DE19919083C1 - Implantable acetabular cup, especially for hip joint endoprostheses - Google Patents

Abstract

An implantable acetabular cup, in particular for hip joint endoprostheses, is described which has a shell (10) to be anchored in the bone and an insert (20.1, 20.2) held in this shell (10) for mounting the joint head. In order to optionally attach inserts (20.1, 20.2) made of different materials by means of a self-locking cone connection in the shell (10), an adapter (28) is provided which can be inserted into the inner cone surface (14) of the shell (10) in order to Reduce the taper angle for the self-locking cone connection.

Description

The invention relates to an implantable socket, ins especially for hip joint endoprostheses, according to the generic term of claim 1.

Joint endoprostheses, especially hip joint endoprostheses consist of an acetabular cup that holds a joint head and slidably stored. With the hip joint endoprosthesis Joint socket anchored in pelvic bone while the joint head is anchored in the femur by means of a shaft. The Ge Steering pan often consists of a shell in the bone is anchored and an insert held in the shell that takes up the joint head and the sliding surface for the joint head forms. This has the advantage of being related to the shell Material and design optimized for anchoring in the bone can be while using the material with regard to on an optimal pairing with the joint head and a maximum life can be selected. In addition, at Removal operations remove the insert from the shell and be replaced.

It is known to use a self-locking To keep the cone connection in the shell. The Shell an inner cone surface into which the insert is used an outer cone surface is hammered in so that the self-locking hold of the insert in the shell results. Should the insert is removed from the shell during a replacement operation against self-locking from the shell knocked out.

The shell is usually mechanical Properties made of metal. Be for use predominantly metal, ceramic or plastic (polyethylene) ver  turns. If the shell is made of metal, there is an under different self-locking angle for the cone connection, each after which of these materials is used for use becomes. For example, metal-kera results for the pairing mik a larger self-locking angle than for the pairing Metal metal. Compliance with the self-locking angle is of great importance because at a larger cone angle the Use does not reliably hold in the shell and because of a smaller cone angle the insert no longer or only to be released from the shell with great difficulty can.

For this reason, it is necessary in the known joint pans manoeuvrable, a shell with one for each material of the insert To provide the cone angle of the inner cone surface of the the self-locking angle of the pairing with the feed material corresponds. This means a significant expense, especially for the storage of the clinics. To have to namely not only stock different shell types be, but also each shell type in different Chen versions for the different materials of the one sentence.

EP 0 694 294 A1 describes an implantable acetabular cup, especially known for hip joint endoprostheses, in which an intermediate sleeve is inserted into the inner cone of the shell which in turn is used with an inner cone surface records. The intermediate sleeve has the shape of a truncated cone jacket, the cone angle of the outer jacket surface and the inner surface and the self-confidence angle between the inner cone surface of the shell and the outer cone of the insert. The intermediate sleeve will held in the inner cone of the shell and the Insert is held in the intermediate sleeve in a self-locking manner. The Intermediate sleeve is used to remove the insert from the socket le. For this purpose, the intermediate sleeve has an outer edge Threaded holes into which set screws are screwed  against the face of the bowl, so the intermediate sleeve with the use against self-locking press out of the bowl. Here too is for everyone Material combination of shell and insert a special cone shape of the shell and the intermediate sleeve required.

From DE 295 17 637 U1 an endoprosthetic acetabular cup is known, the one implantable shell and one held in the shell by means of a cone connection Insert, which forms the bearing surface for the joint head. Between the shell and the insert can be used a ring that has the shape of a circular truncated cone. This Ring is inserted with its outer conical surface in the inner conical surface of the shell and takes up the outer cone of the insert with its inner conical surface. The ring instructs the inner and outer conical surface on the same cone angle and is used for different adaptation of the bearing surface of the insert receiving the joint head in Regarding the implanted cup. Are the inner and outer conical surface of the ring arranged coaxially, the joint head dips into the shell at different depths. Are the Axes of the inner conical surface and the outer conical surface of the ring at an angle inclined towards each other, there is a different angle of inclination of the Rod bearing receiving surface of the insert opposite the implanted shell.

The invention has for its object an implantable Joint socket, in particular for hip joint endoprostheses for To provide, in which a uniform shell for Inserts made of different materials can be used.

This object is achieved by a Ge Steering pan with the features of claim 1.

Advantageous embodiments of the invention are in the sub claims specified.

According to the invention an adapter is provided which is in the inside cone of the cup of the socket can be used to the cone angle for use according to the self-locking angle of the respective material used for the insert adapt. The shell has an inner cone surface, the Cone angle the largest at the commonly used Materials of use occurring self-locking angle corresponds, e.g. B. the self-locking angle of a ceramic one sentence. If an insert made of this material, e.g. B. a Kera mic insert used, this insert can be used immediately in the Sehale can be used and is self-locking in the Inner cone of the shell held. Should a bet be made from a other material is used, which is paired with the Metal of the shell on a smaller self-locking angle points, the adapter is inserted into the inner cone of the shell sets, now the smaller cone angle of the inner shell surface of the adapter the self-locking angle for use Are defined.

