Abstract:
In order to improve an orthopedic fixation device for connecting a first anchoring element ( 12 ) which has a connecting section ( 26 ) and can be anchored in or on a bone ( 18 ) to a connecting element ( 14 ) which can be connected to a second anchoring element which can be anchored in or on a bone, wherein the fixation device is movable relative to the connecting element and to the anchoring element in an adjusting position and can be secured on the connecting element and on the anchoring element in a fixing position, such that the connecting element can be secured on the anchoring element in a particularly simple manner it is suggested that a single tensioning member ( 50; 122; 166; 172 ) which is supported so as to be movable be provided for transferring the fixation device from the adjusting position into the fixing position and vice versa.

Description:
[0001]     This application is a continuation of International application No. PCT/EP2005/011455 filed on Oct. 26, 2005.  
         [0002]     The present disclosure relates to the subject matter disclosed in International application No. PCT/EP2005/011455 of Oct. 26, 2005 and German application No. 10 2004 056 091.9 of Nov. 12, 2004, which are incorporated herein by reference in their entirety and for all purposes. 
     
    
     BACKGROUND OF THE INVENTION  
       [0003]     The invention relates to an orthopedic fixation device for connecting a first anchoring element, which has a connecting section and can be anchored in or on a bone, to a connecting element which can be connected to a second anchoring element which can be anchored in or on a bone, wherein the fixation device is movable relative to the connecting element and to the anchoring element in an adjusting position and can be secured on the connecting element and on the anchoring element in a fixing position.  
         [0004]     Furthermore, the invention relates to an orthopedic fixation system comprising at least two anchoring elements which can be anchored in or on a bone, at least one connecting element for connecting the at least two anchoring elements and at least one orthopedic fixation device for connecting the at least one connecting element to a connecting section of one of the at least two anchoring elements.  
         [0005]     Orthopedic fixation devices and fixation systems such as those described at the outset are used to position and fix different bones or bone fragments in place relative to one another. For this purpose, anchoring elements in the form of bone screws or bone hooks are normally inserted into the respective bone fragments and connected permanently or temporarily by means of a connecting element which is secured to both anchoring elements. Fixation devices are known, with which the connecting element can be secured on the anchoring element laterally offset in relation to the connecting section. The connection between anchoring element and connecting element can be provided after insertion of the anchoring element so that the anchoring element itself, for example, a bone screw need no longer be turned in the bone, which can lead to an undesired loosening of a screw once screwed in.  
         [0006]     In contrast to bone screws which have a forked head for accommodating a connecting element, the provision of a connection between the anchoring element and the connecting element in the case of known fixation devices has proven to be extremely complicated since, on the one hand, the fixation device must be secured to the anchoring element and, on the other hand, the connecting element must be secured to the fixation device.  
         [0007]     It is, therefore, the object of the present invention to improve an orthopedic fixation device as well as an orthopedic fixation system of the respective type described at the outset such that the connecting element can be secured on the anchoring element in a particularly simple manner.  
       SUMMARY OF THE INVENTION  
       [0008]     This object is accomplished in accordance with the invention, in an orthopedic fixation device of the type described at the outset, in that a single tensioning member supported so as to be movable is provided for transferring the fixation device from the adjusting position into the fixing position and vice versa.  
         [0009]     In contrast to the fixation devices known from the state of the art, it is sufficient to move only the tensioning member, whereby the fixation device can be secured, on the one hand, on the connecting element and, on the other hand, on the anchoring element. Therefore, only one locking step is necessary in order to secure three elements relative to one another at the same time. This is advantageous, in particular, when the connecting element is intended to be secured to the anchoring element laterally offset relative to a longitudinal axis of this anchoring element. In any case, the fixation device according to the invention allows the anchoring element to be inserted first of all into a bone or a bone fragment in the desired manner, the connecting element to subsequently be adjusted relative to the anchoring element in the desired manner and the fixation device to then be secured not only to the anchoring element but also to the connecting element in a single step as a result of movement of the tensioning member.  
         [0010]     It is advantageous when the fixation device comprises at least one first supporting element and when the tensioning member is supported on the at least one first supporting element so as to be rotatable. The fixation device can then be transferred from the adjusting position into the fixing position as a result of a simple rotation of the tensioning member relative to the first supporting element.  
         [0011]     It is favorable when the fixation device comprises at least one first supporting element and when the tensioning member is supported relative to the first supporting element so as to be translatable. This configuration, also in combination with a possible rotatability of the tensioning member relative to the first supporting element, allows transfer of the fixation device from the adjusting position into the fixing position as a result of a simple, translational movement of the tensioning member relative to the first supporting element.  
