DD301734A9 - 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 finger joint. It is a substantially rotationally symmetrical hollow body and has a connecting end for receiving a detachable connection part of an artificial joint, so that there is no injury to the bone anchorage in an exchange of the joint. The anchoring element has a tissue-compatible and micro-pitted surface, which ensures that at least partially with the tissue, a permanent ossifying merging takes place. Fig. 2 shows a complete artificial finger joint. Fig. 2 {finger joint, artificial, exchangeable; Anchoring element}

Description

Field of application of the invention

The present invention relates to an anchoring element for holding an artificial joint part and an artificial joint.

A preferred embodiment of the invention will be described in detail with reference to a restoration of a finger joint. However, the invention is not limited thereto.

The invention may be used for other similar joints such as toe joints, elbow joints and so on. The invention may also be used in restorations after amputation or similar injuries.

Characteristic of the known state of the art

Restorations of finger joints containing prostheses have originally been performed on MCP joints that change in rheumatic disease. Prostheses known for this purpose have Swanson Silastic finger joints. Such joints are made of a silicone-like material, are elongated and have ends with a substantially circular cross-section. The ends can be inserted and anchored in the bone marrow cavity of each bone. The middle part of the prosthesis is elastically deformable and thus forms the actual joint part. The St.George prosthesis, a cemented prosthesis, is also known as an artificial finger joint.

A problem with these conventional prostheses is that the anchoring element that holds the actual prosthetic mechanism loosens or hurts the surrounding tissue, and undesirable displacement of the prosthesis in the direction of the load occurs.

For this purpose, attempts have been made in recent years to use supports on titanium which are anchored in the bone marrow cavity of the bone, with the intention that they grow in ossicles, as described by Hagert et al. ("Metacarpophalangal Joint Replacement with Osseo-integrated Endoprojtheses" in Scand, J. Plast., Reconstr Surg., 20, pp. 207 to 218, 1986) It is already known to anchor oral and extraoral prostheses in the bone tissue Over the last 25 years, coalescence in dentistry has been further developed by Prof. Branemark and his colleagues with excellent results in inserting retainers into the cheekbones to hold teeth or bridges. "The experiments that Hagert performed on these The inacceptable results seem to be due to the very different conditions that occur when applying this "dentistry technique" to the restoration of finger joints with a prosthesis. For example, in the known techniques, the bracket is anchored at right angles to the longitudinal axis of the bone. In the finger joint, the holder is arranged along the axis of the bone. As a result, completely different loads and forces act on the anchoring elements.

Today, the main problem in orthopedic surgery with prostheses continues to be the loosening of the bone anchoring unit. However, with a success rate of more than 90% for dental implants over a period of 20 years, a number of altered problems occur which have not heretofore been considered. One of the main problems is increasing wear of the joint part. Thus, a different type of prosthesis design compared to the previously used is required if the ossifying method is to be used together. In order to exchange the joint part without injuring the bone anchorage, the system of prostheses must be divided into components in which the joint part can be separated from the actual anchoring element. Moreover, if the two-step method is used, it may be possible to join the hinge part in a second step if the patient or at least the artificial joint of the patient is not to become immobile. Two factors must be taken into consideration: First, the joint part is subject to wear and must therefore be exchangeable. Second, the hinge part must be replaceable in order to use the two-step process.

Object of the invention

It has now surprisingly been found that the problems and disadvantages of the above-described Techn ^! ken can be eliminated by the present invention.

Explanation of the essence of the invention

The invention is based on extensive experimental biological analyzes of the structure and function of the joints in the course of a disease or during a defense reaction following degradation of the bone tissue through erosion or inflammation and extensive studies of the blood supply to the bone marrow. It has been shown that in the synthetic exchange of destroyed, artificial cartilages and tendons, bone and bone marrow must be treated as a structural and functional unit. It is essential to consider this for bone and bone marrow fusion, especially for long periods when the hard tissue must serve as a stop. The invention is therefore based on the realization that, in anchoring a prosthetic replacement for a joint surface and tendons to parts of the skeleton near the joint, the interaction between bone marrow and bone tissue must be considered. This means that a linking element in the bone marrow cavity of a long bone must be anchored by mechanical elements that allow a pathway between bone marrow and bone tissue as far as technically possible, possibly over the entire length of the anchoring element, in particular on the interface between bone marrow and compact Bone in the wall of the Knochenmarkhöhlung consideration is taken.

