DE19940348A1 - Prosthesis for artificial hip joint; has neck with end section for femoral head and second end section that fits in shaft, where second end section axis intersects first end section and shaft axis - Google Patents

Abstract

The prosthesis has a shaft (1) for implantation in a femur and a neck (2) with a first end section (8) to support a femoral head. The neck has a second end section (17) that can be inserted into an adapter (4) in the shaft by a pressure fit. The longitudinal centre axis of the second end section intersects a head surface (20) of the first end section, which faces the femoral head, and the shaft longitudinal axis.

Description

The invention relates to a two-part endoprosthesis, especially for an artificial hip joint, consisting of a shaft for implantation, for example in the proximal Femur, and from one at a first end portion, especially a femoral neck, the neck having a second end section in a receptacle of the shaft Press fit or the like can be inserted.

With advanced wear and tear of the hip joint, coxathrosis, the joint function of the femoral head and socket is irreparably disturbed, so that these parts have to be replaced by artificial parts. A hip joint, as shown in FIG. 5 as known prior art, consists of a hip head 9 , which is rotatably or pivotably mounted in an artificial socket 10 . The femoral head 9 is held on a neck 2 of a two-part endoprosthesis, the neck 2 being inserted in the area of the second end section into a receptacle 4 on the shaft 1 of the prosthesis. The shaft 1 is anchored in the femur 11 with bone cement. The artificial joint socket 10 is also anchored in the bony socket 13 with bone cement 12 . This known two-part endoprosthesis makes it possible to adjust the angle of inclination of the neck 2 with respect to a central longitudinal axis by means of an individual positioning of the particularly angled neck 2 relative to the shaft 1 . The connection between the shaft and the neck takes place in the known two-part endoprosthesis by means of a clamping cone. However, due to the high turning, tilting and bending moments that occur on the neck, the neck can be inadvertently rotated relative to the shaft, so that the shaft is fixed in an undesired position. Sometimes there is even the problem that the neck is completely detached from the shaft.

Furthermore, it is already known the connection between the Neck and shaft by an elliptical in cross section To produce a press cone. In this known embodiment is, however, an individual setting or positioning of the neck in relation to the Shaft only possible to a limited extent. Necks must be with different inclinations are available, leading to leads to a very high storage and cost expenditure.

In contrast, the invention is based on the object Endoprosthesis with the characteristics mentioned above to develop further so that the doctor is able to intraoperatively the angle of rotation and / or the neck projection to optimize in length and / or inclination.

This object is achieved according to the invention in the two-part Endoprosthesis with the features mentioned in the essentially solved in that the neck in the area of second end section a cross-sectional profile like a Multi-spline profile and the inclusion of a multi-spline profile have corresponding cross-sectional profile, the Neck in the inserted position in a plurality defined angular positions with respect to the shaft on this can be fixed non-rotatably.

By this measure, an interference fit between the shaft and the neck by means of a positive profile created so that the neck in different positions or solid angles with respect to the shaft adjustable and can be determined securely. For example, the Solid angle between the first end portion of the neck and the Shank in the range from about 0 to, for example, in extreme cases  90 ° can be set. There is also another advantage in that the bearing surface between the second end portion of the neck and the uptake of the shaft through the training a positive profile is increased overall, so that the holding or clamping force increases overall.

According to a first advantageous embodiment of the invention is the neck in the area of the second end section Multi-spline shaft, multi-spline cone or the like is formed. The two-piece endoprosthesis can thus, for example, as a cone any spline, in the form of a spline Cone, with a multi-wedge locking cone or with a multi-wedge Cone adjustment to optimize implantation. The possibilities of this two-part endoprosthesis exist among other things in a surgical correction displastic hips (varus or valgus correction, individual step-by-step grading of the retro or Antetorision). The surgeon is also interoperative in the Capable of both the throat projection and the retro / Optimize the anti-torsion angle step by step.

There is also the option of using the multi-wedge profile only on partial areas along a length Attach the central longitudinal axis of the neck. same for of course also for that in the side wall of the recording of the Attached cross-sectional profile. The same must be true Multi-spline profile not over the entire circumference of the neck or extend the inner circumference of the receptacle. So can it may be sufficient, for example, only some sectors of the To be provided with a corresponding multi-wedge profile. It is understood that the invention is also modified in this way can be that the shaft with a pin on the Has outer wall attached multi-wedge profile and the neck with a correspondingly profiled holder for the pin is provided.  

