DE202005014269U1 - Endoprosthesis set for e.g. femur bone replacement, has distraction instrument inserted at its tip in overlapping region of transversal channel, such that instrument is displaced opposite to insertion direction when instrument is actuated - Google Patents

Abstract

The set has a plug connector including a projection on a segment (1) and a receiving element on another segment, and a distraction instrument (6). A transversal channel (4) partially overlaps a front side of the projection in a lateral manner and joins to the receiving element. The instrument includes a displacement surface which acts in a frontal manner upon the projection. The instrument is inserted at its tip in an overlapping region of the channel, such that the instrument is displaced opposite to the insertion direction when the instrument is actuated by moving equipment.

Description

The The invention relates to an endoprosthesis set comprising a plug connection with a projection on one and a receptacle on another Segment and a distraction instrument.

to Supply of large-scale bone defects endoprostheses are known which consist of several segments. Especially in endoprostheses for long bone replacement, such as for the femur, kick big personnel due to leverage at joints of the segments on. The coupling devices used there must therefore withstand considerable loads. They are strong enough dimensioned. This has the advantage of a safe and lasting Connection, but in case of a reoperation often only difficult to solve is. Especially for endoprostheses that are in operation high mechanical loads un subject, it may come to a kind of cold welding. Leave the segments then separate only with great effort. This is time consuming and leads to extend Operation times. There to solve considerable forces need to be applied There is also a risk of patient impairment Reaction forces, and moreover a not insignificant risk of injury to the surgeon and the patient slipping tools.

It is known, multipart prostheses by a connector with a cone (EP-A-0 474 015). To protect against an unintentional Solve points the cone on a circumferential groove, in which a grub screw as Fuse element engages. To release the connection must first the grub screw should be removed. The backup is thus canceled. Measures for support the separation of the prosthesis parts are not disclosed.

Of the Invention is based on the object, a Endoprothesensatz the initially mentioned type to improve that the segments also are easier to separate after high load.

The inventive solution lies in the characteristics of the independent Claim. Advantageous developments are the subject of the dependent claims.

at a Endoprothesensatz comprising a plug connection with a Projection on one and a reception on another segment and on Distraction instrument, wherein according to the invention in the Recording opening, the front of the projection laterally partially overlapping transverse channel is provided in the non-overlapping Area the distraction instrument with a frontal on the ledge acting displacement on his Tip is so usable that when operating the distraction instrument moved against the one setting direction. Under deeper here is one greater distance from the edge of the receiving opening Understood.

The Invention is based on the finding that by means of the transverse channel an independent one Access to a crucial point of the connector created is, from which a separation of the projection from the receptacle easily to accomplish is. This site is inaccessible in itself Reason of the recording. The cross channel opens the access. By the inventive arrangement is achieved by introducing a distraction instrument with a displacement surface, preferably as a slope is formed on a wedge-like tip using the wedge effect a connection solving Force against the insertion direction can be applied. In order to The plug connection can be easily pressed on from the inside out. Even very tight-fitting connectors can be solved in this way. The position of the distraction instrument is through the transverse channel fixed. hazards due to slipping instruments are not thanks to the invention to fear more.

It is appropriate, one Feed device for to provide the distraction instrument attached to the endoprosthesis supported. The over from the surgeon the distraction instrument applied force to separate the segments then causes a drag on the segment with the transverse channel. The body of the Patients will be according to the principle actio and reactio kept powerless. Its load is reduced continue through it. A particularly expedient embodiment is a thread feeding device with an arranged in the transverse channel internal thread and an the distraction instrument arranged external thread.

To the easy operation the distraction instrument advantageously has a handle on. Preferably, it is designed as a rotary knob. This can be done safely, and it can do that for the threaded feeding device applied required torque become.

The tip of the distraction instrument is preferably designed as a cone. It can be a full cone or a truncated cone. For reasons of injury safety with the distraction instrument removed, a truncated tip design is beneficial. A rotationally symmetrical design of the tip makes it possible that the separating effect of the distraction instrument is independent of its orientation to the endoprosthesis. This is especially important when the advancement of the distraction instrument is associated with a rotational movement, as in the case of the thread feeder.

