Abstract:
The invention relates to a bone fixation means ( 1 ) comprising: A) a longtitudinal shaft ( 2 ) with longtitudinal axis ( 3 ), and; B) an anchoring element ( 4 ), which can be fixed inside a bone and which has the same longitudinal axis ( 3 ) and is characterized in that; C) interacting means ( 5; 6 ) are provided on the shaft ( 2 ) and on the anchoring element ( 4 ), which either permit or prevent a rotation of the anchoring element ( 4 ) about the longitudinal axis ( 3 ) relative to the shaft ( 2 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a bone fixation means of the introductory portion of claim  1 . 
     Such bone fixation means are used, for example, for the medical care of fractures at the proximal femur, particularly of trochanteric fractures and fractures of the neck of the femur. Such devices comprise essentially a bone plate, which can be fixed to the femur with an angular sleeve, which is to be brought into the neck of the femur for accommodating the shaft of the bone fixation means in a rotationally stable manner. 
     All the known hip screws, which are to be used with bone plates that can be fastened to the femur, have the disadvantage that their out-of-round shaft, which is to be introduced into the sleeve of the bone plate, is firmly connected with the anchoring element (screw or blade) of the bone fixation means. 
     If, after the implantation of the hip screw, the surgeon wishes to guide the out-of-round sleeve of the bone plate over the out-of-round shaft of the hip screw, then the bone plate of the DHS is not parallel to the femur and, instead, must be rotated into this position, the hip screw, captured in the sleeve, being rotated along. Accordingly, the hip screw is screwed further forward or back a little once again. This advance or retraction is impermissibly large especially in the case of implants employing blades which have a steep pitch, the so-called helical blades. 
     For hip screws, with a conventional, flat thread, the shaft of the screw can be aligned without problems so that the sleeve tab, when pushed over the out-of-round shaft of the screw, automatically lies parallel to the femur. Normally, once it has been turned upside down over the sleeve, the plate is not rotated further. 
     In the case of helical blades with a steep pitch (helix), this alignment is difficult, since such implants translate a large distance in or out when rotated only a small amount. 
     SUMMARY OF THE INVENTION 
     The invention is to provide a remedy here. It is an object of the invention to provide a bone fixation means, which comprises a lockable coupling, which can be unlocked, between the shaft and the anchoring element of the bone fixation means, so that the shaft can be rotated relative to the anchoring element about the longitudinal axis or locked rotationally. 
     Pursuant to the invention, this objective is accomplished with a bone fixation means, which has the distinguishing features of claim  1 . 
     The advantages, attained by the invention, are, essentially, the following:
         The present invention permits bone fixation means with novel anchoring elements to be used, such as, for example, helical blades with a steep pitch (helix), in combination with a conventional sleeve tab, such as those, which have been on the market for more than 20 years already.   The compatibility between the new bone fixation means and the conventional tabs permits the surgeon to make a decision in the course of the surgery between conventional bone screws and the new bone fixation means.       

     In a preferred embodiment, the bone fixation means comprise axial locking-in-position means, by means of which the shaft and the anchoring element are held together axially. With that, the advantage can be achieved that, during the implantation of the bone fixation means, the anchoring element may be rotated relative to the shaft, while, nevertheless, the two parts are held together axially and cannot fall apart. 
     The axial locking-in-position means and the interacting means may be realized partly or completely from the same elements or may also be configured independently of one another. Moreover, the axial locking-in-position means may or may not be detachable. It may be possible to snap the axial locking-in-position means in-place or the latter may comprise radially elastic blades with elevations, which can be snapped into grooves, so that a simple assembly of shaft and anchoring element can be attained. 
     In a different embodiment, the blades are disposed at the anchoring element and the groove at the shaft. The elevations preferably are convex and can be snapped into a ring-shaped groove. 
     In yet another embodiment, the axial locking-in-position means comprise two pins, which penetrate the cavity wall diametrically at the end of the anchoring element and the tips of which engage a groove at the shaft, the groove being concentric with the longitudinal axis. With that, a construction of the axial locking-in-position means, which is simple to produce, can be attained. 
