DE20314173U1 - Surgical device - Google Patents

Abstract

Surgical device with two parts movable relative to one another and with a clamping device for fixing the parts relative to one another, characterized in that the clamping device for generating clamping forces has at least one area which is filled with a material (11) which is dependent on its liquid content and / or, depending on its temperature, its volume changes so much that the clamping device changes from a release state into a clamping state.

Description

The invention relates to a surgical Device with two relatively movable parts and with a clamping device for fixing the parts relative to each other.

With surgical devices, especially those that are implanted in the body, that is for example in bone replacement implants, in endoprostheses or in orthopedic Holders are common the problem that parts of this Device first have to be moved against each other for example to adjust the position or to adapt the shape of the surgical Device during implantation, and that after that these parts are relative must be fixed to each other. It is known to relate these parts via a clamping device to define each other, many of these known clamping devices work with mechanically adjustable clamping elements, for example with clamping screws, with eccentrics or similar manually adjustable Divide. Although in many cases sufficient, it can be difficult to operate these clamping elements because them often in very difficult to access Places to be placed.

It is also known to use clamping devices with clamping elements which consist of parts made of so-called shape memory metals. These metals have the property that when a certain transition temperature is exceeded they change their crystal structure in such a way that their shape changes. This change in shape can be used to bring two parts together ( US 5,290,289 ). However, these clamping devices make the use of special shape memory alloys necessary, in addition, all parts must be constructed in such a way that the shape changes of the shape memory alloy elements can be converted into a clamping movement.

It is an object of the invention generic surgical Train the device so that simple way a solution or clamping of the parts movable against each other can be achieved can without this manual operation necessary and without that Shape Memory Alloys must be used.

This task is accomplished with a surgical device of the type described in the introduction solved in that the clamping device to generate clamping forces has at least one area which is filled with a material, which is dependent of its liquid content and / or dependent from its temperature changes its volume so much that the clamping device of a release state changes into a clamped state.

As part of the present development so consciously Materials used are either dependent on their liquid content or dependent on the temperature - if necessary also dependent of both parameters - one strong volume change behavior demonstrate. This volume change behavior passes over the normal volume change behavior due to the atomic movement, it is about rather a volume behavior, which is caused by a restructuring of the structure the material is conditioned, with temperature-dependent volume change for example by a reversible conversion of the crystal lattice of the Materials, with a change in volume by the liquid content either by the osmotic effect of the material or by a atomic or molecular interaction between the material and the liquid, Of course combinations of these effects are also possible.

For example, according to one preferred embodiment the material is under hydration swelling material, for example a hydrogel.

Such substances are known per se and are also used in surgical bone screws, prosthetic sockets and the like in order to fix these elements in the bone. These surgical holding elements are superficially coated with such a hydrogel substance, this substance is intended to replace the otherwise customary, hardenable bone cement that is otherwise used to fix these holding elements in bone cavities ( US 5,645,592 ). A large number of such possible substances are described in the context of this publication, and reference is expressly made to this description. However, the use of these swelling materials in the context of this publication is limited to the definition of surgical holding elements in the bone; the swelling medium is to replace the otherwise customary bone cement in accordance with this previously known use.

It is particularly advantageous for of the invention, if the material is a polymer, in particular can the material from one of the following materials be or at least contain one of the following materials as an ingredient:

• polyvinyl alcohol
• polyacrylate
• polyacrylic acid
• polyhydroxyalkyl acrylate
• polyacrylonitrile
• polyacrylamide
• Polyhydroxyalcyl-2-methyl
• Polyvinylphyrrolidon
• Copolymer and terpolymers based on N-vinylphyrrolidone, Acrylic acid, Hydroxy alkyl acrylate, acrylamide.

These substances are those which have a strongly swelling behavior when liquid, for example water, is added so that their volume increases greatly, this process is reversible.

If material is used, its volume change through a change in temperature it is particularly advantageous if the material is a plastic that when exceeded a transition temperature its volume changes abruptly, this is usually caused by a rearrangement of the crystal lattice of the plastic reached.

For example, the material could be polytetrafluoroethylene his.

The relative to be determined Parts can for example the parts of an orthopedic holding device, how it is used to stabilize the spine, it can are parts of an endoprosthesis or parts of one Implant, which is used for example as a bone replacement implant becomes.

According to a first preferred embodiment it is provided that the Material between the two parts to be determined relative to each other is arranged and rests directly on both parts. The definition of the two parts is thus done by the expanding material between them is arranged, which abuts both parts in the expanded state and this over a frictional connection and if necessary via a positive fit to each other.

For example, that this Material in one of the two open chamber Parts is arranged and that that other part closes this receiving chamber.

