DE3417923A1 - Endoprosthesis and dowel for anchorage in a material with bone-like strength - Google Patents

Abstract

The endoprosthesis comprises a hollow anchorage part 24 which can be spread apart. A spreading body 26, by which the anchorage part 24 inserted in a hole 23 in the bone can be clamped on the walls of the hole in the bone and is as a result anchored in the bone 20 without cement, can be introduced into the cavity of the anchorage part 24. The outer end of the anchorage part 24 or of the spreading body 26 is formed as a part 25 of a bone 20, which part is to be replaced. The anchorage part 24 may be provided with an external screw thread 24.2. For anchorage in a material of bone-like strength, the dowel is designed like the endoprosthesis, and its anchorage part is provided with an external screw thread for screwing into a hole provided with an internal screw thread. <IMAGE>

Description

Endoprosthesis and dowel for anchoring in one

Material with bone-like strength.

The invention relates to an endoprosthesis with a hollow anchoring part for cementless anchoring in a cavity of a bone.

By DE-OS 24 11 617 an acetabular cup endoprosthesis is this Kind known. In this known endoprosthesis, the hollow anchoring part is for cement-free anchoring in a hole in the basin with one of support ribs existing external thread. In the cavity of the anchoring part is located a dome-shaped joint socket made of ceramic, which is used to hold the ball head of the hip joint.

The supporting ribs of the external thread of this known endoprosthesis are provided with cutting grooves so that when screwing the anchoring part into the basin bore the support ribs cut a thread into the bone. This must be proportionate great forces are expended.

It is also not ensured that when screwing in the known Endoprosthesis the joint socket is the right one for proper functioning of the artificial joint is given the necessary position relative to the pelvis.

A similar endoprosthesis is known from DE-OS 23 14 175, in which, however, the insertion of the endoprosthesis is made even more difficult by the fact that there For the external thread of the anchoring part, first insert it into the hole in the basin Thread must be cut with a special tool.

The invention is based on the object of providing an endoproder ## fi ## ieschnell, mentioned with a very thesis / to create that quickly, easily and with a very precise positioning in a bore of a bone can be attached.

This object is achieved according to the invention in that the anchoring part Is designed to be expandable and that an expansion body in the cavity of the anchoring part is present, by means of which the anchoring part can be expanded. This will achieved that only for the anchoring part of the endoprosthesis according to the invention a hole must be made into which the anchoring part of the endoprosthesis fits in. The anchoring part inserted in this way can now be exactly according to the medical Needs to be aligned.

Only when that has happened is the anchoring part by means of the expansion body spread so that its outer surface is clamped to the inner wall of the bore. The expansion body can cause such a strong pressure that a tight fit of the endopro- this is guaranteed.

The invention enables a particularly firm fit without cement Realize the endoprosthesis when drilling the bone before insertion of the anchoring part is expanded at its inner end. If the e.g. with an anchoring part provided with a cylindrical outer circumference in the bone bore inserted and expanded by means of the expansion body, then the anchoring part and thus the endoprosthesis held positively in the bone bore so that the endoprosthesis can be loaded immediately after insertion.

There is a particular advantage of the endoprosthesis according to the invention that, in the event that it occasionally needs to be removed from the bone, the spreader can be removed first. If the elastic forces of the As part of the anchoring part, it shrinks a little and thereby detaches itself from the surrounding area Bone tissue, so that the anchoring part can be easily removed from the bone bore and when using a new prosthesis, a correspondingly designed anchoring part can be reinserted into the bone bore. Even if the shrinking The tension force causing it is not sufficient to immediately after removing the expansion body To cause shrinkage, this clamping force facilitates the loosening of the expansion body and causes shrinkage with a minimal movement of the anchoring part. The invention thus makes it possible to replace endoprostheses that take a long time were previously anchored in a bone without opening the hole in the bone enlarged and weakened the bone.

