shaft region ( 24 ) of the shaft ( 21 ) forming a recess ( 29 ) is removed, which partially or completely from a Ausnehmungsrand ( 30.1 . 30.2 ) of the forged shaft ( 21 ) and that of a the outer surface ( 28 ) having recess bottom ( 30.3 ) of the shaft ( 21 ), after which the metal powder of titanium or of the titanium alloy is irradiated by means of a laser beam onto the outer surface ( 28 ) of the recess ( 29 ) sintered and / or in the outer surface ( 28 ) is melted down.

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