Title of Invention	EXTERNAL FIXATION DEVICE FOR OSTEOSYNTHESIS
Abstract	The invention relates to an external fixer (1) for osteosynthesis, wherein a frame (2), which is provided with at least one bar (3a, 3b), absorbs the mechanical strain and can be joined to the bone by connecting means, wherein the connecting means are joined to the frame by means of clamping jaws (4). A module (5a), which can be placed on the frame, is also provided and is used to cause a relative movement of two bone fragments towards each other. The module comprises at least two components (6a,7a). The first component (6a) can be connected to the frame and the second component (7a) can be connected to at least one clamping jaw of a connecting means which is joined to a first bone fragment. The module also comprises a means (8a) enabling the second component to move in relation to the first component, such that the bone fragment, which is connected to the second component by means of the clamping jaw can be moved as a result of said relative movement.

Title of Invention

EXTERNAL FIXATION DEVICE FOR OSTEOSYNTHESIS

Abstract

The invention relates to an external fixer (1) for osteosynthesis, wherein a frame (2), which is provided with at least one bar (3a, 3b), absorbs the mechanical strain and can be joined to the bone by connecting means, wherein the connecting means are joined to the frame by means of clamping jaws (4). A module (5a), which can be placed on the frame, is also provided and is used to cause a relative movement of two bone fragments towards each other. The module comprises at least two components (6a,7a). The first component (6a) can be connected to the frame and the second component (7a) can be connected to at least one clamping jaw of a connecting means which is joined to a first bone fragment. The module also comprises a means (8a) enabling the second component to move in relation to the first component, such that the bone fragment, which is connected to the second component by means of the clamping jaw can be moved as a result of said relative movement.

