Artificial hip socket.

The invention relates to a carrier element of the specified in the preamble of claim 1. - wherein the actual pan is subsequently used in the attached in the pelvis supporting element, so that by selecting an appropriate socket insert an adaptation to different Liche diameter of ball joints of the associated shaft prostheses is possible - and associated operations.

Such a carrier element is known from FR-A-20 99 259th The carrier element there illustrated in particular in Figure 12 is disadvantageous in that a relatively large amount of bone substance is schäd.igt determined by the attachment of the thread to a set on the highest point centering and continue mounting only in a single predetermined position is possible that the Manufacture of Ausparung must be established for the support member in the hip bone.

Furthermore, from DE-A-24 11 617 is also a support element is known with which a joint surface can be snapped, wherein here the support ribs are indeed disposed thread-shaped on an outer surface, the outer surface of the jacket surface of a truncated cone corresponds to - the carrier element, however, is again only be screwed in a single position which is determined by the shape of the previously inserted into the bone milled.

In many cases, it is desirable or even necessary to make a correction of the position or orientation of the shank part of the prosthesis receiving hemisphere recess even after the creation of the acetabulum or the support element receiving cutout.

The specified in claim 1 the invention has for its object to provide a support element which can be introduced so different after production of the finished cut-out that the surgeon, to the choice of particularly viable bone regions and secondly a certain alignment of the reference direction of the future hip joint prosthesis is made possible by the direction selected during the screwing of the thread.

The invention is based on the recognition that the introduction of force should be in the pelvic bone as possible in the direction of the forces that occur upon loading of the prosthesis, which can be done on the one hand through the top portions of the rounded support member and the same in annular formation on the projecting through the annular socket part. The fixing of the pan by thread segments of the carrier element focuses on the Kortikalisbereich.

Especially advantageous is the fact that for producing the recess in the bone, a commercial milling with hemispherical shape is usable.

In preferred embodiments of the invention, in particular the insertion of the support element is made easier by the thread profile generates the necessary counter-thread when screwing in itself, so that a previous thread cutting is unnecessary.

The fact that in the first separately screwed into the pelvic bone support element a circular recess is provided, the diameter of which is formed preferably greater than the height of the remaining ring of the view through to the bottom of the milled recess is released so that judges when screwing without additional aids easy can be when the carrier element has reached its end position.

The annular design is carried low such that the resulting elasticity corresponds with respect to deformation of the ring to that of the surrounding bone region so that a high degree of homogeneity of the ring used and the pelvic region and has led to the initiation of loading forces always occurs over a large area. Thus the effects of the notch behavior of the thread and the risk of bone resorption are reduced. Base inlay has to with respect to the support member with respect to its diameter, a certain play, so that the loading forces can be absorbed largely without deformation of the insert.

To ensure optimal application of force in the basin, the contact surface is use / support member perpendicular to the preferred occurring force, ie for example by approximately 45 ° to the screwing - arranged - and concentrically around it. The conical shape has the advantage that the use of rotation is secure in the ring and that the forces, in particular the axially acting forces, to be taken not only by a collar of the insert but also by the conical wall of the insert.

Usual thread profiles, such as those used for normal bone screws, ungeeig net in most cases, there is no guarantee that - as with cylindrical or conical thread cutters - the one cutting groove adjacent edge of the mentioned before, when screwing part of a thread segment also first with the not threaded portions of the bone surface comes into contact.

This has its reason in the fact that the diameter of the protruding portions of the thread tangent hemisphere is greater than the corresponding radius of the reamed in the bone portions. When interpenetration of the two hemispherical surfaces of the distance between the two spherical surfaces takes apart to in the introduction direction, so that the initial contact between bone surface and be drastic Gewindesegementen not necessarily take place in the cutting groove, but rather on the "back" of the thread segment. The reason is that the contacting portions of the recess in the bone and the threaded bearing surface of the element to be screwed are not collimated, as would be the case with a cylindrical or conical thread. When cutting with the "back" of the thread flanks, the case applied forces are so great but that a "self-tapping" of the thread through the support member is virtually eliminated. An insertion without pre-cutting of the thread is so in practice only if the thread flanks in the form described, producing concentrated possible contact when you first touch the bone wall and pierce into the bone surface. The trailing edge may then have the not agile in cutting tools "free angle". This form of the thread segments is preferably achieved in that the past in the rotation direction when screws areas of the highest elevations of the thread segments are progressively removed, what can be done by rounding or by milling through a corresponding removal of the thread segments.

With this - deviating from the normal shape of a bone thread design of the thread segments, the advantage is further connected, that in preferred truncated design of the past in the direction of rotation when screwing in areas the stability of the position of the supporting element is raised in the implanted state, since the notch effect is reduced and thus can not lead to a deeper penetration and thus a loosening of the support member by the forces occurring during deformation of the bone.

The annular configuration has the advantage that the elasticity of the support element can be largely adapted by material selection and design to that of the surrounding bone areas, so that the element with respect to the forces to be transmitted is not a foreign body and occurs spread over the largest possible surface areas the application of force. In that regard, it is also advantageous if the inserted into the support member pan, which is preferably made of plastic, with coming in deformable areas in the support member in contact parts having a certain play, the introduction of force from the prosthesis forth or via appropriate stop surfaces to the carrier element carried out. in the bones.

