DE19701778C2 - Joint socket for a hip joint endoprosthesis - Google Patents

Description

The invention relates to a socket for a Hip joint endoprosthesis, with an elongated shape Pan body and a pan insert (inlay) on the Front of a hemispherical cavity to accommodate one Has joint ball.

Endoprostheses for the replacement of the hip joint have been around for a long time Time known. For this purpose, DE 72 40 856 U1 or DE 26 11 985 A1.

DE 23 01 810 A1 describes an acetabular cup which consists of an outer and an inner cap, the Inner cap is detachably housed in the outer cap and in turn picks up a joint ball.

From US 5,192,329 is a socket for a Hip joint endoprosthesis known to have a socket body and a hemispherical cavity for receiving a joint ball having. The pan body is elongated and forms in Section perpendicular to the center axis of the cavity almost an oval.

EP 0 585 503 A1 discloses a double-shell Acetabular cup with oval cross-section and spherical Bearing shell known. An outer shell is made of metal and one Inner shell is made of plastic. The oval shape is coming by inserting straight spacers on the inside and Outer shell. The outer shell can be in different Directions are used. The definitive location of the spherical bearing shell is only with the insertion of a matching inner shell.  

From DE 44 42 559 A1 there is a joint socket for a known hip joint. The outside of the socket has a semi-oval shape. The recess is however rotationally symmetrical.

EP 0 303 006 B1 describes a revision pan which as a replacement for an implanted socket elaborated roof of the acetabulum is suitable. This Joint socket includes a socket body that is on the front a hemispherical cavity for receiving a joint ball has, the axis of the cavity off-center of the The pan body lies and the pan body in section oblong perpendicular to the axis of the cavity located in the center is oval shaped. The well-known joint socket sees one elongated pan body, which is both in Longitudinal direction and in the direction transverse to it symmetrically is formed, namely approximately forms an oval. The hemispherical cavity is preferably in the area where the anatomical cavity was in the acetabulum. The meaning this construction is that the socket closely approximates anatomy,  as when loosening the roof of the tile by loosening it prosthetic socket is created. Accordingly, only still minimal bone to be removed or replaced in order insert the socket.

A disadvantage of the prior art, however, is the symmetrical Training the socket with the result that usually only a so-called two-point bracing of the same within the Acetabulum is attainable. To the connecting line between These two points apply tilting moments that follow Longer implantation times lead to loosening of the cup can. The socket must then be replaced again.

The present invention has for its object a Joint socket of the type mentioned to create the one statically determined tension within the acetabulum allowed so that no tilting moments can take effect, too loosen the pan. Most importantly, one to obtain defined multi-point bracing.

This object is achieved by the characterizing Features of claim 1 solved, advantageous Further training and constructive details in the subclaims are described. In this regard, claims are made in particular 2 referred, after which the pan body in front view under other has a kidney or bean-shaped outline. This outline leads to a three-point bracing on the convex extreme points. This tension is determined statically and accordingly stable.

Alternatively, the outline of the pan body could be trapezoidal, triangular, crescent-shaped, heart-shaped, arrow-shaped, be semicircular or the like asymmetrical. It only has to be ensured that a static certain multi-point bracing is obtained to a stable To achieve implantation.

The embodiment is also of particular advantage according to claim 6, according to which the pan insert within a  corresponding recess can be fixed in the socket body, in different angular positions relative to Center axis of the mentioned recess, the recess is preferably formed concentrically in the socket body. At eccentric hemispherical cavity in the Pan insert then this cavity into a desired one Bring position relative to the pan body. So you can not only the cranio / caudal position of the hemispherical cavity, but also vary the medio / lateral position of the same. This is an advantage if the pan due to bone defects cannot be implanted in the ideal position.

Furthermore, the embodiment should be mentioned separately according to claims 9 and 10, according to which the front of the Socket body is roofed forward in the cranial area, while in the caudal area inwards or backwards withdrawn. Through the roof in the cranial area If the socket is in a steep position, the joint ball will dislocate prevented. The withdrawal in the caudal area enables in in such a case, sufficient adduction of the leg.