         [0012]     In accordance with a preferred embodiment of the invention, it may be provided for the connecting element, in the adjusting position, to be displaceable relative to the anchoring element parallel to itself towards the anchoring element or away from it. This configuration makes it possible, for example, to hold the connecting element on the anchoring element in the adjusting position by means of the fixation device and, when required, to reduce a distance between the connecting element and the connecting section of the anchoring element in the desired manner without the connecting element needing to be pivoted relative to the anchoring element.  
         [0013]     In order to ensure a particularly good securement of the connecting element on the fixation device in the fixing position, it is advantageous when the fixation device has a connecting element receiving means, which corresponds to the connecting element, for accommodating the connecting element.  
         [0014]     In a similar way, an optimum securement of the fixation device on the connecting section of the anchoring element can be ensured when the fixation device has a connecting section receiving means, which corresponds to the connecting section, for accommodating the connecting section.  
         [0015]     In order to facilitate pivoting of the connecting element relative to the anchoring element, it is advantageous when the connecting section receiving means is rotatable about a first axis of rotation relative to the connecting element receiving means.  
         [0016]     In principle, it would be conceivable to secure the anchoring element, the fixation device and the connecting element in the fixing position by means of form locking connections. In accordance with a preferred embodiment of the invention, it may be provided for a first clamping device to be provided for clampingly securing the fixation device on the connecting element in the fixing position, for a second clamping device to be provided for clampingly securing the fixation device on the anchoring element in the fixing position and for the first clamping device to comprise the tensioning member and for the second clamping device to comprise the tensioning member. The tensioning member is, in the configuration according to the invention, therefore part of both clamping devices which makes it possible to actuate both clamping devices, i.e., transfer the fixation device into the fixing position or to release them, i.e., transfer the fixation device from the fixing position into the adjusting position at the same time as a result of movement of the tensioning member.  
         [0017]     It is advantageous when the fixation device comprises a first supporting element supporting the connecting element receiving means and a second supporting element which supports the connecting section receiving means and is supported on the first supporting element so as to be rotatable about an axis of rotation in the adjusting position. The two supporting elements form, as it were, a two-part movable frame and enable the connecting element to be pivoted relative to the anchoring element about the first axis of rotation.  
         [0018]     The construction of the fixation device is particularly simple when the tensioning member forms a bearing shaft defining the first axis of rotation. The tensioning member therefore has a double function; on the one hand, it serves as a bearing shaft, on the other hand, as a means for transferring the fixation device from the adjusting position into the fixing position and vice versa. The design of the fixation device may also be simplified as a result of this construction.  
         [0019]     It is advantageous when the first clamping device comprises a first clamping element which has a slide-on surface which abuts directly or indirectly on a first actuating surface of a first clamping member of the first supporting element and when the first clamping element is movable as a result of movement of the tensioning member in such a manner that the first slide-on surface slides on the first actuating surface and can reduce a cross section of the connecting element receiving means in such a manner that the connecting element can be secured in the connecting element receiving means. It is, therefore, possible to move the tensioning member and as a result of its movement drive, so to speak, the first clamping element which can move a clamping member directly or indirectly as a result of the slide-on surface sliding on the actuating surface. As a result, the fixation device is transferred from the adjusting position into the fixing position in that the cross section of the connecting element receiving means is reduced by the slide-on movement which leads to a desired clamping of the connecting element in the connecting element receiving means.  
         [0020]     In order to be able to use individual parts of the fixation device for different sizes of supporting elements, it is favorable when a first force transfer member arranged between the first slide-on surface and the first actuating surface is provided for transferring a force from the first clamping element to the first clamping member. For example, the parts could also be manufactured from different materials.  
         [0021]     It is advantageous when the first slide-on surface and the first actuating surface are inclined relative to the first axis of rotation. As a result, a slide-on movement can take place when the tensioning member is moved parallel to the axis of rotation. A parallel movement also results indirectly due to rotation of the tensioning member when this is designed, for example, in the form of a screw bolt which therefore facilitates a superimposed translation-rotation movement.  
         [0022]     In accordance with a further, preferred embodiment of the invention, it may be provided for the first slide-on surface to be a first outer surface of a first eccentric rotatable about the first axis of rotation and for the first actuating surface to be curved concavely in the direction towards the first axis of rotation at least in sections. As a result of the eccentric, a distance between the first outer surface and the first actuating surface can be altered as a result of a rotation of the tensioning member and clamping brought about in this way. The actuating surface can be shaped, for example, so as to be hollow cylindrical in sections, the outer surface of the eccentric so as to be cylindrical.  
         [0023]     The first clamping element can be advantageously designed in the shape of a cone. The cone can, therefore, have a conical outer surface which serves at the same time as a slide-on surface. A slide-on movement relative to the first actuating surface can be brought about with the cone in every rotary position of the tensioning member, for example, as a result of a translational movement of the cone parallel to the first axis of rotation.  