The spreadability of the anchoring part can be achieved by that consisting of an elastically flexible material anchoring part with at least is provided with a slot that extends to at least one end of the anchoring part goes through, so that the parts separated by the slot spread outward can be. The anchoring part can, however, also consist of non-elastically flexible material Material, e.g. consist of at least two ceramic parts that are flexible with are connected to a part of the anchoring part that holds these parts together.

In an advantageous embodiment of the endoprosthesis according to the invention can at least a part of the anchoring part or the expansion body as a too be formed replacing part of a bone. Part of the expansion body can e.g. protrude from the anchoring part and form a femoral head endoprosthesis form the femoral neck on which either the femoral head is attached or the femoral head itself forms the femoral head at its outer end.

In another embodiment, the expansion body can be used as a joint socket be formed, which is inserted into the anchoring part, which is hollow and expandable is trained.

In a particularly advantageous embodiment, the anchoring part is provided with an external thread. When spreading, the outer edges then clamp the thread forming rib on the inner wall of the bore, so that thereby a firm fit of the prosthesis can already be achieved. During the healing process then fill the threads with callus, so that the endoprosthesis is practical grows together with the receiving bone.

In special cases it can be useful to check before inserting the Cut a suitable internal thread into the anchoring part in the bone bore. It can be sufficient that the thread has only a very small depth, so that only part of the helical rib that forms the external thread of the anchoring part forms, engages in the internal thread.

The subsequent spreading of the anchoring part is then a very tight fit is achieved, so that the prosthesis shortly after the onset can be exposed to greater loads.

In the case that an endoprosthesis with an anchoring part that with is provided with an external thread, removed and possibly replaced by a new endoprosthesis must be replaced, this embodiment has the advantage that after shrinking of the anchoring part this can be screwed out of the bone hole, the internal thread then remaining in the bone bore to be screwed in a new prosthesis can be used. So that the shrinking and / or unscrewing is not obstructed by the callus entering the expansion slot of the anchoring part has grown in, this slot can be closed by a flexible material are executed.

This can be done, for example, in such a way that the expansion slot is closed on the outside by a flexible metal or plastic skin, which at Spreading is pulled smooth. However, the slot can also be made by an elastically resilient one Material connected to the slotted walls, such as e.g. is known at Schwingmetall.

Another possibility, the unscrewing in spite of the expansion slot to facilitate the filling callus bar, consists in the fact that the slot edges and the ends of the thread-forming ends formed by the interruption in the slot Rib are designed as cutting.

The invention also relates to a dowel for commercial purposes, the an expandable hollow anchoring part and an expansion body for expanding of the anchoring part.

For anchoring in a material with bone-like strength, e.g. in plaster of paris, concrete, wood or the like. Such a dowel according to the invention is with provided with an external thread.

For this dowel, the hole must be drilled before inserting the dowel be provided with an internal thread. After screwing in of the dowel the anchoring part is spread by means of the expansion body, so that a very firm form-fitting anchoring of the dowel in the material with bone-like strength is achieved.

The invention is illustrated in the following description of the drawings Embodiments illustrated in a highly schematically simplified manner are explained in detail.

1 and 2 show axial sections of the proximal end of a (forearm) spoke with a spoked head endoprosthesis with a non-spread or spread anchoring part; 3 shows a section along the line III-III in FIG. 2; 4 shows an axial section of the proximal end of a thigh bone (femur) with inserted femoral neck and Femoral head endoprosthesis, the anchoring part of which is shown in an expanded state is; FIG. 5 shows a section along the line V - V in FIG. 4; FIG. 6 and 7 partially sectional side views of the proximal end of a (forearm) elbow with a joint socket endoprosthesis of the elbow joint with two expansion bodies in unspread or in the expanded state; 8 is a side view of an acetabular cup endoprosthesis; 9 shows an axial section of the anchoring body of the endoprosthesis according to FIG. 8; Fig. 10 shows a section corresponding to FIG. 9 of the endoprosthesis according to FIG. 8 in the installed position State; 11 shows a section of an anchoring part in which the expansion slot is closed by flexible parts; Fig. 12 is a broken line Top view of the anchoring part according to FIG. 11; FIGS. 13 and 14 correspond to FIG Representations of two modified exemplary embodiments; 15 shows an axial section an embodiment of a dowel anchored in a threaded hole.

