DE3319916A1 - Implant and a combination of parts containing this implant - Google Patents

Abstract

Implant comprising at least two parts, the first (1) of which can be pushed onto a conical peg (3) on the second part (2). At the same time, a nut (7) is provided between the cone (3) and a shaft (4) of the second part (2) for lifting the first part (1) off the cone (3). An implant section having working surfaces (8) for a retaining tool (10), for example an open-jaw spanner, is provided between the nut (7) and the cone (3). This spanner can be used to arrest the implant on rotation of the nut (7). At the same time, the open-jaw spanner (10) is pressed by the nut (7) against the first part (1) until it detaches from the cone (3). <IMAGE>

Description

description

The invention relates to an implant as in the preamble of the patent claim 1, as well as a combination of parts with such an implant.

In the German patent application P 33 08 229 there is an implant of at least two parts, the first of which on a conical spigot on the second Part is plugged, has been proposed, which is characterized in that the The pin has a thread with a nut between its foot and its cone, which can be screwed against the first attached part to such an extent that it is removed from the cone solves. It was assumed that with implants, especially endoprostheses, there may be a need to replace or re-anchor implant parts. In order to facilitate the explantation of a fixed part in the bone when replacing a (first) part To avoid cemented (second) part of the prosthesis, the first part must be Replace the second part remaining in the bone. This separation the wedged parts require great forces, and there is a risk of that as a result of manipulation, for example as a result of slipping of chisel-like Tools that are commonly used to separate bone or soft tissue to be damaged.

Accordingly, the older proposal was based on the task of a To create an implant in which the two parts separate more easily permit; should especially the strength and lasting Durability of the connector between the two parts is not affected will.

An advantageous further development of the older proposal was to that the first and / or second part of attack surfaces for a holding tool against twisting around the thread axis.

Such implants can be used, for example, as hip or knee prostheses Find use. In addition to a shaft, the second part has a conical one Pin on which the first part can be attached, on which there is an artificial one Articular surface is located. This is subject to wear and tear, which is also part of it can lead to the fact that the corresponding prosthesis part must be replaced. Furthermore it is also the case if only the other associated articular surface is involved in a reoperation has to be replaced, expediently, of the proposed implant as well to replace the first part with the articular surface, as this only requires a small amount of additional work and possibly saves another operation that may be required later. So both articular surfaces are renewed during an operation. Needs The operating surgeon no longer has to pay attention to that during the operation absolutely damage to the joint surfaces on the proposed implant be avoided.

Especially with "collarless" hip joint prostheses, that is, with those the pin of the second part seamlessly into passes over the shaft, it has now been shown that the proposed implant is difficult to use because between the shaft and the screwed-on nut (with which the first part (artificial joint ball) can be lifted off the conical shaft of the second part can) bad contact surfaces for a holding tool against twisting around the thread axis have it attached. It has also been shown that holding on to the first part (Joint ball) is difficult to carry out when turning the nut: because of different Ball diameter different tools would have to be kept ready, which also are unwieldy, especially with larger ball diameters. They grip badly too on the smooth spherical surface, so that there is always the risk of bad The seat of the tool creates chips that fall into the surgical wound and cause complications being able to lead. It has also been shown that the mother in the proposed implant can limit the mobility of the artificial joint.

In order to avoid these disadvantages, there is a need for the present invention hence the task of creating an implant of the type specified at the outset, in which the two parts can be easily separated from each other in other ways without Strength and long-term durability of the connector between the two parts or the mobility of the artificial joint can be significantly impaired.

This object is achieved by the implant with the features of Claim 1. In the subclaims, advantageous developments are given, being claims 7 and following on a combination of parts denote which contains the implant and a largely complete assembly kit including the special tools required.

With the invention it has been achieved that the first part of the second still with the help of one between the shaft and the cone on the second Part of the arranged nut can be loosened. The mother sits in the implanted state no longer directly on the first part, but rather it is located between the mother and the first part (e.g. joint ball) a gap. In this space are on the first part of attack surfaces for a holding tool with which twisting of the implant when turning the nut can be prevented, so that the occurrence of the tight fit of the implanted prosthesis shaft impairing Forces is prevented.

