DD301699A9 - ANCHORING ELEMENT FOR HOLDING A CUSTOMIZED JOINT PART - Google Patents

Abstract

The anchoring element serves to hold an exchangeable articulated part of an artificial joint, preferably a foot or hip joint. It consists of an at least partially hollow guide and centering bushing with one or more connected thereto plate / s with mounting screws. The guide and centering bushing has a receptacle for detachable connection to the joint part, so that no injury to the bone anchoring takes place when the joint is replaced. The anchoring element has a corrugated and tissue-compatible surface, which ensures that at least partially with the tissue a permanently ossifying merging takes place. Fig. 4 shows a view of an artificial joint. Jump and tibia are each connected to an anchoring element, which establish a detachable connection to the artificial joint. Fig. 4 {hip joint; ankle; artificially; interchangeable; Anchoring element; Connection; Bone}

Description

Field of application of the invention

The present invention relates to an anchoring element for holding a joint part of an artificial joint for restoring an ankle, hip joint or other joint.

The preferred embodiments are described below with reference to the restoration of the foot and hip joints. However, the invention is not limited thereto.

The invention can also be used in similar joints, especially in load-bearing joints. The invention may also be used in restoring after amputation or other injuries.

Characteristic of the known state of the art

For a considerable period of time attempts have been made to replace destroyed joints with artificial prostheses. The prostheses have been anchored in the bone tissue either directly or by means of an intermediate adhesive layer, usually bone cement. For the prostheses, various materials have been used, such as stainless steel, chromium and cobalt alloys, titanium alloys, aluminum alloys, ceramics, carbon fiber and many other materials. Much ingenuity has been applied to the surface and surface textures that were believed to provide the best possible anchorage stability.The greatest problem of orthopedic surgery with prostheses is still how good the components of the prosthesis are in the bone tissue Experiments which involve a strong mechanical connection between implant and bone tissue ("press-fit", see EP 149527) and the use of bone cement (polymethyl methacrylate) have not led to satisfactory results.

Conventionally, the prostheses are secured in the bone cement. Great care has been taken to remove the bone marrow from the exposed bone - the cavity has even been rinsed clean before the prosthesis is inserted and then secured in the bone cement. However, the cemented prostheses often loosen up. This is particularly the case with prostheses cemented into a load bearing joint such as ankle and hip joints. It has also been found that bone cement used prior to hardening tends to infiltrate adjacent bone tissue. Based on this, seepage provides some mechanical stability, but in young, overweight, or more active individuals, the joint between bone and cement is ultimately destroyed by microshifts. A layer of connective tissue grows between the prosthesis and the knee, and eventually the joint loosens.

Another method used today is a cementless method, which aims at a biological security of the prosthesis, z. For example, a direct contact between prosthesis and bone tissue is desired without an intermediate layer of a connective tissue or an adhesive-working layer. In order to achieve satisfactory stability of the anchor, various materials and surface structures have been tested for the prosthesis, and a technique known as "press-fit" has been used to hold the prosthesis in place after insertion However, experiments (see Schimmel et Huiskes, Primary fit of the Lord cementless total hip, Acta, Orthop Scand 1988: 59 (6): 638-642) suggest that this method does not actually work. It has been found that this method leads to an extremely unfavorable three-point load with stress concentrations (EP 176711). The problem can not be solved simply by selecting a "suitable surface of a material." There are a number of other factors that are of crucial importance.

For this purpose, attempts have been made in recent years to anchor holders made of titanium into the bone marrow cavity of the bone in order to ingrowth ossifying, as described by Hagertetal. "Metacarpophalangal Joint Replacement with Osseointegrated Endoprostheses" in Scand., J. Plast., Reconstr Surg 20: 207-218, 1986. It is known to anchor oral and extra-oral prostheses to the bone tissue thereon Growing together in dentistry has been developed by Prof. Branemark and his colleagues over the past 25 years with excellent results by using retainers in the cheekbones to hold teeth and bridges, but the experiments performed by Hagert reveal this technique The unacceptable results seem to be due to the very different conditions that occur when using the "technique of dentistry" in the prosthetic restoration of finger joints. These problems are of course even more difficult in the case of ankle and hip joint prostheses, after completely different loads act on these joints. Today, the main problem in orthopedic surgery with prostheses still is that the bone anchoring unit loosens. However, with a success rate of more than 90% over a period of 20 years, there are a number of other problems which, in so far, have not yet had to be considered. One of the main problems is increasing wear of the joint part. There is a different type of prosthetic design compared to the previously used when asked if the ossifying process should be used. In order to exchange the joint part without damaging the bone anchorage, the system of the prosthesis must be divided into components in which the joint part can be separated from the actual anchoring element. In addition, when using the two-step method, it must be possible to connect the hinge part in a second step, if the patient or the artificial joint of the patient should not be immobile. There are two circumstances to consider:

1. The joint part is subject to wear and must therefore be interchangeable.

2. The joint part must be interchangeable in order to use the two-stage process can.

Object of the invention

It has now surprisingly been found that the problems and disadvantages of the techniques described above can be eliminated by the present invention.