In FIGS. 1 to 3, the proximal end 20 is a (forearm) spoke shown, from which the spoke head is separated along the cutting surface 21 is.

The cavity 22 of the spoke is cylindrical at the proximal end Bore 23 widened to receive a spoke head endoprosthesis 24, 25, 26, an anchoring part 24, an expansion body 26 and a spoke head replacement The anchoring part 24 forms a frustoconical sleeve which almost is provided over its entire length with a slot 24.1, which extends up to her in the Fig. 1 and 2 below the end is passed.

This sleeve-shaped anchoring part consists of one for endoprostheses suitable metal and is on the outside with a helical circumferential rib 24.2 provided, which runs out radially on the outside into a pointed edge 24.4, which runs along a frustoconical Surface extends so that this rib 24.2 forms a frustoconical external thread.

The inner wall of the anchoring part 24 is internally threaded 24.3 provided. On the upper end of the anchoring part 24 in FIGS. 1 and 2 the plastic spoke head replacement 25 is attached.

For screwing into the cavity of the sleeve-shaped anchoring part 24 a cylindrical screw bolt is provided, which forms the expansion body 26, when it is screwed into the cavity of the anchoring part 24, this expands so that the edge 24.4 runs essentially in a cylindrical surface.

When the radial head endoprosthesis 24, 25, 26 is inserted, the proximal The spoke head to be replaced is removed from the end of the spoke. Then the cavity 22 of the spoke widened to a diameter to form the cylindrical bore 23, which corresponds to the largest diameter of the edge 24.4. In the so widened hole 23, the most appropriate part, which carries the replacement of the spoke head 5, becomes the core part 24 used and, if the / edge 24.4 to the cylindrical inner surface of the bore 23 comes to rest, screwed into the bore 23 until the spoke head replacement 25 abuts the cut surface 21. Then it is called a cylindrical Spreader body 26 formed by screw bolts, the external thread of which corresponds to the internal thread 24.3 of the anchoring part 24 corresponds, screwed into the anchoring part. For this purpose, the face of the expansion body pointing upward in FIG. 2 is used 26 with a slot 26.1 or the like for the Engaging one Screwing tool provided. During the screwing in, the anchoring part 24 can be held on the head replacement 25 with a suitable tool.

By screwing the expansion body 26 into the cavity of the anchoring part 24 this is widened as a result of the axial slot 24.1, so that the edge 24.4 pressed against the cylindrical inner wall of the bore 23 and thereby the spoke head endoprosthesis is clamped in the spoke.

The spoke head replacement 25 can be made from any suitable endoprosthesis Plastic, e.g. made of polyethylene or Sylastica. It can also do this with a ceramic fabric can be used.

By drilling open the lumen of the proximal end 20 of the spoke the bone is stimulated to form callus, which then the threads of the Fills the external thread formed by the rib 24.2 and so a form-fitting and forms a firm connection between the endoprosthesis and the spoke. This connection is very easy to solve. You only need the expansion body 26 from the anchoring part Unscrew 24. The anchoring part shrinks due to the elastic forces and slightly compresses the callus mass that may be in the slot 24.1, so that the connecting collar of the anchoring part is loosened with the bone thread and then it is possible to unscrew the endoprosthesis from the SPeiche.

In the illustrated embodiment, the anchoring part 24 only has one slot 24.1. However, he can have two diametrically opposed or have a plurality of symmetrically arranged slots 24.1.

In the embodiment shown in FIGS. 4 and 5 are all parts which correspond to the exemplary embodiment according to FIGS. 1 to 3 are given reference numbers denotes, which are larger by 10 than the reference numbers of the previous embodiment, so that by referring to the description of the previous embodiment Is referred to.

