DE10014401A1 - Puller for loosening individual parts of an endoprosthesis - Google Patents

Abstract

A device (24), in particular a pulling instrument, for releasing the individual parts of an endoprosthesis (13), for example for an artificial hip joint or the like, is described. The extractor is used to release the interference fit between the shaft (3) and neck (2) or neck (2) and joint ball (1) of the endoprosthesis (13) and has two legs, the free ends (25) of which are in a groove (4) can be inserted between the shaft (3) and neck (2) or neck (2) and joint ball (1). The legs (8) can be moved away from one another by means of a spreading device and drive the parts of the endoprosthesis (13) to be released apart (FIG. 1).

Description

The invention relates to a device, in particular Puller, for loosening individual parts of a Endoprosthesis, for example for an artificial hip joint or the like, in particular for releasing the press fit from Shaft and neck or neck and joint ball of the endoprosthesis.

An endoprosthesis is u. a. Part of an artificial Hip joint and consists of a neck, a shaft and one Joint ball. The neck is both in the shaft, in one Bone is fixed, as well as on the joint ball that is in the Articulated socket sits, attachable in the press fit. If at Do not insert an artificial hip joint into the endoprosthesis is adjusted correctly or even when the Endoprosthesis, it is necessary to use the joint ball and / or if necessary, also detach the shaft from the neck. So far, devices have been used that are based on a Leverage. Here occur due to the leverage possibly very large lateral forces in the thigh or pelvic area, whereby the prosthesis in a predicament can arise, which may result considerable bone injuries result. Furthermore can the prosthesis itself be affected, so that new prosthesis parts may be used have to.

In contrast, the invention is based on the object Specify device of the type mentioned with which the individual parts of an endoprosthesis in a gentle manner can be resolved from each other and the problems become more familiar Techniques can be avoided.  

This object is achieved with the device according to the invention the features mentioned in the introduction essentially solved that the device has two legs, the free ends in a groove between the shaft and neck or neck and Joint ball of the endoprosthesis can be inserted and the legs are movable away from each other by means of a spreading device. This measure can be inserted into the groove Thighs and spreading the thighs the parts of the Endoprosthesis can be safely separated from each other. Here are the Leg held securely in the groove and preferably include the Neck of the endoprosthesis at least over a partial area. As soon as the legs away from each other by means of the spreading device are moved, those fastened together in the press fit Parts of the endoprosthesis gently and easily from each other solved without large transverse forces or the like occur could.

According to a first advantageous embodiment of the invention the legs are at one end by means of a pin bearing, preferably pivotable on bolts on a handle stored. In this respect, the device has approximately one pliers-like structure, but with the two legs preferably via an associated bolt each Bolt bearing are attached to the handle.

According to another advantageous embodiment of the invention are the free end sections of the legs on the bolt opposite section each as a tongue-like outer sheet educated. This creates the prerequisite that the tongue-like outer leaves slightly in the starting position and simply inserted into the groove of the endoprosthesis can.

At least one, preferably both, are particularly advantageous the mutually facing inner surfaces of the legs or outer leaves in the area of the free end as  Sloping surfaces executed. The sloping surfaces open in Direction of the free end of the outer leaves preferably below an angle of between the inclined surfaces of approx. 4 °.

Furthermore, it has proven to be advantageous that the inclined surfaces inclined towards the free end of the outer sheet a taper is formed, the inclined surface one Inclination or a cone angle of approx. 2 ° has or forms.

Furthermore, it has proven to be extremely advantageous that the spreading device between legs or Outer leaves slidably arranged tongue-like Has inner sheet, which in the area of the free end but preferably two-sided complementary inclined surfaces has, each preferably an inclination or have or form a cone angle of approx. 2 °.

The inner sheet has due to the arrangement of the Sloping surfaces towards the free end a thickening, which with the taper at the free ends of the outer leaves corresponds.