It is also advantageous if the bottom of the pan body has one or more passages passing through a lid, in particular slidably or rotatably mounted The lid can be closed. This makes it possible to look for Insert the socket body in the patient's pelvis Control insertion depth and cancellous bone between bone and the bottom of the pan body. For a contact between the pan insert or inlay, which is preferably is made of plastic, and to prevent the bone, the mentioned passage in the bottom of the pan body with a lid closed, preferably a rotatably mounted Cover. An alternative solution provides that the return or Outside of the pan insert made of the same material or a similar material to the pan body and so to shape that when inserting the pan insert in the Pan body the back of the pan insert one or several passages in the bottom of the pan body like a lid  closes. This solution is mainly handling-related but also very advantageous in terms of production technology.

To further increase the fixation of the socket body, you can this on the outside several about evenly over the Folding ribs with knife-like arrangement arranged circumferentially Have cutting, with the impact ribs approximately extend parallel to the central axis of the socket body.

Furthermore, the pan body in the cranial and / or caudal area holes for passage of bone screws, the screw holes are preferably hourglass or venturi-like, so that the screws under different constraint Brackets can be screwed in. Also stuffing elements be provided to remove unused screw holes close. The screw holes are preferably located between the mentioned ribs of the pan body.

The fixation of the pan insert in the corresponding The pan body is advantageously recessed by a snap mechanism. It is conceivable for this purpose a circumferential bead on the outside of the pan insert provide the in a corresponding annular groove within the Recess of the pan body engages.

The surface of those trained in the pan insert hemispherical cavity is preferably with a sliding layer provided, in particular a sliding layer made of metal, ceramic or an abrasion-resistant plastic. The pan insert can also entirely from one of the aforementioned materials, in particular ceramics or a combination of these Materials are made.

To fix the pan insert within the corresponding recess in the socket body under one predetermined angle relative to the central axis of the mentioned The pan insert can have at least one recess on the edge radially outwardly extending projection or alternatively  have at least one recess, the or the at least one in the recess of the pan body trained recess or one in the recess of the Socket body-shaped projection corresponds. Preferably, several are distributed evenly over the circumference arranged projections or depressions formed.

A preferred embodiment of a joint socket designed according to the invention using the attached drawing explained in more detail. Show it:

Fig. 1 is a base element according to the invention in side view;

Fig. 2 is a base element according to the invention in plan view;

FIG. 3 shows the socket body according to FIG. 2 in section along the longitudinal line AA in FIG. 2;

Fig. 4 shows the base element as in Figures 1 to 3 in a perspective view obliquely from above.

Figure 5 is a socket insert (inlay) for the base element as in Figures 1 to 4 in a perspective view obliquely from above..;

FIG. 6 bottom view of the pan insert according to FIG. 5;

Fig. 7 shows the socket insert according to Fig 6 in side view.

Fig. 8 shows the socket insert according to FIG 6 in the section along the line AA in Fig. 6.; and

Fig. 9 shows a pan insert with molded lid in section.

In FIGS. 1 to 4, an elongate shaped base element 10 is shown a socket for a hip joint endoprosthesis. Figs. 5 to 8 show a rotationally symmetrical socket insert 11, which has on the front side a semi-spherical hollow 12 for receiving a joint ball, not shown. The pan insert 11 is intended to be received within a corresponding recess 13 in the pan body 10 .

As can be seen very well in FIG. 2, the pan body 10 is elongated in front or top view, the outline 14 being asymmetrical with respect to the longitudinal axis 15 . Specifically, in the illustrated embodiment, the outline of the socket body 10 is kidney-shaped or bean-shaped in front or top view. This outline is formed by connecting or bridging two quarter spherical shells 17 and 18 opposite one another at an angle "c" relative to the transverse axis 16 of the socket body 10 , these quarter spherical shells being flattened on the bottom in accordance with FIGS. 1 and 3. It should be noted at this point that the socket body can also be defined instead of by quarter spherical shells by the described assembly of halves or partial sections of two rotating bodies such as spherical segments, spherical caps, cones, cylinders or the like. Or also prismatic bodies. In the case of such shaped bodies, the axes of rotation or symmetry, which are essentially parallel to the center axis 34 mentioned further below, then take the place of the spherical centers.