To detach the first part from the second part of the implant is therefore the holding tool set on the attack surfaces, the nut in the direction of the Holding tool rotated and thus pressed the holding tool against the first part. When turning the nut further, the holding tool moves on the contact surfaces on the first part of the implant. The holding tool serves as a spacer between Mother and first part. It transfers the power from the mother to the first part, because in this way it is lifted from the cone of the second part.

The fact that in the implanted state between the first Part and the mother now have a space in between the attack surfaces located, allows greater mobility for the joint, for example consists of the joint head and an artificial acetabulum.

An attack surface is preferably a flat surface (a so-called chamfering) the part of a cylindrical and / or prism-shaped implant section between the nut and the cone. The axis of this implant section runs essentially parallel to the thread and / or cone axis. The flat surface is when implanting of the shaft clearly visible and makes it easier to adjust the shaft direction.

In particular, there are two attack surfaces that run parallel to one another present on opposite sides of the implant. For example it can be the side surfaces of a square.

The implant is part of such a design of the attack surfaces Containing parts combination with a holding tool suitable for the attack surfaces, that must have the properties appropriate to its purpose: It must be between the first part and the nut screwed onto the thread can be brought into engagement and at the same time - according to its function as a spacer - a strength must have those of the nut, the thread and stop surfaces on the first part for the holding tool is adapted so that the first part is with the help of the nut with the interposition of one on the one hand on the nut and on the other hand on the stop surface of the first part adjacent holding tool can lift off the cone.

For example, if the attack surfaces are the outer surfaces of a square, an open-end wrench is particularly suitable as a holding tool.

When the largest cone diameter is larger than that for the square required wrench size, the wrench can be used when pressing the joint ball get stuck on the cone if the thicker end of the cone comes out of the attached joint ball protrudes. To prevent it from getting stuck, it is advisable to use an open-end wrench to provide the wrench size on one of its two flat sides to the other Distance of the attack surfaces, so the wrench size for the square, adapted is, while the width across flats of the open-end wrench is on its other flat side is larger than the largest cone diameter.

Another variant of an attack surface is that in the A longitudinal groove is provided between the nut and the cone of the implant section which one side wall serves as an attack surface for a nut wrench. A such a key has the advantage of requiring little space. So he can help to keep the surgical wound small. The same advantage is also achieved by that the mother of the implant contour is largely adapted. Appropriately has they have an annular approach at the end that turns away from the cone on, which largely seals the thread against penetrating body fluid.

Also the purpose of keeping the surgical wound as small as possible, pursues a further advantageous development the part combination, in which a ratchet wrench is provided as a turning tool for the nut. With him the operation time can also be shortened. A common wrench for a hexagon nut has to be swiveled by 60 e before it can be replaced again must be set. The surgical wound must therefore be so large that there is such a thing Rotation is possible. The constant new approaches costs time. A ratchet wrench on the other hand, as described for example in DE-OS 31 29 710, only needs to be swiveled by a few degrees and then does not even have to be pulled off and reinserted, but it is simply swiveled back before the next swivel stroke. If such a ratchet wrench according to the advantageous development in a mouth-shaped head contains a mouth-shaped chuck that rotates in one direction freely rotatable, but is self-locking in several positions in the other, the problem can arise that the nut just then stops turning should be when the mouth-shaped chuck in the ratchet wrench its mouth-shaped Head locks. The ratchet wrench is still in from the mother Can be removed in axial direction because the first part (joint head) has now been removed from the two-part one Implant could be removed.

In another embodiment of the invention, the mother is with a circumferential toothing, grooving or perforation provided in such a way that one in his The function of a slot nut wrench with a pin, a Engage nose or a counter tooth in the corresponding recess of the mother can and a loosening or tightening with short angular strokes. This allows handling with a simple tool, with the point of engagement for the pin or counter tooth of the tool preferably on the one facing away from the operator Side is located, so that the force holding the pin in engagement by the action the holding tool designed as an open-end wrench can be compensated and in this respect also the emergence of the tight fit of the implanted shaft loosening forces is prevented. If a locknut wrench is used as a holding tool is used, the nose is for this reason - based on rectified keys - to be placed opposite the corresponding nose of the other key so that compensate for the forces holding the lugs in engagement.