According to an extremely advantageous embodiment of the invention is the multi-wedge profile through the circumference of the neck or recesses and / or elevations distributed during the recording educated.

In particular, these recesses and / or elevation be meandering or wave-like.

According to another embodiment of the invention, the Cross-sectional profile are designed in the manner of a rosette.

The fact that the depressions and / or elevations in essentially in the longitudinal direction of the neck or the Is a simple insertion of the second End section of the neck in the socket of the shaft guaranteed.

Advantageously, the multi-spline profile has between about 6 to 18, preferably 8 to 12 wells and / or elevations.

According to another advantageous embodiment of the invention the neck preferably has an angle of about 10 ° to 20 °, in particular about 15 °. The angle is approximately arranged in the middle of the neck.

According to yet another advantageous embodiment of the Invention, it is appropriate that the neck of the two-part Endoprosthesis with different neck lengths respectively Neck projections is provided. While the necks after the State of the art not only in different lengths, but also with respect to the angle respectively Solid angles are kept at different angles should be, it is the neck of the two-part according to the invention Endoprosthesis only required, different To provide neck lengths or neck protrusions, whereby the Warehousing and costs can be significantly reduced.

Further goals, advantages, features and possible applications of the present invention result from the following Description of an embodiment based on the Drawings. All of them are described and / or illustrated presented features for themselves or in any more meaningful Combining the subject of the present invention, too regardless of their summary in the claims or their dependency.

Show it:

Fig. 1 shows a cross section through an embodiment of the two-part endoprosthesis according to the invention with an inserted shaft and the neck, the free end of the neck for receiving a femoral head is used,

Fig. 2, the two-part stent of Fig. 1, but rotated by 90 °,

Fig. 3 is a perspective view of an embodiment of the stem of the endoprosthesis according to the invention,

Fig. 4 is a schematic representation of the inserted in the receptacle of the shaft second end portion of the neck and

Fig. 5 shows the structure of an artificial hip joint according to the prior art in a schematic representation.

The embodiment of the two-part endoprosthesis according to the invention shown in FIGS . 1 to 4 consists of a shaft 1 , for example for implantation in a proximal Fermur bones, and of a neck 2 , which is attached to a first end section 8 , for example a femoral head 9 ( FIG. 5) wearing. The neck 2 can be inserted with a second end section 17 into a receptacle 4 of the shaft 1 in a press fit or the like.

In the area of the second end section 17 , the neck 2 has a cross-sectional profile in the manner of a multi-spline profile 16 . The receptacle 4 of the shaft 1 is also equipped in the side wall with a corresponding cross-sectional profile, for example a multi-spline profile 16 . As a result of this measure, the neck 2 can be fixed in a non-rotatable manner relative to the shaft 1 in the inserted position in a plurality of defined angular positions.

The neck 2 is formed in the region of the second end section 17 , in particular as a splined shaft, splined cone or the like. Not shown in the drawing is the variant that the multi-spline profile 16 is only attached to partial areas in the longitudinal direction along a central longitudinal axis 14 of the neck 2 .

As can be seen in particular from FIGS. 3 and 4, the splined profile 16 distributed over the circumference of the neck 2 or the receiver 4 wells 3, 5 and / or protrusions 6, 7 are formed. The depressions 3 , 5 and 6 , 7 are meandering or wave-like. The cross-sectional profile can also be designed in the manner of a rosette. The depressions 3 , 5 and / or elevations 6 , 7 run essentially in the longitudinal direction of the neck 2 or the receptacle 4 . The multi-spline profile 16 has between approximately 6 and 18, preferably 8 to 12, depressions 3 , 5 and / or elevations 6 , 7 .

As shown in FIGS. 1, 3 in particular, the neck 2 has an angle 15 of preferably approximately 10 ° to 20 °, in particular approximately 15 °. The bend is arranged approximately in the middle of the neck 2 .

A plurality of necks 2 with different neck lengths or neck protrusions are preferably provided, which can be inserted into the receptacle 4 of the shaft 1 according to individual requirements.

By individually positioning the neck 2 with respect to the shaft 1 , different solid angles of the first end section 8 carrying the femoral head 9 can be realized with respect to the central longitudinal axis 14 of the neck 2 . The special profiling of the neck 2 in the region of the second end section 17 results in defined adjustment possibilities of the neck 2 relative to the shaft 1 that are fixed in their angular position.

