EP1381333A2

EP1381333A2 - Acetabular system

Info

Publication number: EP1381333A2
Application number: EP02732639A
Authority: EP
Inventors: R. Windhager; W. Winkelmann
Original assignee: Implantcast GmbH
Current assignee: Implantcast GmbH
Priority date: 2001-04-18
Filing date: 2002-04-16
Publication date: 2004-01-21
Also published as: WO2002083035A3; DE10118985A1; WO2002083035A2; DE10118985C2

Abstract

An acetabular system contains a hemispherical acetabular implant (2) and at least one spacer (20, 20', 20'). At least one groove originates from the edge (8) of the acetabular implant (2) while running inside the wall (10) of the acetabular implant (2) in a manner that is transversal to the edge (8) and can be accessed from the exterior (4) of the acetabular implant (2). The spacer (20, 20', 20') comprises a projection (22) that fits inside the groove. The exterior of the spacer in the area of the projection (22) is adapted to the outer contour of the acetabular implant (2) in the area of the groove.

Description

Hüftαelenkpfannβn system

The invention relates to an acetabular cup system which can be used in particular for the reconstruction of the acetabular region after removal of a loosened artificial acetabular cup with more or less pronounced bone defects.

It is quite common for artificial acetabular cups to loosen over time. Then a new surgical intervention is required, usually with a new acetabular implant. If the patient has bone defects in the area of the implant, there are various ways of ensuring that the new acetabular implant is held in place. A larger acetabular implant than the removed one can be inserted, with or without bone cement. The bone defects can also be filled with cement or foreign bones. Hip cup implants are also used that have a fixed metal spacer to fill in a bone defect. Another option is the use of support shells that are widely supported in the intestine and ischium. However, all of these conventional methods have disadvantages. If the defect is filled with cement or foreign bones, in many cases the problems can only be remedied for a limited time. Furthermore, the use of large foreign bone grafts leads to a high failure rate. Reconstruction prostheses with a metal spacer often do not correspond to the individual defect. A large surgical access route with extensive muscle detachment is required for the implantation of support shells.

It is an object of the invention to provide a patient-friendly and economical possibility for the reconstruction of an artificial acetabular cup.

This object is achieved by an acetabular cup system with the features of claim 1. Advantageous refinements of the invention result from the subclaims.

The acetabular cup system according to the invention has a hemispherical acetabular implant, from the edge of which at least one groove extends, which runs transversely to the edge in the wall of the acetabular implant and is accessible from the outside of the acetabular implant. Furthermore, at least one spacer is provided, which has a projection which fits into the groove and whose outside in the region of the projection is matched to the outer contour of the acetabular implant in the region of the groove. In a preferred embodiment, the groove and the projection are set up for a positive connection, the groove preferably being designed as a dovetail groove (and the projection having a shape matched to it).

The protrusion of the spacer can be inserted into the groove from the edge of the acetabular implant. If the

Spacer is connected to the acetabular implant, it forms a kind of larger projection for filling a bone end fekts. Remaining cavities between the implant and the patient's bone are grown through by tissue or can optionally be filled in in a conventional manner, for example with bone cement; however, because of the high quality of the spacer, there are far fewer follow-up problems than with conventional methods.

In a preferred embodiment of the invention, a plurality of spacers of the same and / or different shape and / or size are provided. In this case, the acetabular cup system is a modular system that allows the prosthesis to be individually adapted to the given situation during the operation. By selecting the spacers matched to the existing bone defects, an optimal anchoring and thus a permanent reconstruction can be achieved. The spacers connected to the acetabular implant can be supported in places of good bone quality. If the remaining cavities are small enough due to the selection of suitable spacers, the use of bone cement or the like is even unnecessary. Tissues grow through these bone defects (biological reconstruction).

The acetabular cup system preferably has a securing device in order to secure a spacer connected to the acetabular implant against displacement. For example, the securing device can contain a plate which can be screwed onto the edge of the acetabular implant and which, with a projection, covers a spacer connected to the acetabular implant and can preferably be screwed to the spacer. The size and shape of the projection of the plate is preferably matched to the end side of the spacer under consideration. In order to adapt to different configurations of spacers connected to the acetabular implant, the system preferably contains several plates, which are provided with different arrangements of projections. It is advantageous if these plates extend over the entire edge of the acetabular cup extend implant, with the respective existing projections covering the spacers.