Full Text	FORM 2 THE PATENT ACT 197 0 (39 Of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and rule 13) TITLE OF INVENTION EXTERNAL FIXER FOR OSTEOSYNTHESIS APPLICANT(S) a) Name b) Nationality c) Address :SYNTHES GMBH :SWISS Company :EIMATTSTRASSE3, CH-4436 OBERDORF, SWITZERLAND 3. PREAMBLE TO THE DESCRIPTION The following specification particularly decribe the invention and the manner in which it is to be performed : - The present invention relates to an external fixateur for osteosynthesis according to the pre-characterizing clause of Claim 1. Orthopaedic corrections, such as, for example, limb extension,are carried out nowadays, inter alia, using so-called fixateurs. The proximal end of a bone is connected by means of bone-retaining pins through the skin to an external frame (located outside the body) which, during the extension process, bears the mechanical loads which are normally borne by the bone. The connection between the screws and the frame is realised by means of clamping jaws. The distal end of the bone is likewise connected to the frame by means of bone-retaining pins through the skin.The bone fixed in this manner can then be parted by means of an osteotomy (saw-cut) between the proximal and distal screws. All forces which are normally taken up by the bone now pass via the frame. After some days, the bone begins to form fibrous tissue in an attempt to close the artificially created gap.As soon as the two bone fragments have connected with the fibrous tissue, the extension can be started.The distal and proximal fragments are slowly drawn apart (approx. 1 mm per day) , and the tissue and the bone also grow. When the desired extension is reached, the procedure is stopped and the external fixateur is left in place until the bone has been consolidated and can bear all forces itself. According to the same principle of operation as in the case of the extension, bone segments can also be transported from one part of the bone to the other in order to close a gap which has formed, for example, by the removal of a tumour. The 2 distal and proximal fragments are then held in their anatomically correct position by the frame. Additionally bone-retaining pins are mounted in between and the osteotomy is carried out. The middle segment thus formed is displaced without changing the total length of the bone. The displacement is stopped when the gap has closed. The problem is that the external frame firstly must be rigid in order to be able to bear forces and secondly must permit a movement of the fragment in a defined axis (parallel to the extension direction).This movement must furthermore be defined as a function of time (for example, 0.2 5 mm every six hours). The prior art discloses a special frame which extends telescopically and permits a defined extension by means of an internal spindle drive.This unit must be very exactly constructed and is permitted to have only little play so that the fracture is not excessively stressed. The complicated constructions are often expensive to produce. Furthermore, a disadvantage of telescopic constructional systems is that the stability of the frame is impaired thereby so that telescopic 30 constructional systems generally have to be made comparatively solid in order to ensure that the bearing forces are reliably taken up. The prior art furthermore discloses arrangements which differ from the telescopic constructional system of a supporting rail. DE 32 29 313 discloses a device whose supporting rails consist of in each case two rigid support parts which in each case are connected to boneretaining pins of a bone fragment so that a relative longitudinal displacement of the bone fragments is possible. The second supporting part is in the form of an auxiliary rail. The auxiliary rail is displaceable 3 on the main rail, with the result that the relative movement of the bone fragments is achieved. This device, too, must be kept relatively coarse and solid since strong forces occur on carrying out the movement of the bone fragments relative to one another and have to be dissipated. Finally, DE 36 11 319 adopts another approach for avoiding telescopic rails. In this device, two rods are arranged parallel and form an external support frame. This too is connected to the bone with the aid of screws or bone-retaining pins. A relative movement of two bone fragments is now possible by means of a play in the guidance of the screws or bone-retaining pins so that the bone-retaining pins can change their angle relative to the rods and hence to the frame by the movement of the bone. The rods therefore do not change their position relative to one another.Compensation of the movement of the bone fragments is achieved by angling of the bone-retaining pins.Precise guidance and defined changes in length are not possible with this device. It is therefore an object of the present invention to provide an external fixateur for osteosynthesis which avoids said disadvantages. It should both be stable and reliably take up the transmitted forces and be easy and simple to change in length. A comparatively simple design is also desired. This object is achieved by an external fixateur according to the invention for osteosynthesis according to Claim 1. Variants and developments of the invention are mentioned in the sub-claims. The fixateur according to the invention has a frame comprising at least one rod which takes up the mechanical loads. Frame . 4 and bone are connected via connecting means known per se, in particular boneretaining pins. These connecting means in turn are connected to the frame via so-called clamping jaws.These clamping jaws permit detachable fixing and arbitrary arrangement and grouping on the frame.According to the invention, a module which can be mounted on the frame is provided. By means of the module, a movement of two bone fragments relative to one another can be effected. It has at least two components. The first of the at least two components can be connected to the frame. The second of the two components can be connected to at least one clamping jaw of a connecting means which is connected to a bone fragment. Expressed otherwise, the second component can be fixed on the clamping jaw. The module furthermore has a means with which the second component can be moved relative to the first component. As a result, a relative movement is achieved. This ensures that, by means of the clamping jaw to which the second component is connected, the bone fragment connected to the clamping jaw and hence to the second component can be moved. The present invention is therefore based on a traditional frame having simple, non-telescopic elements. These simple rods are widely used and permit a modular design of various frames. A preferred design is the parallel arrangement of two rods so that a double rail forms. The frame is oriented so that it points in the direction of displacement. Such a frame is provided with clamping jaws on which the boneretaining pins are fixed. The forces pass via the immobile frame without mechanical displacement units.The actual invention is an additional device, designated as module herein, which is preferably mounted only temporarily to effect an extension 5 increment and, if required, can be removed again at any time without having to remove the entire fixateur. The time scheme for such an extension procedure may consist of a short extension time (approx. '2 minutes) and a long static time (approx. 6 hours). During the static time, all clamping jaws of the fixateur are tightened and the module is ineffective and not under mechanical load. The stability is ensured in an operationally safe manner by the simple frame. In the short extension phase the bone is brought into a position without load. During the extension period,those clamping jaws which hold the bone fragment to be transported are slightly loosened so that they can be displaced on the frame. The module mounted according to the invention now permits a controlled displacement of the clamping jaws along the frame. This can be achieved, by turning a hand wheel. The displacement is effected in particular by a threaded spindle. In the variant shown in the working example, the spindle can alternatively also be rotated directly via a hexagon nut instead of via the hand wheel. After displacement of the clamping jaws by a certain distance (e.g. 0.25 mm), the clamping jaws are tightened again and, independently of the module, the force flows directly to the frame. The module is not used during the static period. After extension is complete, i.e. the bone has reached the correct anatomical length or the gap has been closed the module can be removed and the frame remains alone on the bone until the latter has consolidated. Owing to the relatively weak mechanical load of the module, it can be constructed to be much more delicate than a conventional extension apparatus. It is therefore possible to 6 construct the module to be very light, for example of aluminium, so that it can be left on the frame in the static periods too. The frame is preferably formed from at least two rods arranged parallel. However, other arrangements are also conceivable and in principle the design of a frame having only one rod is possible. The list of reference numerals and the drawing,together with the subjects described or protected in the Claims, are an integral part of the disclosure of this Application. The drawing is not limiting but represents only one working example. Description of figures The figures are described in relation to one another and as a whole. Identical reference -numerals denote identical components, and reference numerals with different indices indicate functionally identical components. Fig. 1 shows a perspective diagram of an external fixateur according to the invention and Fig. 2 shows a schematic perspective diagram of a fixateur module according to the invention. 