Explanation of the Wosons of the invention

The invention relates to an anchoring torque for holding a hinge part of an artificial joint, wherein the anchoring ngseloment having an at least partially hollow guide and centering bushing for holding the hinge part, wherein the anchoring element is formed of a material that is compatible with the bone and bone marrow tissue, wherein the anchoring element has a surface which may at least partially grow together osseous with the tissue to achieve a permanent anchoring with the bone and bone marrow tissue. The invention also relates to an artificial joint for restoring a foot joint, a hip joint or another joint. Other features and advantages of the invention will become apparent from the following description of the preferred embodiments of the invention with reference to the accompanying drawings.

embodiment

The invention is explained in more detail by way of example with reference to the drawings. The drawings show

1 is an exploded view of an anchoring element according to a first embodiment of the invention; FIG. 2 is an exploded view of an anchoring element according to a second embodiment of the invention. The anchoring element of Fig. 2 generally corresponds to the anchoring element of FIG. 1, except that the

Anchoring element of Figure 2 has no wing-like plate and is arranged in an inverted position. Figure 3 is a perspective view of a first stage in the restoration of an ankle using the anchoring elements of Figs. 1 and 2

4 is a perspective view, similar to FIG. 3, after a completed restoration; FIG. 5 is a perspective view of a restoration of an ankle using an anchoring element according to a third embodiment of the invention;

Referring to FIG. 1, a non-rotationally symmetrical anchoring element 6 according to a first embodiment of the invention has a front plate 1. From the front panel 1 protrudes back a hollow, centrally located guide and centering bush (socket) 8 out. The bush 8 is substantially cylindrical in shape and is provided with a longitudinal corrugation on its radially outer surface. The corrugation promotes the growing together. The corrugation may expediently be identical to that of an axial projection of conical-tapered, rotationally symmetrical holders, which are used in dentistry. The end 9 of the socket 8, which is facing away from the front plate 1, has an internal thread which fits to an external thread of a screw 11. The side facing away from the joint of the bushing 8 is slotted, wherein a cavity 12 for receiving an insert 13 in a first step (as described below) is exposed. The back of the insert 13 has a pin 18 which fits into a corresponding recess (not shown) in the pin 11 when the insert is seated in place. From the front of the insert protrude leg substantially 14,15 outwards. When the insert 13 is in place, the legs 14, 15 with recessed flat surfaces 16, 17 (Figure 2) fit together on either side of the slot and cavity 12. The front edges 19, 20 of the legs 14, 15 are consequently brought into contact with projections 21, 22 on the front plate 1 when the insert 13 is finally positioned with a screw 23 cooperating with a threaded bore 25 on the end face of the insert 13 , The insert 13 also has a front projection 24. The front plate 1 has two holes, one on each side of the socket 8, for receiving the fastening screws 31.

The anchoring element 6 (Fig. 1) has a central, wing-like plate 26 which protrudes from the bushing 8. The anchoring element 6 '(Figure 2) does not have pine such plate. The upper end of the plate 26, which faces away from the bushing 8, has a threaded bushing 27 for receiving a screw 28. Both the plate 26 and the threaded bushing 27 are provided with a longitudinal corrugation which, like the corrugation 10, extends extends in the insertion direction of the anchoring element 6. The corrugations promote growing together. The plate 26 has a plurality of holes 29. The holes 29 give cutting edges.

In particular, the anchoring elements 6, 6 'of FIGS. 1 and 2 are preferably made entirely of titanium. The surfaces of the insert 13 and the front plate 1 are not corrugated to promote a growing together. When the anchoring element 6 (or 6 ') grows into the bone tissue, the insert 13 is removed and replaced by a permanent insert 13' (Figure 4) with an artificial joint part B.

Consequently, according to Fig. 3, the invention allows the original joint A to remain intact until the anchoring element 6, 6 'has grown in. The defective joint A is then replaced by the artificial joint B. The artificial joint B is positioned between the anchoring elements 6, 6 'as shown in FIG.