This reduces the effort required to manufacture the socket  and in particular the cost of warehousing in the Kli nik significantly reduced. It is only necessary now, Schalenty pen to keep in stock, which is in terms of anchoring differentiate. It is no longer necessary from any of these Types also different versions for different stock materials of the mission.

The adapter is in a preferred embodiment in the shell snapped in so that the adapter can be easily inserted can. The snap connection preferably consists of an the adapter-formed outer bead, which in a rear cut the shell snaps. To snap in allow, the adapter is axially slotted, preferred as a continuous axial slot is provided to the Diameter of the entire adapter for insertion or He take out to shrink.

The invention is described below with reference to the drawing illustrated embodiments explained in more detail. Show it

Fig. 1 a socket joint in a partly axially sectioned side view,

Fig. 2 shows a first embodiment of the adapter in axial view and in side view and

Fig. 3 shows a second embodiment of the adapter in axial view and in side view.

Fig. 1 shows the socket of an implantable Händge joint endoprosthesis. The joint socket has a shell 10 which is formed with a self-tapping external thread 12 so that it can be screwed into the pelvic bone. The shell 10 is preferably made of a titanium. Other designs of the shell 10 and other ways of fastening the shell 10 in the bone are also known and can be used in the same way according to the invention.

The shell 10 has an inner conical surface 14 which tapers inwards and at its inner end merges with an undercut 16 of enlarged diameter into the rounded flat shell bottom 18 .

An insert 20.1 or 20.2 is inserted into the shell 10 , which has an inner concave hemispherical bearing surface 22 . In the bearing surface 22 , the Ku head of the hip joint endoprosthesis, not shown, is inserted and slidably mounted.

The inner cone surface 14 , which has the shape of a straight circular cone, has a cone angle which corresponds to the self-locking angle of a metal-ceramic sliding pair. This cone angle (angle between two diametrical mantelli lines) is approximately 19 °.

An insert 20.1 made of ceramic material can be inserted into the inner conical surface 14 of the shell 10 . This insert 20.1 has an outer circumferential surface 24.1 which corresponds to the shape of the inner cone surface 14 of the shell 10 , ie also has the shape of a straight circular truncated cone, the cone angle of which corresponds to the cone angle of the inner cone surface 14 of the shell 10 . An insert base 26 adjoins the outer lateral surface 24.1 and is received in the shell base 18 of the shell 10 . If the insert 20.1 made of ceramic material is inserted into the shell 10 and struck lightly, there is a self-locking cone connection between the outer circumferential surface 24.1 of the insert 20.1 and the inner cone surface 14 of the shell 10 , which holds the insert 20.1 firmly in the shell 10 .

In order to be able to remove the insert 20.1 from the shell 10 if necessary, known means are not provided on the insert 20.1 , known means are provided in order to be able to apply an extraction instrument with which the insert can be used with light hammer blows while overcoming the self-locking the cone connection can be released again.

As an alternative to the insert 20.1 made of ceramic material, an insert 20.2 made of metal can also be inserted into the shell 10 . Since a metal-metal sliding pairing has a smaller self-locking angle than the metal-ceramic sliding pairing, an adapter 28 is inserted into the inner conical surface 14 of the shell 10 . The adapter 28 is made of metal, preferably titanium, like the shell 10 . The adapter 28 has the shape of a straight circular truncated cone jacket. The outer lateral surface 30 of the adapter 28 has the same cone angle as the inner conical surface 14 of the shell 10 . In this way, the adapter 28 can be inserted into the inner conical surface 14 . The inner lateral surface 32 of the adapter 28 has a smaller cone angle than the outer lateral surface 30 . This cone angle of the inner conical surface 32 corresponds to the self-locking angle of a metal-metal sliding pair and is, for example, approximately 10 °.

In the inserted into the shell 10 of the adapter 28 A is used set 20.2 of metal. The shape of the insert 20.2 essentially corresponds to that of the insert 20.1 made of ceramic material. However, its frustoconical outer surface 24.2 has a cone angle which corresponds to the cone angle of the inner surface 32 of the adapter 28 . If the insert 20.2 is hammered into the adapter 28 , this results in a self-locking cone connection between the outer surface 24.2 of the insert 20.2 and the inner surface 32 of the adapter 28 . This self-locking Konusver connection holds the insert 20.2 made of metal in the adapter 28 , which in turn is held in the shell 10 . Here too, the insert 20.2 can be released from the adapter 28 in the manner described above by overcoming the self-locking of the cone connection.

Fig. 2 shows a first embodiment of the adapter 28th The adapter 28 has the shape of a truncated cone jacket, at the end of which a circumferential outer bead 34 is formed with the smaller diameter. With this outer bead 34 , the adapter 28 snaps into the undercut 16 of the shell 10 , which adjoins the inner conical surface 14 on the inside. As a result, the adapter 28 is held in a form-fitting manner in the inner conical surface 14 of the shell 10 .