In the embodiment shown in Figs. 4 and 5 is it is a femoral neck and femoral head endoprosthesis 34, 35, 36, which is in the proximal End 30 of the femur is anchored. The natural femoral neck and the The hip joint head are separated from the femoral end 30 along the cutting surface 31. The thigh cavity 32 is at the proximal end to the cylindrical bore 33 drilled out. In this bore 33 the anchoring part 34 of the prosthesis is through Spreading by means of the expansion body 36 in the embodiment according to the Fig. 1 to 3 described manner clamped.

In contrast to the previously described embodiment, there is here the expansion body 36 consists of a smooth cylindrical bent at its upper end Bolt. Also the interior of the expanding body, which is sleeve-shaped in the unspread state 34 is not provided with a thread here, but forms one downwards frustoconical tapering smooth surface caused by the driving in of the expansion body 36 is widened to a cylindrical bore, in which then the sharp edge 34.4 of the rib 34.2 of the expansion body on the inner wall of the cylindrical bore 33 is pressed. Here, too, the expandability is preferably made of metal Anchoring part 34 by a longitudinal slot 34. Caused.

The bent end protruding from the femur end 30 of the expansion body 36 forms the femoral neck replacement 36.2. On the very end this femoral neck replacement 36.2 the femoral head replacement 35 is attached.

So that the expansion body 36 does not twist in the anchoring part 34 can, it is provided with an ear 36.3 which has a bore 36.4. This Ear 36.3 is for engagement in a slot 30.1 in the sawn-off end of the femur intended.

The femoral neck and femoral head endoprosthesis shown in FIGS 34, 35, 36 is connected to the femur in a similar way to that of the previous example. The only difference is here that here the expansion body 36 is not screwed into the anchoring part 34, but is driven e.g. by hammer blows until the ear 36.3 in the slot 30.1 engages and the anchoring part 34 is expanded so far by the expansion body 36 has been that the edge 34.4 of the anchoring part 34 on the cylindrical Inside wall of the bore 33 clamped.

In FIGS. 6 and 7, a joint socket endoprosthesis is shown Ellengelenes shown. So much for the parts used in this exemplary embodiment correspond to the first embodiment, these parts are enlarged by 20 Designated reference numerals, so that with respect to this embodiment reference is made to the description of the first embodiment.

The proximal end 40 of a (forearm) elbow is arched with a Provided cut surface 41, which is provided for receiving a joint socket replacement 45 is. In addition, two cylindrical blind bores43 are drilled into the ellbow end 40, the serve to accommodate anchoring parts 44 designed as retaining dowels. These Anchoring parts 44 are essentially like the anchoring parts 24 of the first Embodiment designed as a frustoconical sleeves, the cavity with an internal thread is provided, which is provided for the engagement of expansion bodies 46 is the same here as the expansion body according to the first embodiment are trained. The two anchoring parts 44 are at their outer ends with a flange 44.5 provided. In the joint socket replacement 45 are for the penetration of the anchoring parts 44 bores 45.1 are provided in the concave outer surface of the joint socket replacement 45 with an extension 45.2 for the engagement of the flange edge 44.5 are provided.

Then the ellbow end 40 with the cut surface 41 and the bores 43 is provided, the joint socket replacement 45 is applied to the cut surface 41 in such a way that that the bores 45.1 of the joint socket replacement 45 with the bores 43 of the Cover Ellenendes 40. Then the unexpanded anchoring parts, as shown in Fig. 6, inserted through the bores 45.1 into the bores 43 and optionally also screwed in towards the end. Then the expansion bodies 46 are then in the anchoring parts 44 screwed in. So that the anchoring parts do not rotate, the flange edges 44.5 with holes 44.6 for engagement be provided a tool that when screwing in and unscrewing the Spreader 46 prevents the anchoring parts 44 from rotating, and by means of this If necessary, the anchoring part can also be unscrewed from the ollar end 40 can.

