DE102004043325A1 - Surgical appliance, to clamp and secure two parts for a bone implant and the like, has a clamp material which swells with a fluid or changes its shape by temperature changes, to give a simple clamp/release action - Google Patents

Abstract

The surgical appliance, with two arms (3,4) with a relative movement between them, has a clamp to secure them against each other. The clamp is of a material (11), within an impermeable membrane or a netting, which alters its shape according to its fluid content or its temperature. The arms give relative movements to orthopedic holders (1,2) or parts of a prosthesis.

Description

The The invention relates to a surgical device with two relative mutually movable parts and with a clamping device for Fixing the parts relative to each other.

at surgical devices, especially those implanted in the body For example, in bone replacement implants, in endoprostheses or orthopedic Holding devices, often exists the problem that parts of this Device first have to be moved against each other, for example, to adapt the position or to adapt the shape of the surgical Device during implantation, and that thereafter these parts relative must be fixed to each other. It is known to relatively these parts via a clamping device to fix 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 Share. Although in many cases sufficient, it may be difficult to operate these clamping elements, as they often very difficult to access Jobs are placed.

It is also known to use clamping devices with clamping elements which consist of parts of so-called shape memory metals. These metals have the property that when they exceed a certain transition temperature they change their crystal structure so that their shape is changed. This change in shape can be used to bring about a clamping of two parts ( US 5,290,289 ). However, these clamps necessitate the use of special shape memory alloys, and all parts must be constructed so that the shape changes of the shape memory alloy elements can be translated into a clamping motion.

It Object of the invention, a generic surgical device form so that on simple way a solution or clamping of the mutually movable parts can be achieved can, without that a manual operation is necessary is and without that Shape Memory Alloys must be used.

These Task is in a surgical device of the type described above Type according to the invention thereby solved, that the Clamping device for generating clamping forces at least one area which is filled with a material which depends on its liquid content and / or dependent from its temperature its volume changed so much that the clamping device of a release state in a clamping state passes.

in the So the framework of the present development becomes consciously materials used, which is either dependent from their fluid content or dependent from the temperature - if necessary also dependent from both parameters - a strong volume change behavior demonstrate. This volume change behavior goes over the normal volume change behavior due to the atomic movement clearly, it is Rather, it is a volume behavior that results from a reconstruction of the structure of the material, with temperature-dependent volume change for example, by a reversible conversion of the crystal lattice of Materials, with a change in volume by the liquid content either by the osmotic action 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 can according to a preferred embodiment the material under hydration be swelling material, such as a hydrogel.

In itself such substances are already known and are also used in surgical bone screws, prosthetic shafts and the like to fix these elements in the bone. In this case, these surgical holding elements are superficially coated with such a hydrogel substance, this substance is intended to replace the otherwise customary curable bone cement which is otherwise used to fix these holding elements in bone cavities ( US 5,645,592 ). In the context of this document a large number of such possible substances are described, and this description is expressly incorporated by reference. However, the use of these swelling materials in the context of this document is limited to the setting of surgical holding elements in the bone, the swelling medium should replace according to this prior art use exclusively the usual bone cement.

It is particularly advantageous in the invention, when the material is a polymer, in particular, the material of any of the following materials be available or contain at least one of the following materials as a component:
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.

It these substances are those which, on supply of Liquid, For example, water, have a strong swelling behavior and thus greatly increase their volume, this one Process is reversible.

If Material is used, its volume change due to a change in temperature is caused, it is particularly advantageous if the material a plastic is when passing a transition temperature leaps in volume, This is usually done by rearrangement of the crystal lattice reached the plastic.

For example could the material be polytetrafluoroethylene.

The For example, the parts can be defined relative to one another an orthopedic holding device as it is used to stabilize the spine, it can These are parts of an endoprosthesis or even parts of a Implantates, for example, used as a bone replacement implant becomes.

According to one first preferred embodiment is provided that the Material between the two relative to each other parts to be determined is arranged and rests directly on both parts. The determination the two parts thus takes place in that between them the expanding material is arranged, which rests in the expanded state on both parts and this over a frictional connection and optionally via a positive engagement relative determines each other.

For example can be provided that the Material in a unilaterally open receiving chamber of one of the two Parts is arranged and that the other part closes this receiving chamber.

at another embodiment fills the material an annulus between an opening one part and the other part, which dips into the opening and smaller outer dimensions as the opening.

