DE19635307A1 - Hip joint prosthesis component with cage and supporting plate - Google Patents

Abstract

An anchoring cage (26) should be a forging and its several anchoring posts (28-44) have core (46) and a sequence of anchoring shoulders (48) or holes. The opposing post surfaces in the outsides of the cage (26) are drop-forged as against the surfaces facing into the cage which are post-machined. The prosthesis segments (10) are held together by holding elements (22), either shrink-fits or simply welded together. One segment has a perforated plate whose perforation rim walls are spherical or of semicircular section, and when using a plate sector this has anchoring posts extending at right angles from the plate surface. Thus the cage can present a number of plate segments which are corrugated in two directions and have a number of perforations offset from one another in adjoining cage segments. The prosthesis component is preferably made of Ti or Ti alloy.

Description

The invention relates to a prosthesis part according to the upper Concept of claim 1.

Such a prosthesis part is in DE 37 07 518 A1 described.

After implanting such a prosthesis part Spongiosa grows between the anchoring pillars of the Anchoring cage, which makes the prosthesis part dynamic and firmly attached to the end of the femur becomes.

Such prosthetic parts have so far been precision castings. The production of the lost molds is high Cost associated, so that the prosthesis parts are expensive are.

A prosthesis part is intended by the present invention further developed according to the preamble of claim 1 be that it has the benefits of being cementless implanted Prosthesis parts with an open anchoring cage that offers a variety of anchoring surfaces, but is cheaper to manufacture.

This object is achieved by a pro thesis part with the features specified in claim 1.

Anchoring cages can also be made by forging Manufacture inexpensively in small series. The blacksmith ble metals, from which the prosthetic part fiction  according to, are also characterized by good strength and toughness as desired for prosthetic parts is. The metal is also preserved by forging favorable structure.

Advantageous developments of the invention are in Unter claims specified.

A prosthesis part as specified in claim 2 on the one hand has one for the ingrowth of cancellous bone particularly favorable open structure, but can be despite the still inexpensive to produce, the contour the anchoring pillar partly through forging in the die, the other part by machining is generated. Machining can be done despite the relatively complicated contour of the anchoring cages on numerically controlled machine tools handle inexpensively, the latter under Zu basic drawing data for the anchoring cages can be controlled.

With the development of the invention according to claim 3 it is also possible to remove those from the outer surface of the cage turned, i.e. inward-facing surface sections to manufacture the anchoring pillar by drop forging len or easier to manufacture, because there is good access to these areas.

When building a prosthesis part from several segments is obtained according to claim 4 in a very simple manner holding the different cage segments together.

By attaching the holding elements according to claim 5 he you keep a very robust and also high loads resistant blocking of the holding elements.  

With the development of the invention according to claim 6 is another improvement in cohesion between between the different cage segments.

Alternatively you can also use Ver join welding as indicated in claim 7.

According to claim 8 is obtained in a very simple manner an anchoring cage with simple geometry of the plates shaped cage segments.

The development of the invention according to claim 9 is with a view to a good ingrowth of cancellous bone and with a view to keeping notch stresses in the latter an advantage.

The development of the invention according to claim 10 with regard to simple geometry of the prosthesis segments with large anchoring area and ready at the same time provision of a large number of anchoring shoulders advantageous.

According to claim 11, the prosthesis part as a whole built up plate-shaped cage segments, so result overall, particularly favorable manufacturing costs with anchoring cage well open.

The developments of the invention according to the Claims 12 to 14 with regard to a particular intimate mutual penetration of bone structure and anchoring cage an advantage.

The manufacture of the prosthesis part from titanium or one Titanium alloy according to claim 15 is with regard to  high mechanical resilience and good biocompatibility of the prosthesis part is an advantage.

The invention based on embodiment examples with reference to the drawing explained. In this show:

Figure 1 is a side, ventral view of a Prothe senteiles for an artificial hip joint.

FIG. 2 shows a top view of the right, medial side of the prosthesis part shown in FIG. 1, with a support pin being shown in axial section;

Fig. 3 is a lateral, anterior view of a central segment of prosthesis of the prosthesis of FIGS. 1 and 2;

Figure 4 is an axial plan view of a modified anchoring posts for the prosthetic segment of Fig. 3.

