DE102012207450A1 - Surgical instrument for releasing clamping fit of pivot insert in joint socket e.g. acetabular cups, has insertion guide whose distance from inner surface of joint insert is short with respect to central position of joint insert - Google Patents

Abstract

The surgical instrument (4) has two supports which project in distal direction from the instrument and are connected with a central to the joint socket (1). A central insertion guide (6) is arranged centrally with respect to the supports, such that it is projected distally from the instrument having the shape of the inner surface of the joint insert (2). The distance of central guide from the inner surface of the joint insert is short with respect to central position of joint insert.

Description

The present invention relates to a dissolution instrument, in particular a solution instrument for a ceramic hinge insert in a joint socket, in order to possibly release it from the press fit in the respective joint socket without damaging the ceramic joint insert.

State of the art

In acetabular cups, for example in acetabular cups, articulated inserts are often held by a clamping cone connection. To be able to release such joint inserts again from the socket, it is either necessary to destroy the joint inserts or provide special devices on the socket, which allow ejection of the joint insert from the socket. For example, in the DE 295 16473 U1 a screw assembly on the socket described by which the hinge insert can be pushed out of the socket. But this makes it necessary; form the joint socket accordingly and release an opening in the joint insert.

Another instrument for releasing a hinge insert is applied to the hinged socket such that the inner surfaces of the step of the instrument abut against the upper circular edge of the socket from the outside. Then hit with a hammer on a pestle, which is provided at the proximal end of the instrument. Thereafter, the instrument is applied to a circumferentially different position of the socket and rebounded. After a few strokes, the clamping connection between the socket and the joint insert is released, so that the joint insert can be removed from the socket.

A disadvantage of this instrument is that it must be brought into contact with the joint socket at a certain angle and that the impact must also be applied in a certain direction. If the instrument is placed at a wrong angle to the acetabular cup, such as a acetabulum, it may cause the instrument to slip when the impact is applied, causing injury to the patient, be it at the hip bone or surrounding tissue. It may also be that the joint insert is damaged and destroyed.

In the DE 196 11 248 A1 a socket is described, which has for detachment of the insert from the outer shell to the outer shell a lug to which a percussion device is immovably applied. Also, therefore, the outer pan must be designed in a certain way to allow the solution of outer pan and use.

In the DE 197 08 604 C1 discloses a surgical instrument for releasing the pinch fit of a hinge insert in a socket. This instrument has at least two supports which can be placed on the edge of the joint socket and which are connected to a striking surface arranged centrally with respect to the joint socket and pointing away from the open side of the joint socket.

It is an object of the present invention to provide a surgical instrument, with the aid of the clamping connection between the joint insert and the socket can be solved without the need for special constructive embodiments of the joint insert and the socket would be necessary. In addition, it is an object of the present invention to safely prevent slippage of the instrument from the socket.

This object is achieved according to the invention by a surgical instrument of the generic type, which has at least two supports which can be applied to the edge of the socket, projecting from the instrument in the distal direction and having a face directed away from the open side of the socket are connected. In addition, the instrument has an insertion aid arranged centrally with respect to the supports, which protrudes distally from the instrument and essentially has the shape of the inner surface of the hinge insert. In this case, the insertion aid holds a small distance to the inner surface of the hinge insert with central alignment in the hinge insert.

More specifically, the insertion aid, which also acts as a centering aid, largely fills the hinge insert, at least in the region of its opening. However, with centric alignment of the insertion aid in the joint insert, a small gap always remains between the inner surface of the joint insert and the surface of the insertion aid. In the region of the distal end of the insertion aid, a greater distance is provided relative to the inner surface of the joint insert than in the proximal region of the insertion aid. In addition, the distance of the inner surface of the hinge insert from the surface of the insertion aid in an axial section through the instrument and the socket is variable. A tangent to the point of the cut figure where the distance between the hinge insert and the insertion aid assumes a local minimum, that is the point with the shortest distance between the hinge insert and the insertion aid, forms an acute point with the longitudinal axis of the instrument Angle between 5 ° and 45 °, preferably between 10 ° and 35 ° and more preferably between 15 ° and 25 °.