         [0024]     Assembly of the fixation device is simplified when the first clamping element and the tensioning member are designed in one piece. In this way, it is possible to prevent the clamping element and the tensioning member from being able to detach from one another in an undesired manner.  
         [0025]     Depending on the construction of the fixation device, it may, however, be advantageous with a view to the assembly when the first clamping element and the tensioning member are designed in two parts. This allows, for example, parts to be pushed together first of all and then securely connected to one another.  
         [0026]     The first clamping element and the tensioning member are preferably connected to one another so as to be non-rotatable. This prevents any loosening of the first clamping element from the tensioning member as a result of rotation of the tensioning member.  
         [0027]     It may favorably be provided for the tensioning member to have a first external thread section, for the first clamping element to have a first internal thread section corresponding to the first external thread section and for the first clamping element to be displaceable parallel to itself as a result of rotation of the tensioning member about its longitudinal axis. This construction is similar to the construction of a threaded spindle, wherein the tensioning member is used as a drive element in order to be able to displace the clamping element parallel to itself. The clamping element is advantageously guided for this purpose in a corresponding guide which prevents any rotation of the clamping element as a result of a rotary movement of the tensioning member.  
         [0028]     Furthermore, it may be favorable when the second clamping device comprises a second clamping element which has a second slide-on surface which abuts directly or indirectly on a second actuating surface of the second supporting element and when the second clamping element can be moved as a result of movement of the tensioning member in such a manner that the second slide-on surface slides on the second actuating surface and a clamping member limiting the connecting section receiving means in sections can be moved in such a manner that a cross section of the connecting section receiving means can be reduced such that the connecting section of the anchoring element can be secured in the connecting section receiving means. The second clamping element can be moved with the tensioning member, whereby a slide-on movement between the clamping element and the clamping member abutting directly or indirectly on it is made possible in order to reduce a cross section of the connecting section receiving means. As a result of the reduction in the cross section, the connecting section can be secured in the connecting section receiving means.  
         [0029]     A slide-on movement is possible in a simple manner when the second slide-on surface and the second actuating surface are inclined relative to the first axis of rotation. Slide-on movement is thus made possible when the tensioning member is moved, for example, as a result of movement parallel to the first axis of rotation either as a result of a pure translation movement or as a result of a superimposed translation-rotation movement.  
         [0030]     It Is favorable when the second slide-on surface Is a second outer surface of a second eccentric rotatable about the first axis of rotation and when the second actuating surface is curved concavely in the direction towards the first axis of rotation at least in sections. The eccentric, the outer surface of which is arranged eccentrically to the first axis of rotation, can reduce a distance between the second slide-on surface and the second actuating surface when the tensioning member and, with it, the eccentric is rotated about the first axis of rotation. The second outer surface may be a cylindrical surface, the second actuating surface a hollow cylindrical surface or at least a surface section of this type.  
         [0031]     A particularly simple construction of the fixation device results when the second clamping element is designed at least partially in the shape of a cone. This also means that only a part or a section of the second clamping element may have a conical or at least inclined surface. Such a clamping element is particularly easy to produce.  
         [0032]     In order to increase the stability of the fixation device, it may be advantageous when the second clamping element and the tensioning member are designed in one piece. Furthermore, this avoids the second clamping element and the tensioning member being able to become detached from one another when this is not desired.  
         [0033]     The second clamping element and the tensioning member are preferably designed in two parts. This can make an assembly of different parts even possible at all. Furthermore, the combination of different tensioning members with different clamping elements is possible during the assembly.  
         [0034]     In order to ensure that the second clamping element is rotated as well as a result of rotation of the tensioning member, it is favorable when the second clamping element and the tensioning member are connected to one another so as to be non-rotatable.  
         [0035]     In accordance with a preferred embodiment of the invention, it may be provided for the tensioning member to have a second external thread section, for the second clamping element to have a second internal thread section corresponding to the second external thread section and for the second clamping element to be displaceable parallel to itself as a result of rotation of the tensioning member about its longitudinal axis. As a result of this configuration, a spindle drive is, as it were, formed for driving the second clamping element as a result of rotation of the tensioning member. So that the second clamping element is not co-rotated as a result of rotation of the tensioning member, a corresponding guide for the second clamping element can be provided.  
         [0036]     The first and the second external thread sections are favorably thread sections running in opposite directions. This makes it possible for the two clamping elements to be moved at the same time towards one another or away from one another as a result of rotation of the tensioning member.  
         [0037]     In this respect, it may be advantageous when the first external thread section is a right-hand thread section and when the second external thread section is a left-hand thread section. This makes it possible, for example, to drive the two clamping members with the tensioning member, as a result of rotation of the tensioning member in the clockwise direction, in such a manner that they are moved towards one another, whereby the fixation device can be transferred from the adjusting position into the fixing position.  