To the metal-made adapter 28 snap, with its external bead 34 into the undercut 16, the adapter 28 has an axial through slot 36, the width sen, for example, is about 3 mm. The adapter 28 can be axially pressed into the inner cone of the shell 10 or by means of a suitable tool against its elasticity to the extent of the width of this slot 36 , so that the adapter 28 can be inserted into the inner cone surface 16 of the shell 10 . After insertion, the adapter 28 is released so that it spreads apart again elastically and engages with its outer bead 34 in the rear cut 16 of the shell 10 and is held in the shell 10 in a form-fitting manner. The elasticity of the adapter 28 holds it with its outer circumferential surface 30 lying flat and stable against the inner cone surface 16 of the shell 10 . Conversely, the adapter 28 can be removed from the shell 10 again by pulling the adapter 28 together by the width of the slot 36 .

In Fig. 3, a further embodiment of the adapter 28 is shown ge. In this embodiment, the adapter 28 is not continuously slotted, but instead has in its inner edge with the smaller diameter a multiplicity of axial incisions 38 offset with respect to one another in the same angular division. Through the incisions 38 , the inner edge of the adapter 28 is divided into individual spring tongues, each having the outer bead 34 as a detent at its free end. When the adapter 28 is pressed into the inner conical surface 14 of the shell 10 , these spring tongues formed by the incisions 38 are pressed elastically inward until the outer bead 34 comes into the undercut 16 and the spring tongues can spread apart again, so that the adapter 28 in the shell with a positive fit 10 is held. In this embodiment, the adapter 28 is inseparably connected to the shell 10 .

It is readily apparent that in the shell 10 and an insert made of plastic z. B. can be used from polyethylene. In this version, the insert corresponds in shape to the insert 20.1 made of ceramic material. Since the plastic material has a higher elastic deformability, an outer bead can be formed on the outer circumferential surface of the insert made of plastic, which corresponds to the outer bead 34 of the adapter 28 , so that the insert made of plastic material with this outer bead in the undercut 16th the shell 10 can snap. The plastic insert is thus held in a form-fitting manner, so that no self-locking cone connection is necessary.

Reference list

10th

Bowl

12th

External thread

14

Inner cone surface

16

Undercut

18th

Shell bottom

20.1

Insert (ceramic)

20.2

Insert (metal)

22

storage area

24.1

outer surface of

20.1

24.2

outer surface of

20.2

26

Insert floor

28

adapter

30th

outer surface of

28

32

inner surface of

28

34

Outer bead

36

slot

38

Incisions

Claims (8)

1. Implantable acetabular cup, in particular for hip joint endoprostheses, with a shell ( 10 ) and an insert ( 20.1 , 20.2 ) held in the shell ( 10 ) by means of a self-locking conical connection, characterized by an adapter ( 28 ) which is used to reduce the cone angle of the self-locking conical connection can be used in the shell ( 10 ) and has the shape of a truncated cone whose outer surface ( 30 ) has a larger cone angle than its inner surface ( 32 ). 2. joint socket according to claim 1, characterized in that the shell ( 10 ) has an inner conical surface ( 14 ) whose cone angle corresponds to the self-locking angle of an insert ( 20.1 ) made of ceramic material, that the cone angle of the outer lateral surface ( 30 ) of the adapter ( 28 ) corresponds to the cone angle of the inner cone surface ( 14 ) of the shell ( 10 ) and that the cone angle of the inner lateral surface ( 32 ) of the adapter ( 28 ) corresponds to the self-locking angle of an insert ( 20.2 ) made of metal. 3. joint socket according to claim 2, characterized in that the shell ( 10 ) consists of metal, that the adapter ( 28 ) consists of metal, that the cone angle (angle between two diametrical surface lines) of the inner conical surface ( 14 ) of the shell ( 10 ) and the cone angle of the outer lateral surface ( 30 ) of the adapter ( 28 ) is approximately 19 ° and that the cone angle of the inner lateral surface ( 32 ) of the adapter ( 28 ) is approximately 10 °. 4. joint socket according to one of the preceding claims, characterized in that the adapter ( 28 ) in the shell ( 10 ) can be positively latched. 5. joint socket according to claim 4, characterized in that the adapter ( 28 ) has an outer bead ( 34 ) which engages in an undercut ( 16 ) of the shell ( 10 ). 6. joint socket according to claim 5, characterized in that the outer bead ( 34 ) is formed on the end of the adapter ( 28 ) with the smaller diameter and that the undercut ( 16 ) on the inside against the inner conical surface ( 14 ) of the shell ( 10 ) connects. 7. joint socket according to claim 6, characterized in that the adapter ( 28 ) is axially slotted at least in the region of the outer bead ( 34 ). 8. joint socket according to claim 7, characterized in that the adapter ( 28 ) has an axially continuous slot ( 36 ).