3 5 Fig. 1 shows a perspective diagram of a fixateur 1 according to the invention. The fixateur 1 has a frame 2 in which, in the working example of Figure 1, two rods 3a, 3b are provided. A number of clamping jaws 4 are provided on the frame 2, more precisely on the rods 3a and 3b. In the working example of Figure 1, in each case 4 clamping jaws 4a, 4b, 4c, 4d or 4e, 7 4f, 4g, 4h are arranged to form a group. Each clamping jaw is connected to a connecting means, for example to a boneretaining pin. The bone-retaining pin is introduced into the bone. The clamping jaws permit connection of the bone to the rods 3a, 3b and hence to the frame 2. When the bone is cut through, the load is therefore transmitted via the connecting means to the frame. The bone-retaining pins have been omitted in the diagram of Figure 1. All that is shown is the bore for a bone-retaining pin, which is designated by way of example on the clamping jaw 4b with the reference numeral 14. According to the invention, a module 5 is provided.For a better explanation, the module 5 is shown schematically in Figure 2. In Figure 1, the module 5a is connected to the frame 2. The module has a first component 6 and a second component 7. According to the invention, the first component 6 can be connected to the frame. This connection is particularly strong.The second component 7 on the other hand is displaceably connected to the frame. It is supported on the clamping jaws 4, which are connected via the bone-retaining pins or another connecting means to the bone fragment to be displaced. The diagram of Figure 1 shows that the first component 6a, too, is preferably connected to the clamping jaws 4e and 4g. The connection of the first component 6a and of the second component 7a of the module 5a to the corresponding clamping jaw is preferably effected with the aid of the same screws and nuts 9 with which the clamping jaws 4 are also fixed on the rod 3a, 3b. If it is now intended to effect a displacement of a bone fragment, the nuts 9a-d are slightly undone, for example by a half to a whole turn. As a result, the clamping jaws 4a-4d 8 become displaceable on the rods 3a,3b. However, it should be noted that the threaded rod 8a of the module 5a initially prevents this. It performs a certain retaining function which proves to be very advantageous during the displacement phase. For displacement of the bone fragment, the threaded rod 8a is now rotated by turning the hand wheel 15a. It is also possible to provide a hexagon nut 16a, 16b so that the rotational movement is effected not by means of the hand wheel but by means of a corresponding tool. By rotating the threaded spindle 8a, a relative movement is produced, indicated by the arrow 10. The length of the displacement can be defined by the pitch of the threaded spindle. Thus, for example, a complete turn may correspond to a distance of 1 mm, which is a usual distance per day for a bone extension. It should be noted that the nuts 9e-9h are not undone during the extension process. They remain tight. The diagram of Figure 2 shows the design of the module 5b in detail. Both the first component and the second component have recesses 12a, 12b, 12c for engaging in each case one clamping jaw 4. The two components 6b, 7b are mounted on the clamping jaws 4. Furthermore, bores 11a, lib, lie are provided into which the screws of the clamping jaws 4 can be inserted. By means of this design, an accurate fit of the first component 6b and of the second component 7b on the clamping jaws 4 is achieved, as is evident, for example, from the diagram of Figure 1. It should be pointed out that, in the diagram of Figures 1 and 2, the first component engages only two clamping jaws 4e and 4g in each case, whereas the second component 7 engages four clamping jaws 4a, 4b, 4c, 4d. As is easily evident to the person skilled in the art this design can be modified as desired without departing from the principle according to the invention. 9 From the diagram of Figure 2, it is furthermore clear that a movement of the components 6b and 7b relative to one another is possible in both directions, indicated by the arrow 13. In the working example of Figure l,the first component 6a is fixed whereas the second component 7a experiences a relative movement as a result of the movement of the threaded spindle 8a, for example with the aid of the hand wheel 15b.Alternatively, however the component 6 can also be moved by arranging the component 7 in a fixed manner.Furthermore, the bone fragment could also be displaced in both directions if the component 6 is fixed. The direction of rotation on the spindle determines the displacement direction. The module 5 according to the invention can consequently be mounted independently of the desired displacement direction of the bone fragment. It is therefore also distinguished by universality. List of reference numerals 1 - External fixateur 2 - Frame 3 - Rod 4 - Clamping jaw 5 - Module 6 - First component 7 - Second component 8 - Threaded spindle 9 - Nut 10 - 13 - Arrow 11 - Bore 12 - Recess for clamping jaw 14 - Bore for bone-retaining pin 15 - Hand wheel 16 - Hexagon nut 10 WE CLAIM : 1. External fixateur (1) for osteosynthesis,comprising a frame (2) having at least one rod (3) , for taking up mechanical loads, the frame (2) being capable of being connected to a bone via connecting means which can be connected to the frame by means of clamping jaws (4) , characterized in that a module (5) which can optionally be mounted on the frame and by means of which a movement of two bone fragments relative to one another can be effected is provided, the module having at least two components (6, 7) of which the first component (6) can be connected to the frame and the second component (7) can be connected to at least one clamping jaw of a connecting means which is connected to a bone fragment, and the module having a means (8) with which the second component can be moved relative to the first component so that, as a result of this relative movement, the bone fragment connected by the clamping jaw to the second component can be moved. 2. Fixateur according to Claim 1, characterized in that at least two rods (3) arranged parallel are provided as frame (2). 3. Fixateur according to Claim 1 or 2, characterized in that the first component (6) can be connected to the frame (2) by means of fixing to a clamping jaw. 4. Fixateur according to any of the preceding Claims, characterized in that the means is a threaded spindle (8) which can be turned manually, in particular by means of a hand wheel (15), or with the aid of a tool. 11 5. Fixateur according to any of the preceding Claims, characterized in that the first component (6) and/or the second component (7) have at least one recess (12) which can be mounted above one clamping jaw (4) each. 6. Fixateur according to any of the preceding Claims,characterized in that the first component (6) and/or the second component (7) have bores (11) for the passage of a fixing means, .in particular of a screw, and hence for fixing to a clamping jaw. 7. Fixateur according to any of the preceding Claims,characterized in that the module is composed at least partly of a light metal, preferably of aluminium or of an aluminium alloy. 8. Fixateur according to any of the preceding Claims,characterized in that the means comprises an electric drive. 9. Fixateur according to Claim 8, characterized in that the electric drive has a timer and an incremental limiter so that the displacement movement can take place with automatic control. 10. Fixateur according to any of the preceding Claims,characterized in that the means has a readable display for the displacement movement. 12