         [0038]     It is advantageous when the second supporting element is supported on the connecting section via the second clamping member in the fixing position. In this way, connecting sections with different cross sections can be accommodated by the connecting section receiving means and can be secured in it.  
         [0039]     So that as few individual parts as possible have to be joined together during the production of the fixation device, it is advantageous when the second clamping member and the second supporting element are designed in one piece. For example, the second clamping member can be designed in the form of a movable tab held on the supporting element.  
         [0040]     In order to be able to adapt the fixation device, when required, to specific anchoring elements during a surgical procedure, it is favorable when the second clamping member and the second supporting element are designed in two parts. This allows clamping members of a desired strength or thickness to be selected and arranged on the fixation device.  
         [0041]     So that the connecting element can be moved parallel to itself in the direction towards the anchoring element, it is advantageous when the second supporting element is supported on the connecting section so as to be rotatable about a second axis of rotation in the adjusting position. In other words, this means that the connecting section itself or the second supporting element each form a supporting element for the respectively other element for forming a rotary bearing.  
         [0042]     A particularly simple construction of the fixation device results when the first and the second axes of rotation extend parallel to one another. In addition, movement of the connecting element parallel to itself towards the anchoring element is allowed in this way.  
         [0043]     In order to be able to adjust an angle of inclination of the connecting element relative to the anchoring element, it is advantageous when the connecting element receiving means is supported on the first supporting element so as to be rotatable about a third axis of rotation and when the third axis of rotation extends transversely to a longitudinal axis of the connecting element receiving means. The rotatability can, in addition, be limited by angular stops provided accordingly so that a rotatability, for example, in an angular range of ±30° is possible, preferably ±15°.  
         [0044]     An optimum adaptation for connecting different bone parts or bone fragments may be achieved when the third axis of rotation extends transversely to the first and/or to the second axis of rotation.  
         [0045]     So that the fixation device can be secured on the anchoring element only after anchoring of the anchoring element in or on a bone, it is favorable when the connecting section forms the proximal end of the anchoring element or is arranged in the area of the proximal end of the anchoring element. It is, therefore, possible to place the fixation device, for example, onto the connecting section after insertion of the anchoring element.  
         [0046]     In principle, it would be conceivable to design the connecting section receiving means in such a manner that a cylindrical connecting section can be accommodated. In order to increase the adjustability of the fixation device and, therefore, of the connecting element relative to the anchoring element even further, it is advantageous when the connecting section receiving means Is designed in the form of a spherical joint receiving means for accommodating a spherical connecting section.  
         [0047]     So that the tensioning member can be moved in a simple manner, it is advantageous when it has a tool receiving means for accommodating a tensioning tool and when the tensioning member is movable with the tensioning tool.  
         [0048]     The object specified at the outset is accomplished in accordance with the invention, in addition, in an orthopedic fixation system of the type described at the outset, in that the at least one orthopedic fixation device is one of the fixation devices described above. As already explained, the fixation device can be transferred from the adjusting position into the fixing position in a single step with such a fixation device. Dependent on the special configuration of the fixation device, the overall orthopedic fixation system then has the advantages described above.  
         [0049]     In order to be able to connect the fixation device to the anchoring element in a simple manner, it is advantageous when the connecting section is designed so as to be thread-free and is cylindrical or essentially cylindrical in shape. In the adjusting position, the fixation device can be rotated in a simple manner relative to the anchoring element since the connecting section forms a more or less perfect bearing shaft.  
         [0050]     In order to be able to form a spherical joint with the fixation device, it is favorable when the connecting section of the anchoring element is in the shape of a spherical cap or essentially in the shape of a spherical cap.  
         [0051]     In accordance with a preferred embodiment of the fixation system, it may be provided for the anchoring element to comprise a screw thread section forming its distal end for screwing into a bone.  
         [0052]     Furthermore, it can be advantageous when the anchoring element comprises a hook forming its distal end for anchoring the anchoring element in a bone.  
         [0053]     The connecting element is preferably a bar or a connecting plate with at least one bar-like plate section. Connecting elements of this type may be connected in a simple manner by means of a fixation device according to the invention to an anchoring element of any optional type.  