Corresponding to the expansion body 26 of the first embodiment Here the outer ends of the expansion body 46 are provided with a hexagon socket 46.1.

8, 9 and 10 show an embodiment of an acetabular cup endoprosthesis shown, which consists of a sleeve-shaped anchoring part 54 and a one Joint socket replacement forming expansion body 56 consists.

The in Fig. 9 upper edge of the anchoring part 54, in which the Slot 54.1 does not extend, is provided with an extension into which an internal thread 54.3 is incised. The expansion body 56, which is preferably made of plastic or Ceramic or another material suitable for endoprostheses has a outer cylindrical surface 56.5, which at its upper end in FIG. 10 in a with an externally threaded collar 56.6 merges into the thread 54.3 of the anchoring part 54 can be screwed in. In contrast to the previously described exemplary embodiments is here the expansion body 56 not as a bolt, but directly as a joint socket for Recording of the femoral head of a thigh bone indicated by dash-dotted lines in FIG. 10 designed and provided with a conical pan surface 55 for this purpose.

When inserting the acetabular cup endoprosthesis according to FIGS. 8 to 10 is a cylindrical blind hole 53 for the first in the pelvic bone 50 Anchoring part 54 drilled into which the anchoring part is then inserted and possibly is screwed in easily. Then the expansion body is in the anchoring part 54 56 inserted and with its collar 56.6 in the thread 54.3 of the anchoring part screwed in, so that thereby the anchoring part 54 spreads and the outer Edge 54.4 clamped on the cylindrical wall of the bore 53. So that the anchoring part 54 does not rotate when the expansion body 56 is screwed in, are in the outer end face of the anchoring part 54 provided bores 54.6 for a suitable tool. To screw in the expansion body 56, it has the socket surface on the outer edge of its 55 forming inner wall diametrically opposed recesses 56.7 on.

In the embodiment of an anchoring part 74 according to FIGS 12 are both the expansion slot 74.1 and the interruptions in the thread rib 74.2 closed at the expansion slot by flexible parts 74.7. These parts are made slightly thicker, so that they are due to the taper in the spread state continue flush with the surface of the anchor member 74 and the rib 74.2 and thereby prevent that in the slot 74.1 or in the interruptions of the rib 74.2 Ingrown callus that causes the anchoring part to shrink and / or unscrew would hinder.

In the embodiment of FIG. 13, only the slot 84.1 is through a resilient thin part 84.7 (e.g. a thinning of the anchoring part 84 forming metal or the like.) Closed. The adjacent ends of the thread rib 84.2 are designed as cutting 84.8 to when unscrewing the anchoring part 84 cut through the callus that has grown into the interruption of the rib 84.2 is.

In the embodiment of an anchoring part 94 according to FIG both the edges of the slot 94.1 and the adjacent ends of the rib 94.2 formed as cutting 94.8.

In the illustrated preferred exemplary embodiments, the anchoring part is provided with an external thread. However, the external thread is not absolutely necessary. If the anchoring part does not have an external thread, then it can still go through the Spreading in a cylindrical or, advantageously, in a downward direction inside widening bone bore are spread, so that a non-positive or positive connection is created.

In Fig. 15 there is shown a dowel for industrial purposes which having an expandable sleeve-shaped anchoring part 64, the outer surface of which is provided with a thread 64.2.

An expansion body engages in the cavity 64.3 of the anchoring part 64 66 a, which is provided at its end with a connection part 67, which is shown in the Embodiment is designed as an eyelet. The outer diameter of the expansion body is slightly larger than the inner diameter of the anchoring part 64, which is made of metal exists and for elastic expandability with an axially continuous slot 64.1 is provided.

For anchoring the dowel in a body 60 made of a mass with bone-like Strength, e.g. in a wall, a threaded hole 63 is drilled into it, the Internal thread 63.2 is adapted to the external thread 64.2 of the anchoring part 64. Then the anchoring part 64, which is at its lower end face in FIG. 11 with a hexagon socket 64.5 or another recess for the engagement of a The tool is screwed into the threaded hole 63.

