AU2007250380B2

AU2007250380B2 - Knee endoprosthesis

Info

Publication number: AU2007250380B2
Application number: AU2007250380A
Authority: AU
Inventors: Christine Seyfert
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-05-17
Filing date: 2007-04-17
Publication date: 2012-04-05
Anticipated expiration: 2027-04-17
Also published as: WO2007131466A1; DE502007005959D1; JP5127823B2; ATE491415T1; EP2026718B1; AU2007250380A1; JP2009537186A; DE102006023378B3; EP2026718A1

Abstract

A knee endoprosthesis with a prosthesis arrangement (2) that can be placed on the tibial plateau (1), wherein the prosthesis arrangement (2) has a medial component (3) and a lateral component (4). In order to provide a secure hold of the anterior cruciate ligament (5), the knee endoprosthesis is designed and developed in such a way that the medial component (3) and the lateral component (4) can be coupled by means of a connecting element (6) that can be placed dorsally with respect to the anterior cruciate ligament (5).

Description

Dr. Christine Seyfert S60448AU Knee endoprosthesis The invention relates to a knee endoprosthesis comprising a prosthesis arrangement that can be placed on the tibial plateau, wherein the prosthesis arrangement has a medial component and a lateral component. 5 Knee endoprostheses of the aforementioned type are known in practice and exist in different configurations, and can additionally comprise one or two webs. Artificial knee joints in the form of total endoprostheses are implanted in patients who have significant wear of the joint surface or complete destruction of the joint. The reconstruction of essentially normal biomechanical properties in the knee joint is the highest aim in this 10 regard. A standard total knee endoprosthesis is usually implanted with resection of the bone surface and of the anterior cruciate ligament. With the resection of the anterior cruciate ligament, apart from losing a large part of the proprioception, important biomechanical elements, such as the final rotation of the tibia during extension, are also sacrificed. 15 Patients with an intact anterior cruciate ligament therefore increasingly desire prosthetic components which maintain a biomechanically healthy anatomical structure. For this reason, current research on new knee implants is focused on the maintenance of the anterior cruciate ligament. There are a few types of knee endoprosthesis on the market with which the anterior cruciate ligament can be preserved. 20 The anterior cruciate ligament originates from the tibial eminences and runs in the lateral direction to the lateral femoral condyle and is attached in the notch there. The origin of the anterior cruciate ligament includes not only the eminences, but fans out broadly to include the central ventral edge of the tibia. Conventional artificial tibial plateaux which preserve the anterior cruciate ligament have a 25 ventral web. For this web to be placed, the ventral fibres of the anterior cruciate ligament have to be sacrificed so that the web can be guided past on the ventral side of the main attachment of the anterior cruciate ligament. Excessive resection of the bone, apart from causing the inevitable damage to the ventral portions, also jeopardises the remainder of the anterior cruciate ligament.