Full Text

FORM 2
THE PATENT ACT 197 0 (39 Of 1970)
&

The Patents Rules, 2003
COMPLETE SPECIFICATION
(See Section 10, and rule 13)
TITLE OF INVENTION
EXTERNAL FIXER FOR OSTEOSYNTHESIS

APPLICANT(S)
a) Name
b) Nationality
c) Address

:SYNTHES GMBH :SWISS Company :EIMATTSTRASSE3,
CH-4436 OBERDORF,
SWITZERLAND

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly decribe the invention and the manner in which it is to be performed : -

The present invention relates to an external fixateur for osteosynthesis according to the pre-characterizing clause of Claim 1.
Orthopaedic corrections, such as, for example, limb extension,are carried out nowadays, inter alia, using so-called fixateurs. The proximal end of a bone is connected by means of bone-retaining pins through the skin to an external frame (located outside the body) which, during the extension process, bears the mechanical loads which are normally borne by the bone. The connection between the screws and the frame is realised by means of clamping jaws.
The distal end of the bone is likewise connected to the frame by means of bone-retaining pins through the skin.The bone fixed in this manner can then be parted by means of an osteotomy (saw-cut) between the proximal and distal screws. All forces which are normally taken up by the bone now pass via the frame.
After some days, the bone begins to form fibrous tissue in an attempt to close the artificially created gap.As soon as the two bone fragments have connected with the fibrous tissue, the extension can be started.The distal and proximal fragments are slowly drawn apart (approx. 1 mm per day) , and the tissue and the bone also grow. When the desired extension is reached, the procedure is stopped and the external fixateur is left in place until the bone has been consolidated and can bear all forces itself.
According to the same principle of operation as in the case of the extension, bone segments can also be transported from one part of the bone to the other in order to close a gap which has formed, for example, by the removal of a tumour. The
2