The outer leaves and the inner leaf have at the free end in each case one preferably arranged centrally, essentially arcuate recess in which the neck of the Endoprosthesis, essentially flush with the edge of the recess adjacent, recordable. Through this measure, one secure hold of the device on the parts to be solved Endoprosthesis. In the starting position of the instrument the inner sheet stands in opposite to the outer sheets to a certain extent or the inner sheet is opposite the outer leaves so that the semicircular Recesses of the legs or the outer leaves and of the inner sheet are substantially aligned.  

In this position the extractor is used with the Outer leaves and the inner leaf in the groove around the neck of the Endoprosthesis inserted, the recesses of the Engage the outer leaves and the inner leaf in the groove. By Spreading the outer leaves by moving the The inner leaf can be turned from the inside of the neck Loosen the endoprosthesis.

The outer surfaces of the outer leaves are particularly advantageous in the end or release position essentially aligned parallel to each other. In this position you can the inner surfaces of the outer leaves the outer surfaces of the The inner sheet is essentially flush.

Furthermore, the spreading device advantageously has one Sliding mechanism for the inner sheet with which the Inner sheet in the end or release position between the free ends of the legs or outer leaves retractable and retractable. Through this Measure is ordered based on the corresponding Sloping surfaces on outer sheets and inner sheet by pulling in a stroke movement of the inner sheet between the outer sheets of the outer leaves, which are the parts to be solved Gently pushes the endoprosthesis apart. This stroke movement of the Outer leaves take place essentially in the direction of Neck axis of the endoprosthesis or neck, so that Shear forces practically do not occur.

The sliding mechanism is particularly advantageous a threaded shaft, a threaded spindle or the like formed, which is rotatably received in the handle and with a corresponding thread one end of the Inner leaf arranged sliding part is engaged. Consequently can by rotating this shaft respectively  Threaded spindle a sensitive and metered stroke movement of the Outer leaves are generated.

According to an advantageous embodiment of the invention Shaft stored in a shaft bearing on the handle, by means of an axial bearing secured against axial displacement and preferably at the free end protruding from the handle connected with a twist grip.

According to a further embodiment of the invention Sliding part an upper and / or a lower longitudinal web, the or that in a corresponding slot, recess or the like of the or the legs are performed. Because of this measure results in a safe degree management of the Inner sheet during the displacement process or Spreading process of the outer leaves.

The stroke or the is particularly advantageous Spreading the free ends of the legs respectively Outer leaves when pulling the inner leaf between the Outer leaves below 3%, preferably below 1%, particularly preferred about 0.6% of the leg length between the free end and the Swivel bearing of the leg.

According to a specific embodiment of the invention the maximum stroke of the outer leaves under approx. 1 mm and the Leg length at about 100 mm.

The spreader moves the particularly advantageous Legs or outer leaves essentially axially, especially in the direction of the neck axis of the endoprosthesis apart.

Overall, when loosening the parts of the endoprosthesis practically exclusively forces are used in the axial Act in the direction of the holding axis of the endoprosthesis. Size  Lateral forces, as in the known lever techniques do not exist, the remaining ones, extremely minimal transverse forces are exerted by the device itself intercepted, so that damage to the individual parts of the Endoprosthesis or the bone is not to be feared are. Also the acetabular cup, in which the joint ball of the Endoprosthesis is inserted when the joint ball is released spared from the neck. This is due to the targeted use of the practically acting exclusively in the axial direction Dissolving forces attributable to the lifting movement of the Legs or outer leaves are generated. Moreover is also due to the extremely low inclination of the inclined surfaces of preferably about 2 ° and the thread mechanism for Moving the inner sheet relative to the outer sheets for an extremely sensitive, metered stroke movement of the Outside leaves catered for. Can also by the enormous Gear ratio between gear input on handwheel and Transmission output, namely the stroke movement of the outer blades due to relatively low input forces, very high forces for Loosen the parts of the endoprosthesis in the area of the outer leaves be generated.

Further goals, advantages, features and possible applications of the present invention result from the following Description of an embodiment based on the Drawings. All of them are described and / or illustrated presented features for themselves or in any more meaningful Combining the subject of the present invention, too regardless of their summary in the claims or their dependency.

