DE19821048C1 - Insertion instrument for bone endoprosthesis has expansion head to connect insert to instrument - Google Patents

Abstract

The bone prosthesis insertion instrument has a connector for the insert formed of a distal expansion head (8,22) which can be relatively adjusted on slide faces (9,25). The expansion head has a screw head 922) and a hexagonal insert (8) which can move between connection and release positions.

Description

The invention relates to an insertion instrument for Endo prostheses for inserting an implant into the ent speaking cavity of a bone with a distal one and a proximal end, a grip area and one by connecting elements of the insertion instrument and of the implant formed connecting device for temporary connection with mutual axial and ra dialer definition of insertion instrument and implant, the connecting elements of the insertion instrument are formed by at least two expansion elements, the relative to each other in a solve and a verb tion position can be brought, and wherein the Spreizele elements in the release position a shape and a position have a separation of the insertion instrument from the implant while in the connector position have a shape and a position, which enables surfaces or edges of the expansion elements light, with surfaces or edges of the connecting elements to contact the implant, creating a firm Connection of insertion instrument and implant under Training of a force and / or positive connection ent stands.

Generic insertion instruments are used for insertion and for the exact placement of an implant,  for example an endoprosthesis, in the corresponding one Cavity, e.g. B. in a long bone. To this end the endoprosthesis, which is in the direction of the shaft on the Insertion instrument is seated, pressed into the cavity, aligned and cemented. To change the Ver prosthesis position during cement hardening avoid the insertion instrument from the prosthesis away. It is important that the connection is possible to solve as quickly and stress-free without the Change the position of the prosthesis.

An insertion instrument is for example from DE 44 06 388 A1 knows. With this instrument the Ver connection to the implant by a screw connection posed. The instrument points to this at its dista len end on a threaded portion that with a Ge wind blind hole on the prosthesis corresponds. To loosen the screw connection at least one part of the insertion instrument so that a Torque can be transferred to the prosthesis. On load-free removal of the instrument without changes The prosthesis position is therefore difficult and requires great manual skill of the ope rateurs. It is also complex and time-consuming.

A generic acetabular positioning Tool is for example from DE 94 90 464 U1 knows, with the two expansion elements from the release position be transferred to the connection position by inserted by a between the expansion elements spreading tool. From the DE  44 39 309 A1 and DE 92 12 846 U1 are hip prosthesis Gripping devices known with which the femur excellent end of the hip used in these steering prosthesis can be gripped. The prosthesis Clamping elements encompassing the shaft guide them surrounding sleeve-shaped sliding surface, whereby the prosthesis head is fixed between the clamping elements becomes. Finally, an instruction from EP 0408109 A1 insert and extract a hip joint pro these known, at the distal end of two relative to mutually movable jaws are arranged, the Pro grasp the head of the thesis and with the latter a form fit can enter into a connection.

The choice of expansion elements as connecting elements has the advantage that the insertion instrument is special light, fast and without any additional burden exercise can be removed from the implant. The The operator connects the insertion instrument before the on placing the implant with the same by pressing the Spreading elements by means of a suitable actuation direction moved to the connection position. He can now the insertion instrument-implant unit with one hand hold and thereby the implant in the cavity posi function. When loosening has the use of spreader bars ment the advantage that he rela Do not twist the implant, but the spread elements only from the connection position in the Must release position and then the In can remove the instrument.  

The generic instruments described above ha all have the disadvantageous property that to spread the spreading elements a further spreading tool or Clamping tool must be provided.

Accordingly, it is the task of the present inventor dung, an insertion instrument of the type described at the beginning To simplify the way it is constructed.

This task is for an insertion tool for Endoprostheses of the type described in the beginning solved accordingly in that the spreading elements rela tiv are mutually displaceable and thereby on Sliding surfaces rest against each other in such a way that the chaff z elements from the release position to the connector position and vice versa.

Due to the formation of sliding surfaces, a stu seamless transition from the release position to the connection position and vice versa. This is especially true special for pulling off the insertion instrument from the Implant advantageous because it is jerk-free in this way can happen.

It is particularly advantageous if the spreading elements arranged at the distal end of the insertion instrument are. In this embodiment, the insert forms strument the extension of the implant. So is even with an implant of the Sen longitudinal axis recognizable for the surgeon.  