It is possible, too, that this a part as a sleeve is formed, on its inside a layer of the material wearing.

at a further preferred embodiment is provided that the Material between two relatively movable elements is arranged, which by their relative movement, the two parts by jamming over a frictional connection and / or define a form fit.

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

The Determining the two parts can be done by a pure adhesion, but it is also possible that by the increase in volume a positive connection of the two Relative to each other parts to be determined, adhesion and positive engagement can also occur together.

The Material may be surrounded by a membrane or a net, so that this Material is held together, for example in tube form or in pillow form.

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

The following description of preferred embodiments of the invention used in conjunction with the drawings for further explanation. Show it:

1 : The clamp connection between a bar and two hinged arms of a clamp;

2 a sectional view taken along line 2-2 in FIG 1 ;

3 a connection between a rod and a cup-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 ball head and a shell surrounding it;

8th a connection between a prosthesis stem and a locking nail inserted therein;

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 receptacle with a snap-in cover member;

12 a connection between a sphere and a surrounding shell;

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

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

The Invention will be described below by way of different examples of compounds of two parts discussed, these parts are parts of surgical devices, for example of orthopedic Holding devices, such as those used in the spinal region, of implants or endoprostheses.

One frequent Problem with such surgical devices, in particular in orthopedic Holding devices, is the definition of a rod relative to a Clamping element, which then optionally additionally with another rod is connected, so that out these bars Holding devices of the desired Form can be built then over Bone screws connected to the bone structures to be stabilized become. It is common, for example necessary, such rods to connect with pedicle screws, which in the vertebral body of the spinal column be screwed in, and this connection between pedicle screws and bars will over special clamping pieces produced.

In 1 is schematically such a rod 1 shown relative to a clamp 2 should be set. This clamp has two pivotally connected arms 3 . 4 on, at their free ends 5 . 6 over jaws 7 . 8th on the outside of the bar 1 abut and thereby take this between themselves. Between the poor 3 . 4 is at the free ends 5 . 6 opposite ends 9 . 10 volume changeable material 11 introduced, in the illustrated embodiment in the form of a block of this material 11 , the material 11 rests on both inner sides of the arms 3 . 4 off and is with the poor 3 . 4 connected. When 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 staff 1 pressed.

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

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

In the connection according to 3 and 4 becomes a staff 1 taken in a cup-shaped receptacle 12 a holding element 13 , this recording 12 surround the staff 1 over half its circumference or possibly slightly more, so that the rod 1 optionally under elastic bending of the recording 12 can be inserted in this. In the recording 12 is at least one lateral chamber 14 provided, in which a volume changeable material 11 is filled. This chamber 14 is for recording 12 open, and in this area is the staff 1 this closing at the chamber 14 at. If the material 11 its volume increases due to fluid contact or temperature change, it jams the rod 1 in the recording 12 and thereby puts this relative to the retaining element 13 firmly.

In the embodiment of the 3 and 4 Thus, the determination is made by direct contact of the two parts to be joined together, so the rod 1 and the retaining element 13 , with the volume changeable material 11 while in the embodiment of the 1 and 2 the determination has been made by a movement of one of the two parts, namely the two arms 3 . 4 the clamp 2 while fixing the rod 1 even then over the jaws 7 . 8th he follows.

Similarly, in the embodiment of the 5 by volume changeable material 11 two clamping elements shifted against each other to a rod 1 with a clamping device 15 connect to. This comprises a plate-shaped contact element 16 , an angled contact element 17 coming from both sides to the staff 1 and a tie rod 18 , the two investment elements 16 . 17 interspersed 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 angled abutment element 17 is an intermediate layer of the variable volume material 11 in the form of a plate-shaped component, and increasing the volume of the material 11 pushes this material 11 the two investment elements 16 and 17 against each other, so that the rod 1 sandwiched between them.

A similar construction is in accordance with the embodiment 6 chosen, however, while the angled contact element is replaced by a rod 1 receiving collet-like shell 20 , and the variable volume 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 tension the rod 1 in her one.

In 7 is the definition of a spherical part 21 in a bowl that absorbs this 22 shown. This shell 22 has in its thickened wall several to the interior of the shell 22 open chambers 23 on that with variable-volume material 11 are filled and those of the spherical part 21 be closed. This results in a similar manner as in the embodiment of the 3 and 4 a jamming of the spherical part 21 relative to the shell 22 when the material is 11 expands.

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

In 9 is a clamping sleeve 29 shown, it is a simple sleeve whose inner wall with material 11 is coated, or in the one sleeve of variable volume material 11 is inserted. Such a sleeve 29 for example, an in 9 not shown rod are pushed and is on this by increasing the volume of the material 11 established.