When the instrument is positioned on a socket from which the hinge insert is to be removed, the insertion aid enters the recess of the hinge insert as a centering aid. As the instrument continues to slide in, the instrument centers on the acetabulum until the posts abut the upper edge of the socket. The centering allows thus a quick and reliable placement of the supports on the upper edge of the socket without significant slippage of the instrument on the edge of the socket. Without significant slippage means that the supports can not change their position so far that they slip off the top of the socket. When the supports rest on the upper edge of the socket, it may happen that the insertion aid abuts a position on the inner surface of the hinge insert, namely at the location described above, at which the distance between the hinge insert and insertion aid has a minimum. If a shock or an impulse is then applied to the instrument in a substantially axial direction, for example by striking the proximal striking surface with a hammer, the predominant part of this impact or impulse is transmitted through the supports to the joint socket. Since, however, contact between the insertion aid and the joint insert may be present at at least one point, a portion of the pulse or the impact may also be transmitted there. So that at this point only a very small force transmission can take place and thus damage to the hinge insert and in particular its inner surface is prevented, the insertion is compared to the hinge insert designed so that the potential contact point is located in an area where the tangent to the insertion occupies the acute angle described above. This has the consequence that the axially introduced into the instrument load can be transmitted at this point only to a very small extent and largely slides off the insertion on the inner surface of the hinge insert.

According to an advantageous embodiment of the present invention, the insertion aid is substantially hemispherical. Since the inner surface of the hinge insert is also substantially hemispherical in shape, it is ensured that the two forms substantially correspond. Advantageously, the insertion aid is flattened at its distal end, so that at this point the gap is increased to the hinge insert relative to the edge region. In addition, the insertion aid has a slightly smaller diameter than the hinge insert.

According to a further advantageous embodiment of the present invention, the insertion of plastic is formed, preferably made of PEEK (polyetheretherketone). The present instrument is particularly suitable for solving joint inserts made of ceramic from a joint socket. Plastic has a particularly low coefficient of friction compared to ceramic, which is to be judged to be particularly advantageous. In turn, PEEK is particularly suitable as a used plastic, as PEEK is dimensionally stable and unchanging even during reprocessing.

According to another advantageous embodiment of the present invention, the insertion aid is detachably mounted on the instrument and in particular screwed. There are joint inserts with different inner diameters and there are joint sockets with different outer diameters, which do not depend on each other. This means that a certain joint socket can accommodate different joint inserts with different inner diameters and that different joint inserts with the same inner diameter can be inserted into different joint sockets. The distance of the supports of the instrument to each other and thus the size of the instrument depends on the diameter of the joint socket, since the supports must rest on the upper edge of the socket. The size of the insertion aid depends on the inner diameter of the joint insert. But there are different sized sockets with one and the same inner diameter of the built-in joint insert. Likewise, a certain inner diameter of the joint insert may occur in joint pans of different sizes. In this respect, it is advantageous if you can combine different sizes of the instrument with different sized insertion aids to keep the number of components to be provided low. Therefore, it makes sense if an insertion aid is detachably attachable to the instrument, in particular, of course, can be screwed to the instrument.

According to a particularly advantageous embodiment of the present invention, two supports are provided on the instrument, which can be applied to diametrically opposite portions of the edge of the socket. Two supports allow a particularly easy insertion of the instrument into the hinge insert or the socket. In addition, two load introduction points are very well suited to release the hinge insert from the socket with just a single punch or impulse.

According to a further advantageous embodiment of the present invention, the striking surface is formed on a shaft which is replaceable mounted on the instrument. In this way, a shaft or shaft component is sufficient, which with The instrument of the required size and an insertion aid of the required size can be assembled.

