DE19611247A1 - Prosthetic joint cup removal involves drilling through into cavity between inner and outer cup shells so extractor hooks into inner shell to apply withdrawal force. - Google Patents

Abstract

The cup shell insert (12) is drilled through into the cavity (17) between inner and outer shells (12,11) and an extractor (40) hook (42) engaged with the bore (37) so the actuated extractor exerts extracting force on the cup shell (12). The hook is fitted to a main body (41) engaging the bore (37). The main body is elongated in form and has an axially adjusting striker mass (44) and is fitted at its non-hook end with an endstop (43) to limit the mass (44) movement. The drilling template has axial supporting areas to bear on the cup (10) as well as radial supporting areas to seat the template on the cup. The template is axially bored out for the drill shaft.

Description

The invention relates to a method for Ent remove a prosthetic acetabular cup, which sits with an interference fit in an outer shell, the Outer shell and the insert shell in the middle of the shell form a cavity.

Especially in joints with strong mechanical loading stress, for example hip joints, become a Sentence shells that take up a joint ball from one Material of great hardness used. These insert shells are with a press fit, for example with a conical one Clamping, fixed in the outer shell. In the floor area in the middle of the shell are the outer shell and the on set shell a cavity, so with axial loading the clamp seat is not loosened, but strengthened. Due to the clamp seat attachment is a replacement Insert shell for damage, canting and. the  Insert shell only by destroying the insert shell with Chisels etc. possible. Thereby high me chanic loads on and sharp fragments of the one Nesting material can enter the surrounding tissue devices.

The object of the invention is a method for a to provide improved removal of an insert shell.

This object is achieved by the features of claim 1 solved.

The claim 1 includes the process steps: Durchboh insert the insert into the cavity, insert and hooking a hook part of an extractor into the hole in the insert shell, and actuation of the Pull-out device for applying a pull-out force on the insert shell. By piercing the one Sentence shell becomes an approach for an extractor created. With the pull-out device is then a axial pull-out force applied to the insert shell, so that the insert shell from its clamp seat in the Outer shell can be gently pulled out. With this Procedures are not high impact on the Ge Steering pan applied. Through the destructive and splinter-free removal of the insert shell is also the Danger of tissue contamination avoided.

Preference is given to piercing the insert shell a drilling template is placed on the insert shell. With the drilling template, the hole is exactly at one specified location of the insert shell, for example in the middle, drilled. This ensures who that the pull-out forces evenly on the clamp  areas are distributed and tilted when moving out pull is avoided. The drilling template can also cover the insert shell in such a way that no drilling dust can escape from the socket.

The pull-out device for the procedure is available preferably from a base body that on one side Has hook part, which in the hole of the Einsatzscha le can intervene. The body also has one Impact mass element with which a mechanical Im pulse in a direction away from the hook part of the Base body can be generated. The mechanical im pulse of the pull-out device is on the hook part the starting point of the one created by the drilling Transfer type shell. It is a simple and effective mechanical pull-out device created.

The impact mass element can axially on the base body be slidably arranged, the base body on a stop on the end facing away from the hook part points, the axial movement of the impact mass element limited. When striking the striking mass element the stop is the impulse over the stop on the entire base body including the hook part and transferred from the hook part to the insert shell.

The drilling template for drilling the prosthetic joint pan insert tray according to the Ver driving consists of a stencil body attached to its mounting side axial and radial support areas for axial and radial support of the template body pers on the socket. The template body also has a continuous axial guide bore for guiding an inserted drill shaft  Drill on. The axial and radial support areas are used to place the drilling template on the insert shell. Through the guide hole for the Drill shank is the exact hole position in the one set shell set. This ensures that it is always represents the extractor at a well location is applied at which the pull-out force of the pull-out direction evenly distributed on the clamping surfaces becomes. This ensures that the Insert shell ensures and tilting of the one Nesting tray is avoided.

The drilling template preferably has a depth hit that with a stop of the drill like this interacts that the drilling depth of the drill shaft be is bordered. The drilling depth is determined by the depth stop set so that the insert shell completely is pierced, but the drill immediately after Drill through the insert shell with its stop against pushes the depth stop. This will start drilling and Damage to the outer shell prevented.

The radial support areas of the template body can formed by an axial spherical protuberance be that fits into the recess of the insert shell. The protuberance has approximately the shape of a one setting joint ball. This makes the location of the Bohr template reproducible very precisely.