In order that several spacers can be connected to the acetabular implant, in a preferred embodiment the acetabular implant has several grooves. These grooves can be distributed over the entire outside of the acetabular implant. As a rule, however, it is sufficient if the acetabular implant has several grooves in the area to be positioned facing away from the patient's seat and pubic bone, since this zone is most susceptible to bone defects.

The acetabular implant can have at least one opening or bore through its wall for receiving a fastening element to be anchored in the patient's bone, preferably a bore in the center of the acetabular implant and a plurality of bores distributed around it. The latter are preferably located at locations that are aligned with the patient's ischium and pubis after implantation.

With the help of the bores and fastening elements guided through the bores (e.g. bone screws), a stable anchorage of the acetabular implant can be achieved in the zone of the force transmission, in which in practically all cases there is still sufficient bone quality. This applies in particular to the central hole, but fixing screws leading to the ischium and pubic bone can usually be well anchored.

The material for the acetabular implant and the spacers are e.g. Titanium or titanium alloys in question. The inside of the acetabular implant can be made from a lining

Have polyolefin, preferably made of a UHMW polyethylene

(ie a particularly high molecular weight polyethylene material). The acetabular cup system according to the invention thus allows adaptation to the individual situation of the patient and enables shorter operating times. The surgical access route is smaller than when using conventional support shells, which results in faster post-operative rehabilitation of the patient. Overall, there is an optimal biomechanical reconstruction combined with a longer durability of the implant.

The invention is explained in more detail below using an exemplary embodiment. The drawings show in

FIG. 1 shows a longitudinal section through an acetabular implant according to an embodiment of the acetabular cup system according to the invention with a spacer inserted,

FIG. 2 shows a cross section through the wall of the acetabular implant in the area of the plane marked II-II in FIG. 1,

FIG. 3 shows a top view of the acetabular implant from FIG. 1, to which a total of three spacers are attached,

FIG. 4 shows a plan view of a spacer,

Figure 5 is a plan view of a spacer with a different shape and

Figure 6 is a plan view of a plate which can be screwed onto the edge of the acetabular implant.

1 shows an acetabular implant 2 of the acetabular cup system in a longitudinal section. The sectional plane runs through the axis II drawn in FIG. 3. Implant 2 is designed like a hemisphere and has an outer side 4, an inner side 6, an edge 8 and a wall 10.

Starting from the edge 8, a groove 12 is milled into the wall 10, see also FIG. 2. In the exemplary embodiment, the groove 12 is designed as a dovetail groove, i.e. it has a trapezoidal cross section. In the exemplary embodiment, the axis of the groove 12 runs in the paper plane of FIG. 1. Offset in the azimuth direction, two further identical grooves are provided in the exemplary embodiment. However, a larger number of grooves, which are arranged distributed over the periphery of the edge 8, is also conceivable. The grooves are used to attach spacers, as explained in more detail below.

In its center, the acetabular implant 2 has an opening or bore 14, see FIGS. 1 and 3. In the exemplary embodiment, the acetabular implant 2 contains two further bores 16 and 17, see FIG. 3. The bore 14 and the bores 16 and 17 are to accommodate fasteners such as Bone screws determined, with the help of which the acetabular implant 2 is anchored in the bone of a patient. The acetabular implant 2 is preferably used in such a way that the bores 16 and 17 point toward the patient's ischium and pubis, since the fastening elements in these bones generally hold well.

In a variant of this embodiment, a further bore is provided in the region of the lower end of the groove 12, that is to say approximately halfway between the edge 8 and the central bore 14.

In the exemplary embodiment, the inside 6 of the acetabular implant 2 is provided with a lining made of UHMW polyethylene (polyethylene with a particularly high molecular weight). This is a common measure for hip joint implants that reduces the friction between the acetabular implant and the joint head. Four threaded holes 18 are made in the edge 8 of the acetabular implant 2, see FIG. 3.

Spacers 20, 20 'and 20 "are a further component of the acetabular cup system. The surgeon preferably has spacers of various shapes and sizes to choose from, so that during the operation he selects one or more spacers and connects them to the acetabular implant 2 can, as explained below with reference to the spacer 20. The spacers 20, 20 'and 20 "are used to fill in bone defects.

The spacer 20 (see also FIG. 4) has a projection 22 which, in the exemplary embodiment, is designed like a dovetail and fits into the groove 12 or one of the other grooves on the acetabular implant 2. The outer side 24 of the spacer 20 is adapted in the region of the projection 22 to the outer contour of the acetabular implant 2 in the region of the groove 12 (or the other grooves). In order to connect the spacer 20 to the acetabular implant 2, it is inserted from the edge 8 with the projection 22 into the groove 12. FIG. 1 illustrates the final position of the spacer 20 on the acetabular implant 2. When the depth of the groove 12 and the length of the projection 22 are coordinated with one another, the end face 26 of the spacer 20 is aligned with the edge 8 in one plane. The connection produced by the projection 22 engaging in the groove 12 is form-fitting and therefore very stable. The spacer 20 is provided with a threaded bore 28 on the end face 26.