     In a further embodiment, aligned annular grooves for accommodating a retaining ring, concentric with the longitudinal axis, are provided at the cavity wall at the rear end of the anchoring element and at the shaft. 
     The interacting means may be equipped frictionally or positively. In the case of a frictional configuration, the following, for example, are suitable:
         conical elements, which may be wedged in a complementary conical borehole. In one embodiment, the conical elements are hammered in. In a different embodiment, the conical elements are wedged with the help of a screw mechanism. In yet another embodiment, the conical element is provided with a conical external thread and the conical borehole with an internal thread. Conical elements, which can be hammered in, make a simple configuration of the coupling possible, whereas the last-described conical connection represents a simple detachable variation; or   radially elastic blades, which are mounted, for example, at the anchoring element and can be placed by means of a conical screw against the wall of the central borehole in the shaft. The simple way of handling the interacting means is advantageous here.       

     In the case of a positive configuration of the interacting means, denticulations, for example, which may be mounted at the shaft and at the anchoring element, preferably at the end face, and be brought into mutual engagement, are suitable. 
     In one embodiment, one of the denticulations is mounted firmly at the anchoring element while the second denticulation is mounted at a fixation element, which is axially displaceable and locked in position rotatably at the shaft. The fixation element can be shifted axially by means of a screw, which can be rotated from the free end of the shaft. 
     In a different embodiment, one of the denticulation&#39;s is disposed at ring element at the shaft, which is locked in position rotationally, whereas the second denticulation is mounted at a fixation element, which is also locked in position rotationally, but can be shifted axially. The fixation element can be shifted axially analogously by means of a screw, which can be rotated from the free end of the shaft, until the denticulations are in mutual engagement or are remote from one another. 
     The anchoring element may be constructed as a screw with a thread lead of more than 50 mm and preferably of more than 80 mm. 
     The use of a helical blade has numerous clinical advantages over the use of a conventional hip screw:
         a) Cutting of the implant out of the bone is avoided by the larger contacting surface.   b) As the helical blade is hammered into the head of the femur, the bone material is compressed around the implant. This additionally minimizes the risk that the implant will cut out from the bone.   c) In contrast to the conventional screw, the helical blade prevents rotation of the head of the femur on the implant.       

     In a further embodiment, the shaft of the bone fixation means is constructed out-of-round when viewed in a cross-section, which is orthogonal to the longitudinal axis. With that, the advantage can be attained that sleeve tab can be inverted over the out-of-round shaft of the bone fixation means, independently of the extent to which the bone fixation means was bought in to the head of the femur. The bone fixation means thus can be brought in two the optimum position in the head of the femur and then anchored rotationally stably. 
     In one embodiment, the fixation device for the osteosynthesis comprises a bone plate, which can be fastened to the femur, with an angularly adjoining sleeve, which is suitable for accommodating the shaft of the bone fixation means. Preferably, the shaft is provided on the outside and the sleeve on the inside with complementary, out-of-round cross sections. 
     Further advantageous developments of the invention are characterized in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention and further developments of the invention are described in even greater detail in the following by means of partially diagrammatic representations of several examples. In the drawing, 
         FIG. 1   a  shows a side view of an embodiment of the inventive bone fixation means, 
         FIG. 1   b  shows a side view of a further embodiment of the inventive bone fixation means, 
         FIG. 1   c  shows a side view of yet another embodiment of the inventive bone fixation means, 
         FIG. 1   d  shows a side view of a different embodiment of the inventive bone fixation means, 
         FIG. 2   a  shows a diagrammatic representation of the axial locking-in-position means of the embodiment of the inventive bone fixation means shown in  FIG. 1   a,    
         FIG. 2   b  shows a diagrammatic representation of the axial locking-in-position means of the embodiment of the inventive bone fixation means shown in  FIG. 1   b,    
         FIG. 2   c  shows a diagrammatic representation of the axial locking-in-position means of the embodiment of the inventive bone fixation means shown in  FIG. 1   c,    
         FIG. 2   d  shows a perspective representation of the embodiment of a retaining ring of the locking-in-position means shown in  FIG. 2   c.    