In another embodiment fills the material an annulus between an opening of one part and the other part, which dips into the opening and has smaller external dimensions than the opening.

It is also possible that the one part is designed as a sleeve which has a layer of material on the inside.

In a further preferred embodiment it is envisaged that Material between two relatively movable elements is arranged, the two parts by their relative movement by jamming over a frictional connection and / or to establish a positive connection.

It can be provided that at least one of the two movable elements through one of the two parts itself is formed.

The definition of the two parts can done by a pure frictional connection, but it is also possible that by the volume increase is a positive fit between the two Parts to be determined relative to each other, non-positive and positive can also occur together.

The material can be from a membrane or be surrounded by a net so that the material is held together is, for example in the form of a tube or in the form of a pillow.

It is advantageous if the membrane for the material impermeable and for liquids permeable is so that liquid penetrate into the interior of the membrane and there the swelling and so that the volume increase of Material can cause.

The following description preferred embodiments the invention serves in conjunction with the drawing for a more detailed explanation. Show it:

1 : The clamp connection between a rod and two pivotable arms of a clamp;

2 : a sectional view along line 2-2 in 1 ;

3 : a connection between a rod and a bowl-shaped receiving part;

4 : a sectional view taken along line 4-4 in 3 ;

5 : a connection between a rod and two mutually displaceable clamping elements;

6 : a connection between a rod and a collet receiving it;

7 : a connection between a spherical head and a shell surrounding it;

8th : a connection between a prosthesis socket and a locking nail inserted into it;

9 : a longitudinal sectional view through a clamping sleeve;

10 : a connection between a rod and a clamping device with a displaceable clamping piece;

11 : a connection between a rod and a receiving shell with a snap-in cover element;

12 : a connection between a ball and a shell surrounding it;

13 : a connection between a rod and a ring surrounding it and

14 : a connection of two prosthesis parts via a cone clamp.

The invention is set out below discussed different examples of connections of two parts, these Parts are parts of surgical devices, for example of orthopedic Holding devices, such as those used in the spinal area, of implants or endoprostheses.

A common problem with such surgical devices, in particular with orthopedic holding devices, is the fixing of a rod relative to a clamping element, which is then optionally also connected to a further rod, so that holding devices of the desired shape can be built up from these rods, which can then be built over Bone screws are connected to the bone structures to be stabilized. For example, it is often necessary to connect such rods with pedicle screws, which are screwed into the vertebral body of the spine, and this connection between pedicle screws and rods is established via special clamping pieces.

In 1 is a schematic of such a rod 1 shown relative to a clamp 2 to be determined. This clamp has two pivotally connected arms 3 . 4 on that at their free ends 5 . 6 over jaws 7 . 8th on the outside of the rod 1 and take it between them. Between the poor 3 . 4 is at their free ends 5 . 6 opposite ends 9 . 10 volume changeable material 11 introduced, in the illustrated embodiment in the form of a block made of this material 11 , the material 11 supports itself on both inner sides of the arms 3 . 4 and is with the poor 3 . 4 connected. If the volume of the material 11 changed, this leads to a pivoting of the two arms 3 . 4 against each other, and thereby the jaws 7 . 8th more or less firmly against the rod 1 pressed.

The volume change of the material 11 can be done, for example, by adding liquid if it is the material 11 is a swellable material, this liquid can be surrounding body fluid with which the material 11 comes into contact as soon as the clamp with the rod is implanted in the body. It is also possible that the material 11 is temperature-dependent volume-changing material, the behavior of which is adjusted by suitable pretreatment, for example polymerization, in such a way that the volume at body temperature rises suddenly compared to a slightly lower temperature.

The material 11 can be surrounded by a membrane, not shown in the drawing, so that the material 11 enters the volume predetermined by the membrane, this membrane can be stretchable, so that the volume change of the material 11 is recorded, moreover, the membrane is liquid-permeable, so that surrounding liquid with the material 11 can come into contact and lead to the desired volume change.

When connecting according 3 and 4 becomes a staff 1 recorded in a bowl-shaped recording 12 a holding element 13 , this shot 12 surrounds the rod 1 over half of its circumference or possibly slightly more so that the rod 1 if necessary with elastic bending of the receptacle 12 can be inserted into this. In the recording 12 is at least one side chamber 14 provided in which a volume-changeable material 11 is filled. This chamber 14 is for inclusion 12 open, and in this area is the staff 1 closing this on the chamber 14 on. If the material 11 if its volume increases due to liquid contact or a change in temperature, it jams the rod 1 in the recording 12 and thereby places it relative to the holding element 13 firmly.