Together with the preferably as an annular Heel designed axial support areas is there through an easy to put on the insert shell Drilling template created that is quick and accurate Drilling the hole allowed.  

The stencil body can be used for flushing holes Have drained drilling fluids. This can the drilling site is cooled and the drilling dust is discharged become.

The method and devices are preferred to be used for insert shells made of ceramic stand. In ceramics in particular, because of its zer fragility a careful and gentle removal from the clamp seat particularly necessary.

The following is with reference to the drawings an embodiment of the inventive method rens and the devices according to the invention he closer purifies.

Show it:

Fig. 1 is a socket with attached Bohrschab lone in longitudinal section and a drill, and

Fig. 2, the socket with hooked Ausziehvor direction.

In Fig. 1, a metal-ceramic joint socket 10 is provided, which consists of a metallic outer shell 11 , in which a ceramic insert shell 12 is inserted with a clamp fit. The outer shell 11 has an inner cone 15, while the insert cup 12 has a matching outer cone sixteenth The one set shell 12 is firmly inserted into the outer shell 11 , so that between the outer cone 16 and the inner cone 15 a clamping force acts with which the insert shell 12 is fixed against axial movements in the outer shell 11 . Such clamping seats of Kera mic insert shells are usually only removable from the outer shell by breaking the insert shell into several parts.

The bottom regions of the outer shell 11 and the insert shell 12 form a cavity 17 between them. The cavity 17 is necessary since the insert shell 12 must not be axially supported in order not to weaken or even loosen the clamping effect of the cone clamping. Axial loads on the socket 10 lead to a strengthening of the clamp seat and not to a weakening thereof.

A drilling template 20 placed on the socket 10 consists of a template body 21 which has an axial guide bore 22 . On the socket 10 facing side of the drilling template 20 , a spherical protuberance 25 is arranged, which fits exactly into the spherical inside 18 of the insert shell 12 and forms radial support areas. The protuberance 25 is surrounded by an annular shoulder 26 , which acts as an axial support area.

The template body 21 is such shell to the insert 12 is placed, that the protuberance 25 to the insert shell 18 and inside the shoulder ring 26 rotating on an opening side annular surface 19 of the insert shell rest without play 12th As a result, the position and orientation of the guide bore 22 in relation to the insert shell 12 is clearly and reproducibly defined. The guide bore 22 runs axially exactly in the central axis of the insert shell 12 . The template body 21 has at the joint end facing a cylindrical axial recess 28 , the diameter of which is larger than that of the guide bore 22 and which has an annular end face 29 as a depth stop.

The drilling template 20 is held in the insert shell by hand, but can also be glued to the socket 10 or can be held independently in the socket 10 due to gravity.

Before the opening of the recess 28 , a drill 30 is arranged, of which only one drill shaft 31 with a diamond drill tip 32 and on the drill shaft 31 at closing a stop body 33 with a stop surface 34 is shown. The diameter of the drill shaft 31 is slightly smaller than that of the Füh approximately 22 , as well as the diameter of the stop body 33 is slightly smaller than the diameter of the recess 28th The drill shaft 31 can thus be pushed through the guide bore 22 and with its drill tip 32 drill a through hole 37 into the shell 12 .

The drilling depth of the drill 30 is determined by the position of the end face 29 of the drilling template 20 . If the stop surface 34 of the drill 30 abuts against the end face 29 of the drilling template 20 , the drill 30 can no longer penetrate into the socket 10 . The drilling depth is determined such that the drilling tip 32 just pierces the bottom wall of the insert shell 12 and protrudes slightly into the cavity 17 .

In FIG. 2, the socket 10 is shown with removed drilling template and the at tach ment puller 40th It consists of an elongated rod body 41 , at one end a hook part 42 and at the other end a stop ring 43 is arranged as a stop. On the rod body 41 , a cylindrical impact body 44 is axially displaceable, which is axially displaceable between a handle part 45 and the impact ring 43 .

When the insert cup to be removed from the outer shell 11 12 because of wear, damage, or canted seat, the drilling template 20 is placed to expose the joint socket 10 without clearance on the insert shell 12th Thereafter, the drill stem is inserted into the guide bore 22 31 and pushed so far through the guide bore 22, seated on the insert shell 12 to the drill bit 32nd The drill is put into operation and a bore 37 is drilled in the insert shell 12 . Shortly after the drill bit 32 has pierced the bottom wall of the insert shell 12 , the abutting surface 34 of the drill 30 abuts against the end face 29 of the drilling template 20 , so that the drill bit 32 cannot penetrate further into the cavity 17 of the socket 10 . This ensures that the drill 30 can not cause any damage to the outer shell 11 .