The circular design of the support element on the one hand those areas of bone, which allow a maximum power intake, preferably for the introduction of force - used, so that an optimum retention effect is present while the data transmitted from the prosthesis pressure forces through the ring on the bottom of the pan - with respect to transverse forces and the pan bottom are introduced directly into the bone, considers that this holding action is not needed by a thread or the like.

In one adapted to the carrier element according to the invention of system employed in this socket parts, the surgeon can effect corrections with respect to the later position of the future point of rotation of the prosthesis after the screwing of the element by selection of a specifically suitable therefore still. Given the desired position of the fulcrum and the axial alignment of the recess for receiving the prosthetic head is for example using an appropriate sterile gauge determined and used accordingly Chosen pan member having the desired dimensions. A system adapted to the carrier element according to the invention accordingly has pan parts of different heights or radially offset pivot points for the Femurprothesenteil, wherein combinations of the above to be changed using a single insert part are possible. An alignment of the inclination of the axis of reference is performed by a corresponding inclined screwing of the support element itself, so far no subsequent compensation by the pan to be used part is necessary.

The annular support member is preferably made of titanium, while the cup inserts are made of plastic. This yields the advantage that the - economically producible - Appearances can be readily maintained on different versions, while the support element respectively per outer diameter only once has to be kept in stock to meet all occurring cases justice. Socket insert and support element together form a hemispherical insert.

Other preferred further developments are indicated in the dependent claims. An advantageous embodiment is shown in the figures and is described in more detail below. Show it:<ul><li>Figure 1 shows an embodiment of the support element of the invention with an inserted socket part in side view,</li><li>Figure 2 seen obliquely the support member shown in Figure 1 in a perspective view from below,</li><li>Figure 2a shows a detail of Figure 2,</li><li>3 shows a socket insert for the one shown in Figure 2 support element, also in a perspective view,</li><li>Figure 4 is a sectional view of a deployable in support element insert,</li><li>Figure 5 is a sectional views of a support member used in a Knochenexkavitation,</li><li>Figure 6 is a sectional view of the carrier element according to FIG 5 during the screwing and</li><li>Figure 7 illustrates the geometrical relationships in Figure 6 in an enlarged view.</li></ul>

In the illustrated in Figure 1 supporting member 1, which ring-shaped and corresponds to the outer surface of the surface of a spherical zone, a number of thread-like arranged thread segments 2 are provided which are separated by cutting grooves third The thread segments are sharp-edged at their forward run when screwing parts and stand here furthest from the spherical surface. They form sharp peaks which are exemplary designated 4 in the cutting grooves. In relation to the expended when screwing rotation - more remote areas, the thread segments are truncated at their outer edges formed to flattened, which can thread segments by milling or the like performed by a parallel processing of the superposed.. The annular support member is preferably made of titanium, its elastic properties corresponds with a suitable cross-sectional dimension approximately to those of the surrounding bone material.

A socket insert 5 is adapted to the inner cross-sectional dimensions of the carrier element 1 and can be used in the screwed already in the bone support element from below, the upper dome-shaped section 6 of the insert projects beyond the carrier element and the mounted when inserted inside the bone cutout bears.

In the figures 2 and 3 carrier element 1 and insert part 5 are shown separately for itself in perspective. The two parts have adapted to each other conically shaped regions 7 and 8, which may be subject to a certain game. Through this game rather the elasticity of the ring by a slight bending of the ring form can be effective. The force is applied on the edges of the truncated cone 8. The reproduced in Figure 3 insert 5 has a recess 16 for receiving the head of the femoral stem on its underside. Recesses 17 to 20 permit to a lug 21 with a lug 22 on the support ring 1 different positions of use. 5

In Figure 2a is shown as a segment of the Figure 2, a single thread segment. 2 It is apparent that with advance movement in the arrow direction for screwing the preceding guided highest range is used as a cutting tool, while the rear part has a sufficient clearance angle and in this way reliably prevents a jamming of the ring during the screwing. The "back" of the thread segment is preferably produced by applying one or more times over milling, so that there is accordingly a polygonal or rounded structure of the thread segment. Of the preceding guided during the screwing region corresponds to the complete thread profile, while the tracked parts are in their maximum vertical extension increasingly reduced with respect to the spherical surface.

The parts 1 and 5 are reciprocally snapped, wherein in a corresponding groove of the insert part, a wire ring is inserted 9, which engages in a corresponding groove 10 of the carrier element first Recesses 11 and 12 on the underside of the support member serve to receive a Einschraubwerkzeuges, wherein due to the uniform distribution of the recesses (two of which are not visible) an exact conducting during the screwing is also possible. The domed shaped portion 6 of the insert 5 has a structuring 13, which comes into contact with the bone surface.