In one operation, the skin over the tibia 32 (or tibial bone) and anklebone 23 (or anklebone ankle) is opened near the joint A, and appropriate centers for the central appendage of the anchoring element 6 are determined. Then, four holes are carefully drilled in the tibia 32, and three corresponding holes are carefully drilled in the talus 33. The holes in the tibia 32 and the talus 33 are connected to each other with slots. Then a precise preparation is carried out, wherein for the anchoring elements 6, 6 'is the last preparation, when screws 31,28 are screwed. The paragraphs in the front plate 1 and in the threaded bushing 27 serve as a guide for the screws 31, 28. The screws 31, 28 provide additional stability and position the anchoring elements 6, 6 '. Once the anchoring elements 6,6 'have been positioned, a smooth polished insert 13 is placed in the socket of each anchoring element 6,6'. The anchoring elements 6, 6 'are then left in the bone 32, 33 until an ossifying ingrowth occurs. For anchoring elements inserted in the bone near a joint to restore an ankle of an ankle, the period of ingrowth is between three and six months. The joint A is completely intact during the ingrowth of the two anchoring elements 6, 6 '.

After the period of ingrowth, the injured or worn joint A is removed and replaced by the artificial joint part B. The artificial joint part B is expediently secured by means of the inserts 13 ', which are in the

respective anchoring elements 6, 6 'are opposite. Alternatively, the artificial joint B may be prepared in advance with two inserts 13 '. In the lotzteron case, during the period of ingrowth in the guide bushing 8, the present inserts 13 are replaced by new inserts 13 '.

Of course, instead of the two-stage procedure described above, the ankle can also be restored in one step. In such a restoration, however, there is the problem of loading the ankle before the anchoring elements 6, 6 'are sufficiently ingrown.

The anchoring elements 6,6 'can also be trusted in the automatic ingrowth of the anchoring elements 6,6' in the bone tissue without the special anchoring screws 31,28, vorwendet. In this case, however, where joints, such as ankles, e ^; ne certain load, these screws help 31,28 distribute the load and the anchoring elements 6,6 'to position accurately.

In the restoration of an ankle, as shown in FIGS. 1 to 4, the anchors are ngsele monte 6,6 'transverse to the longitudinal axis of the ankle. The two anchoring elements 6, 6 'use the same basic principle, but the anchoring element 6 for the tibia 32 has the special stabilizing and anchoring wing or plate 26. There is no room for such a plane in the ankle of the ankle. On the other hand, even in the tibia 32, the holding plate 26 is not urgently needed. Two anchoring elements 6 '(such as shown in Fig. 2) may be used to achieve the necessary restoration of the joint.

The invention, with the stable, ossifying ingrowth of the anchoring elements 6, 6 'into the bone tissue, is based on a comprehensive, experimental biological analysis of the structure and function of the joints in the course of a disease or during a defense reaction after a decomposition of the bone tissue Erosion or inflammation and extensive studies of blood supply to the bone marrow. It has been demonstrated that the synthetic replacement of damaged, artificial cartilage and tendons must be based on the basic principle that bone and marrow tissue form a unit with regard to structure and functioning. An interaction of the two components, considered at least over a longer period, is absolutely necessary if the hard tissue is to act as a supporting element. The invention is therefore based on the realization that, in anchoring a prosthetic exchange of a joint surface and tendons to parts of the skeleton near the joint, the interaction between bone marrow and bone tissue must be taken into account. Thus, fasteners used for this purpose in accordance with the invention must be made of a material which is compatible with the tissue and must be provided with a surface structure which ensures flawless, biological coalescence with the bone and marrow tissue. Of course, holes 29 in plate 26 particularly promote such ingrowth. When the anchoring element is used, the edges of the holes 29 perform a cutting function and ensure that the base plate fits well into the surrounding tissue and that a portion of the tissue is directed through the holes 29, resulting in a corresponding ingrowth of the anchoring element. 6 into its surroundings.

Referring to Fig. 5, which depicts an artificial hip joint, an anchoring element 6 "is used which has a central guide bushing 8 'with longitudinal corrugations 10 oriented in the insertion direction, unlike the anchoring element 6, the anchoring element 6" is made For reasons of space, there are provided with two wing-like plates 26 'which protrude from the bushing 8 "." As in the basic construction above, the plates 26' have through holes 29 with cutting edges. "Also provided in the plates 26 'are through holes for screws 31' have stepped diameters so that when they are screwed into the holes, they come into contact with the plate 26 'and consequently the ends 2 in the bone are prevented from causing damage The plates 26' are also provided with grooves 10, which run in the direction of insertion to a favorable ingrowth of the anchoring elements 6 "in the bone and bone marrow tissue to enable. The end of the guide bush 8 ', which is turned away from the hip joint, is closed with a pin-like screw 1V. The lower, the hinge-facing end of the screw 1 V is provided with a thread 34 so that the screw 11 'in the end 35 of the socket 8', which receives an artificial joint 36, can be screwed. All parts of the anchoring element 6 "are made of titanium.