After the drill 30 has been removed from the borehole 37 and the guide bore 32 , the drilling template 20 is removed again from the socket 10 .

Now the hook part 42 of the pull-out device 40 is hooked into the borehole 37 so that it engages behind the bottom wall of the insert shell 12 . This creates an approach for the application of axial forces in the disengaging direction. With the impact body 44 mechanical impulses can now be initiated in the disengaging direction via the hook 42 on the insert shell 12 . For this purpose, the striking body 12 is guided to the grip part 45 and moves with a rapid movement against the stop ring 32 . When the striking body 44 strikes against the stop ring 43 , the impulse of the striking body 44 is transmitted to the hook part 42 via the rod body 41 . The hook part 42 in turn transmits the pulse to the insert shell 12 , so that a pulse in the disengaging direction of the insert shell 12 is transmitted. As a result, the clamping fit between the inner cone 15 and the outer cone 16 is loosened, so that the insert shell 12 can easily be removed from the outer shell 11 . After cleaning, a new insert shell can be inserted into the outer shell 11 .

There are no steps when removing the insert shell strong mechanical impulses. Also a splinter education is avoided.

Claims (10)

1. A method of a prosthetic Ge removing steering pans insert shell (12), which sits with a clamping fit in an outer shell (11), wherein the outer shell (11) and the insert shell (12) form in the shell center a cavity (17), with the procedural steps:

• - Drill through the insert shell ( 12 ) into the cavity ( 17 ),
• - Inserting and hooking a hook part ( 42 ) of a pull-out device ( 40 ) into the bore ( 37 ) in the insert shell ( 12 ), and
• - Actuation of the pull-out device ( 40 ) for applying a pull-out force to the insert shell ( 12 ).

2. The method for removing a prosthetic Ge socket socket according to claim 1 with the first step:

• - Place a drilling template ( 20 ) on the A set shell ( 12 ).

3. pull-out device for releasing a prosthetic socket socket insert ( 12 ) according to the method according to claim 1 or 2,
with a base body ( 41 ) which has on one side the hook part ( 42 ) which can engage in the bore ( 37 ) of the insert shell ( 12 ), and
which has an impact mass element ( 44 ) with which a mechanical pulse can be generated in a direction of the base body ( 41 ) facing away from the hook part ( 42 ). 4. Extracting device according to claim 3, characterized in that the base body ( 41 ) is stretched langge, that the striking mass element ( 44 ) on the base body ( 41 ) is arranged axially displaceable, and that the base body ( 41 ) on the Ha part ( 42 ) opposite end has a stop ( 43 ) which limits the axial movement of the Schlagmas senelements ( 44 ). 5. drilling template for drilling the prosthetic joint socket insert ( 12 ) according to the method of claim 1, with
a stencil body ( 21 ), on its set-on axial support areas ( 26 ) for axially supporting the stencil body ( 21 ) on the Ge steering socket ( 10 ), and radial support areas ( 25 ) for radial support of the set-up stencil body ( 21 ) on the socket ( 10 ), and
a continuous axial guide bore ( 22 ) for guiding an inserted drill shank ( 31 ) of a drill ( 30 ). 6. Drilling template according to claim 5, characterized in that the template body ( 21 ) has a deep fen stop ( 29 ) which cooperates with a stop ( 34 ) of the drill ( 30 ) such that the drilling depth of the drill shaft ( 31 ) is limited. 7. Drilling template according to claim 5 or 6, characterized in that the radial support regions of an axial spherical protuberance ( 25 ) are gebil det, which fits into the recess ( 18 ) of the set shell ( 12 ). 8. Drilling template according to one of claims 5-7, characterized in that the axial Stützbe rich are formed by an annular shoulder ( 26 ) which can be placed on a peripheral edge ( 19 ) of the insert shell ( 12 ). 9. drilling template according to one of claims 3-8, characterized in that the template body ( 31 ) has rinsing holes for introducing and discharging drilling fluids. 10. A method for removing a prosthetic Ge joint socket insert shell ( 12 ) or device therefor according to one of claims 1-9, characterized in that the insert shell ( 12 ) consists of Kera mik.