It is expedient if the expansion elements are in the axial direction Ver direction of the insertion tool against each other are slidable and if the sliding surfaces are inclined to Longitudinal axis of the insertion instrument. To this There is a relative axial movement of the expansion element mente particularly easy in a radial Redirected movement. Are the spreading elements for the purpose the connection with an implant in an opening of the same introduced, then leads an axial movement of the Spreading elements while sliding into a radia len, which makes them move relatively apart and finally a positive and / or positive connection can form the opening in the implant. Here are un Different forms of implant opening possible for example openings with or without an undercut.

According to a particularly preferred embodiment form of the invention it is provided that the spreader elements through one end of a hollow shaft of the insert instrumentes and by a protruding from it Pressure body are formed and that the obliquely ver running edge of the shaft and a sloping top of the pressure body form the sliding surfaces. By this configuration only needs a spreading element re who can be moved relative to the insertion instrument  the. As a result, the construction and manufacturing process wall significantly reduced. It is also conceivable that Pressure body to replace what the use of the one setting instrument for implants with different Allows receiving elements.

It is particularly advantageous if the shaft overlaps a contact edge in a recess of the implant insertable extension which is one of the Spreading elements forms. The contact edge accordingly forms a stop that has a defined axial position tion between the insertion instrument and the implant enables. Inserting the insert too deep mentes in the receiving element of the implant is ver avoided. In addition, one of the insertion instrument is axial pressure not exerted on the movable pressure body transferred to the implant by. This is particularly easy the moving parts of the instrument.

It is favorable if the pressure body with a Shaft penetrating tie rod is connected. By the pull rod is a power transmission in the axial Possible direction of the instrument on the pressure body. As already described above, this leads to the fact that expand the expansion body in the radial direction and there by forming a connection with the implant.

According to a preferred embodiment of the invention it is advantageous if the pull rod within the Shaft at the distal end in the radial direction play having. If the spreading elements are relative to each other the axial movement will slide into a radial one  Redirected movement. This requires a certain game the pull rod in the radial direction. It would be exemplary but also conceivable that the tie rod with the An pressure body is not firmly connected and this relative are mutually displaceable in the radial direction.

It when the tie rod is a particularly advantageous has elastic range, whereby the tie rod in stretched in the axial direction and in the radial direction can be bent. Through these properties the Tie rods can always occur manufacturing tolerances be easily balanced. Furthermore, there are no others moving parts between the drawbar and the on pressure hull necessary. This reduces the construction ons and manufacturing costs considerably. The due to the axial movement of the drawbar caused radial movement tion of the expansion elements also forces the pull rod radial motion component if this with the An pressure body is firmly connected. Leaves particularly easy this requirement is met by a tie rod ren, which has an elastic region.

According to a particularly preferred embodiment form of the invention is the tie rod with a Zugvor connected direction that a defined shift in allows axial direction. This defined ver Slidability is necessary because the corresponding on acquisition elements, for example openings, of the implants are specified. To overstretch the train to avoid rod, it is beneficial to their axial Ver limit sliding distance. By this limitation at the same time the expansion of the expansion elements in ra  limited direction. This enables a defi ned default setting for the force and / or shape necessary forces.

It when the pulling device is particularly advantageous one attached to the proximal end of the hollow shaft includes the eccentric lever. An eccentric lever can be easily be pivoted with one hand. It means that the expansion elements from the release into the connection Override position if the eccentric lever corresponds is pivoted. In particular, by the length of the Lever for connecting or releasing the insert The force required by the implant is preset become. The lever also has the advantage that the stel development of the expansion elements from the position of the lever is recognizable.

According to a preferred embodiment, that the eccentric lever in the release position laterally from Instrument protrudes. This way it is instantly recognizable bar that the spreading elements in the release position are located.

It is favorable if the eccentric lever in the connection position on the side of the instrument. The Ver binding position of the expansion elements is immediately over the position of the eccentric lever can be seen. A wide one rer advantage is that the eccentric lever by the hand of the Operateurs is enclosed when this is the instrument holds on to the grip area. This makes it unintended undoing the connection between the insertion instrument and  Impossible to implant. Furthermore, through this position the operating area is not unnecessarily restricted.