Fig. 5 is a plan view of a modified middle prosthesis segment, which can be used instead of the Pro thesensegmentes of FIG. 3;

Fig. 6 is a section along the section line VI-VI of Fig. 5;

Fig. 7 is a lateral, anterior view of another prosthesis middle segment, which is useful in the prosthetic part according to Figures 1 and 2.

Figure 8 is an enlarged partial section through the Pro thesis segment of Figure 7 along the section line VIII-VIII.

Fig. 9 is an anterior view of another prosthesis middle segment, which is useful in the prosthetic part according to Figures 1 and 2.

Fig. 10; an enlarged partial section through the Pro thesis segment of Figure 9 along the section line XX;

FIG. 11 is a ventral view of a prosthesis blank for a further modified prosthetic component;

FIG. 12 shows a section along the section line XII-XII of FIG. 11; and

Fig. 13 is a section perpendicular to the central plane through another prosthetic part.

In Fig. 1, a total of 10 a prosthesis part is designated, which is used for implantation in the dashed indicated upper end of a femur 12 . For this purpose, the upper section of the femur 12 carrying the joint ball is resected and a recess 14 is produced in the thigh bone, which corresponds to the clear outer contour of the prosthesis part 10 .

The prosthesis part 12 has a support plate 16 which has a horizontal plate section 18 and a plate section 20 which rises obliquely upwards towards the minor trochanter. A support pin 22 , which rises obliquely upwards, is formed on the plate section 18 , onto which a joint ball 24 , indicated by dashed lines, can be placed.

An anchoring cage, designated overall by 26, is cast onto the underside of the support plate 16 . This cage structure consists of four curved longitudinal anchoring posts 28 , 30 , 32 , 34 , which essentially define the shape of a curved pyramid with a rectangular cross section at the top and an increasingly round cross section at the bottom. From the upper end of the plate section 18 proceed two curved additional anchoring posts 36 , 38 , the shape of which is adapted to the greater trochanter of the femur and which are smaller from one another than the adjacent anchoring posts 32 and 34 .

Inside the pre-by the anchoring posts 28-38 discontinued clear contour of the anchor cage 26 more anchoring posts are provided, which run ver in oblique directions between the anchoring posts 28-38. Of these, three such anchoring cage 26 stiffening anchoring pillars 40 , 42 , 44 are shown.

The anchoring pillars each have a cylindrical core 46 with a plurality of axially spaced anchor bolts 48 .

Typically, the cores 46 of the anchoring pillars 28 to 34 have a diameter of 2.0-4.5 mm, the diameter of the anchoring collars are each approximately 0.8-1.5 mm larger than the diameter of the cores. The axial extension of the anchoring collars is about 0.6-1.2 mm, their distance from each other about 3-6 mm.

For the stiffening inner anchoring posts 40 , 42 , 44 , the cores can have a diameter of approximately 1.5-3 mm, the diameter of the anchoring collars can be approximately 0.6-1.2 mm larger than the core diameter, and the axial dimension of the anchoring collars can be about 0.5-1 mm, their axial distance about 2-4 mm.

At the lower end of the anchor cage 26, a shaft portion 50 is integrally formed. This has an olive-shaped end section 52 . A channel 54 extends through the interior of the shaft section 50 .

To implant the prosthesis part described above, the end of the thigh bone is resected as described above, the upper edge of the cortical being receiving a contour corresponding to the edge contour of the support plate 16 . The bone material removed from the bone end during the production of the recess 14 is ground in a bone mill and filled into the anchoring cage 26 . The prosthesis part 10 is then inserted into the proximal end of the femur 12 , so that the support plate 16 now forms a new upper end for the bone.

After insertion of the prosthesis part 10 , this part is resiliently connected to the upper end of the femur. In the further healing process, the ground cancellous bone grows together and fills the cage structure, while growing up against the cortical bone and the remaining cancellous bone remains.

After completion of the healing process, one has a continuous spongiosavo lumen in the area of the anchoring cage 26 , which has grown around the cage structure.