distal and proximal fragments are then held in their anatomically correct position by the frame. Additionally bone-retaining pins are mounted in between and the osteotomy is carried out. The middle segment thus formed is displaced without changing the total length of the bone. The displacement is stopped when the gap has closed.
The problem is that the external frame firstly must be rigid in order to be able to bear forces and secondly must permit a movement of the fragment in a defined axis (parallel to the extension direction).This movement must furthermore be defined as a function of time (for example, 0.2 5 mm every six hours).
The prior art discloses a special frame which extends telescopically and permits a defined extension by means of an internal spindle drive.This unit must be very exactly constructed and is permitted to have only little play so that the fracture is not excessively stressed. The complicated constructions are often expensive to produce.
Furthermore, a disadvantage of telescopic constructional systems is that the stability of the frame is impaired thereby so that telescopic 30 constructional systems generally have to be made comparatively solid in order to ensure that the bearing forces are reliably taken up.
The prior art furthermore discloses arrangements which differ from the telescopic constructional system of a supporting rail. DE 32 29 313 discloses a device whose supporting rails consist of in each case two rigid support parts which in each case are connected to boneretaining pins of a bone fragment so that a relative longitudinal displacement of the bone fragments is possible. The second supporting part is in the form of an auxiliary rail. The auxiliary rail is displaceable
3

on the main rail, with the result that the relative movement of the bone fragments is achieved. This device, too, must be kept relatively coarse and solid since strong forces occur on carrying out the movement of the bone fragments relative to one another and have to be dissipated.
Finally, DE 36 11 319 adopts another approach for avoiding telescopic rails. In this device, two rods are arranged parallel and form an external support frame. This too is connected to the bone with the aid of screws or bone-retaining pins. A relative movement of two bone fragments is now possible by means of a play in the guidance of the screws or bone-retaining pins so that the bone-retaining pins can change their angle relative to the rods and hence to the frame by the movement of the bone. The rods therefore do not change their position relative to one another.Compensation of the movement of the bone fragments is achieved by angling of the bone-retaining pins.Precise guidance and defined changes in length are not possible with this device.
It is therefore an object of the present invention to provide an external fixateur for osteosynthesis which avoids said disadvantages. It should both be stable and reliably take up the transmitted forces and be easy and simple to change in length. A comparatively simple design is also desired.
This object is achieved by an external fixateur according to
the invention for osteosynthesis according to Claim 1.
Variants and developments of the invention are mentioned in
the sub-claims.
The fixateur according to the invention has a frame comprising at least one rod which takes up the mechanical loads. Frame
. 4

and bone are connected via connecting means known per se, in particular boneretaining pins. These connecting means in turn are connected to the frame via so-called clamping jaws.These clamping jaws permit detachable fixing and arbitrary arrangement and grouping on the frame.According to the invention, a module which can be mounted on the frame is provided. By means of the module, a movement of two bone fragments relative to one another can be effected. It has at least two components. The first of the at least two components can be connected to the frame. The second of the two components can be connected to at least one clamping jaw of a connecting means which is connected to a bone fragment. Expressed otherwise, the second component can be fixed on the clamping jaw.
The module furthermore has a means with which the second component can be moved relative to the first component. As a result, a relative movement is achieved. This ensures that, by means of the clamping jaw to which the second component is connected, the bone fragment connected to the clamping jaw and hence to the second component can be moved.
The present invention is therefore based on a traditional frame having simple, non-telescopic elements. These simple rods are widely used and permit a modular design of various frames. A preferred design is the parallel arrangement of two rods so that a double rail forms. The frame is oriented so that it points in the direction of displacement. Such a frame is provided with clamping jaws on which the boneretaining pins are fixed. The forces pass via the immobile frame without mechanical displacement units.The actual invention is an additional device, designated as module herein, which is preferably mounted only temporarily to effect an extension
5