         [0054]     The following description of preferred embodiments of the invention serves to explain the invention in greater detail in conjunction with the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0055]      FIG. 1 : shows a perspective overall view of a first embodiment of a fixation system according to the invention;  
         [0056]      FIG. 2 : shows a partially disassembled fixation device in the fixing position;  
         [0057]      FIG. 3 : shows an exploded illustration of the fixation system illustrated in  FIG. 1 ;  
         [0058]      FIG. 4 : shows a further, perspective view of the exploded illustration in  FIG. 3 ;  
         [0059]      FIG. 5 : shows a sectional view along line  5 - 5  in  FIG. 1 ;  
         [0060]      FIG. 6 : shows a sectional view similar to  FIG. 5  through a second embodiment of a fixation device in the adjusting position;  
         [0061]      FIG. 7 : shows a view similar to  FIG. 6  of the second embodiment but in the fixing position;  
         [0062]      FIG. 8 : shows a sectional view similar to  FIG. 5  through a third embodiment of a fixation device;  
         [0063]      FIG. 9 : shows a sectional view similar to  FIG. 5  through a fourth embodiment of a fixation device;  
         [0064]      FIG. 10 : shows a sectional view similar to  FIG. 5  through a fifth embodiment of a fixation device;  
         [0065]      FIG. 11 : shows a sectional view similar to  FIG. 5  through a sixth embodiment of a fixation device;  
         [0066]      FIG. 12 : shows a sectional view similar to  FIG. 5  through a seventh embodiment of a fixation device; and  
         [0067]      FIG. 13 : shows a sectional view similar to  FIG. 5  through an eighth embodiment of a fixation device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0068]     FIGS.  1  to  5  illustrate by way of example part of a fixation system provided altogether with the reference numeral  10  with an anchoring element in the form of a bone screw  12 , a connecting element in the form of a bar  14  defining a longitudinal axis  15  as well as a first embodiment of a clamping connector  16  according to the invention, with which the bar  14  can be secured to the bone screw  12  in a fixing position.  
         [0069]     Different bones or bone fragments  18  may be positioned and fixed relative to one another with the fixation system in that the same or similar bone screws  12  are turned into the respective bone fragment  18  and connected to one another by means of the bar  14 , in particular, by using the clamping connector  16  or similar connecting elements. In principle, the bar  14  could also be secured to the second bone fragment which is not illustrated via a bone screw with a completely different configuration and having a clamping part arranged thereon.  
         [0070]     The bone screw  12  has an elongated cylindrical shaft  20  which is provided with an external thread  24  over approximately three quarters of its overall length proceeding from a tip  22  for screwing into the bone fragment  18 . A proximal end of the bone screw  12  forms a cylindrical connecting section  26  which has a smooth outer cylindrical surface. For turning the bone screw  12  into the bone fragment  18 , a tool element receiving means in the form of an internal polygon  28  is provided which is designed so as to be symmetric to a longitudinal axis of the bone screw  12 .  
         [0071]     The bar  14  has a suitable length for connecting two anchoring elements to one another and has a circular cross section.  
         [0072]     The clamping connector  16  comprises an offset bridge  32  which has an essentially hollow cylindrical connecting section receiving means  34  which can be pushed onto the connecting section  26  parallel to the longitudinal axis  30  in a distal direction of the bone screw. The offset bridge  32  is, altogether, designed essentially in the shape of an oval sleeve which has its greatest height in the area of the connecting section receiving means  34 . In the assembled state, the connecting section  26  is surrounded over approximately 220° of its circumference by a first, curved wall section of the oral sleeve, the height of which, apart from the first curved wall section, is in the remaining area only approximately half the overall height in the area of the connecting section receiving means  34 .  
         [0073]     A clamping member  36  pointing towards the longitudinal axis  30  abuts on the connecting section  26  in the direction towards the section of the offset bridge  32  which is lower in height and this clamping member is connected in a spring-like manner to the part of the offset bridge  32  limiting the connecting section receiving means  34  via a narrow web  38  extending parallel to the longitudinal axis  30 . The clamping member  36  is essentially designed in a parallelepiped shape and has a concave contact surface  40  which points in the direction towards the connecting section  26  and a pressure surface  42  which points in the opposite direction. The clamping member  36  extends parallel to the longitudinal axis over a length which is greater than a height of the lower section of the offset bridge  32  so that the clamping member  36  projects somewhat beyond a wall of the offset bridge  32  on both sides. Furthermore, an inner surface of the oval offset bridge  32  is inclined through approximately 15° relative to the longitudinal axis  30 , namely in a distal direction away from the longitudinal axis  30 , in a second curved sector which points towards the connecting section receiving means  34 . The inclined surface forms a conical actuating surface section  44 .  
         [0074]     The area of the offset bridge  32  pointing away from the connecting section receiving means  34  is inserted into a U-shaped receiving means  48  of a joint member  46  and secured by means of a tensioning member  50 . For this purpose, an upper side wall  52  and a lower side wall  54 , which limit the receiving means  48  to the side, are provided with concentric bores  56  and  58 , wherein the bore  58  provided in the lower side wall  54  is smaller in diameter than the bore  56  in the upper side wall  52 . The tensioning member  50  defines with its longitudinal axis  60  a first axis of rotation, about which the joint member  46  can be pivoted relative to the offset bridge  32 .  