Around a festering of the top or even a mushrooming of the projection to avoid, is the outer edge the projection is preferably cured. In order to He can the occurring when separating the segments considerable personnel safely record. It may be appropriate several cross channels over the To arrange the circumference of the segment distributed. This does not necessarily need be done at regular intervals. With two channels can they may be offset by 90 degrees, for example. One achieves so that the respective tips in two levels to act on the lead. deadlocks the projection in the receiving opening can to make it easier to solve become.

A preferred variant for the distraction instrument is that the displacement surface as lateral surface an eccentric is formed. This eccentric is inserted of the distraction instrument inserted into the transverse channel such that it has a small extent in the direction of insertion. Is the distraction instrument inserted into the transverse channel, so that the displacement surface itself Seen in the insertion direction behind the projection, so can the distraction instrument are rotated about its axis. there rotates the outer surface formed as an eccentric, whereby the expansion increases in the insertion direction. The Displacement surface comes by in abutment with the end face of the projection, and acts on these on further actuation of the distraction instrument with one against the insertion direction directed force. The projection is thereby pushed out of the receiving opening. - Another Variant is that the displacement surface on the outer shell of an expansion element is trained. The expansion element may be a pressure bellows act with a liquid or a gas is applied. This makes it possible the expansion element in a slackened state in the transverse channel introduce, until it is inserted so far that the displacement surface on the front of the Projection can act. Then in a second step, the expansion element actuated, by, for example, supplied compressed gas becomes. The expansion element expands, with the outer surface as Displacement surface acts and a force acting against the insertion direction on the projection exercises. The projection is thereby forced out of the recording.

To the Protection of the cross channel from contamination or clogging by Tissue may be provided a plug. He is expediently in such a way that, when inserted, it does not stick to the projection still rests out of the transverse channel to the outside. The danger a loosening or emigration of the plug then does not exist. Irritations of the surrounding tissue are likewise not to be feared. So that the plug is not too far or too little deep in the cross channel is introduced, it is favorable to provide a depth stop. He can be one in the desired Depth of the transverse channel or shoulder disposed on the plug itself be educated. What is important is that they are not out of the contour of the Endoprosthesis to the outside protrudes, and is not in contact with the projection.

at a particularly expedient variant, the possibly independent Deserves protection, the distraction instrument is made in two parts. One Part is formed by a Arbeitsab section, the other of a Operating section. They are over a quick coupling connected to each other. This can be a groove and spring connection, if for the feed as described a thread is provided. The of The working part formed part can be permanently on the Endoprosthesis remain. The part formed by the operation section is designed to be used if necessary and by means of the quick coupling to be connected to the work section for separating the segments. It It is understood that in this case the one of the working section formed part is such that it is in the inserted state does not contact the projection and also does not protrude beyond the contour of the endoprosthesis.

The Invention will be explained below with reference to the drawing, in the one advantageous embodiment is shown. Show it:

1 a view of the Endoprothesensatz;

2 an enlarged detail of the connector of two segments; and

3 Sectional views corresponding to the detailed representation for several stages in the separation of the segments; and

4 a, b partial views of two variants of the distraction instrument; and

5 Schematic diagrams relating to the stages when separating the segments with the variants of the distraction tools.

Illustrated as an embodiment is an elongated endoprosthesis as a replacement for a long bones, such as the femur. It consists of several segments 1 . 2 of varying length, two of which are in 1 are shown. They have an approximately rod-like shape. They are over a plug connection 3 connected with each other. At the joints is also a rotation lock 4 formed in the form of cooperating noses and grooves.

At the one segment 1 , the shorter with a length of about 40 mm, is an axially extending male cone 31 arranged as a projection. At the other segment 2 , the longer with a length of about 100 mm, is a shape-related female cone as a centrally located receiving opening 32 formed in the axial direction. In the inserted state are the mutually facing end faces of the segments 1 . 2 almost flush with each other. The distance between the outer edge of the male cone forms 31 from the edge 22 the receiving opening 32 a plug-in depth measure 34 , Male and female cone 31 . 32 are manufactured with tight tolerances, so that a backlash-free connector 3 results in a tight fit.