increment and, if required, can be removed again at any time without having to remove the entire fixateur.
The time scheme for such an extension procedure may consist of a short extension time (approx. '2 minutes) and a long static time (approx. 6 hours). During the static time, all clamping jaws of the fixateur are tightened and the module is ineffective and not under mechanical load. The stability is ensured in an operationally safe manner by the simple frame. In the short extension phase the bone is brought into a position without load. During the extension period,those clamping jaws which hold the bone fragment to be transported are slightly loosened so that they can be displaced on the frame. The module mounted according to the invention now permits a controlled displacement of the clamping jaws along the frame. This can be achieved, by turning a hand wheel. The displacement is effected in particular by a threaded spindle. In the variant shown in the working example, the spindle can alternatively also be rotated directly via a hexagon nut instead of via the hand wheel.
After displacement of the clamping jaws by a certain distance (e.g. 0.25 mm), the clamping jaws are tightened again and, independently of the module, the force flows directly to the frame. The module is not used during the static period.
After extension is complete, i.e. the bone has reached the correct anatomical length or the gap has been closed the module can be removed and the frame remains alone on the bone until the latter has consolidated.
Owing to the relatively weak mechanical load of the module, it can be constructed to be much more delicate than a conventional extension apparatus. It is therefore possible to
6

construct the module to be very light, for example of aluminium, so that it can be left on the frame in the static periods too.
The frame is preferably formed from at least two rods arranged parallel. However, other arrangements are also conceivable and in principle the design of a frame having only one rod is possible.
The list of reference numerals and the drawing,together with the subjects described or protected in the Claims, are an integral part of the disclosure of this Application. The drawing is not limiting but represents only one working example.
Description of figures
The figures are described in relation to one another and as a whole. Identical reference -numerals denote identical components, and reference numerals with different indices indicate functionally identical components.
Fig. 1 shows a perspective diagram of an external fixateur according to the invention and
Fig. 2 shows a schematic perspective diagram of a fixateur module according to the invention. 3 5
Fig. 1 shows a perspective diagram of a fixateur 1 according to the invention. The fixateur 1 has a frame 2 in which, in the working example of Figure 1, two rods 3a, 3b are provided. A number of clamping jaws 4 are provided on the frame 2, more precisely on the rods 3a and 3b. In the working example of Figure 1, in each case 4 clamping jaws 4a, 4b, 4c, 4d or 4e,
7

4f, 4g, 4h are arranged to form a group. Each clamping jaw is connected to a connecting means, for example to a boneretaining pin. The bone-retaining pin is introduced into the bone. The clamping jaws permit connection of the bone to the rods 3a, 3b and hence to the frame 2. When the bone is cut through, the load is therefore transmitted via the connecting means to the frame. The bone-retaining pins have been omitted in the diagram of Figure 1. All that is shown is the bore for a bone-retaining pin, which is designated by way of example on the clamping jaw 4b with the reference numeral 14.
According to the invention, a module 5 is provided.For a better explanation, the module 5 is shown schematically in Figure 2. In Figure 1, the module 5a is connected to the frame
2. The module has a first component 6 and a second component
7. According to the invention, the first component 6 can be connected to the frame. This connection is particularly strong.The second component 7 on the other hand is displaceably connected to the frame. It is supported on the clamping jaws 4, which are connected via the bone-retaining pins or another connecting means to the bone fragment to be displaced.
The diagram of Figure 1 shows that the first component 6a, too, is preferably connected to the clamping jaws 4e and 4g. The connection of the first component 6a and of the second component 7a of the module 5a to the corresponding clamping jaw is preferably effected with the aid of the same screws and nuts 9 with which the clamping jaws 4 are also fixed on the rod 3a, 3b.
If it is now intended to effect a displacement of a bone fragment, the nuts 9a-d are slightly undone, for example by a half to a whole turn. As a result, the clamping jaws 4a-4d
8