Show it:

Fig. 1 is a schematic longitudinal sectional view of an embodiment of the invention Abziehinstrumentes in the position of use at an endoprosthesis,

Fig. 2 is a side view of the withdrawal instrument of FIG. 1 ° about the longitudinal axis rotated by 90,

Fig. 3 is a longitudinal sectional view of a leg of the Abziehinstrumentes of Fig. 1,

Fig. 4 is a side view of the leg of FIG. 3, but rotated by 90 °,

Fig. 5 is a side view of the inner panel with sliding parts of the Abziehinstrumentes of Fig. 1,

Fig. 6 is a longitudinal sectional view of the inner panel shown in FIG. 5, but rotated by 90 °,

Fig. 7 is an enlarged view of the free end of the inner sheet of Fig. 5 and

Fig. 8 is a rear view of the sliding part of Fig. 5.

The device 24 shown in the figures, in particular a pulling instrument, is used to loosen the individual parts of an endoprosthesis 13 , for example for an artificial hip joint or the like, in particular to loosen the press fit of the shaft 3 and neck 2 or neck 2 and joint ball 1 of the endoprosthesis. For this purpose, the device 24 has two legs 8 , the free ends 25 of which can be inserted into a groove 4 between the shaft 3 and neck 2 or neck 2 or joint ball 1 of the endoprosthesis 13 . The legs 8 can be moved away from one another in the region of the groove 4 by means of a spreading device. The legs 8 are pivotally supported at one end by means of a pin bearing 19 , preferably via pins 7 , on a handle 12 . At the other end in the area of free end sections, the legs 8 are each formed as a tongue-like outer sheet 6 , which for example has a thickness of less than 2 mm.

As can be seen in particular from FIG. 3, at least one, preferably both, of the mutually facing inner surfaces 26 of the legs 8 or outer leaves 6 are formed as inclined surfaces 27 in the region of the free end. The inclined surfaces 27 are arranged such that a taper 18 is formed at the free end 25 of the outer sheet 6 . The inclination of the inclined surfaces 27 with respect to a central longitudinal plane or the cone angle of the inclined surfaces 27 is approximately 2 °.

The spreading device has a tongue-like inner leaf 5 which is displaceably arranged between the legs 8 or outer leaves 6 and which in the region of the free end 25 has inclined surfaces 28 , which are preferably complementary on two sides, each preferably having an inclination of approximately 2 ° or a cone 16 of about 2 °. The inclined surfaces 28 are arranged at the free end of the inner sheet 5 such that a thickening 23 is formed here, which corresponds to the tapering 18 of the outer sheets 6 . In the end or release position, as shown in FIG. 1, in the exemplary embodiment selected here, the outer leaves 6 lie on the inner leaf 5 over their entire surface, the outer surfaces 21 of the outer leaves 6 in this end or release position, in which the inner surfaces 26 of the outer sheets 6 lie flush with the outer surfaces 30 of the inner sheet, are aligned substantially parallel to one another.

The outer sheets and also the inner sheet have at the free end 25 a preferably centrally arranged, essentially arcuate recess 29 into which the neck 2 of the endoprosthesis 13 , essentially flush with the edge of the recess 13 , can be received.

The spreading device has a sliding mechanism for the inner sheet 5 , with which the inner sheet 5 can be drawn into the end or release position between the free ends 25 of the legs 8 or outer sheets 6 . The displacement mechanism for the inner sheet 5 is formed by a shaft 10 with a thread 17 , a threaded spindle or the like, which is rotatably received in the handle 12 and engages with a corresponding thread 14 on one end of the inner sheet 5 arranged sliding part 20 . The shaft 10 is further mounted in a shaft bearing 15 on the handle 12 , secured against axial displacement by means of an axial bearing 22 and preferably connected to a turning handle 11 at the free end protruding from the handle.

The sliding part 20 has an upper and lower longitudinal web 31 , which are guided in longitudinal slots in corresponding slots, recesses 32 of the legs 8 .