The inserts are available in different versions are available, which after screwing of the support part 1, a suitable insert element is selected. For this purpose are only the inventive system suitable Tiefenmeßelemente available, which have basically the shape of the insert shown in Figure 3, in addition in the dome a (illustrated by dashed lines) recess 14 can be provided, which when viewed from below - through the screwed ring 1 round - an assessment permits if the dome-shaped section 6 of the insert 5 reaches the bone. The recess 14 thus forms a kind of "windows". In the particular this window "measuring insert" having enfällt the ring 9, being instead provided preferably markings on the cylindrical portion Mar, indicating with respect to the edge between a cylindrical and tapered portion of the insert 1, which of several inserts in the case in each the best seat provides.

It is apparent that the circular shape of the support element 1 on the one hand for a stable fit of the prosthetic element (without the use of bone cement) provides in such a way that the actual pan 5 is held precisely and can not leave their once found optimally adjusted position. The transmitting preferably occur during loading of the prosthesis compressive forces carried out but for the most part on the dome-shaped portion of the insert and partly also on the conical hub, being connected to it are automatically centered.

The ring allows the screwing as a result of its internal opening a large-scale view through to the interior of the bone cavity, so that it can be assessed reliably when the support element 1 has reached its final position when screwing. Especially with tapered threads the full working load is only achieved if the screw is fully screwed and the carrier connects flush with the bone cavity.

In the figure 4 an embodiment of an insert with different variants of recesses (shown in phantom) is shown in section, of part of the system according to the invention, wherein all inserts are adapted in their cylindrical and conical outer region on those shown in the respective figures annular support first However, (shown in phantom versions 22 and 23) Due to the different relative position of the recess 16 can be shifted according to the head of the femoral neck prosthesis, so that an individual adjustment is possible the fulcrum. The dashed lines 22 illustrated embodiments allows a different height position with respect to the bone surface, while the dotted embodiment 23 is formed the eccentric receptacle for the prosthetic head for a. The eccentricity can be brought by rotating the insert in an appropriate direction, the different locking positions respectively set position fix (recesses 17 to 20 in Figure 3 with the nose 22 in Figure 2).

In a preferred - not shown - Embodiment 3 elevations are provided on the insert 5 in figure which are 12 for the wrench on the insert 1 adapted in Figure 2 in the cutouts 11. Thus, a rotation of the insert 5 is also guaranteed when the nose 22 is omitted. The recesses 11 and 12 so that a double function.

There are other possible bets that combine different heights and axle assemblies with each other, so that the requirements arising under consideration of in its optimum position - for example at dysplasia - screwed support ring in any way account can be taken. A desired inclination of the axis direction is determined not by a special A rate, but on the screwing of the support element, as shown below. To record a - not shown - so-called "dual head prosthesis", the recess 16, 22 or 23 is formed on a ball the size of the femoral head-joint ball snapped. Such "dual head prosthesis" forms a complete hip prosthesis in which match the external dimensions of the socket that of healthy joint ball.

In Figures 5 and 6, the possibility of an inclined screwing is reproduced in a Knochenexkavation 15 at the local sectional views. It is apparent that can be achieved in the self-tapping nature of the threads in communication with the surface which forms a part of a sphere, various positions in the semi-spherical milled bone cavity. Thus the .Tragelement according to the carrying capacity of the bone and the desired alignment of the prosthesis can bring. The outer surface of the circular ring corresponds to the surface of a spherical zone.

In figure_'6 is schematically shown how the cutting of the thread segments of the support element takes place in the recess.

Since the radius of the milled recess is smaller than the radius of the not the outer edges of the thread segments tangent hemisphere and the tangents to the respective radii at the contact point - take place as in cylindrical or übli Chen conical threads in parallel, but form an acute angle with each other and the two spherical surfaces toward the bone yet increasingly away from each other, is because the thread segments have a certain slope and the preceding guided member is in an area where the two spherical surfaces do not touch each other without the measures described here does not ensure that the thread segment in the region the cutting groove engages the bone surface. The thread segments would initially come rather with their backs to the bone surface in contact and prevent the self-cutting of the ring to be screwed. Only the corresponding flattening of the past in the screwing portions of the thread segments creates the necessary elevation of the advanced guided part, so that the cutting edges - preferably punctiform - can engage and thus also have the necessary in each cutting tool clearance angle.

Figure 7 shows the conditions when screwing in accordance with Figure 6 are shown in an enlarged geometric representation, the two triangles 24 and 25 on the inner periphery represent the leading and trailing edge of a thread segment, whose back is not, as shown in Figure 2a, chamfered or . is rounded. Because of the slope of the thread segment are the sectional areas as shown in FIG 7 at different heights, the top (shown in phantom) triangle 24 the forward run when screwing edge symbolizes. With a height difference a result of the slope, the forward run (cutting) edge is by the amount b away from the hemispherical shaped excavation 15, while the rear surface (lower triangle 25) rests. Thus, the thread segment lies with his back on the bone wall, without being able to penetrate as a cutting tool. The consequence is that the support member does not cut into the bone wall for forming of the thread, but there slipping off or jammed. It is thus apparent how the chamfers made screwing without prior threading easier - especially if this is to be screwed in a hemispherical recess with an inclined axis, as is shown in FIG. 6