Depending on the individual requirements, several necks 2 can be available which have a different neck length or neck projection. However, by means of the special cross-sectional profile, all available necks are fixed non-rotatably in one of several defined angular positions on the shaft 1 in the inserted position. This grid between the cross-sectional profile of the neck 2 and the cross-sectional profile of the receptacle 4 of the shaft 1 enables the neck to be set in a defined manner in the steps predetermined by the latching. For example, twelve or more and also fewer detents can be provided distributed over the circumference. This makes it possible for the solid angle between the first end section 8 of the neck 2 to be set in the range from 0 to, for example, 90 ° in the extreme case. The contact surface between the second end portion 17 of the neck 2 and the side wall of the receptacle 4 of the shaft 1 is increased by the formation of a positive profile, so that the holding force of the press fit is increased overall.

Within the framework it is of course also possible to use necks different lengths, overhangs, angles, grid, Use diameter or the like.

The individual shape of the second end section 17 of the neck can also be variable, for example this second end section 17 can be designed as a cylindrical or also conical body, the shape of the receptacle 4 then being adapted accordingly.

Reference list

1

shaft

2nd

neck

3rd

Deepening on the spigot

4th

admission

5

Depression on the shaft

6

Rise on the cone

7

Raised on the shaft

8th

first end section

9

Femoral head

10th

artificial socket

11

Femur

12th

Bone cement

13

bony pan

14

Central longitudinal axis

15

Angling

16

Multi-spline profile

17th

second end section

Claims (11)

1. Two-part endoprosthesis, in particular for an artificial hip joint, consisting of a shaft ( 1 ) for implantation, for example in the proximal femur bone, and of a neck ( 2. ) Carrying a femoral head ( 9 ), in particular on a first end section ( 8 ) ), the neck ( 2 ) having a second end section ( 17 ) being insertable into a receptacle ( 4 ) of the shaft ( 1 ) in a press fit or the like, characterized in that the neck ( 2 ) in the region of the second end section ( 17 ) a cross-sectional profile in the manner of a multi-wedge profile ( 16 ) and the receptacle ( 4 ) have a cross-sectional profile corresponding to the multi-wedge profile ( 16 ), the neck ( 2 ) in the inserted position in a plurality of defined angular positions with respect to the shaft ( 1 ) being non-rotatably fixable thereon is. 2. Endoprosthesis according to claim 1, characterized in that the neck ( 2 ) in the region of the second end section ( 17 ) is designed as a splined shaft, splined cone or the like. 3. Endoprosthesis according to one of claims 1 or 2, characterized in that the multi-spline profile ( 16 ) is attached to partial areas in the longitudinal extent along a central longitudinal axis ( 14 ) of the neck ( 2 ). 4. Endoprosthesis according to one of the preceding claims, characterized in that the multi-wedge profile ( 16 ) through the circumference of the neck ( 2 ) or the receptacle ( 4 ) distributed depressions ( 3 , 5 ) and / or elevations ( 6 , 7 ) is formed. 5. Endoprosthesis according to claim 4, characterized in that the depressions ( 3 , 5 ) and / or elevations ( 6 , 7 ) are meandering or wave-like. 6. Endoprosthesis according to one of the preceding claims, characterized in that the cross-sectional profile according to Art a rosette is formed. 7. Endoprosthesis according to one of claims 4 to 6, characterized in that the depressions ( 3 , 5 ) and / or elevations ( 6 , 7 ) extend substantially in the longitudinal direction of the neck ( 2 ) or the receptacle ( 4 ). 8. Endoprosthesis according to one of the preceding claims, characterized in that the multi-spline profile ( 16 ) has between about six to eighteen, preferably eight to twelve depressions ( 3 , 5 ) and / or elevations ( 6 , 7 ). 9. Endoprosthesis according to one of the preceding claims, characterized in that the neck has an angle ( 15 ), preferably from about 10 ° to 20 °, in particular about 15 °. 10. Endoprosthesis according to claim 10, characterized in that the bend ( 15 ) is arranged approximately in the middle of the neck ( 2 ). 11. Endoprosthesis according to one of the preceding claims, characterized in that the neck ( 2 ) is provided with different neck lengths or neck protrusions.