Basically, it can be provided that the spreader elements have a polygonally limited cross-sectional area point. For example, the expansion elements in Form of an external hexagon are formed with egg ner corresponding hexagon socket opening of the implant corresponds. If the insertion instructions are twisted ment-implant unit around its longitudinal axis becomes a purely by connection formed additionally supported by this form fit. An unintentional slipping or spinning of the insertion instruments This prevents tes relative to the implant.

In principle, it would also be possible for the spreading element elements have an identical cross-section. Thereby is a complex shape of the receiving opening of the Avoided implant, which in turn the construction and manufacturing costs reduced.

In principle, it would also be advantageous if the one setting instrument a blow at its proximal end has area. To insert the implant into the the corresponding bone cavity is also different use a striking tool, such as a hammer det. In order not to damage the insertion instrument, is a special design of a face green stig.

The following description of a preferred embodiment tion form of the invention serves in connection with the Drawing of the detailed explanation. The drawing shows:

FIG. 1 is a longitudinal section through an instrument Einsetzin, which is fitted in the release position to an implant;

FIG. 2 is an enlarged sectional view of the connection area A of the insertion instrument and implant in FIG. 1;

Fig. 3 is a cross section along the line 3-3 in Fig. 2;

Fig. 4 shows a longitudinal section through a Einsetzin instrument with associated implant in the connection position;

Fig. 5 is an enlargement of the connection area B in Fig. 4; and

Fig. 6 shows a cross section along the line 6-6 in Fig. 5.

In Fig. 1, an insertion instrument 1 is shown, which can be connected to an endoprosthesis 2 . A tubular shaft 3 with a circular cross section extends along the longitudinal axis of the insertion instrument 1 and is surrounded by a grip jacket 4 at its proximal end. The grip jacket 4 extends from the proximal end of the insertion instrument 1 to approximately one third of the length of the shaft 3 . A ra dialer projection 5 of the shaft 3 forms for the grip jacket 4 in the direction of the distal end of the insertion instrument 1 a stop. Two diametrically opposed clamping pins 6 and 7 penetrate completely through the handle casing 4 and extend up to about half the wall thickness of the shaft 3 into it, whereby the handle casing 4 is secured immovably and non-rotatably relative to the shaft 3 .

The shaft 3 tapers slightly conically starting from the projection 5 up to its distal end. The di stale end is formed over a short section as an outer hexagon, the corner points of the regular cross-section hexagon of the outer hexagon 8 lie on a circle, the diameter of which lies between the inner diameter and the outer diameter of the shaft 3 . The edge 9 of the external hexagon 8 lies in a plane whose normal is inclined by approximately 20 ° with respect to the longitudinal axis of the shaft 3 . By forming the distal end of the insertion instrument 1 as an external hexagon 8 is formed at the transition from the cross-section in the round portion of the shaft 3 to the outer hexagon 8 is a Aufsetzkante 10th This can be seen particularly well in FIGS. 2 and 5.

The inner diameter of the hollow shaft 3 expands within the extension range of the Griffman means 4 in one step to the proximal end of the insert 1 .

The proximal end of the grip jacket 4 extends over the length of the shaft 3 in the form of two half-shell bearing blocks 12 , through which an eccentric lever 13 is laterally limited. An eccentric head 15 of the Ex zenterhebels 13 has parallel side surfaces that fit exactly between the pillow blocks 12 . The eccentric head 15 has an incision, the incision floor 17 runs parallel to the arm 16 of the eccentric lever 13 ver. As a result, the eccentric head 15 itself forms two bearing blocks which are connected by a bearing pin 14 , the longitudinal axis of which extends transversely to the longitudinal axis of the shaft 3 . The bearing pin 14 penetrates egg ne eyelet 18 of a tie rod 19 which is positively fitted into the section of the shaft 3 which has an inside diameter and is displaceable therein in the axial direction. The tie rod 19 extends approximately 3/4 of the length of the enlarged from the inside section of the shaft 3rd