As can best be seen from FIG. 2, the prosthesis part 10 consists of three prosthesis segments: a prosthesis segment 10 A located on the left in FIG. 2 comprises the anchoring pillars 28 , 30 as well as adjacent anchoring pillars, which in the by the anchoring pillars 28 , 30 predetermined area or run parallel to this. Furthermore, the prosthesis segment 10 A includes a segment 16 A of the support plate 16 , a segment 50 A of the shaft section 50 , an upper pin segment 60 A, and a pin segment 62 A located below.

Correspondingly, a central prosthesis segment 10 B comprises those anchoring pillars which run in a central plane of the prosthesis part 10 or adjacent thereto, a segment 16 B of the support plate 16 , a segment 50 B of the shaft section 50 , an upper pin segment 60 B and a lower pin segment 62 B. A slot in segment 50 B of shaft section 50 B (similar to that shown in FIG. 3) forms channel 54 together with slot-free shaft sections 50 A and 50 C of prosthesis segments 10 A and 10 C.

Finally, a right in Fig. 2 Pro thesis segment 10 C includes the anchoring piers 32 , 34 and other anchoring piers that run in the area defined by the anchoring piers 32 , 34 or are adjacent to it, a segment 16 C of the support plate 16 , a segment 50 C of the shaft section 50 , an upper pin segment 60 C and a lower pin segment 62 C.

The overhead pin segments 60 A, 60 B, 60 C taken together form an inner pin, on which the support pin 22 designed as a cup-shaped part is shrunk in the hot state.

Similarly, the underlying pin segments 62 A, 62 B and 62 C together form an inner pin, on which an end piece 64 is shrunk in the hot state.

In this way, the three prosthesis segments 10 A, 10 B and 10 C are firmly held together at the upper and lower ends.

The individual prosthesis segments are each undercut dung-free and can be in a two-part die shape ready to be forged. For example after drop forging remaining burrs are removed by machining away.

If desired, you can choose between the small prosthesis segments working together Provide projections and recesses, which together each form positioning interlocking connections.

Fig. 3 shows a modified mid-segment prosthesis 10 B:

At the segment 16 B of the support plate 16 is a downwardly extending wall 66 is formed, the edge contour is accordingly the clear outer contour of the prosthesis part 10 is selected.

Anchoring posts 68 are formed on the wall 66 , perpendicular to the wall plane, which in turn have a core 70 and axially successive anchoring collars 72 carried by this core. Furthermore, a plurality of through openings 74 is easily seen in the wall.

The anchoring pillars 68 are made from pillar blanks by machining, which were formed on the wall 66 during the forging of the prosthesis segment 10 B. The through openings 74 are also made in forging except for a small remaining web, the opening walls having a substantially semicircular cross section. The webs remaining in drop forging are cut out with a tool.

The prosthesis segment 10 B can also be inexpensively manufactured in a two-part die shape; The post-processing is inexpensive and can be carried out quickly.

In order to save the machining of the anchoring pillars 68 , the anchoring surfaces working together with the cancellous bone can also be provided in the form of anchoring channels instead of in the form of anchoring ties, as shown in FIG. 4. These anchoring surfaces are in the forging direction and can thus be produced when the prosthesis segment 10 B is forged.

Filling in by the four anchoring pillars 28 , 30 , 32 , 34 limited interior of the anchoring cage 26 with anchoring surfaces can also be carried out according to FIGS . 5 and 6 so that perpendicular to a molded onto the segment 16 B wall 66 during die forging the anchoring ribs 76 projecting from the wall sides.

The anchoring ribs 76 are arranged like a net or truss and not only increase the contact area with a healing cancellous bone but also stiffen the wall 66 .

These can have different and contoured heights (extension perpendicular to the plane of FIG. 5), as is desired in each case for filling the cage structure.

In the anchoring ribs 76 through machining 77 pass through openings 77 are incorporated.

Even with such a prosthesis segment, a good mechanical connection is obtained between cancellous bone that has grown back into the interior of the anchoring cage 26 and the prosthesis part 10 .