         [0075]     The tensioning member  50  is divided altogether into four sections, namely a first, cylindrical bearing section  62  corresponding to the bore  58  and a right-hand thread section  64  which adjoins thereto and is somewhat larger in its external diameter than the bearing section  62 . The right-hand thread section  64  is adjoined by a second cylindrical section  66  which corresponds to the bore  56  and the external diameter of which is somewhat larger than that of the right-hand thread section  64 . An end of the tensioning member  50  located opposite the bearing section  62  is formed by a left-hand thread section  68  which has an external diameter which is somewhat enlarged in comparison with the cylindrical section  66 . As a result of this configuration, the tensioning member  50  can be pushed through the bore  56  starting with the bearing section  62 , wherein following the assembly of the clamping connector  16  the bearing section  62  and the cylindrical section  66  are each guided in the bores  56  and  58 , respectively. A tool element receiving means in the form of an inner polygon  70  is provided concentrically to the longitudinal axis  60  in the area of the left-hand thread section  68  for accommodating a tensioning tool  72 , the distal end of which is illustrated schematically in  FIG. 5 . The tensioning member  50  can be turned about its longitudinal axis  60  with the tensioning tool  72 .  
         [0076]     A threaded bolt  74 , on which a clamping jaw  78  is secured by means of a nut  76 , projects from the joint member  46  transversely to the longitudinal axis and pointing in the opposite direction to the receiving means  48 . A longitudinal axis  80  of the threaded bolt  74  extends transversely to the longitudinal axis  60 . A connecting element receiving means is provided on the clamping jaw  78  in the form of an essentially hollow cylindrical bar receiving means  82 , into which the bar  14  can be pushed or also clicked transversely to its longitudinal axis. For this purpose, the bar receiving means  82  is open parallel to its longitudinal axis  15  over a sufficient angular range. The bar receiving means  82  has a clamping section  84  which points in the direction towards the longitudinal axis  60  and can be somewhat springy as a result of a material weakening. A clamping member  86  abuts on the clamping section  84  and this has a plane actuating surface  88  inclined through approximately 25° relative to the longitudinal axis  60 . The clamping member  86  is supported on the joint member  46  for displacement parallel to the longitudinal axis  80 , namely in that a T-shaped projection  90  of the clamping member  86  is guided in a T-shaped groove  92  in the upper side wall  52 .  
         [0077]     A first clamping member  94 , which is designed essentially in a parallelepiped shape, is provided for clampingly tensioning the bar  14  in the bar receiving means  82 , wherein an end face corresponding to the actuating surface  88  is beveled and forms a slide-on surface  96 . The first clamping member  94  is provided with a bore having an internal thread  98  corresponding to the left-hand thread section  68  and is guided in a U-shaped recess  100  on an upper side of the upper side wall  52  and, as a result, is secured against any rotation about the longitudinal axis  60 .  
         [0078]     Furthermore, a second clamping member  102  is provided which is designed in the shape of a parallelepiped and has a second slide-on surface  104  corresponding to the conical actuating surface section  44 . Furthermore, the second clamping member  102  is provided with a bore provided with an internal thread  106 , wherein the internal thread  106  is designed to correspond to the right-hand thread section  64 .  
         [0079]     In addition, flattened areas  108  inclined relative to one another at a respective angle of 45° are provided on an outer wall of the U-shaped recess  100  as well as two recesses  110  located diametrically opposite one another. The flattened areas  108  and the recesses  110  serve to accommodate an insert tool for the clamping connector  16  which is not illustrated.  
         [0080]     The mode of operation of the fixation system  10 , in particular, the clamping connector  16  will be explained in greater detail in the following with reference to  FIG. 5 .  
         [0081]     The clamping connector  16  is illustrated in  FIG. 5  in the so-called adjusting position. This means that the connecting section  26  can be inserted into the connecting section receiving means  34  which allows a rotation of the offset bridge  32  about the longitudinal axis  30  at the same time. Furthermore, the joint member  46  can be pivoted about the longitudinal axis  60  relative to the offset bridge  32 . In addition, the bar  14  can be displaced in the bar receiving means  82 .  
         [0082]     Once the bone screw  12  has been anchored in the bone fragment  18  in the desired manner, the clamping connector  16  is placed on the bone screw  12  and the bar  14  positioned in the bar receiving means  82 . A surgeon can now adjust a relative position of the bar  14  in relation to the bone screw  12  in the desired manner. In this respect, he also has the possibility of varying an inclination of the longitudinal axis  15  of the bar  14  relative to the longitudinal axes  30  and  60 , namely by pivoting the clamping jaw  78  about the longitudinal axis  80 . In this respect, lateral stops are provided which are not illustrated in detail and which limit a pivoting range of the clamping jaw  78  about the longitudinal axis  80  to approximately ±15°.  