The expansion body 66 is then hammered into the hollow space 64.3, so that the anchoring part 64 is clamped in the thread of the threaded bore 63.

The expansion body 66 and the anchoring part 64 can also, as in Exemplary embodiment according to FIGS. 1 - 3 provided with external and internal threads and be frustoconical.

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Claims (17)

Claims 1. Endoprosthesis with a hollow anchoring part (24, 34, 44, 54) for cementless anchoring in a cavity (23, 33, 43, 53) of a Bone, characterized in that the anchoring part is designed to be expandable is and that in the cavity of the anchoring part an expansion body (26, 36, 46, 56) is present, by means of which the anchoring part can be expanded. 2. Endoporthesis according to claim 1, characterized in that the Anchoring part (24, 34, 44, 54) consists of an elastically flexible material and to produce the expandability with at least one slot (24.1, 34.1, 54.1) is provided. 3. End prosthesis according to claim 1 or 2, characterized in that the anchoring part (24, 34, 44, 54) consists of an expandable and a non-expandable Part consists. 4. Endoprosthesis according to claim 3, characterized in that in the non-expandable part has an internal thread (54.3) and that the expansion body (56) is provided with an external thread that fits into the internal thread. 5. Endoprosthesis according to one of claims 1 to 3, characterized in that that the expansion body (36) is designed as a smooth bolt. 6. Endoprosthesis according to one of claims 1 to 5, characterized in that that of the two surfaces that occur when the expansion body (26, 36, 46, 56) engages into the cavity of the anchoring part (24, 34, 44, 54) lie against one another, one is frustoconical and the other is cylindrical. 7. Endoprosthesis according to one of claims 1 to 6, characterized in that that at least part of the anchoring part (24) or the expansion body (36, 56) as a part to be replaced (25 or 36.2, 35, 55) of a bone or as a carrier this is formed. 8. Endoprosthesis according to claim 7, characterized in that for Formation of a femoral head endoprosthesis a part of the expansion body (36) the femoral neck (36.2) forms, which carries the femoral head (35). 9. Endoprosthesis according to claim 8, characterized in that the Spreader (36) for engaging a slot (30.1) in the femur (30) has a positioning projection (36.3). 10. Endoprosthesis according to claim 7, characterized in that for Formation of a joint socket endoprosthesis of the expansion body (56) than in the anchoring part (54) insertable joint socket (55) is formed. 11. Endoprosthesis according to one of claims 1 to 6, characterized in that that at least one of the anchoring part (44) and the expansion body (46) formed Unit is designed as a dowel for anchoring a replacement (45). 12. Endoprosthesis according to claim 11, characterized in that for a joint socket replacement (45) at least two dowels (44, 46) are provided. 13. Endoprosthesis according to one of claims 1 to 12, characterized in that that the anchoring part (24, 34, 44, 54) with an external thread (24) forming Rib (24.2, 34.2, 44.2, 54.2, 74.2, 84.2, 94.2) is provided. 14. Endoprosthesis according to one of claims 2 to 13, characterized in that that the slot (74.1, 84.1) is closed by a flexible part (74.7 or 84.7) is. 15. Endoprosthesis according to claim 13, characterized in that the Slot (74.1, 84.1) and the interruptions of the rib /74.2 and 84.2) by a compliant part (74.7 or 84.7) are closed. 16. Endoprosthesis according to one of claims 2 to 14, characterized in that that the slot (84.1) adjacent ends of the rib (84.2, 94.2) and / or the Edges of the slot (94.1) are designed as cutting edges (84.8 or 94.8) 17th Dowel with an expandable hollow anchoring part (64) and an expansion body (66) for spreading the anchoring part, characterized in that for the Anchoring in a material with bone-like strength of the anchoring part (64) is provided with an external thread (64.2).