According to another particularly advantageous embodiment of the present invention, the shaft is a socketing instrument. This means that the instrument and the insertion aid can be screwed onto the socket-driving instrument and thus the instrument according to the invention can be provided. With this structure, further, the required material can be reduced, since no shaft member must be provided in addition to the joint socket-Einschlaginstrument.

According to another advantageous embodiment of the present invention, the shaft is surrounded by a gripping surface. The grip surface may also be provided with a protective portion which, in the event of a failure on the striking surface of the instrument, protects the hand gripping the instrument.

According to another advantageous embodiment of the present invention can be provided that the striking surface is designed as a connection part for a mechanically operated impact tool. This may be, for example, a pneumatically or electrically operated impact tool, which is connected to the impact surface with the instrument so that blows generated by the impact tool are transmitted to the instrument. In this sense, the expression "impact surface" is to be understood as meaning that on the one hand a surface is hit by a hammer or a similar instrument, on the other hand, but also a part of the instrument that receives shocks generated by a percussion tool and in the instrument transmits.

Further advantages and features of the invention will become apparent to those skilled in the art from the attached figures and the detailed description of the embodiments.

1 shows a side sectional view of an embodiment of an instrument according to the invention and a joint socket with a hinge insert;

2 shows an enlarged section of the 1 ;

3 shows a section corresponding to the 2 in the inserted state; and

4 shows a side sectional view of the embodiment according to 1 in disassembled condition.

A first embodiment of the present invention is described with reference to FIGS 1 to 4 described in detail.

The surgical instrument 4 for releasing the clamping seat of a hinge insert 2 in a joint socket 1 according to the first embodiment has two at the edge 3 the joint socket 1 adjustable supports 5 on. These two supports 5 stand by the instrument 4 in the distal direction and are centered on the acetabulum 1 arranged and from the open side of the socket 1 path pointing away 10 connected. The joint insert 2 is in the socket 1 press-fit. The instrument 4 furthermore has a centric to the supports 5 arranged insertion aid 6 on the distal of the instrument 4 protrudes and essentially the shape of the inner surface of the hinge insert 2 having. The inner surface 8th of the joint insert 2 and the outer surface of the insertion aid 6 Both are essentially hemispherical. The insertion aid 6 thus maintains central alignment in the hinge insert 2 a small distance to the inner surface 8th of the joint insert 2 one.

The insertion aid 6 according to the present embodiment is made of PEEK (polyetheretherketone) and has an internal thread 11 , which on a corresponding male threaded portion 12 can be screwed, the distal of the instrument 4 protrudes. The insertion aid 6 is at its distal end 13 also flattened so that there is a larger gap to the inner surface 8th of the joint insert 2 is present as at the site 9 or near the edge of the hinge insert 2 , The instrument 4 also has a shaft 7 which can be used alone as a pan impact instrument. The shaft has this 7 via an external thread 14 that works both in a female thread section 15 of the instrument 4 as well as in a female thread section 21 the joint socket 1 can be screwed. The joint socket 1 which is used here has holes 22 with the help of which the socket can be screwed to the remaining bone of the patient, as well as projections 23 that the joint socket 1 after beating them into the bone, hold in the bone.

The shaft 7 is from a gripping area 16 surrounded so that it can be kept more pleasant and secure. In this embodiment, the gripping surface has 16 over indentations 17 and surveys 18 , The wells 17 form a comfortable bed for every finger and the elevations 18 Separate the fingers from each other and also serve the support. holes 19 and 20 are perpendicular to each other and perpendicular to the axis A of the shaft 7 drilled through the handle area. These holes 19 and 20 make the handle and thus the whole shaft 7 lighter, provide an even better grip of the hand on the grip surface 16 and provide a ventilation of the palm, resulting in a better feel of the grip surface 16 leads. A suitable handle material also reduces the stress on the wrist of the hand which is the shaft 7 stops while a punch or impulse hits the clubface 10 and thus the instrument 4 is applied. In the present embodiment, however, the gripping surface 16 us the clubface 10 integrally formed of metal.