In Figure 5, the spacer 20 'is shown in plan view of its end face 26'. The spacer 20 'has the same components as the spacer 20, i.e. a projection 22' and an outer side 24 ', the shape of which corresponds to the projection 22 and the outer side 24 of the spacer 20, but otherwise a different basic shape, see also Figure 3. Figure 3 also shows that the spacer 20 "is constructed in mirror image of the spacer 20 '.

In addition to the spacers 20, 20 '20 "shown in the figures, many other shapes and sizes of spacers are conceivable. The surgeon preferably has a larger number of spacers to choose from during the operation, so that he can individually select the suitable spacers and adapt them to the Surgery can combine with the acetabular implant 2.

FIG. 6 shows a plate 30 in a top view. The plate 30 has three projections 32, 32 'and 32 "and a total of seven through bores 34. It serves as a securing device to prevent the spacers 20, 20', 20" connected to the acetabular implant 2 from shifting. The shape of the plate 30 is matched to the shape of the edge 8 and the shape of the end faces of the spacers 20, 20 ', 20 ". The holes 34 allow screws to be inserted into the threaded holes 18 and 28, 28' and the corresponding threaded hole on the Spacer 20 "can be screwed in.

The shape of the projections 32, 32 'and 32 "of the plate 30 shown in FIG. 6 corresponds to the shapes of the end faces 26, 26' and that of the spacer 20". Preferably, the acetabular cup system includes other plates to choose from where the protrusions correspond to a different selection or configuration of spacers.

An advantageous material for the acetabular implant 2 is titanium or a titanium alloy. The spacers are preferably made of the same material. The plate 30 can also be made from this material.

Claims

claims

1. acetabular cup system,

- With a hemispherical acetabular implant (2), from the edge (8) of which at least one groove (12) extends, which runs transversely to the edge (8) in the wall (10) of the acetabular implant (2) and from the outside (4) the acetabular implant (2) is accessible, and

- With at least one spacer (20) which has a projection (22) which fits into the groove (12) and whose outside (24) in the region of the projection (22) on the outer contour of the acetabular implant (2) in the region of the groove (12 ) is adjusted.

2. acetabular cup system according to claim 1, characterized in that the groove (12) and the projection (22) are set up for a positive connection.

3. acetabular cup system according to claim 2, characterized in that the groove (12) is designed as a dovetail groove.

An acetabular cup system according to one of claims 1 to 3, characterized in that several spacers (20, 20 ', 20 ") of the same and / or different shape and / or size are provided.

5. acetabular cup system according to one of claims 1 to 4, characterized by a securing device (30) which is set up to secure a spacer (20, 20 ', 20 ") connected to the acetabular implant (2) against displacement ,

6. acetabular cup system according to claim 5, characterized in that the securing device has a plate (30) which can be screwed onto the edge (8) of the acetabular implant (2) and which has a projection (32) with one The acetabular implant (2) connected to the spacer (20) is covered and can preferably be screwed to the spacer (20).

7. acetabular cup system according to claim 6, characterized in that a plurality of plates (30) with different arrangements of projections (32, 32 ', 32 ") are provided, which have different configurations of spacers (20) connected to the acetabular implant (2) , 20 ', 20 ") are coordinated.

8. acetabular cup system according to one of claims 1 to 7, characterized in that the acetabular implant (2) in the area to be positioned facing away from the patient's seat and pubic bone has a plurality of grooves (12).

9. acetabular cup system according to one of claims 1 to 8, characterized in that the acetabular implant (2) has at least one through its wall (10) leading opening (14, 16, 17) for receiving a fastening element to be anchored in the patient's bone A bore (14) is preferably provided in the center of the acetabular implant (2) and, after the implantation, bores (16, 17) aligned on the ischium and pubis of the patient.

10. acetabular cup system according to one of claims 1 to 9, characterized in that the acetabular implant (2) and / or the spacer or spacers (20, 20 ', 20 ") have titanium or a titanium alloy.

11. acetabular cup system according to one of claims 1 to 10, characterized in that the inside of the acetabular implant (2) has a lining made of a polyolefin, preferably made of UHMW polyethylene.