At its distal end, the tie rod 19 has a blind hole 20 provided with an internal thread. In this, the proximal end of a pull rod 21 , which is provided with a corresponding external thread, is screwed in and extends to the distal end of the shaft 3 . At its distal end, the pull rod 21 has a hexagonal screw head 22 , the outer shape of which corresponds to that of the outer hexagon 8 . The surface 25 of the screw head 22 facing the edge 9 of the external hexagon 8 is chamfered and runs parallel to that in which the edge 9 of the external hexagon 8 lies (cf. FIGS. 2 and 5). The outer diameter of the pull rod 21 is significantly smaller than the inner diameter of the shaft 3 , whereby the train rod 21 has 3 play within the shaft and can be moved with the screw head 22 transversely to the longitudinal axis of the shaft 3 .

The endoprosthesis 2 has a receiving opening in the form of a hexagon socket 23 at its end facing the insertion instrument 1 . The depth of the opening is chosen so that the screw head 22 of the insertion instrument 1 does not touch the bottom of the opening when the insertion instrument 1 strikes the endoprosthesis 2 with its attachment edge 10 .

In the following, the connection of the insertion instrument 1 with the endoprosthesis 2 will be explained with reference to FIGS . 1 to 6.

In the release position, the arm 16 of the eccentric lever 13 protrudes laterally from the insert instrument 1 at an angle of 90 °. Due to the axially symmetrical arrangement of the tie rod 19 and the tie rod 21 within the shaft 3 , the cross sections of the hexagon 8 and the screw head 22 overlap (see FIG. 3). The distal end of the insert 1 formed by the external hexagon 8 and the screw head 22 can now be inserted into the internal hexagon 23 of the endoprosthesis 2 until the attachment edge 10 sits on the edge of the opening of the internal hexagon 23 , as shown in FIG. 2 is.

To connect the insertion instrument 1 with the endo prosthesis 2 , the eccentric lever 13 is pivoted until the arm 16 is aligned parallel to the longitudinal axis of the shaft 3 . Due to the eccentric shape of the eccentric head 15 , the tie rod 19 connected to it via the bearing pin 14 with the eyelet 18 is pulled in the direction of the proximal end of the insertion instrument 1 . The connected via the tie rod 21 with the tie rod 19 ne screw head 22 also moves in the axial direction until its edge 9 facing beveled surface 25 touches the edge 9 . The pull rod 21 is still deeply drawn into the shaft 3 at the transition to the connection position, and the inclined surface 25 of the screw head 22 slides on the edge 9 of the hexagon socket 8 (see FIG. 5). This sliding has the result that the contours of the hexagon socket 8 and the screw head 22 slide relative to each other ver, as shown in Fig. 6. The hexagon 8 and the screw head 22 thus move away from one another in the radial direction, as can be seen in FIG. 5. This finally leads to a frictional connection between one side of the hexagon socket 8 and the screw head 22 and the inner surfaces of the hexagon socket 23 facing them.

The insertion instrument 1 and the endoprosthesis 2 are thus firmly connected to one another. A rotation of the setting instrument around the longitudinal axis of the shaft 3 does not lead to slipping of the external hexagon 8 or the screw head 22 in the internal hexagon 23 , since the hexagonal contour of the three parts leads to an additional tilting of further surfaces during a rotation.

The prevailing clamping force between the insertion instrument 1 and the endopro thesis 2 can be adjusted by the tensile force and the inclination of the inclined surfaces at the edge 9 and the screw head 22 . In the present case, the tensile force is effected by a Schnellspannver circuit, which is formed by the eccentric lever 13 . The force metering for the clamping force is set by the pull rod operated in the elastic range. Alternatively, a spring element is also conceivable, which can be arranged at any point between the eccentric lever 13 and the screw head 22 .

Due to the construction chosen here, tensile forces can also be transmitted to a limited extent. These depend essentially on the coefficient of static friction of the contacting surfaces of the hexagon socket 23 , the screw head 22 and the hexagon socket 8 . A corresponding increase in this static friction coefficient, for example through a special coating, could allow higher tensile forces. Alternatively, it would be conceivable to connect the implant frictionally with the insertion instrument not only by clamping without an undercut as described above, but also to shape the outer contours of the screw head 22 and the hexagon socket 8 and the inner contour of the hexagon socket 23 so that these interlock positively during the radial expansion, which could result in clamping with an undercut.