In the prosthesis segment 10 B according to FIGS. 7 and 8, anchoring ribs 76 are forged on a wall 66 hanging from the support plate segment 16 B in the direction of the main stress lines, which carry successive anchoring collars 79 in the longitudinal direction of the ribs, which are dimensioned similarly to the main anchoring pillars 38 to 34 . The height (extension perpendicular to the plane of the drawing) of the anchoring ribs 76 is again chosen as is desired in view of filling the space spanned by the anchoring pillars 28 to 32 with anchoring surfaces. If desired, the anchoring ribs 76 can again be provided with through openings (corresponding to the through openings 77 of FIG. 6).

The prosthesis segment 10 B according to FIGS . 9 and 10 is very similar to that according to FIGS . 7 and 8, only the wall 66 is omitted and the shaft section segment 50 B is connected to the support plate segment 16 B via three of the anchoring ribs 76 , which are now located extend on both sides of the central surface of the prosthesis segment 10 B. In this way, the anchoring cage of the prosthesis part obtained with the prosthesis segment 10 B according to FIGS . 9 and 10 is even more open.

Referring to FIG. 11 and 12 can be for manufacturing also assume a one-piece blank, which is already provided with all gewün schten surface contours of the anchoring posts during the drop forging, in so far as this can be generated in the pressing direction of a prosthetic member 10. This blank is similar to the prosthesis part 10 B according to FIGS. 7 and 8, with the proviso that under the anchoring ribs 76 are marginal, which span the same space as the anchoring pillars 28 to 34 , so that the anchoring ribs are overall higher. Optionally, one can also assume a blank without wall 66 , which speaks a prosthesis segment 10 B according to FIGS. 9 and 10.

As can be seen from FIG. 12, the marginal anchoring ribs 76 are machined:

The material volumes 78 lying behind them are partially removed under NC-controlled machining (upper left section of FIG. 12), whereby the inner surface of the anchoring pillars 28 to 32 and the surfaces of any further anchoring pillars which are adjacent to the median plane of the prosthesis part are removed generated.

Optionally, the side anchoring ribs can also be provided with a row of through openings 81 which follow one another in the longitudinal direction of the ribs, in which case through holes 83 are produced simultaneously in the central anchoring ribs 76 , as shown in the lower right section of FIG. 12.

In the prosthesis part shown in FIG. 13, the anchoring cage 26 is formed by a plurality of anchoring plates 80 , 82 , 84 , 86 .

The anchoring plates 80 , 82 , 84 , 86 are alternately provided with indentations 88 from one and the other side, the whole in such a way that a two-dimensional corrugation of the plates is obtained. In addition, through openings 90 are provided in the anchoring plates, which, as shown at 92 , have a semicircular cross-sectional edge wall.

In practice, the through openings 92 have a diameter of approximately 3 to approximately 8 mm, preferably approximately 5 mm.

Due to the corrugation of the anchoring plates described above and the through openings 90 , an intimate interlocking between ingrown cancellous bone material and the anchoring cage 26 is obtained.

The through openings 90 of adjacent cage segments 80 , 82 , 84 , 86 are offset from one another.

At the upper end of the anchoring plates 80 , 82 , 84 , 86 square cross-section retaining elements 94 , 96 , 98 , 100 are integrally formed; narrower retaining strips 102 , 104 , 106 , 108 are found at the lower plates.

The upper retaining strips 94-100 take place in the interior of a recess 110 , which is provided in the now thicker formed support plate 16 . The support plate 16 is shrunk onto the holding strips 94 , 96 , 98 , 100 in the hot state.

The holding strips 94 to 108 can in turn be provided with positive locking elements (not shown), on the one hand to facilitate their alignment, and on the other hand to prevent the holding strips from moving against one another.

Furthermore, the outer ones of the retaining strips can be provided with side surfaces which are inclined downwards and inwards, the side surfaces of the recess 110 which cooperate with these being correspondingly inclined. In this way, an even more secure connection of the holding strips to the support plate 16 is ensured after it has been shrunk on.

To hold the lower ends of the anchoring plates 80 , 82 , 84 , 86 together , an olive-shaped end body 116 is shrunk hot onto the lower holding strips 102 , 104 , 106 , 108 .