become displaceable on the rods 3a,3b. However, it should be noted that the threaded rod 8a of the module 5a initially prevents this. It performs a certain retaining function which proves to be very advantageous during the displacement phase.
For displacement of the bone fragment, the threaded rod 8a is now rotated by turning the hand wheel 15a. It is also possible to provide a hexagon nut 16a, 16b so that the rotational movement is effected not by means of the hand wheel but by means of a corresponding tool. By rotating the threaded spindle 8a, a relative movement is produced, indicated by the arrow 10. The length of the displacement can be defined by the pitch of the threaded spindle. Thus, for example, a complete turn may correspond to a distance of 1 mm, which is a usual distance per day for a bone extension. It should be noted that the nuts 9e-9h are not undone during the extension process. They remain tight.
The diagram of Figure 2 shows the design of the module 5b in detail. Both the first component and the second component have recesses 12a, 12b, 12c for engaging in each case one clamping jaw 4. The two components 6b, 7b are mounted on the clamping jaws 4. Furthermore, bores 11a, lib, lie are provided into which the screws of the clamping jaws 4 can be inserted. By means of this design, an accurate fit of the first component 6b and of the second component 7b on the clamping jaws 4 is achieved, as is evident, for example, from the diagram of Figure 1. It should be pointed out that, in the diagram of Figures 1 and 2, the first component engages only two clamping jaws 4e and 4g in each case, whereas the second component 7 engages four clamping jaws 4a, 4b, 4c, 4d. As is easily evident to the person skilled in the art this design can be modified as desired without departing from the principle according to the invention.
9

From the diagram of Figure 2, it is furthermore clear that a movement of the components 6b and 7b relative to one another is possible in both directions, indicated by the arrow 13. In the working example of Figure l,the first component 6a is fixed whereas the second component 7a experiences a relative movement as a result of the movement of the threaded spindle 8a, for example with the aid of the hand wheel 15b.Alternatively, however the component 6 can also be moved by arranging the component 7 in a fixed manner.Furthermore, the bone fragment could also be displaced in both directions if the component 6 is fixed. The direction of rotation on the spindle determines the displacement direction. The module 5 according to the invention can consequently be mounted independently of the desired displacement direction of the bone fragment. It is therefore also distinguished by universality.
List of reference numerals
1 - External fixateur
2 - Frame
3 - Rod
4 - Clamping jaw
5 - Module
6 - First component
7 - Second component
8 - Threaded spindle
9 - Nut

10 - 13 - Arrow
11 - Bore
12 - Recess for clamping jaw

14 - Bore for bone-retaining pin
15 - Hand wheel
16 - Hexagon nut
10

WE CLAIM :
1. External fixateur (1) for osteosynthesis,comprising a frame (2) having at least one rod (3) , for taking up mechanical loads, the frame (2) being capable of being connected to a bone via connecting means which can be connected to the frame by means of clamping jaws (4) , characterized in that a module (5) which can optionally be mounted on the frame and by means of which a movement of two bone fragments relative to one another can be effected is provided, the module having at least two components (6, 7) of which the first component (6) can be connected to the frame and the second component (7) can be connected to at least one clamping jaw of a connecting means which is connected to a bone fragment, and the module having a means (8) with which the second component can be moved relative to the first component so that, as a result of this relative movement, the bone fragment connected by the clamping jaw to the second component can be moved.
2. Fixateur according to Claim 1, characterized in that at least two rods (3) arranged parallel are provided as frame (2).
3. Fixateur according to Claim 1 or 2, characterized in that the first component (6) can be connected to the frame (2) by means of fixing to a clamping jaw.
4. Fixateur according to any of the preceding Claims, characterized in that the means is a threaded spindle (8) which can be turned manually, in particular by means of a hand wheel (15), or with the aid of a tool.
11

5. Fixateur according to any of the preceding Claims, characterized in that the first component (6) and/or the second component (7) have at least one recess (12) which can be mounted above one clamping jaw (4) each.
6. Fixateur according to any of the preceding Claims,characterized in that the first component (6) and/or the second component (7) have bores (11) for the passage of a fixing means, .in particular of a screw, and hence for fixing to a clamping jaw.
7. Fixateur according to any of the preceding Claims,characterized in that the module is composed at least partly of a light metal, preferably of aluminium or of an aluminium alloy.
8. Fixateur according to any of the preceding Claims,characterized in that the means comprises an electric drive.
9. Fixateur according to Claim 8, characterized in that the electric drive has a timer and an incremental limiter so that the displacement movement can take place with automatic control.
10. Fixateur according to any of the preceding Claims,characterized in that the means has a readable display for the displacement movement.

12

EXTERNAL FIXATION DEVICE FOR OSTEOSYNTHESIS

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