A further possibility for preserving the anterior cruciate ligament consists in the implantation of two half-slides which serve as medial and lateral components. However, the implantation error in the form of an imprecisely symmetrical orientation of the non-coupled medial and lateral slides is very severe, with the result that this 5 method has hardly been used in recent times. It is therefore an object of the present invention to configure and develop a knee endoprosthesis of the aforementioned type such that the anterior cruciate ligament is reliably retained using means which have a simple design. This aim is achieved with a knee endoprosthesis having the features of claim 1. 10 According thereto, the knee endoprosthesis of the aforementioned type is configured and developed such that the medial and lateral components can be coupled by means of a connecting element which can be placed dorsally in relation to the anterior cruciate ligament. In an embodiment, there is provided a knee endoprosthesis comprising a prosthesis 15 arrangement that can be placed on the tibial plateau, wherein the prosthesis arrangement has a medial component and a lateral component, characterized in that the medial component and the lateral component can be coupled by means of a connecting element which can be placed dorsally in relation to the anterior cruciate ligament. According to the invention, it has been recognised that by the design of a suitable 20 connecting element for the medial and lateral components, the aforementioned problem is solved in surprisingly simple manner. In concrete terms, the connecting element linking the medial component and the lateral component can be placed dorsally in relation to the anterior cruciate ligament. This effectively results in the formation of a free space for the anterior cruciate ligament, so that damage to, or partial resection of 25 the anterior cruciate ligament is not required. The anterior cruciate ligament therefore remains unaltered and all of the proprioceptive function thereof is preserved. This enables the production of a biomechanically almost natural joint in which only the destroyed surfaces of the tibia are replaced by the formation of a suitable artificial tibial plateau. 31651 10_1 (GHMatters) P79800.AU 9/03/12 - 2a The present invention therefore provides a knee endoprosthesis with which reliable preservation of the anterior cruciate ligament is achieved using simple design means. In concrete terms, the connecting element can be configured as a web which is mounted dorsally between the anterior and posterior cruciate ligaments. This avoids damage to 5 the cruciate ligaments. With regard to a secure and simple coupling of the components which, in advantageous manner, are configured like the medial and lateral tibial plateau, the medial component and/or the lateral component can be coupled via a plug-type connection to the connecting 10 31651101 (GHMancrs) P79800.AU 9/03/12 -3 element. Due to the simplicity of the coupling of the components, the knee endoprosthesis is suitable for a minimally invasive operation technique. In particularly advantageous manner, the plug-type connection can be a conical plug-type connection. By this means, a particularly easy and secure plug-type connection is provided. 5 The connection thereby produced is equivalent to a cold welding technique. In the interests of particularly good toleration of the knee endoprosthesis in the body of the patient, the medial component and/or the lateral component and/or the connecting element can comprise a material which is biomechanically similar to bone. Tantalum or Trabecular Metal or a material similar to Trabecular Metal@ has provided to be particularly suitable 10 in this regard. In the interests of a particularly easily handled knee endoprosthesis, the medial component or the lateral component can be configured to be integral with the connecting element. By this means, a partial preassembly of one of the two components with the connecting element can be brought about, so that during an operation, only the connection between the 15 remaining component and the connecting element has to be made. This saves operating time. With this embodiment, the prosthesis arrangement for the region of the tibia no longer consists of three, but rather only two modular components. In particularly advantageous manner, the prosthesis arrangement can be constructed in entirely modular manner, together with the connecting element. This brings about a high 20 degree of adaptability to different physiological conditions. In concrete terms, due to the modularity, a high level of variation of sizes is provided which, for example, manifests itself in a range of different sizes of the medial and lateral artificial tibial plateau or components and in different web lengths or connecting element lengths. This contributes, to a large degree, to the possibility of a minimally invasive operation technique, wherein 25 the anterior cruciate ligament is not damaged. The knee endoprosthesis according to the invention does not involve any substantial change to the conventional femoral components. With regard to a particularly durable and reliable function of the knee endoprosthesis, the upper side of the prosthesis arrangement facing away from the tibia can have at least one receptacle for at least one inlay. In 30 particularly advantageous manner, an inlay or inlays of this type can preferably be highly cross-linked PE inlays. The inlays serve to provide reliable gliding of the prosthesis -4 components. In a particularly advantageous embodiment, an inlay can be placed medially and a further inlay can be placed laterally in the receptacle or receptacles. In this way, an inlay can be assigned to each femoral condyle. By this means, in particularly advantageous and simple 5 manner, both the medial component and the lateral component can each comprise a receptacle. Also in advantageous manner, the inlay or inlays can be slideably placed in a bearing. In order to ensure individual adaptation of the inlays to the physiological properties, the inlay or inlays can be available with different heights and/or in different sizes. 10 The tibial components - medial, lateral and web - and the femoral components can be made available in various combinable sizes. In particular cases, the connecting element can have an additional component, preferably configured as a web and arranged ventrally in relation to the anterior cruciate ligament. The knee endoprosthesis according to the invention is preferably provided for a cementless 15 implant technique. No significant amendments to the conventional femoral components are necessary. The underside of the prosthesis arrangement is adapted to the same demands as conventional prosthesis arrangements or plateaux for cementless implantation. With the knee endoprosthesis according to the invention, a new tibial component of a knee endoprosthesis is provided, while retaining the cruciate ligaments. The connecting element 20 for the medial and lateral components is arranged along the dorsal side of the anterior cruciate ligament and not ventrally. This is a modular system which can be cold welded by means of conical plug-type connections. It is suitable for a minimally invasive operative technique and the modularity of the system ensures the best possible size adaptability. It is possible for separate size selections to be made for the medial and lateral components as 25 well as for the connecting element and for the inlay height. There is a variety of possibilities for embodying and developing the teaching of the present invention in advantageous manner. In this regard, reference is made to the subclaims and to the following description of an exemplary embodiment of the knee endoprosthesis according to the invention, which makes reference to the drawings. In conjunction with the 30 explanation of the preferred exemplary embodiment of the knee endoprosthesis according -5 to the invention based on the drawings, more generally, preferred embodiments and developments of the teaching will now also be described. In the drawings: Fig. 1 shows a schematic plan view of a normal tibial plateau, and Fig. 2 shows a schematic plan view of an exemplary embodiment of a prosthesis 5 arrangement of a knee endoprosthesis according to the invention placed on the tibial plateau. Fig. 1 shows a schematic plan view of the plateau I of the tibia, wherein the anterior cruciate ligament 5 and the posterior cruciate ligament 7 are shown in the front and rear regions, respectively, of the tibia. Also shown with dashed lines are the tuberositas tibiae 8 10 and the fibular head 9. Fig. 2 shows a schematic plan view of the plateau 1 of the tibia with a prosthesis arrangement 2 of an exemplary embodiment of a knee endoprosthesis according to the invention placed thereon. The prosthesis arrangement 2 has a medial component 3 and a lateral component 4. With regard to reliable retention of the anterior cruciate ligament 5, 15 the medial components 3 and the lateral components 4 can be coupled by means of a connecting element 6 which can be arranged dorsally in relation to the anterior cruciate ligament 5. The medial component 3, the lateral component 4 and the connecting element 6 are shown with solid lines. Under the prosthesis arrangement 2, the tuberositas tibiae 8 can be seen, as well as the head 20 9 of the fibula. The anterior cruciate ligament 5 lies between the medial component 3 and the lateral component 4. The posterior cruciate ligament 7 extends beyond the connecting element 6. The connecting element 6 is configured as a web and couples the medial component 3 and the lateral component 4 via conical plug-type connections which, for the sake of clarity, are 25 not shown. The dimensions of the plug-type connections are dependent on the type of the material of the components 3 and 4 and of the connecting element 6 and the overall thickness of the implant. With regard to further advantageous embodiments of the knee endoprosthesis according to the invention, to avoid repetition, reference is made to the general part of the description 30 and to the claims below.