In the present embodiment, the diameter of the insertion aid 6 slightly smaller than the diameter of the inner surface 8th of the hinge insert, which is a ceramic insert here. The spot 9 with the smallest distance between the insertion aid 6 and the inner surface 8th of the ceramic joint insert 2 is relatively close to the edge of the ceramic hinge insert 2 , The angle α between the tangent T at this point 9 and the axis A of the instrument 4 is about 25 ° in this embodiment. The gap between the inner surface 8th of the joint insert 2 and the outer surface of the insertion aid 6 is formed at the narrowest point, preferably between 0.1 mm and 0.2 mm wide, in the present embodiment, it is 0.15 mm. This gap is small enough to allow sufficient centering of the instrument 4 to the socket 1 to make sure without the supports 5 from the top edge 3 the joint socket 1 can slip off. On the other hand, the gap is thus large enough to damage the inner surface 8th of the joint insert 2 to prevent when a punch or impulse on the clubface 10 is applied and thereby the instrument 4 and / or the insertion aid 6 deformed. The insertion aid 6 comes in contact with the hinge insert at one point at most 2 ,

Should the introduction help 6 at two or more points in contact with the hinge insert 2 come, so would the introduction guide 6 in the joint insert 6 Wedge would put pressure on the hinge insert 2 Apply and thus a moment in the joint insert 2 produce, which in particular in a ceramic hinge insert 2 can lead to its damage.

Will now be a hit on the clubface 10 and thus the instrument 4 Applied, the impact pulse is through the two supports 5 on the socket 1 transfer. The impact causes the clamping in the cone connection between the clamping surface 24 on the socket 1 and the clamping surface 25 at the joint insert 2 lifted and the hinge insert 2 dissolves from the socket 1 , If doing the insertion 6 in contact with the inner surface 8th of the joint insert 2 come, so the insertion aid slides 6 due to the acute angle α at the Innanfläche 8th along without transmitting significant forces. After removing the instrument 4 can the joint insert 2 from the socket 1 be removed. Subsequently, the joint socket 1 be explanted with special instruments.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 29516473 U1 [0002]
• DE 19611248 A1 [0005]
• DE 19708604 C1 [0006]

Claims (9)

Surgical instrument for releasing the clamping seat of a joint insert ( 2 ) in a socket ( 1 ) with at least two on the edge ( 3 ) of the socket ( 1 ) adjustable supports ( 5 ) of the instrument ( 4 ) protrude in the distal direction and with a centric to the socket ( 1 ), from the open side of the socket ( 1 ) groundbreaking face ( 10 ), characterized in that the instrument ( 4 ) furthermore a centric to the supports ( 5 ) insertion aid ( 6 ) distal to the instrument ( 4 ) protrudes and substantially the shape of the inner surface of the hinge insert ( 2 ), wherein the insertion aid ( 6 ) with central alignment in the hinge insert ( 2 ) a small distance to the inner surface of the hinge insert ( 2 ). Surgical instrument according to claim 1, characterized in that the insertion aid ( 6 ) is substantially hemispherical. Surgical instrument according to claim 1 or 2, characterized in that the insertion aid ( 6 ) is formed of plastic, preferably of PEEK. Surgical instrument according to one of the preceding claims, characterized in that the insertion aid ( 6 ) on the instrument ( 4 ) detachable and in particular screwed. Surgical instrument according to one of the preceding claims, characterized in that two supports ( 5 ) are provided, which at diametrically opposite portions of the edge ( 3 ) of the socket ( 1 ) can be applied. Surgical instrument according to one of the preceding claims, characterized in that the striking surface on a shaft ( 7 ) which is replaceable on the instrument ( 4 ) is mountable. Surgical instrument according to claim 6, characterized in that the shaft ( 7 ) is surrounded by a gripping surface. Surgical instrument according to claim 6 or 7, characterized in that the shaft ( 7 ) is a socketing instrument. Surgical instrument according to one of the preceding claims, characterized in that the striking surface is formed as a connection part for a mechanically operated impact tool.

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