During surgery, a lateral incision is made and a furrier wire is inserted through the lateral layers into the collum. At the same time, fluoroscopy allows orientation in two planes. A relatively large hole is then drilled to receive the bushing 8 'and slots are formed to receive the plates 26', 26 ", holes are then drilled perpendicularly to the screws 31 ', the latter holes having two different diameters, respectively The diameter of the screws 31 'is then allowed to grow in. Finally, the artificial joint part 36 is attached subsequent to the period of ingrowth, Alternatively, the entire operation can be done in one step. act as a preparation tool when inserted into the tissue. Alternatively, special preparation instruments may be used to achieve optimal conditions for ingrowth into the bone and may be left there as additional support and further to optimize stability. The ingrowth depends in part on the cutting edges of the anchoring elements, which give a perfect alignment with the surrounding tissue.

The basic principle of the present invention is therefore the recognition that bone and marrow tissue form a structural and functional unit and the interaction between them must be taken into account in this, if a surgical exchange is to be made. This means that, as far as technically possible, a connecting path between bone marrow and bone tissue must be made possible.

The above-mentioned anchoring screws may be shaped like the anchoring elements shown in my copending US application US 406486, which is formed as a hollow, substantially cylindrical barrel-like body with an external thread and, if appropriate, also with decreasing wall thickness. The open end of the body may be tapered and may be provided with slots starting at the open end. Thus, self threading is achieved when the helical body is scraped into the bone and the removed bone tissue is captured within the screw to ensure suitable ossification. Although the invention has been described in connection with a preferred Ausführungsalt, the skilled person many other modifications and modifications and other Einsaumöglichkeiten opened. It is therefore stated that the invention is not limited by this specific disclosure, but nui by di-i appended claims.

Claims (16)

An anchoring element for holding a joint part of an artificial joint, characterized in that the Vo. Anchoring element has an at least höhe hollow guide and centering bushing (bushing) for holding the joint part, wherein the anchoring element is formed of a material, which is compatible with the bone and bone marrow tissue, wherein the anchoring element has a surface which at least partially ossifying with the Tissue can grow together, u η to achieve a permanent anchorage in the bone and bone marrow tissue. 2. Anchoring element according to claim 1, characterized in that the artificial joint is an ankle. 3. Anchoring element according to claim 1, characterized in that the artificial joint is a hip joint. 4. Anchoring element according to claim 1, characterized in that this is not rotationally symmetrical. 5. Anchoring element according to claim 1, characterized in that it consists entirely of titanium. 6. Anchoring element according to claim 1, characterized in that the bushing has a longitudinal corrugation to promote the ingrowth. 7. Anchoring element according to claim 1, characterized in that this additionally comprises a front plate, wherein the socket protrudes from the front plate, wherein the socket has a slot and a cavity for connecting the joint part with the anchoring element. 8. Vorankerungselement according to claim 7, characterized in that this additionally comprises an insert which is replaceably positionable in the socket, wherein the insert piece covers the slot and the cavity. 9. Anchoring element according to claim 7, characterized in that this additionally has a fastening screw and a hole in the front plate for receiving the fastening screw. 10. Anchoring element according to claim 9, characterized in that this additionally comprises a second fastening screw and a second hole for receiving the second fastening screw. 11. Anchoring element according to claim 10, characterized in that the screws have an external thread over the substantially same length as the socket. 12. Anchoring element according to claim 1, characterized in that this additionally comprises a substantially flat, wing-like plate which protrudes from the socket. 13. Anchoring element according to claim 12, characterized in that the wing-like plate has a longitudinal corrugation and holes with cutting edges. 14. Anchoring element according to claim 13, characterized in that this additionally has an anchoring screw, wherein the wing-like plate includes a hole for receiving the screw, wherein the screw is disposed at one end, which faces away from the socket. 15. Anchoring element according to claim 13, characterized in that this additionally comprises a fastening screw, wherein the fastening screw has different diameters for positioning of the screw with respect to the wing-like plate. 16. Anchoring element according to claim 1, characterized in that it connects with a second anchoring element, the bone of a joint with the hinge part as an artificial joint, wherein the anchoring element consists of an at least partially hollow guide and centering sleeve, of which the hinge part is held, and is formed of a material that is compatible with the bone and marrow tissue of the joint, and has a surface that at least partially grows together ossify with the tissue to achieve a permanent anchorage in the bone and bone marrow tissue. For this 2 pages drawings