Preferred exemplary embodiments are explained in more detail with the aid of the drawing explained.

Figure 1 shows a first embodiment of a combination of parts in the form of a hip joint prosthesis with the associated holding tool, FIG Sectional view along the line A-A in Figure Idar.

FIG. 3 shows a section from FIG. 1, modified accordingly another embodiment, while Figure 4 shows the associated holding tool shows.

Figure 5 shows a further embodiment of the nut with associated Operating tool.

In Figure 1 is an artificial hip joint head with a shown in section first part 1 with ball-and-socket joint surface. This first part 1 is pushed onto a conical pin 3 of a second part 2, since it has a shaft 4. Between the cone 3 and the shaft 4 is located a thread 6 on which a nut 7 is screwed. This has in the illustrated State, i.e. the implanted state of the implant, a noticeable distance to the first part 1 of the implant.

Located in the space between the cone 3 and the nut 7 on the second part 2 there is an implant section with contact surfaces for a holding tool, of which a flat attack surface 8 faces the viewer. As in the sectional view A-A tin Figure 2 can be seen, the attack surface 8 is one of four attack surfaces of a square. The opposite of the attack surface 8 parallel The attack surface is denoted by 9. It takes hold of the other two attack surfaces an open-end wrench 10, which is used to hold the second part 2 against rotation serves around the longitudinal axis 11, but at the same time there is also a spacer between the nuts and joint ball.

If the first part 1 is now to be detached from the second part 2, then the nut 7 is screwed in the direction of the cone 3, initially as long as until it touches the spanner 10. If you continue to turn the nut 7 the Open-ended wrench 10 is pressed against a contact surface of part 1 and slowly lifts it from cone 3.

The wrench 10 is when you lift the part 1 in the direction of Axis 11 moves, but remains with the contact surfaces between the thread 10 and the cone 3 are arranged in engagement.

In Figure 1, the spanner has a wrench size on its underside according to the dimensions of the part 2 formed by the attack surfaces Square. The wrench size is expanded at the top of the open-end wrench 10, so that the wrench does not hang on the cone protruding from part 1 remain.

The nut 7 has a largely rounded and thus the part 2 Adapted contour. On its underside in FIG. 1 there is an annular one Approach 12, which in the implanted state rests on a shoulder on the shaft 4, see above that a seal of the thread 6 against penetrating body fluid is given is.

In the detail of Figure 3 is instead of a square a longitudinal groove 13 in the implant section between the cone 3 and the thread 6 intended.

Figure 4 shows how in this longitudinal groove 13 instead of a wrench a locknut wrench can intervene, the strength of which must in turn be selected in such a way that that when you lift off part 1, the distance between this part and the mother 7 can bridge. The groove 13 extends into the cone in, so that the nut wrench moves far enough when lifting part 1 from cone 3 can move towards the cone 3.

In Figure 5 is an alternative embodiment of a nut 7 ' shown with associated operating tool 15, the nut being a substantially Has a cylindrical or conical jacket-shaped outer contour, into the recesses 16 in Circumferential direction are regularly distributed.

A nose designed as a counter tooth engages in these recesses 16 17 or a pin (indicated by dashed lines), so that tightening or loosening the Nut 7 'with small angular strokes is possible if in each successive Recesses 16 is engaged. The recesses 16 can - as required - be arranged distributed with larger or smaller distances in the circumferential direction.

(The dashed end of the recess 16 in FIG indicated that these recesses either in the vertical direction the nut 7 ' can traverse completely or as closed blind holes with round ones or polygonal cross-section.) The point of application of the opposing tooth, the nose or pin 17 is on the side facing away from the operator of the shaft on the tool 15, so that when tightening or loosening the nut 7 ' forces that occur when holding back using the open-ended wrench 10 going be compensated, since with this tool a pressure force is exerted when counter-holding must be a tensile component during the engagement of the opposing tooth or pin 17 requires. In the case of differently designed holding tools, a corresponding when in use, the opposing arrangement of those engaging in the shaft Noses also provided force compensation.