In the embodiment of the 3 and 4 So it is determined by direct contact between the two parts to be connected, that is, the rod 1 and the holding element 13 , with the volume-changeable material 11 , while in the embodiment of the 1 and 2 the determination was made by moving one of the two parts, namely the two arms 3 . 4 the clamp 2 while laying down the rod 1 even then over the jaws 7 . 8th he follows.

Similarly, in the embodiment of the 5 through volume-changeable material 11 two clamping elements moved against each other to form a rod 1 with a clamping device 15 connect to. This comprises a plate-shaped contact element 16 , an angled contact element 17 from both sides to the rod 1 and a tie rod 18 that both investment elements 16 . 17 penetrates and on the one hand on the outside of the plate-shaped contact element 16 and on the other hand on a ring 19 supported. Between this ring 19 and the angular contact element 17 is an intermediate layer made of the volume-changeable material 11 inserted in the form of a plate-shaped component, and when increasing the volume of the material 11 expresses this material 11 the two investment elements 16 and 17 against each other so that the rod 1 gets stuck between them.

A similar structure is according to the design 6 selected, however, the angular contact element is replaced by a rod 1 receiving collet-like shell 20 , and the volume-changing material 11 is in this case between the plate-shaped contact element 16 and the collet-like shell 20 , When increasing the volume of the material 11 becomes the collet-like shell 20 compressed and thereby tensions the rod 1 in her.

In 7 is the definition of a spherical part 21 in a bowl that holds this 22 shown. This bowl 22 points in its thickened wall to the interior of the bowl 22 open chambers 23 on that with voluminous material 11 are filled and that of the spherical part 21 be closed. This results similarly to the embodiment of FIG 3 and 4 a jamming of the spherical part 21 relative to the shell 22 when the material 11 expands.

In 8th is a prosthesis 24 with a shaft 25 shown of a cross hole 26 having. In this cross hole 26 is a locking nail 27 inserted, the outer diameter of which is smaller than the diameter of the transverse bore 26 so that an annular gap 28 between the inner wall of the cross hole 26 and the peripheral surface of the locking nail 27 arises, this annular gap 28 is filled with variable-volume material 11 , The material 11 can be used in the form of a sleeve, it is also possible to the inner wall of the cross hole 26 with an appropriate layer of the material 11 train. As soon as the shaft is inserted into the body and comes into contact with liquid or experiences the body temperature, the material encloses 11 with a volume increase the locking nail 27 tight on all sides and jammed in the cross hole 26 ,

In 9 is a collet 29 shown, it is a simple sleeve, the inner wall with material 11 is coated, or into a sleeve made of volume-changing material 11 is inserted. Such a sleeve 29 can, for example, on an in 9 rod, not shown, is pushed on and is on this by increasing the volume of the material 11 established.

In the embodiment of the 10 becomes a staff 1 in a clamping device 30 set that a terminal block 31 with a receiving opening passing through it 32 includes. This receiving opening 32 is recessed on one side and forms contact surfaces there 33 . 34 for the staff 1 , on the opposite side of these contact surfaces 33 is in the receiving opening 32 a clamp 35 slidably mounted, which in turn on its contact surfaces 33 and 34 corresponding contact surfaces 36 . 37 wearing. The clamp 35 protrudes with a short shaft 38 in a hole 39 in the terminal block 31 into this hole 39 is at the opposite end by a screw 40 locked, and between the shaft 38 and the screw 40 is the hole 39 with variable volume material 11 filled. As the volume increases, this material shifts 11 the clamp 35 towards the contact surfaces 33 and 34 and thereby clamps the stick 1 firmly.

In 11 is a holding element 41 with a U-shaped receptacle 42 shown, in this recording is a rod 1 inserted the U-shaped receptacle 42 is by means of a plug 43 locked. The stopper 43 has two resilient, radially inwardly movable arms 44 on that by protruding outwards 45 corresponding, in the U-shaped receiving space of the recording 42 protruding protrusions 46 engage behind. This allows the stopper 43 can be inserted elastically into its closed position and is secured against being pulled out.

The remaining interior of the recording 42 is made of variable-volume material 11 filled. When the volume is increased, this material jams the rod 1 in the receptacle and thereby fixes it, also the resilient arms of the plug 43 pushed out and insert the stopper 43 thereby in the recording 42 sure firm.

In the embodiment of the 12 is a holding element 47 with a hemispherical holder 48 provided in this cradle 48 is a ball 49 inserted. This has open chambers towards its outer circumference 50 on, in the voluminous material 11 is filled in these chambers 50 are on the outside through the receptacle 48 locked.

When stretching the material 11 this makes the ball in the holder 48 established.