The spherical centers assigned to the quarter spherical shells are also at a distance from one another. The socket body 10 is thus symmetrical with respect to the transverse axis 16 , but not with respect to the longitudinal axis 15 . A so-called three-point bracing within the acetabulum is thereby achieved, specifically at the convex extreme points, which are identified in FIG. 2 by the reference numbers 19 , 20 and 21 . In this way, a permanently stable implantation of the socket body 10 is ensured within the correspondingly worked out acetabulum, in particular cementless implantation.

The pan body is made of a body-compatible metal, for example a cobalt chrome molybdenum alloy, titanium or Titanium alloy.

The pan insert 11 shown in FIGS . 5 to 8 is preferably made of a body-compatible material such as metal, ceramic or plastic, in particular polyethylene or the like, alone or in combination with one another.

The socket insert 11 can be fixed within the recess 13 already mentioned in the socket body 10 , in the embodiment shown in different angular positions relative to the central axis 22 of the recess 13 , this recess 13 preferably being formed concentrically in the socket body 10 . In deviation from this, the recess 13 is offset caudally in the embodiment shown. Furthermore, the input plane of the recess 13 is inclined in the direction from cranial to caudal by the angle "d".

The pan insert 11 is rotationally symmetrical, specifically in the shape of a hemisphere. It can be fixed non-positively and positively within the corresponding recess 13 in the socket body 10 . For this purpose, the socket insert 11 has four radially outwardly extending projections 24 , which are distributed uniformly over the circumference and correspond to a plurality of depressions 25 in the recess 13 of the socket body 10 which are distributed uniformly over the circumference and are arranged diametrically to one another, that the angular position of the pan insert 11 is freely selectable. Furthermore, the hemispherical cavity 12 of the socket insert 11 is arranged eccentrically, in such a way that after inserting the socket insert into the socket body, the center of the sphere of the hemispherical cavity 12, depending on the angular position of the socket insert, lies exactly at the height of the transverse axis 16 of the socket body 10 (angular position 0 Degrees) or caudal, whereby the maximum caudal distance is reached at an angular position of 180 degrees. By varying the angular position, not only can the cranio / caudal position of the ball center be selected, but also the medio / lateral position with respect to the longitudinal axis 15 of the socket body 10 . This is an advantage if the pan cannot be implanted in the ideal position due to bone defects.

Is as shown in FIGS. 1 and 3, the front side of the socket body 10 in the cranial region 26 to the front roof (roof 28). In the caudal area 27 , the front of the socket body 10 is withdrawn inwards or backwards. The roof 28 takes place at an angle "a", while the caudal withdrawal is carried out at an angle "b". These angles are given in relation to a main pan plane 29 , which extends parallel to the flattening 30 of the bottom of the pan body 10 . The angles "a" and "b" can be the same or different sizes. It is also conceivable to provide only one roof and no return, or only one return and no roof.

The positive fixation of the socket insert 11 within the recess 13 of the socket body 10 by means of the projections or knobs 24 arranged on the circumferential edge of the socket insert 11 on the one hand and the corresponding recesses 25 formed on the front circumferential edge of the recess 13 on the other hand can be replaced by a purely non-positive fixation without Projections and recesses. This purely frictional fixation allows any angular position of the socket insert 11 within the recess 13 in the socket body 10 .

The bottom 31 of the pan body 10 has a passage 32 which can be closed by a cover 33 . The cover 33 is rotatably mounted about an axis 34 extending perpendicular to the bottom 31 . The bottom opening 32 extends only over a predetermined circular sector which can be closed by a corresponding sectoral cover. The cover 33 is designed as a sectoral lamella disk.

The passage 32 makes it possible to control the setting depth after inserting the socket body 10 in the acetabulum and / or to insert cancellous bone between the bottom of the socket body 10 and the bone. Then the passage 32 is closed by means of the lid 33 , so that the socket insert 11 does not come into contact with the bone.

According to FIGS. 1, 2 and 4, the socket body 10 on the outside in parallel to the center axis 34 extending engagement webs 35, namely a plurality of approximately uniformly distributed over the periphery of the cup body 10. The impact ribs are provided with knife-like cutting edges on the radial outside. These impact ribs allow an even more stable anchoring of the socket body in the pelvic bone. If necessary, they can also extend to the roof 28 .