At the segment 2 with the receiving opening is a transverse channel 4 intended. He is transverse to the axis 36 the receiving opening 32 oriented, that is in the radial direction. He is at such a distance from the edge 22 the receiving opening 32 arranged that its central axis 46 (in plug-in direction 30 seen) behind the actual reason of the receiving opening 32 lies. Your distance from the edge 22 the receiving opening 32 is larger than the insertion depth dimension 34 However, in the illustrated embodiment, not more than the amount of half the width of the transverse channel 4 , With this arrangement of the cross channel 4 will reach that edge 11 of the male cone 31 when inserted in the outer, that is the edge 22 pointing half of the cross channel 4 lies. The cross channel 4 has an internal thread 45 on. It is preferably designed as a fine thread to allow a high power transmission.

In the cross channel 4 can be a blind plug 5 be used. He is with an external thread 55 provided in the internal thread 45 running. He has on its outward end face a hexagonal recess 57 for receiving a hexagonal wrench (not shown). He can thus easily in the cross channel 4 be screwed in and out again. At its outwardly directed end face is a circumferential stop shoulder 54 intended. It protrudes over the length of the external thread 55 out. It is designed to have a corresponding circumferential recess 44 to the cross channel 4 co. It prevents a too deep screwing in the dummy plug 5 and thus a contact between the bottom of the blanking plug 5 and the inserted male cone 31 , The blind plug 4 Therefore, does not migrate from the transverse bore in implanted endoprosthesis 4 out.

The endoprosthesis set according to the invention further comprises a distraction instrument 6 , It has a working section 61 with a rod-like shaft 62 and an outer thread disposed at its outer portion 65 on. It's running in a bit 63 from, which is designed as a cone. At least the top 63 is hardened. The distraction instrument 6 also has an operating portion 66 on. It includes a leader piece 67 whose extension is the rod-like shaft 62 forms, and a T-shaped knob attached 68 , It serves to make the surgeon the instrument 6 can turn by hand.

The use of the Endoprothesensatzes invention will be described below. It is assumed that for the reoperation of the endoprosthesis single or all segments 1 . 2 must be explanted. For this it is necessary that the plug connection 3 is solved. In the invention this happens in the following way:
In a first step ( 3a ) become the segments to be separated 1 . 2 exposed. It is not necessary that much space is created. It is important that an access route to the cross channel 4 with the inserted blind plug 5 free is.

In a second step ( 3b ) is the blind plug 5 unscrewed. This can be done with a standard hexagon wrench. The cross channel 4 is then open.

In a third step ( 3c ) becomes the distraction instrument 6 stated. It will do so with its tip 63 ahead in the cross channel 4 introduced until the external thread 65 on the rod-like shaft 62 on the internal thread 45 of the cross channel 4 encounters. The summit 63 lies in the middle axis 46 of the cross channel 4 and thus in the insertion direction 30 the connector 3 seen behind the outer edge 11 of the male cone 31 , and laterally offset so far that it is the cone 31 not contacted.

Then in a fourth step, the distraction instrument 6 by the surgeon by means of the gag piece 68 turned by hand clockwise. The distraction instrument 6 screwed by the cross channel 4 one, until the top 63 with her to the edge 22 the receiving opening 32 pointing bevel on the edge 11 of the male cone 31 meets. The distraction instrument 6 can now be further rotated, the male cone 31 with the further forward movement of the tip 63 due to their wedge effect from the receiving opening 32 is pressed until in step 5 ( 3e ) the segments 1 . 2 finally separated.

In a sixth step, this is how it works with detached segment for explantation.

In a first variant of the distraction instrument according to the invention, the rod-like shaft is 62 ' instead of an external thread 65 with an eccentric 65 ' Mistake. The eccentric 65 ' is sized so that it is in the cross channel 4 completely so far immersed that he in the insertion direction 32 seen behind the face of the male cone 31 is located, and there is preferably present. The shaft 62 ' has in its upper portion on a circular outer contour, the diameter of the transverse channel 4 so tuned that a leadership of the shaft 62 ' and thus the distraction instrument 6 ' is reached in the inserted state. The location of the eccentric 65 ' when inserting into the cross channel 4 is in 5a shown. The distraction instrument 6 ' is then operated as described by twisting, with the eccentric 65 ' in the direction of in 5b shown arrow turns. This results in a region of its displacement surface designed as an eccentric path with the front side of the male cone 31 in contact, which is an appreciably greater distance from the axis of rotation of the eccentric 65 ' having. At the beginning, this is done with a low gear ratio, ie based on the angular rotation of the distraction instrument 6 increases the distance of the front side of the male cone 31 contacting area of the displacement surface of the eccentric 63 ' only slightly opposite the axis of rotation. This is a high power translation for breaking loose the male cone 31 from the female cone 32 to disposal. Becomes the distraction instrument 6 ' further rotated, so come visibly more lying further away from the axis of rotation areas of the displacement surface of the eccentric 63 ' with the front of the male cone 31 in contact, causing the segment with the male cone 31 is ejected ( 5c ).