Due to the design of the nut 7 'with a cylindrical or conical jacket-shaped Outer surface and recesses 16 located therein can be shaped achieve which with respect to their outer contour - with the exception of the recesses 16 - That of the transition area of the prosthesis shaft 4 to the cone 3 to a large extent is adapting. - blank page -

Claims (15)

Implant and the combination of parts containing it P a t e n t a n s p r ü c h e Implant consisting of at least two parts, the first one at the end can be plugged onto a cone of a pin of the second part which is attached to the pin afterward has a shaft, between the cone and Shank both a thread for a nut and contact surfaces for a holding tool against twisting around the thread axis, characterized in that the attack surfaces (8, 9) are arranged closer to the cone (3) than those furthest away from the cone Parts of the thread (6) and that the engagement surfaces (8, 9) are designed in such a way that they with the help of the nut (7) a displacement of an engaged Holding tool (10) in the axial direction of the thread (6) in the direction of the attached first part (1). allow until it is detached from the second part (2). 2. The implant according to claim 1, d a d u r c h g e -k e n n z e i c h n e t that an attack surface (8) is flat and part of a cylindrical and / or prism-shaped Is the implant section, the axis (11) of which is essentially parallel to the thread and / or cone axis. 3. Implant according to claim 2, d a d u r c h g e -k e n n z e i c h n e t that the attack surfaces (8, 9) parallel to each other on opposite sides Sides of the implant. 4. Implant according to claim 1, d a d u r c h g e -k e n n z e i c h n e t that the side wall of a longitudinal groove (13) is provided as an engagement surface is. 5. Implant according to one of the preceding claims, d a d u r c h it is not noted that the nut is used as a working surface for a tool contains recesses with surfaces at regular intervals on its circumferential surface, which are defined by vectors pointing in the circumferential direction. 6. The implant according to claim 5, d a d u r c h g e -k e n n z e i c h n e t that the recesses are parts of a toothing, grooves or around Blind bores with a round or rectangular cross-section are involved. 7. Implant according to one of the preceding claims, d a d u r c h it is not noted that the nut (7) of the implant contour largely is adapted. 8. Implant according to one of the preceding claims, d a d u r c h it is not noted that the mother is at that end which is from the Cone (3) turns away, has an annular shoulder (12) sealing the thread. 9. parts combination with the implant according to one of claims 1 to 6, d a d u r c h e k e n n n z e i c h -n e t that they are one of the attack surfaces (8, 9) contains matching holding tool (10) between the first part (1) and the nut screwed onto the thread (7) engageable is, the strength of the holding tool (10) the nut (7) the thread (6) and the stop surface of the first part for the holding tool is arranged in such a way to one another are that the first part (1) with the help of the mother with the interposition of the on the one hand on the nut and on the other hand on the stop surface of the first part (1) adjacent holding tool (10) 'can be lifted off the cone (3). 10. Combination of parts according to claim 9 with the implant according to claim 2 or '3, d u r c h e k e n n -z e i c h n e t that as a holding tool (10) a spanner is provided. 11. Parts combination according to claim 10, d a d u r c h g e k e n n z e i c h n e t that the width across flats of the wrench (10) on one of its two Flat sides is adapted to the distance between the attack surfaces (8, 9), but on the other Flat side is larger than the largest cone diameter. 12. Parts combination according to claim 9, with the implant if claim 4, it is not stated that a locknut wrench is used as a holding tool (14) is provided. 13. Combination of parts according to one of claims 9 to 12, d a d u r c h g e k e n n n z e i c h n e t that as Turning tool for the nut a ratchet wrench is provided which has a mouth-shaped head in a mouth-shaped head Contains chuck that rotates freely in one direction of rotation, but in several directions in the other Positions is self-locking. 14. H parts combination according to claim 7 with the implant according to claim 5 or 6, d u r c h e k e n n -z e i c h n e t that as a turning tool (15) for the nut (7 ') a nut wrench is provided, which one to the Has recess (16) adapted pin or tooth (17). 15. Parts combination according to claim 14, d a d u r c h g e k e n n z e i c h n e t that the pin or tooth (17) when using an open-end wrench (10) as a holding tool on the side opposite the handle, when used a locknut wrench (14) as a holding tool on the parallel-aligned Keys of the engaging nose of the locknut wrench (14) arranged opposite one another is.