The socket body 10 can also have holes in the cranial and / or caudal area for the passage of bone screws, the screw holes preferably being designed in the manner of hourglasses or venturi tubes, so that the screws can be screwed in freely at different angles. If necessary, the screw holes can be closed by assigned plugs, screws or the like. The screw holes preferably each extend between two adjacent impact ribs 35 .

The socket insert 11 is preferably fixed in the corresponding recess 13 of the socket body 10 by means of a snap mechanism, in particular a projection which engages in an annular groove formed in the socket body recess 13 , in particular an annular bead or bead section on the outside of the socket insert 11 . Alternatively, the annular projection can be formed on the inside of the recess 13 , which then corresponds to an annular groove on the outer circumference of the socket insert 11 . In principle, it is also conceivable to hold the socket insert 11 within the recess 13 of the socket body 10 by means of a separate spring ring which can be placed within an annular groove near the upper input edge of the recess 13 and covers the upper edge of the socket insert 11 .

The surface of the cavity 12 formed in the socket insert 11 is preferably provided with a sliding layer, in particular a sliding layer made of metal, ceramic or an abrasion-resistant plastic.

Regarding the angles mentioned above, it should also be mentioned that the angle "c" is at least about 10 degrees. The angles "a" and "b" are 0 to 30, the angle "a" is preferably about 12 to 17 Degrees, and the angle "b" about 8 to 15 degrees.

The angle "d" corresponds approximately to the mean of the angles "a" and "b".

The center points of the quarter spherical shells 17 , 18 mentioned above are also identified in FIG. 2 by the reference numbers 36 , 37 . The distance between these two center points corresponds to the extension of the socket body in the direction of its longitudinal axis 15 . The radius of the quarter spherical shells 17 , 18 is indicated in FIG. 2 by "R". The angle "c" is a measure of the bending of the elongated socket body to form a kidney or bean shape in deviation from an exact oval or ellipsoid shape.

In Fig. 9, a socket insert 11 is shown according to in Fig. 8. The pan insert according to FIG. 9 differs from that according to FIG. 8 in that a shell-like metallic lid 38 with a knob-like closure element in the form of a radially outwardly extending projection 39 is formed on its rear or outside or is otherwise fastened. This lid 38 is a kind of "metalbacking". It preferably consists of the same material as the associated socket body 10 . The projection 39 , which is preferably conical, that is to say designed as a truncated cone, closes a corresponding passage formed in the socket body when the socket insert and socket body are in the assembled state. The socket insert is snapped into the socket body in such a way that the projection 39 guarantees a tight closure of the associated passage in the socket body. The corresponding polar prestressing on the projection 39 takes place through the aforementioned latching of the socket insert along the equatorial periphery in the socket body. Due to this polar / equatorial jamming or latching, the intermediate titanium or the like. Shell 38 need not lie against the inner surface of the socket body 10 , so that there is no fear of metal abrasion in this area. "Metalbacking" also has the advantage that in the area of screw holes in the socket body 10 there is no longer any fear of the polyethylene of the socket insert 11 flowing.

Reference list

10th

Pan body

11

Cup insert (inlay)

12th

hemispherical cavity

13

Recess

14

Outline

15

Longitudinal axis

16

Transverse axis

17th

Quarter ball cup

18th

Quarter ball cup

19th

Extreme tension point

20th

Extreme tension point

21

Extreme tension point

22

Center axis

23

Entrance level

24th

head Start

25th

deepening

26

cranial area

27

caudal area

28

canopy

29

Main pan level

30th

Flattened floor

31

Pan-bottom

32

Continuity

33

cover

34

axis

35

Impact ribs

36

Sphere center

37

Sphere center

38

cover

39

knob-like projection
c = angle
d = angle
a = angle
b = angle

Claims (18)

1. joint socket for a hip joint endoprosthesis, with an elongated socket body ( 10 ) and a socket insert (inlay) ( 11 ) which has a hemispherical cavity ( 12 ) on the front for receiving a joint ball, characterized in that the outline ( 14 ) of the pan body ( 10 ) is asymmetrical in front view at least with respect to the longitudinal axis ( 15 ). 2. Pan according to claim 1, characterized in that the pan body ( 10 ) in a front view

• 1. kidney-shaped or bean-shaped,
• 2. boomerang-like,
• 3. trapezoidal,
• 4. triangular,
• 5. crescent-shaped,
• 6. heart-shaped,
• 7. arrow-shaped or
• 8. semicircular