         FIG. 2   e  shows a section through a different embodiment of a retaining ring for the embodiment of the inventive bone fixation means shown in  FIG. 2   c,    
         FIG. 2   f  shows a view of the embodiment of a retaining ring, shown in  FIG. 2   e,    
         FIG. 2   g  shows a section through a further embodiment of a retaining ring for the embodiment of the inventive bone fixation means shown in  FIG. 2   c,    
         FIG. 2   h  shows a view of the embodiment of a retaining ring shown in  FIG. 2   g,    
         FIG. 2   i  shows a diagrammatic representation of the axial locking-in-position means of the embodiment of the inventive bone fixation means shown in  FIG. 1   d,    
         FIG. 2   k  shows a section, orthogonal to the longitudinal axis, through the sleeve of the axial locking-in-position means shown in  FIG. 2   i    
         FIG. 3   a  shows an enlarged section of the circle A in  FIG. 1   a,    
         FIG. 3   b  shows a section, similar to that of  FIG. 3   a,  of a different embodiment of the inventive bone fixation means, 
         FIG. 3   c  shows a longitudinal section through the bone anchoring element and the fixed end of the shaft of a different embodiment of the inventive bone fixation means, 
         FIG. 3   d  shows a longitudinal section through the bone anchoring element and the fixed end of the shaft of a further embodiment of the inventive bone fixation means, 
         FIG. 3   e  a perspective view of the bone anchoring element of, once again, a further embodiment of the inventive bone fixation means, 
         FIG. 3   f  shows a section, similar to that of  FIG. 3   a,  of once again a different embodiment of the inventive bone fixation means, 
         FIG. 3   g  shows a perspective representation of the wedge element of the embodiment of the inventive bone fixation means, shown in  FIG. 3   d,    
         FIG. 4   a  shows a section, similar to that of  FIG. 3   a,  of a further embodiment of the inventive bone fixation means, 
         FIG. 4   b  shows a longitudinal section through the bone anchoring element and the fixed end of the shaft of a further embodiment of the inventive bone fixation means, 
         FIG. 4   c  shows a longitudinal section through the bone anchoring element and the fixed end of the shaft of a different embodiment of the inventive bone fixation means, 
         FIG. 4   d  shows a longitudinal section through a further embodiment of the inventive bone fixation means and 
         FIG. 5  shows a partial section through the inventive fixation device, implanted in the femur. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIGS. 1 to 4 , different embodiments of the inventive bone fixation means  1  are shown with a coupling  37  between the shaft  2  and the anchoring element  4 , the coupling  37  comprising axial locking-in-position means  12  ( FIGS. 2   a  to  2   k ) and means  5 ;  6  ( FIG. 3 ,  4 ), which make a rotationally locking-in-position possible. In this connection, the interacting means  5 ;  6  can make possible a frictional locking ( FIGS. 3   a  to  3   g ) or a positive locking ( FIGS. 4   a  to  4   d ) of the relative rotational movement between the shaft  2  and the anchoring element  4 . 
     In the embodiments shown in  FIGS. 1   a  to  1   d,  the anchoring element  4  is shown as a spiral blade, which is coaxial with the longitudinal axis  3  and equipped with four helical blades  7 , which are distributed over the periphery, the depression  8  between the blades  7  at the free end  9  of the anchoring element  4  being open. The radial depth of the depressions  8  remains constant on an axial length L and then decreases continuously, until the depressions  8  at the fixed end  10  of the anchoring element  4  changes over into the circumferential surface  11  of the latter. On its circumferential surface  38 , the shaft  2  is provided with two flat spots  39 , which are disposed diametrically opposite to one another and are parallel to the longitudinal axis  3 , so that the shaft  2  can be secured in a complementary borehole of a sleeve  49  ( FIG. 5 ) to prevent rotation about the longitudinal axis  3 . 