Consequently, the invention is directed to an anchoring element for holding a joint part, wherein the anchoring element is substantially rotationally symmetrical, is at least partially hollow and contains a material which is compatible with the tissue of the bone. The anchoring element has a surface which can at least partially grow together ossifying with the tissue and achieve permanent anchoring from the inside out in the longitudinal axis of the bone. The invention also relates to an artificial joint.

Other features and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention.

AusfOhrungsbelsplel

The invention is explained below with reference to an example with reference to the drawings. The drawings show

1 shows a sectional view through an artificial finger joint with an anchoring moment

Fig. 2: a complete artificial finger joint

3 shows an arrangement of the anchoring element in a long bone

4 shows a perspective view of the anchoring element

Fig. 5: a sectional view of the article of Figure 4 along the line V-V

6 is a fragmentary sectional view through the subject of FIG. 4 along the line Vl-Vl, FIG.

which forms a part of the joint part according to the invention

Fig. 7: illustrates the assembly of the hinge part with the anchoring element according to the invention

FIGS. 8-10 illustrate some other embodiments that demonstrate how to achieve and / or improve non-twisting wedging between the anchoring element and the guide bushing.

In Fig. 1, the parts are one? long bone on each side of a joint part 1 of a finger with 2 and 3. A rotationally symmetrical anchoring element 4 is formed as a hollow, substantially cylindrical sleeve-like body 5, with external thread 6 and decreasing thickness of the wall. The open insertion end 7 of the body S is conically tapered and provided with slots 8 and 9, which begin at the open insertion end 7.

A connecting end 13 (FIG. 6) of the anchoring element 4, which lies closest to the joint part 1, is arranged in a guide bush 11. The printed guide bushing 11 is substantially cylindrical and is provided with a longitudinal corrugation on its radially outer surface. This corrugation may expediently be identical to an axial section of conically tapered, rotationally symmetrical brackets used in dentistry. The guide bushing 11 surrounds the connecting end 13. The connecting end 13 of the body 5 is thus firmly connected by wedging with the inner surface 14 of the guide bushing 11 when the body 5 is sufficiently screwed into the bone tissue. The connecting end 13 receives angesteckbar connecting parts 15 of the joint part 1. The connecting parts 15 may be central pins (Fig. 7), which protrude from the hinge part 1. Such pins cooperate with corresponding recesses 16 in the anchoring element 4 or in a connecting piece (not shown), which is expediently arranged between the guide bush 11 and the joint part 1 together. One or more holes may be directly connected to the radially outer surface of the anchoring element 4, with the edges of the holes toward the surface-forming cutting edges. Self-cutting action is thus achieved by screwing the body 5 into the bone 2. The removed bone tissue 17 is received within the anchoring element 4, as Fig. 5 illustrates.

Where the thickness of the wall of the anchoring element 4 gradually decreases to the insertion end 7 and / or where the anchoring element 4 has the longitudinal slots 8 and 9, the requirement for good ductility is met, which increases the risk of stress concentrations that contribute to particular problems the known versions of this type leads, considerably reduced. The arrows B-B in Fig. 1 indicate the flexibility of the open introducer endos 7, such as its ability to conform to the surrounding bone tissue. The same applies to the arrows A-A. The slots 8 and 9 may conveniently be provided with cutting edges and, when the cavity receives the scraped bone tissue 17, as shown in Fig. 5, the anchoring element 4, in itself, is its own preparation tool. At the same time, optimal conditions for normal anatomical and physiological conditions are ensured by minimizing interference with the remaining biological tissue, for example bone marrow and bone tissue.

Fig. 2 shows an artificial joint, as it is achieved with the anchoring element used.

Fig. 3 shows how the anchoring element is positioned in the bone 2. In practice, the anchoring element 4 is positioned in the interface between bone marrow and bone tissue. The wall thickness of the cylindrical sleeve-like body 5 decreases towards the slotted insertion end 7 and ends in a conically tapered cutting edge 12. The edges of the longitudinal slots 8 may also be shaped as cutting edges. The scraped-out bone tissue 17, which results when the anchoring element 4 is screwed into the bone marrow cavity 10, is dispensed into the cavity within the body 5, as illustrated in FIG.