In the embodiment of the 13 is a staff 1 in an annular receiving element 51 plugged in. The rod 1 has several chambers distributed over its circumference 52 on, for example in the form of longitudinal grooves open to the circumference, into the volume-changing material 11 is filled. These chambers 52 are on the outside through the annular receiving element 51 locked so that when the material expands 11 the rod 1 in the annular receiving element 51 is set.

In 14 are two parts 53 . 54 represented a prosthesis. These two parts 53 . 54 are over a cone 55 and a corresponding cone opening 56 connected to each other in that the cone 55 into the cone opening 56 is inserted. However, the cone is lying 55 not directly on the wall of the cone opening 56 but with the interposition of a conical sleeve 57 made of variable-volume material 11 , This can, for example, in the cone opening 56 be used, it is also possible that the cone opening 56 a corresponding coating made of variable-volume material 11 wearing. If the cone 55 into the cone opening 56 is inserted, it is fixed in this position as soon as the material 11 expands under the effect of the surrounding liquid or ambient temperature.

All of the exemplary embodiments described above serve to explain the effect of the volume-changing material 11 , which can be used in a variety of ways to implement the volume change in fixing forces or fixing movements for two parts to be connected. The exemplary embodiments described serve to illustrate these different possibilities, but this is not intended to limit the possible uses of the variable-volume material when connecting different parts.

Claims (18)

Surgical device with two parts which are movable relative to one another and with a clamping device for fixing the parts relative to one another, characterized in that the clamping device for generating clamping forces has at least one area which is covered with a material ( 11 ) is filled, which, depending on its liquid content and / or depending on its temperature, changes its volume so strongly that the clamping device changes from a release state into a Clamped state passes. Surgical device according to claim 1, characterized in that the material ( 11 ) is a material that swells when hydrated. Surgical device according to claim 2, characterized in that the material ( 11 ) is a polymer. Surgical device according to claim 3, characterized in that the material ( 11 ) consists of one of the following materials or contains at least one of the following materials as a constituent: polyvinyl alcohol polyacrylate polyacrylic acid polyhydroxyalkyl acrylate polyacrylonitrile polyacrylamide polyhydroxyalcyl-2-methyl acrylate polyvinylphyrrolidone copolymers and terpolymers based on N-vinylphyrrolidone, acrylic acid, hydroxyalkyl acrylate, acrylate. Surgical device according to claim 1, characterized in that the material ( 11 ) is a plastic that suddenly changes its volume when a transition temperature is exceeded. Surgical device according to claim 5, characterized in that the material ( 11 ) Is polytetrafluoroethylene. Surgical device according to one of the preceding claims, characterized in that the parts to be fixed relative to one another ( 1 . 2 ; 1 . 13 ; 1 . 15 ; 1 . 30 ) Are parts of an orthopedic holding device. Surgical device according to one of claims 1 to 6, characterized in that the parts to be fixed relative to one another ( 21 . 22 ; 24 . 27 ) Are part of an endoprosthesis. Surgical device according to one of claims 1 to 6, characterized in that the parts to be fixed relative to each other parts of an implant are. Surgical device according to one of the preceding claims, characterized in that the material ( 11 ) between the two parts to be determined relative to each other ( 1 . 13 ; 21 . 22 ; 24 . 27 ; 48 . 49 ; 1 . 51 ; 53 . 54 ) is arranged and lies directly on both parts. Surgical device according to claim 10, characterized in that the material ( 11 ) in a receiving chamber open on one side ( 14 ; 23 ; 50 ; 52 ) one of the two parts is arranged and that the other part closes this receiving chamber. Surgical device according to claim 10, characterized in that the material ( 11 ) an annulus ( 28 ; 57 ) between an opening ( 26 ; 56 ) one part ( 24 ; 54 ) and the other part ( 27 ; 55 ) which dips into the opening and has smaller outer dimensions than the opening. Surgical device according to claim 12, characterized in that the one part ( 24 ; 54 ; 29 ) is designed as a sleeve that has a layer of material ( 11 ) wearing. Surgical device according to one of claims 1 to 9, characterized in that the material ( 11 ) between two elements movable relative to each other ( 3 . 4 ; 17 . 19 ; 20 . 19 ; 35 . 40 ) is arranged, which defines the two parts relative to each other by their relative movement. Surgical device according to claim 14, characterized in that that at least one of the two movable elements through one of the two parts itself is formed. Surgical device according to one of the preceding claims, characterized in that the clamping device when the volume of the material ( 11 ) a positive fit between the two parts ( 42 . 44 ) generated. Surgical device according to one of the preceding claims, characterized in that the material ( 11 ) is surrounded by a membrane or a net. Surgical device according to claim 17, characterized in that the membrane for the material ( 11 ) is impermeable and impermeable to liquids.