It is understood that the edge contour of the individual Ver anchor plates 80 , 82 , 84 , 86 is similar to that of the Prothe sensegmente 10 B selected and the anchor plates have received such a macro curvature during die forging that the overall desired outer contour of the anchor cage 26 is obtained.

The manufacture of the anchoring plates 80 , 82 , 84 , 86 takes place in such a way that first flat blanks including the upper and lower holding strips are produced, with the corresponding die forging also making the through openings 90 except for a small, stationary middle web. Then these small webs are cut out and in one or more further forging steps the indentations 88 are produced and the macro-curvature of the anchoring plates is taken care of. The support plate 16 and the olive-shaped end body 116 are then shrunk on.

To strengthen the connection, the holding strips 94 to 100 can be connected to one another by welds 118 and to the support plate 16 by welds 120 . A similar procedure can be used for the lower holding strips 102 to 108 , although not shown in the drawing.

Claims (15)

1. prosthesis part with a support plate ( 16 ) on which a joint part ( 24 ) can be fastened, and with an anchoring cage ( 26 ) which is fixedly connected to the support plate ( 16 ), characterized in that at least the anchoring cage ( 26 ) forgeable material and at least the anchoring cage ( 26 ) is a forged part. 2. Prosthesis part according to claim 1, characterized in that the anchoring cage ( 26 ) has a plurality of anchoring pillars ( 28-44 ; 28-34 , 68 ; 76 ), each having a pillar core ( 46 ; 70 ; 75 ) and on this Arranged successive anchoring collars ( 48 ; 72 ; 79 ) or through openings formed in this ( 72 ), and that the anchoring pillars ( 28-44 ; 28-34 , 68 ; 76 ) on their surfaces in the outer surfaces of the anchoring cage ( 26 ) through Forge drop and are machined on their surfaces facing the inside of the cage. 3. prosthesis part according to claim 1 or 2, characterized in that it consists of a plurality of firmly connected prosthesis segments ( 10 A, 10 B, 10 C), each of which is formed on both sides by either die and / or machining. 4. prosthesis part according to claim 3, characterized in that the prosthesis segments ( 10 A, 10 B, 10 C) are held together by parts of the same overlapping holding elements ( 22 ; 16 , 116 ). 5. prosthesis part according to claim 4, characterized in that the holding elements ( 22 , 64 ; 16 , 116 ) are shrunk up. 6. prosthesis part according to claim 4 or 5, characterized in that the holding elements ( 22 , 66 ; 16 , 116 ) with the prosthesis segments ( 10 A, 10 B, 10 C) are welded ver. 7. prosthesis part according to one of claims 1 to 6, characterized in that the prosthesis segments ( 10 A, 10 B, 10 C) are welded together. 8. prosthesis part according to any one of claims 3-7, characterized in that at least one of the prosthesis segments ( 10 B) with a through openings ( 74 ; 90 ) verse hene plate ( 66 ; 80 , 82 , 84 , 86 ). 9. prosthesis part according to claim 8, characterized in that the edge walls ( 92 ) of the through openings ( 90 ) are crowned, in particular semicircular transversal cross-section. 10. Prosthesis part according to one of claims 3-9, characterized in that at least one of the prosthesis segments ( 10 B) has a plate section ( 66 ) which on at least one side with the plate surface preferably in this direction Rich perpendicular to anchoring piers ( 68 ) is provided. 11. Prosthesis part according to one of claims 8-10, characterized in that the cage structure ( 26 ) is formed by plate-shaped cage segments ( 80 , 82 , 84 , 86 ). 12. Prosthesis part according to claim 11, characterized in that the cage segments ( 80 , 82 , 84 , 86 ) are corrugated, preferably corrugated in two directions ( 88 ). 13. Prosthesis part according to claim 11 or 12, characterized in that the plate-shaped cage segments ( 80 , 82 , 84 , 86 ) have a plurality of through openings ( 90 ). 14. Prosthesis part according to claim 13, characterized in that the through openings ( 90 ) of adjacent cage segments ( 80 , 82 , 84 , 86 ) are offset from one another. 15. prosthesis part according to one of claims 1 to 14, there characterized in that it is made of titanium or one Titanium alloy is made.