In one operation, a portion of the long bone 2 near the joint is cut off so that the bone marrow cavity 10 is exposed. Then, a probe (not shown) is inserted into the medullary cavity to determine a usable longitudinal axis for insertion of the anchoring element 4. The probe is used to find the direction in order to be able to apply the anchoring element 4 centrically as desired. Then, a shoulder for the guide bushing 11 is carefully drilled into the exposed bone marrow cavity 10. After the guide bushing 11 has been inserted, the cylinder sleeve-like body 5 is screwed into the medullary cavity 10, through the guide bush 11 therethrough. The probe has of course been previously removed. The Vorbindungsende 13 of the anchoring element 4 is flared outwardly widening, as shown at 18, so that its diameter is slightly larger than the underlying opening of the guide bushing 11. Thus, finally, a wedging between the connecting end 13 and the guide bushing 11 (if the guide bushing 11 is brought into the position indicated by dashed lines in Figure 6), so that both, guide bush 11 and cylinder sleeve-like body 5, are brought into the desired position.

The anchoring element 4 and the guide bushing 11 are or are made of titanium or coated with titanium. The structure of the titanium surface is such that coalescence is promoted at least at the important parts of the surface. Advantageously, the surface may have irregularities in the form of micro-dimples, as described in Swedish patent specification S 7902035-0, with dimple diameters between 10 and 100 nm, preferably 10 to 300 nm. Alternatively, chemical constituents may be added to the titanium surface layer cause a particular positive tissue reaction, as described for example in Swedish Patent S 8505158-9.

Fig. 8 shows how the upper end 19 of the guide bushing 11, facing the flange 20 of the anchoring element 4, is provided with a projecting edge 21 which is mounted to cooperate with teeth 22 of the flange 20. The anchoring element 4 and the guide bushing 11 are therefore not rotatable and firmly connected when the body 0 is ganug wide screwed into the bone substance.

An alternative connection possibility between the guide bush 11 and the anchoring element 4 is achieved with the arrangement as shown in Fig. 9, wherein an axial corrugation 23 is mounted, which cooperates with the inner surface of the guide bush 11.

A further possibility of connection can be achieved by the arrangement shown in FIG. 10 in that the upper outer edge of the anchoring element 4, which is screwed into the bone tissue, receives a special toothing 24. Although the invention has been described in connection with a preferred embodiment, many other modifications of the modifications and other uses will become apparent to those skilled in the art. It is therefore stated that the invention is not limited by this specific disclosure, but only by the claims.

Claims (14)

An anchoring element for holding a hinge, characterized in that the anchoring element is substantially rotationally symmetrical, is at least partially hollow and contains a material which is compatible with the tissue of the bone, wherein the anchoring element has a surface at least partially with dome tissue ossify together to achieve a permanent anchorage from the inside out in the longitudinal axis of the bone. 2. Anchoring element according to claim 1, characterized in that the material of the anchoring element is titanium. 3. Anchoring element according to claim 1, characterized in that the surface of the anchoring element is coated with titanium. 4. Anchoring element according to claim 1, characterized in that the hinge part is part of an artificial finger joint. 5. Anchoring element according to claim 1, characterized in that the surface of the anchoring element is a radial outer surface and at least partially has micro pits with a diameter of 10 to 300nm. 6. Anchoring element according to claim 1, characterized in that the anchoring element has a cylindrical sleeve-like body with a radially outer surface with external thread for screwing the anchoring element into the bone. 7. anchoring element according to claim 6, characterized in that in addition holes are provided which are directly connected to the radial outer surface, wherein the holes have cutting edges on the radial outer surface. 8. Anchoring element according to claim 7, characterized in that the cylindrical bush-like body is deformable. 9. Anchoring element according to claim 8, characterized in that the cylindrical sleeve-like body has a wall and an open insertion end, wherein the thickness of the wall gradually abnimrr.t against the insertion end. 10. Anchoring element according to claim 9, characterized in that longitudinal slots are provided through the wall, wherein the slots extend from the insertion end to the hinge part. 11. Anchoring element according to claim 10, characterized in that the slots have cutting edges. 12. Anchoring element according to claim 11, characterized in that the cylindrical bush-like body has a connecting end, which is arranged close to the hinge part, and a guide bush, wherein the connecting end is positioned in the guide bush and against rotation of the guide bush, so that the guide bush surrounds the connecting end , 13. Anchoring element according to claim 12, characterized in that the connecting end defines an open end which faces the hinge part to releasably insert the hinge part in the anchoring element. 14. Anchoring element according to claim 1, characterized in that it connects together with a second anchoring element the bone of a joint with the hinge part as an artificial joint, wherein the anchoring element is substantially rotationally symmetrical, is at least partially hollow and contains a material that is compatible with the Tissue of the bone tolerates, wherein the anchoring element has a surface which at least partially grows together ossifying with the tissue, thereby achieving a permanent anchoring from the inside out in the longitudinal axis of the bone. For this 3 pages drawings