       FIGS. 2   a  to  2   k  show embodiments of the axial locking-in-position means  12  in detail. They are part of the coupling  37  ( FIG. 1 ). The axial locking-in-position means  12  only bring about an axial fixation between the shaft  2  and the anchoring element  4 , the rotation of the anchoring element  4  relative to the shaft not being impeded. 
     For the embodiment of the axial locking-in-position means  12 , shown in  FIG. 2   a,  the latter comprise four blades  13 , which are disposed at the fixed and  10  of the anchoring element  4 , distributed uniformly over the periphery and aligned parallel to the longitudinal axis  3  and which can be pushed axially over the fixed end  34  of the shaft  2  and connected with the shaft  2 . These blades  13  can be deformed elastically transversely to the longitudinal axis  3  and, internally, have radial elevations  14 , which can be snapped into a groove  15 , which extends over the whole of the periphery of the shaft  2  and is V-shaped in cross section. The axial locking-in-position means  12  bring about an axial fixation of the shaft  2  relative to the anchoring element  4  in both directions without impeding the free rotation of the anchoring element  4  relative to the shaft  2  about the longitudinal axis  3 . 
     The embodiment of the axial locking-in-position means  12 , shown in  FIG. 2   b,  comprises two locking-in-position pins  21 , which, at the fixed end  10  of the shaft  2 , are mounted radially in the wall of the shaft  2 , and the tips of which protrude radially into the first, expanded segment  31  of the central borehole  18  in the shaft  2  and are captured axially there in a groove  22  extending peripherally on the outside of the peg  35 . Since this groove  22  extends over the whole of the periphery of the peg  35 , the rotation of the shaft  2  relative to the anchoring element  4  is not impeded by the two locking-in-position pins  21 . 
     For the embodiment, shown in  FIG. 2   c,  the axial locking-in-position means  12  are realized by a retaining ring  44 , which is inserted into two concentric annular grooves  50 ;  60 . The annular grooves  50 ;  60  are disposed in such a manner that, at the outside, at the peg  35 , analogously to the embodiment shown in  FIG. 2   b,  a peripherally extending first annular groove  50  and, in the expanded segment  31  of the central borehole  18  in the shaft  2 , a second, peripherally extending annular groove  60  are disposed. The retaining ring  34 , placed in these two annular grooves  50 ;  60 , prevents relative axial movement between the anchoring element  4  and the shaft  2 , while a relative rotational movement of these two parts about the longitudinal axis  2  as axis of rotation is still possible. The retaining ring  44  may be present in various embodiments. For example, the cross-sectional surface of the retaining ring  44 , viewed orthogonally to the longitudinal axis  3 , may be circular ( FIG. 2   c ), rectangular ( FIG. 2   d ), beveled ( FIG. 2   e  to  2   h ) or also graded. 
     In the embodiment, shown in  FIGS. 2   i  and  2   k,  the locking-in-position means  12  are realized owing to the fact that the fixed end  10  of the anchoring element  4  comprises a circularly cylindrical connecting piece  91 , which extends coaxially with the longitudinal axis  3  and is accommodated suitably in a circularly cylindrical opening  92 , which is also coaxial with the longitudinal axis  3 , of a sleeve  93 , which is disposed at the fixed end  34  of the shaft  2 . The connecting piece  91  is provided with a notch  94 , which extends over the whole of the periphery. After the connecting piece  91  is introduced into the opening  92 , several, preferably three depressions  95  are produced in the wall of the sleeve  93  by plastic deformation. The depressions  95  narrow the cross-sectional area of the opening  92  orthogonally to the longitudinal axis  3 , and engage the notch  94 . By making impressions  96  in the wall of the sleeve  93  before the assembly with the shaft  2 , the shape of the depressions  95  can be controlled so that the connecting piece  91  is locked axially relative to the sleeve  93 , while, at the same time, the connecting piece  91  in the sleeve  93  is mounted so that it can be rotated nevertheless about the longitudinal axis  3 . 