         [0083]     In order to secure the bar  14  on the bone screw  12 , the tensioning member  52  is turned in the clockwise direction by means of the tensioning tool  72 . As a consequence, the first clamping member  94  is moved in the direction towards the upper side wall  52  and the second clamping member  102  is likewise moved in the direction towards the upper side wall  52 . Altogether, the two clamping members  94  and  102  are, therefore, moved towards one another during rotation of the tensioning member in the clockwise direction. As a result of the movement of the first clamping member  94  parallel to the longitudinal axis  60 , the first slide-on surface  96  slides on the actuating surface  88 , whereby the clamping member  86  is moved in the direction towards the bar  14  which is indicated by an arrow and presses the clamping section  84  in the direction towards the bar  14 . As a result, the bar  14  is clampingly secured in the bar receiving means  82 . The second slide-on surface  104  slides in an analogue manner on the conical actuating surface section  44 , with the result that the entire offset bridge  32  is drawn in the direction of the arrow to the left in  FIG. 5  parallel to the longitudinal axis  80 . The pressure surface  42  abuts on rounded end faces of the joint member  46  such that the clamping member  36  is moved relative to the connecting section  26  towards it, whereby a cross section of the connecting section receiving means  34  is reduced altogether and the connecting section  26  is held in a clamping manner.  
         [0084]     It is possible with the clamping connector  16  according to the invention to pivot the bar  14  about two axes of rotation extending parallel to one another, namely the longitudinal axes  30  and  60 , relative to the connecting section  26 . In this way, a displacement of the bar  14  parallel to itself in the direction towards the connecting section  26  is possible. Furthermore, it is possible solely as a result of movement of the tensioning member  50  to cause the clamping connector  16  to be transferred from an adjusting position, in which not only the bar  14  but also the connecting section  26  are held loosely on the clamping connector  16 , into the fixing position, in which not only the bar  14  but also the connecting section  26  are secured on the clamping connector  16  so as to be immovable. In order to fix the bar  14  to the bone screw  12 , only one locking step is, therefore, necessary which is carried out by way of rotation of the tensioning member  50 .  
         [0085]     In the reverse way, the clamping connector  16  may also be transferred again from the fixing position into the adjusting position.  
         [0086]     In the following, seven further or also alternative embodiments of the clamping connector  16  will be described in greater detail in conjunction with FIGS.  6  to  13 . For the sake of simplicity, identical or very similar parts in comparison with the clamping connector  16  are given the same reference numerals. Modified parts or elements of the clamping connector are explicitly described and given their own reference numerals.  
         [0087]     A second embodiment of a clamping connector provided altogether with the reference numeral  120  is illustrated in  FIGS. 6 and 7 . A tensioning member provided, altogether, with the reference numeral  122  differs from the tensioning member  50  due to the fact that instead of the two thread sections  64  and  68  adjacent to the bearing section  62  and the cylindrical section  66 , respectively, a respective cylindrical section  124  and  126 , respectively, is provided, arranged eccentrically in relation to the longitudinal axis  60 . In addition, in comparison with the clamping connector  16 , a hollow cylindrical section  128  is provided instead of the conical actuating surface section  44  and an outer surface of the cylindrical section  124  slides on this hollow cylindrical section as a result of rotation of the tensioning member  122  and can move the offset bridge  130  provided altogether with the reference numeral  130  in the direction towards the bar  14 . The clamping member  86  with its actuating surface  88   a  can be displaced in an analogous way by means of the cylindrical section  126  in the direction towards the clamping section  84 , whereby the bar  14  can be held in a clamping manner in the bar receiving means  82 . Therefore, interacting actuating and slide-on surfaces are also provided in the case of the clamping connector  120 , wherein these are not inclined relative to the longitudinal axis  60 . Slide-on movement is brought about on account of the eccentricity of the cylindrical sections  124  and  126 , wherein this eccentricity is apparent on the basis of an eccentric axis  132  which is drawn in parallel to the longitudinal axis  60  in  FIGS. 6 and 7  and forms an axis of symmetry of the cylindrical sections  124  and  126 .  
         [0088]     A third embodiment of a clamping connector provided altogether with the reference numeral  140  is illustrated in  FIG. 8 . The clamping connector  140  corresponds almost identically to the clamping connector  16  but the clamping member  86  has been omitted in this case and so the first slide-on surface  96  abuts directly on the clamping section  84  of the bar receiving means  82 . The first clamping member  94  therefore extends somewhat further in the direction towards the bar receiving means  82  than in the case of the clamping connector  16 . Otherwise, the mode of operation of the clamping connector  140  corresponds to the mode of operation described in conjunction with the clamping connector  16 .  