The stroke or spread of the free ends of the legs 8 or outer leaves 6 when the inner sheet 5 is drawn in between the outer leaves 6 is less than 3%, preferably less than 1%, particularly preferably approximately 0.6% of the leg length of the legs 8 between the free end 25 and the pivot bearing. According to a specific exemplary embodiment, the maximum stroke of the outer leaves 6 is approximately 1 mm or less, the leg length being approximately 100 mm.

The spreading device moves the legs 8 or outer leaves 6 essentially axially apart in the direction of the neck axis 9 of the endoprosthesis 13 .

To release the parts of an endoprosthesis, the device 24 with the outer leaves 6 and the inner leaf 5 is inserted into the groove 4 of the endoprosthesis 13 in the starting position, the semicircular recesses 29 of the legs 8 or of the outer leaves 6 and the inner leaf 5 being inserted into the groove engage the neck 2 of the endoprosthesis 13 . In this starting position, the inner sheet 5 is extended by a certain amount in relation to the outer sheets 6 . Subsequently, the slide mechanism is set by corresponding rotation of the turning handle 11 in motion, whereby via the engaged each other threads 14 of the sliding part 20 and 17 of the shaft 10, the inner sheet 5 with respect to Fig. 1 to the left between the outer sheets 6 to the end In this position, the outer surfaces 21 of the outer leaves 6 are arranged essentially parallel to one another. In this case, the corresponding inclined surfaces 27 , 28 slide on one another, whereby the rotary movement of the rotary handle 11 or the shaft 10 is converted into a lifting movement of the outer leaves 6 . The extremely slight inclination of the inclined surfaces of preferably approximately 2 ° and, under certain circumstances, a very slight pitch of the threads 14 , 17 ensure that the outer leaves 6 are moved apart very delicately.

The stroke of the outer blades 6 required for releasing the parts of the endoprosthesis is extremely small and is in the millimeter range, for example 1 mm or even less. Due to the very large effective length of the pivotably mounted legs 8 compared to this stroke, practically no or only extremely low transverse forces occur, which are however intercepted by the device itself. The fact that to release the parts of the endoprosthesis 13 practically exclusively axial forces are used which act in the direction of the neck axis 9 of the neck 2 of the endoprosthesis 13 , an extremely gentle release of the endoprosthesis parts is ensured. Due to the special sliding mechanism, targeted force metering can also be achieved when loosening the individual endoprosthesis parts. The very small cone angle 16 , the inclined surfaces 27 , 28 or the outer blades 6 or the inner blade 5 also acts in the same direction, which enables easy transmission of force from the inner blade 5 to the outer blades 6 . Overall, a very gentle loosening of the endoprosthesis parts is accomplished by the device according to the invention, whereby both the bones and the endoprosthesis parts themselves are only subjected to a considerably reduced load, in particular lateral forces being largely avoided.

reference numeral

1

Joint ball

2

neck

3rd

shaft

4

Groove

5

Inner sheet

6

Outer sheet

7

bolt

8th

leg

9

Neck axis

10th

wave

11

Twist grip

12th

Grab handle

13

Endoprosthesis

14

thread

15

Shaft bearing

16

Cone angle

17th

thread

18th

rejuvenation

19th

Pin bearing

20th

Sliding part

21

Outside surface

22

Thrust bearing

23

thickening

24th

contraption

25th

free end

26

Inner surface

27

Sloping surface

28

Sloping surface

29

Recess

30th

Outside surface

31

Longitudinal web

30th

Recess

33

Claims (16)