     Aside from the axial locking-in-position means  12  ( FIGS. 2   a  to  2   k ), the coupling  37  ( FIG. 1 ) comprises the interacting means  5 ;  6 , by means of which the relative rotation about the longitudinal axis  3  between the anchoring elements  4  and the shaft  2  can alternatively be locked or unlocked. 
       FIGS. 3   a  to  3   g  shows different embodiments of couplings  37 , which make a frictional locking of the relative rotational movement between the shaft  2  and the anchoring element  4  possible. 
     In  FIG. 3   a,  the coupling  37  comprises, as first interacting means  5 , a conical element  16 , which is coaxial with the longitudinal axis  3 , and, a second interacting means  6 , a conical borehole  17 , which is complementary to the conical element  16 , in the shaft  2  and in the anchoring element  4 . Moreover, the transition between the first inner conical segment  19  of the borehole  18 , which is disposed in the shaft  2 , and a second inner conical segment  20 , which is disposed in the anchoring element  4 , is continuous. The conical element  16  is mounted in the conical segments  19 ;  20 , so that it can be shifted axially. The inner conical segments  19 ;  20 , as well as the conical element  16  expand towards the fixed end  10  of the anchoring element  4 . By means of a bolt (not shown), which can be passed through the central borehole  18  in the shaft  2 , the conical element  16  can be pressed with the help of an additional instrument, such as a hammer, against the free end  9  ( FIG. 1 ) of the anchoring element  4 , until it is wedged in the two inner conical segments  19 ;  20 . In order to make the wedging possible with the least expenditure of force, the conical element  16  is slotted in the longitudinal direction. Since the conical element  16  is wedged in both inner conical segments  19 ;  20 , the shaft  2  and the anchoring element  4  are connected frictionally with one another in the wedged position of the conical element  16  and blocked to prevent any relative rotation. In this embodiment, however, the conical element  16  cannot be loosened once again. 
     The embodiment of the interacting means  5 ;  6 , shown in  FIG. 3   b,  differs from the embodiment of the interacting means  5 ;  6  shown in  FIG. 3   a  only in that the conical element  16  can be pressed against the free end  9  ( FIG. 1 ) of the anchoring element  4  not with the help of an additional instrument ( FIG. 3   a ), but with the help of a screw element  51 , which has been introduced into the shaft  2 . Over the whole of its length, the conical element  16  is captured axially in a peripherally extending groove  52  at the screw element  51 , but can rotate freely relative to the screw element  51 . The screw element  51  can be screwed into an internal thread  53  of a cylindrical expansion  54  of the borehole  18 , which is disposed at the fixed end  34  of the shaft  2 . 
       FIG. 3   c  shows an embodiment of the coupling  37 , the interacting means  5 ;  6  of which can be locked by friction. The axial locking-in-position means  12 , similar to the embodiment shown in  FIG. 2   a,  is constructed as radially elastic blades  13 . However, they differ owing to the fact that they are not pushed over the fixed end  34  of the shaft  2 , but, instead, are disposed in the central borehole  18  in the shaft  2 . The radial elevations  14  moreover are disposed on the outside at the blades  13  and at the groove  15  in the central borehole  18 . The blades  13  enclose a cavity  70 , which is coaxial with the longitudinal axis  3  and the wall of which has a conical inner thread  71 , into which a locking screw  73 , which has a complementary external thread  72 , can be screwed. When the locking screw  73  is tightened, the blades  13 , as first interacting means  5 , are pressed radially against the wall of the borehole  18 , which is suitable as the second interacting means  6 . As a result, the shaft  2  is connected rotationally frictionally with the anchoring element  4 . Since the elevations  14  at the blades  13  engage the groove  15 , even when the blades  13  are not expanded, the actions of the axial locking-in-position means  12  and the interacting means  5 ;  6  are independent of one another. On the other hand, the axial locking-in-position means  12  and the interacting means  5 ;  6  are not constructed independently of one another here. 