Outline ( 14 ). 3. Pan according to claim 1 or 2, characterized in that the pan insert ( 11 ) consists of a body-compatible material, in particular ceramic or plastic, such as polyethylene, or a combination of these materials, while the pan body ( 10 ) made of a body-compatible metal, in particular Cobalt chrome molybdenum alloy, titanium or titanium alloy, is produced. 4. Pan according to claim 1, 2 or 3, characterized in that the back or outside of the pan insert ( 11 ) is made of a body-compatible metal (cover 38 , 39 ), in particular cobalt chromium molybdenum alloy, titanium or titanium alloy, in particular in association to one or more passages in the bottom of the pan body ( 10 ) if such passages are formed. 5. Pan according to one of claims 1 to 4, characterized in that the hemispherical cavity ( 12 ) in the pan insert ( 11 ) is arranged off-center. 6. pan, in particular according to one of claims 1 to 5, characterized in that the pan insert ( 11 ) within a corresponding recess ( 13 ) in the pan body ( 10 ) can be fixed, in particular in different angular positions relative to the central axis ( 22 ) of the recess ( 13 ), this recess ( 13 ) preferably being formed concentrically in the socket body ( 10 ). 7. Pan according to claim 6, characterized in that the pan insert ( 11 ) is a rotationally symmetrical, in particular cylindrical, frustoconical or hemispherical shell, which is non-positively and / or positively fixable within the corresponding recess ( 13 ) in the pan body ( 10 ) . 8. Pan according to claim 2, characterized in that the pan body ( 10 ) with a front kidney or bean-shaped outline ( 14 ) by connecting or bridging two to each other at an angle (c / 2) relative to the transverse axis ( 16 ) of the pan body ( 10 ) oppositely arranged sections of two rotating bodies, such as a ball, cone or cylinder, in particular quarter spherical shells ( 17 , 18 ) is formed. 9. Pan according to one of claims 1 to 8, characterized in that the front of the pan body ( 10 ) in the cranial area ( 26 ) is covered forwards ( 28 ). 10. Pan according to one of claims 1 to 9, characterized in that the front of the pan body ( 10 ) in the caudal area ( 27 ) is withdrawn inwards or backwards. 11. Pan according to one of claims 1 to 10, characterized in that the bottom ( 31 ) of the pan body ( 10 ) has a passage ( 32 ) which can be closed by a lid, in particular displaceably or rotatably mounted lid ( 33 ). 12. Pan according to claim 11, characterized in that the lid on the back or outside of the pan insert ( 11 ) is arranged, in particular is integrally formed. That the cup body (10) extends parallel to the center axis (34) extending engagement webs (35) 13. A socket according to any one of claims 1 to 12, characterized in that on the outside, in particular a plurality of approximately uniformly distributed over the periphery of the socket body (10) engagement webs with knife-like cutting. 14. Pan according to one of claims 1 to 13, characterized in that the pan body ( 10 ) in the cranial and / or caudal area has holes for the passage of bone screws, the screw holes are preferably hourglass or venturi-shaped, so that the Screws can be screwed in at different angles without constraint. 15. pan according to claim 14, characterized in that if necessary, the screw holes by assigned Plugs, screws or other closure elements are lockable. 16. Pan according to one of claims 1 to 15, characterized in that the fixation of the pan insert ( 11 ) in the corresponding recess ( 13 ) of the pan body ( 10 ) by a snap mechanism, in particular in a in the pan body recess ( 13 ) trained annular groove engaging projection, in particular annular bead or bead portion on the outside of the socket insert ( 11 ). 17. Pan according to one of claims 1 to 16, characterized in that the surface of the cavity ( 12 ) formed in the pan insert ( 11 ) is provided with a sliding layer, in particular a sliding layer made of metal, ceramic or an abrasion-resistant plastic. 18. Pan according to one of claims 1 to 17, characterized in that the pan insert ( 11 ) has at the edge at least one radially outwardly extending projection ( 24 ) or alternatively at least one recess which or with at least one in the recess ( 13 ) of the socket body ( 10 ) formed recess ( 25 ) or a projection formed in the recess ( 13 ) of the socket body ( 10 ) corresponds.