-6 Finally, it should be explicitly stated that the exemplary embodiment of a knee endoprosthesis according to the invention described above serves merely to discuss the claimed teaching and does not limit this teaching to the exemplary embodiment.

Claims

1. A knee endoprosthesis comprising a prosthesis arrangement that can be placed on the tibial plateau, wherein the prosthesis arrangement has a medial component and a lateral component, characterized in that the medial component and the 5 lateral component can be coupled by means of a connecting element which can be placed dorsally in relation to the anterior cruciate ligament.

2. The knee endoprosthesis according to claim 1, characterized in that the connecting element is configured as a web.

3. The knee endoprosthesis according to claim I or 2, characterized in that the 10 medial and/or lateral component can be coupled via a plug-type connection to the connecting element.

4. The knee endoprosthesis according to claim 3, characterized in that the plug-type connection is a conical plug-type connection.

5. The knee endoprosthesis according to any one of the claims 1 to 4, characterized is in that the medial component and/or the lateral component and/or the connecting element comprises a material which is biomechanically similar to bone.

6. The knee endoprosthesis according to claim 5, characterized in that the material is tantalum or Trabecular Metal* or a material similar to Trabecular Metal@.

7. The knee endoprosthesis according to any one of the claims 1 to 6, characterized 20 in that the medial component or the lateral component is configured to be integral with the connecting element.

8. The knee endoprosthesis according to any one of the claims I to 7, characterized in that the prosthesis arrangement is constructed in a modular manner, together with the connecting element. 25

9. The knee endoprosthesis according to any one of the claims 1 to 8, characterized in that the upper side of the prosthesis arrangement facing away from the tibia has 31651 0_1 (GHMatters) P79800.AU 9/03/12 - 8 at least one receptacle for at least one inlay.

10. The knee endoprosthesis according to claim 9, characterized in that the at least one inlay is preferably a highly cross-linked PE inlay.

11. The knee endoprosthesis according to claim 9 or 10, characterized in that one 5 inlay is arranged medially and a further inlay is placed laterally, in the receptacle or receptacles.

12. The knee endoprosthesis according to any one of the claims 9 to 11, characterized in that both the medial component and the lateral component each comprise a receptacle. 10

13. The knee endoprosthesis according to any one of the claims 9 to 12, characterized in that the inlay or inlays is or are slideably placed in a bearing.

14. The knee endoprosthesis according to any one of the claims 1 to 13, characterized in that the connecting element has an additional component, preferably configured as a web and arranged ventrally in relation to the anterior cruciate ligament.

15 15. A knee endoprosthesis, substantially as herein described with reference to Figure 2. 3165110_1 (GHMatters) P79800.AU 9/03/12