         [0089]     A fourth embodiment of a clamping connector is provided in  FIG. 9  altogether with the reference numeral  150 . It differs from the clamping connector  16  only due to the fact that the clamping member  36  has been omitted. End faces  152  and  154  of the upper side wall  52  and the lower side wall  54 , respectively, are shaped concavely for this purpose and abut directly on the connecting section  26  of the bone screw  12 . The connecting section  26  is held in a clamping manner in the fixing position between the end faces  152  and  154 , respectively, on the one hand, and an inner surface of the connecting section receiving means  34  located diametrically opposite, on the other hand. As for the rest, the mode of operation of the clamping connector  150  corresponds to that already explained in greater detail in conjunction with the clamping connector  16 .  
         [0090]     A clamping connector provided altogether with the reference numeral  160  is illustrated in  FIG. 10  and this differs from the clamping connector  16  due to the fact that instead of the second clamping member  102  a cone  162  is provided, the inclined conical outer surface  164  of which has a function corresponding to the second slide-on surface  104 . The cone  162  is secured on the tensioning member provided with the reference numeral  166  so as to be axially non-movable. As a result of rotation of the tensioning member  166  in the clockwise direction about the longitudinal axis  60 , the first clamping member  94  is drawn in the direction towards the cone  162 , whereby the offset bridge  32  is drawn in the direction towards the bar  14  and, as a result, tensioned in a clamping manner in the connecting section receiving means  34 , the bar  14  in the bar receiving means  82  due to the exertion of pressure on the clamping section  84 .  
         [0091]     A sixth embodiment of a clamping connector provided altogether with the reference numeral  170  is illustrated in  FIG. 11 . in comparison with the clamping connector  16 , a rivet-like tensioning member  172  serves to transfer the clamping connector  170  from the adjusting position into the fixing position. Instead of the first clamping member  94 , a clamping member  94   a  is provided which corresponds in its shape to the first clamping member  94  but has no internal thread. At the distal end of the tensioning member  172 , located opposite the conical actuating surface section  44 , a projection  174  corresponding to it is provided and this has a second slide-on surface  176  which abuts on the conical actuating surface section  44 . The projection  174  can be designed in one piece with the tensioning member  172  or be connected securely to it. In order to transfer the clamping connector  170  from the adjusting position into the fixing position, the first clamping member  94   a  is pressed by a tensioning tool, which is not illustrated in detail, parallel to the longitudinal axis  60  in the direction towards the upper side wall  52  and the tensioning member  172  is drawn somewhat in the opposite direction at the same time. As soon as the connecting section  26  is secured in the connecting section receiving means  34  and the bar  14  in the bar receiving means  82  in a similar manner to that of the clamping connector  16 , a head  178  of the tensioning member  172  is deformed in such a manner that the first clamping member  94   a  is secured in its position slid onto the actuating surface  88 . A release of the clamping connector  170  is only possible by destroying the tensioning member  172 . It is therefore possible with the clamping connector  170  to provide a one-time connection between the bone screw  12  and the bar  14  which can, however, no longer be released or readjusted.  
         [0092]     In  FIG. 12 , a seventh embodiment of a clamping connector provided altogether with the reference numeral  180  is illustrated. The clamping connector  180  differs from the clamping connector  16  due to the fact that the clamping member  36  is not connected in one piece to the offset bridge  32 , i.e., is not connected to it via a web. Otherwise, the construction corresponds to that of the clamping connector  16  and, therefore, also the principle mode of operation.  
         [0093]     Finally, an eighth embodiment of a clamping connector according to the invention and provided with the reference numeral  190  is illustrated in  FIG. 13 . It differs from the clamping connector  16  only as a result of the configuration of the connecting section receiving means  34  which is provided with the reference numeral  34   a  in the case of the clamping connector  190 . It forms a hollow space in the shape of a spherical cap for accommodating an end, in the shape of a spherical cap, of a bone screw which is not illustrated in detail. The clamping connector  190  can, therefore, be used to secure a bar  14  on a bone screw with a spherical head. In an analogous way to all the other clamping connectors, the clamping connector  190  can be secured not only relative to the bar  14  but also relative to the bone screw not illustrated simply due to movement of the tensioning member  50 .  
         [0094]     With respect to the clamping connector  190  it is to be noted that the clamping connectors  120 ,  140 ,  150 ,  160 ,  170  and  180  described above may also be provided with a connecting section receiving means  34   a  in the shape of a spherical cap.  
         [0095]     Furthermore, it is also possible to omit the clamping member  36  in the case of the clamping connectors  120 ,  140 ,  150 ,  160 ,  170  and  190 , as described in conjunction with the clamping connector  180 . In addition, the clamping member  86  can also be omitted in the case of the clamping connectors  120 ,  150 ,  160 ,  170 ,  180  and  190 .