The eccentric lever 13 is in the connecting position, so a side surface of the eccentric head 15 lies in a plane which runs transversely to the longitudinal axis of the shaft 3 . This side surface of the eccentric head 15 can serve as a striking surface 24 in order, if necessary, to drive the implant into the cavity of a bone using a striking tool, for example a hammer.

Claims (15)

1. insertion instrument for endoprostheses for inserting an implant into the corresponding cavity of a bone with a distal and a proximal end, a grip area and a connecting device formed by connecting elements of the insertion instrument and the implant for temporary connection with mutual axial and radial fixing of insertion instrument and implant, the connecting elements of the insertion instrument being formed by at least two spreading elements which can be brought into a release and a connecting position relative to one another, and wherein the spreading elements have a shape and a position in the release position which separate the A setting instrument from the implant allows, while in the connection position they have a shape and a position that enables surfaces or edges of the expansion elements to come into contact with surfaces or edges of the connection elements of the implant, thereby a firm connection of the insertion instrument and the implant is formed with the formation of a force and / or positive connection, characterized in that the expansion elements ( 8 , 22 ) are displaceable relative to one another and thereby abut one another via sliding surfaces ( 9 , 25 ) such that the expansion elements ( 8 , 22 ) get from the release position into the connection position and vice versa. 2. Insertion instrument according to claim 1, characterized in that the spreading elements ( 8 , 22 ) at the distal end of the insertion instrument ( 1 ) are arranged. 3. Insertion instrument according to one of claims 1 or 2, characterized in that the spreading elements ( 8 , 22 ) in the axial direction of the insertion instruments ( 1 ) are mutually displaceable and that the sliding surfaces ( 9 , 25 ) obliquely to the longitudinal axis of the insertion instrument ( 1 ) run. 4. Insertion instrument according to one of the preceding claims, characterized in that the expansion elements ( 8 , 22 ) by one end ( 8 ) of a hollow shaft ( 3 ) of the insertion instrument ( 1 ) and by a protruding from this to pressure body ( 22 ) are formed and that the inclined edge ( 9 ) of the shaft ( 3 ) and an inclined upper side ( 25 ) of the pressure body ( 22 ) form the sliding surfaces. 5. Inserting instrument according to claim 4, characterized in that the shaft ( 3 ) has an insertion edge ( 10 ) into a recess ( 23 ) of the implant ( 2 ) insertable extension which forms one of the expansion elements ( 8 ). 6. Insertion instrument according to one of claims 4 or 5, characterized in that the pressure body ( 22 ) with a shaft ( 3 ) passing through the rod ( 21 ) is connected. 7. insertion instrument according to claim 6, characterized in that the pull rod ( 21 ) within the shaft ( 3 ) at the distal end in the radial direction Rich game. 8. Insertion instrument according to one of claims 6 or 7, characterized in that the pull rod ( 21 ) has an elastic region, whereby the pull rod ( 21 ) can be stretched in the axial direction and bent in the radial direction. 9. insertion instrument according to one of claims 6 to 8, characterized in that the pull rod ( 21 ) is connected to a pulling device ( 13 , 19 ) which enables a defined displacement in the axial direction Rich. 10. Insertion instrument according to claim 9, characterized in that the pulling device ( 13 , 19 ) comprises egg NEN at the proximal end of the hollow shaft ( 3 ) eccentric lever ( 13 ). 11. Inserting instrument according to claim 10, characterized in that the eccentric lever ( 13 ) protrudes laterally from the instrument ( 1 ) in the release position. 12. Inserting instrument according to one of claims 10 or 11, characterized in that the excenter lever ( 13 ) in the connecting position rests laterally on the instrument ( 1 ). 13. Insertion instrument according to one of the preceding claims, characterized in that the expansion elements ( 8 , 22 ) have a polygonally limited cross-sectional area. 14. Insertion instrument according to one of the preceding claims, characterized in that the expansion elements ( 8 , 22 ) have an identical cross section. 15. Insertion instrument according to one of the preceding claims, characterized in that the insertion instrument ( 1 ) has a striking surface ( 24 ) at its proximal end.