In the embodiment of 10 becomes a staff 1 in a clamping device 30 set, which is a terminal block 31 with a through this receiving opening 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 clamping piece 35 slidably mounted, which in turn on its contact surfaces 33 and 34 facing side corresponding contact surfaces 36 . 37 wearing. The clamping piece 35 sticks out with a short shaft 38 into a hole 39 in the terminal block 31 into it, this hole 39 is at the opposite end by a screw 40 closed, 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 clamping piece 35 in the direction of the contact surfaces 33 and 34 and thereby pin the rod 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 displaceable arms 44 on, by protruding outward projections 45 corresponding, in the U-shaped receiving space of the recording 42 protruding projections 46 engage behind. This allows the plug 43 be resiliently inserted into its closed position and is secured against pulling out.

The remaining interior of the recording 42 is with variable volume material 11 filled. When increasing the volume of this material jammed the rod 1 in the receptacle and fixes him by, in addition, the resilient arms of the plug 43 pressed outwards and put the stopper 43 thereby in the admission 42 sure.

In the embodiment of the 12 is a holding element 47 with a hemispherical receiving tray 48 provided in this receptacle 48 is a ball 49 inserted. This has to its outer periphery open chambers 50 on, in the variable volume material 11 is filled, these chambers 50 be outside by the Aufnah meschale 48 locked. When stretching the material 11 thereby becomes the ball in the receiving tray 48 established.

In the embodiment of the 13 is a bar 1 in an annular receiving element 51 plugged in. The rod 1 has several distributed over its circumference chambers 52 on, for example in the form of circumferentially open longitudinal grooves in the variable volume material 11 is filled. These chambers 52 be outside by the annular receiving element 51 closed, so that when expanding the material 11 the rod 1 in the annular receiving element 51 is fixed.

In 14 are two parts 53 . 54 a prosthesis shown. These two parts 53 . 54 are over a cone cone 55 and a corresponding cone opening 56 connected together by the fact that the cone pin 55 in the cone opening 56 is inserted. However, the cone cone lies 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 of variable volume material 11 wearing. If the cone cone 55 in the cone opening 56 is inserted, he is fixed in this position as soon as the material 11 under the effect of the surrounding liquid or the ambient temperature.

All embodiments described above serve to explain the effect of the variable volume material 11 , which can be used in a variety of ways to implement the change in volume in setting forces or fixing movements for two parts to be joined together. The described embodiments serve to illustrate these different possibilities, but this should not limit the possible uses of the variable volume material in the connection of different parts.

Claims (18)

A surgical device comprising two relatively movable parts and 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 region which is connected to a material ( 11 ) is filled, which depending on its liquid content and / or depending on its temperature its volume changed so much that the clamping device passes from a release state into a clamping state. Surgical device according to claim 1, characterized in that the material ( 11 ) is a liquid-swelling material. 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: polyvinyl alcohol polyacrylate polyacrylic acid polyhydroxyalkylacrylate polyacrylonitrile polyacrylamide polyhydroxyalcyl-2-methylacrylate polyvinylphyrrolidone copolymers and terpolymers based on N-vinylpyrrolidone, acrylic acid, hydroxyalkyl acrylate, acrylamide. Surgical device according to claim 1, characterized in that the material ( 11 ) is a plastic that changes its volume abruptly 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 each other ( 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 each other ( 21 . 22 ; 24 . 27 ) Are parts of an endoprosthesis. Surgical device according to one of claims 1 to 6, characterized in that the relative to each other parts to be determined 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 fixed relative to each other ( 1 . 13 ; 21 . 22 ; 24 . 27 ; 48 . 49 ; 1 . 51 ; 53 . 54 ) is arranged and rests directly on both parts. Surgical device according to claim 10, characterized in that the material ( 11 ) in a unilaterally open receiving chamber ( 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 ) of the 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 formed as a sleeve, which on its inside a layer of the material ( 11 ) wearing. Surgical device according to one of claims 1 to 9, characterized in that the material ( 11 ) between two relatively movable elements ( 3 . 4 ; 17 . 19 ; 20 . 19 ; 35 . 40 ) is arranged, which determines the relative relative to each other by their relative movement, the two parts. Surgical device according to claim 14, characterized characterized in that at least one of the two moving elements through one of the two parts itself is formed. Surgical device according to one of the preceding claims, characterized in that, when the volume of the material increases ( 11 ) a positive connection of 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.