1. The device ( 24 ), in particular a pulling instrument, for releasing the individual parts of an endoprosthesis ( 13 ), for example for an artificial hip joint or the like, in particular for releasing the press fit of the shaft ( 3 ) and neck ( 2 ) or neck ( 2 ) and Joint ball ( 1 ) of the endoprosthesis ( 13 ), characterized in that the device ( 24 ) has two legs whose free ends ( 25 ) fit into a groove ( 4 ) between the shaft ( 3 ) and neck ( 2 ) or neck ( 2 ) and the joint ball ( 1 ) can be inserted, and the legs ( 8 ) can be moved away from one another by means of a spreading device. 2. Device according to claim 1, characterized in that the legs ( 8 ) at one end by means of a pin bearing ( 19 ), preferably via pins ( 7 ) on a handle ( 12 ) are pivotally mounted. 3. Apparatus according to claim 1 or 2, characterized in that the free end portions of the legs ( 8 ) are each formed at the other end as a tongue-like outer sheet 6 . 4. Device according to one of the preceding claims, characterized in that at least one, preferably both of the mutually facing inner surfaces ( 26 ) of the legs ( 8 ) or outer leaves ( 6 ) in the region of the free end ( 25 ) are designed as inclined surfaces. 5. The device according to claim 4, characterized in that a taper ( 18 ) is formed by means of the inclined surface inclined to the free end ( 25 ) of the outer sheet ( 6 ), the inclined surface ( 27 ) preferably having an inclination or a cone angle of approx. 2 ° has or forms. 6. Device according to one of the preceding claims, characterized in that the spreading device has a tongue-like inner leaf ( 5 ) which is arranged displaceably between the legs ( 8 ) or outer leaves ( 6 ) and which is preferably in the region of the free end ( 25 ) has two-sided complementary inclined surfaces ( 28 ), each preferably having or forming an inclination or a cone angle ( 16 ) of approximately 2 °. 7. The device according to claim 6, characterized in that a thickening ( 23 ) is formed by means of the inclined surfaces ( 28 ) to the free end of the inner sheet ( 5 ). 8. Device according to one of the preceding claims 3 to 5, characterized in that the outer leaves ( 6 ) and the inner sheet ( 5 ) at the free end ( 25 ) have a preferably centrally arranged, substantially arcuate recess ( 29 ) in which the neck ( 2 ) of the endoprosthesis ( 13 ), essentially flush with the edge of the recess ( 13 ), can be received. 9. Device according to one of the preceding claims 3 to 8, characterized in that the outer surfaces ( 21 ) of the outer leaves ( 6 ) in their end or release position, in which preferably the inner surfaces of the outer leaves ( 6 ) the outer surfaces ( 30 ) of the inner leaf ( 5 ) lie essentially flush, arranged essentially parallel to one another. 10. Device according to one of the preceding claims, characterized in that the spreading device has a displacement mechanism for the inner sheet ( 5 ) with which the inner sheet ( 5 ) away from the free ends ( 20 ) of the legs ( 8 ) or outer leaves ( 6 ) between these is retractable. 11. The device according to claim 10, characterized in that the displacement mechanism is formed by a shaft ( 10 ) with thread ( 17 ), a threaded spindle or the like, which is rotatably received in the handle ( 12 ) and with a corresponding thread ( 14 ) of a sliding part ( 20 ) arranged at the end of the inner leaf ( 5 ) is in engagement. 12. The apparatus according to claim 11, characterized in that the shaft ( 10 ) in a shaft bearing ( 15 ) on the handle ( 12 ), secured by means of an axial bearing ( 22 ) against axial displacement and preferably on the free, from the handle ( 12 ) protruding end is connected to a rotary handle ( 11 ). 13. The apparatus according to claim 11 or 12, characterized in that the sliding part ( 20 ) has an upper and / or a lower longitudinal web ( 31 ) which or in a corresponding slot, recess ( 32 ) or the like of the or the legs ( 8 ) are performed. 14. Device according to one of the preceding claims, characterized in that the stroke or the spreading of the free ends of the legs ( 8 ) or outer leaves ( 6 ) when pulling in the inner leaf ( 5 ) between the outer leaves ( 6 ) below 3%, preferably below 1%, particularly preferably approximately 0.6% of the leg length between the free end ( 25 ) of the pivot bearing of the leg ( 8 ). 15. The apparatus according to claim 13, characterized in that the maximum stroke under approx. 1 mm and the leg length at approx. 100 mm.   16. Device according to one of the preceding claims, characterized in that the spreading device moves the legs ( 8 ) or outer leaves ( 6 ) substantially axially, preferably in the direction of the neck axis ( 9 ) of the endoprosthesis ( 13 ).