A second variant is in 4b shown. On the shaft 62 '' of the distraction instrument 6 '' is a pressure bellows 65 '' arranged. It is via an inner conduit (not shown) with a pressure fluid port 69 connected. In the depressurized state, the pressure bellows 65 '' slackens and has only a small outer diameter. In this state he can like the eccentric 65 ' into the space behind the front of the male cone 31 be introduced ( 5d ). To separate the segments 1 . 2 is then via the pressure liquid connection 69 a pressure fluid, preferably an isotonic water solution, via an inner connecting channel, not shown, the pressure bellows 65 '' fed. Due to the additionally flowed in pressurized fluid, the pressure bellows expands 65 '' which gives it a greater width ( 5e ). This will create a force (in 5e symbolized by an arrow) from the outside of the bellows as a displacement surface on the front side of the male cone 31 exercised. In this way, the male cone 31 hydraulically from the female cone 32 forced out.

Claims (14)

Endoprosthesis set comprising a plug connection ( 3 ) with a lead ( 31 ) on one and one recording ( 32 ) on another segment ( 1 . 2 ) and a distraction instrument ( 6 ), characterized in that one in the receptacle ( 32 ), the front of the projection ( 31 ) lateral partially overlapping transverse channel ( 4 ), in whose overlap-free area the distraction instrument ( 6 ) with a frontal on the projection ( 31 ) acting displacement surface at its tip is used so that when operating the distraction instrument ( 6 ) against the insertion direction ( 30 ) is moved. Endoprothesensatz according to claim 1, characterized in that the displacement surface as a slope on a wedge-like tip ( 63 ) is trained. Endoprothesensatz according to claim 1, characterized in that the displacement surface as a lateral surface of an eccentric ( 65 ' ) is trained. Endoprothesensatz according to claim 1, characterized in that the displacement surface on the outer jacket of an expansion element, in particular a compressed gas bellows ( 65 '' ), is trained. Endoprothesensatz according to one of claims 1 to 3, characterized in that for actuating the distraction instrument ( 6 ) a feed device is provided, which is supported on the endoprosthesis. Endoprothesensatz according to claim 5, characterized in that the feed device arranged in the transverse channel internal thread ( 45 ) and one on the distraction instrument ( 6 ) arranged external thread ( 65 ) having. Endoprosthesis set according to claim 2, characterized in that the tip ( 63 ) of the distraction instrument ( 6 ) is designed as a cone. Endoprothesensatz according to claim 2 or 7, characterized in that the tip ( 63 ) has a blunting. Endoprosthesis set according to one of the preceding claims, characterized in that the distraction instrument ( 6 ) a handle ( 68 ) for operation. Endoprothesensatz according to any one of the preceding claims, characterized in that the front side of the projection ( 31 ) is at least partially cured. Endoprosthesis set according to one of the preceding claims, characterized in that a plurality of transverse channels ( 4 ) over the circumference of the segment ( 2 ) are arranged distributed. Endoprosthesis set according to one of the preceding claims, characterized in that a transverse channel ( 4 ) plug closing to the outside ( 5 ) is provided. Endoprothesensatz according to any one of the preceding claims, characterized in that a depth stop ( 44 . 54 ) for the stopper ( 5 ) is provided. Endoprosthesis set according to one of the preceding claims, characterized in that the distraction instrument ( 6 ) is made in two parts, one in the segment ( 2 ) with the transverse channel ( 4 ) ( 61 ) are provided with the displacement surface and a removable operating portion.