     The embodiment of the coupling  37 , shown in  FIG. 3   d,  differs from the embodiment shown in  FIG. 3   c  only therein that the conical cavity  70 , surrounded by the blades  13 , has a smooth wall, so that a conical element  16 , complementarily conical, can be wedged in the cavity  70  by means of a locking screw  63 . The conical element  16  is pressed axially by a locking screw  63 , which can be screwed into an internal thread  33  disposed in the borehole  18 , into the cavity  70 . 
     In the case of the embodiment, shown in  FIG. 3   e,  the axial locking-in-position means  12  and the interacting means  5 ;  6 , are developed independently of one another. The axial locking-in-position means  12  are constructed similarly to the embodiment shown in  FIG. 2   b,  that is, a peg  35  with a recess  22 , which is concentric with the longitudinal axis  3 , for the radial accommodation of locking-in-position pins  21  ( FIG. 2   b ) is disposed at the fixed end  10  of the anchoring element  4 . The configuration of the interacting means  5 ;  6  differs from the embodiment shown in  FIG. 3   c  only in that the first interacting means  5  are disposed terminally at the peg  35  and surround the radially elastic tabs  13  without elevations  14 . 
     The embodiment, shown in  FIGS. 3   f  and  3   g,  differs with respect to the interacting means  5 ;  6  from the embodiment shown in  FIG. 3   b  therein that, as first interacting means  5 , instead of the conical element  16  ( FIG. 3   a ), an asymmetric, wedge-shaped clamping elements  61  is disposed in the first expansion  31  of the central borehole  18  of the shaft  2 . This wedged-shaped clamping elements  61 , having a tapered front surface  64 , is pressed against a complementary taper  62  at the peg  35  of the clamping element  44  for blocking purposes. As a second interacting means  6 , a locking screws  63 , by means of which the wedged-shaped clamping element  61  can be pressed against the taper  62  at the fixed end of the anchoring element  4 , is disposed in the second expansion  32  of the central borehole  18  in the shaft  2 , the second expansion  32  having an internal thread  33  here. The axial locking-in-position means  12  is realized similarly to the embodiment shown in  FIG. 2   c.    
     Different embodiments of couplings  37 , which comprise interacting means  5 ;  6  for a positive locking of the relative rotational movement of the shaft  2  and the anchoring element  4 , are shown in  FIGS. 4   a  and  4   d.    
     For the embodiment of the interacting means  5 ;  6 , shown in  FIG. 4   a,  the anchoring element  4  has at its fixed end  10  a peg  35 , which tapers in diameter and can be introduced axially into an expanded segment  35  in the central borehole  18  of the shaft  2  and, at its front surface orthogonal to the longitudinal axis  3 , has a first denticulation  23 . The peg  35 , which is provided with the first denticulation  23 , forms the first of the interacting means  5  here, whereas the second of the interacting means  6  is formed by the axially displaceable fixation element  56 , which is mounted in the first expanded segment  31 . The fixation means  56 , which is constructed ring-shaped here, has a second denticulation  24  at the face surface facing the anchoring element  4 . The two denticulations  23 ;  24  can be caused to engage or disengage by axially shifting this fixation element  56 . The shifting of the fixation element  56  is accomplished axially in both directions by a screw  29 , which can be shifted in the internal thread  33 , mounted in the second expanded segment  32 , by rotating the screw in the clockwise or counterclockwise direction. The means  30  serve to accommodate a screwdriver and may be constructed, for example, as a hexagon drive or a TORX drive. The dimensions are such that a screwdriver (not shown) can be passed from the free end  36  ( FIG. 1 ) of the shaft  2  through the central borehole  18  in the shaft  2  and brought into engagement with the means  30 . 
     The fixation element  56  is axially displaceable in the direction of the longitudinal axis  3 , whereas rotation about the longitudinal axis  3  is prevented. For the embodiment shown in  FIG. 4   a,  the fixation element  56  comprises two pins  27 , which are disposed diametrically opposite to one another and pass through the wall of the fixation element  56  and the tips of which are captured axially in a second annular groove  28  at the screw  29 , so that the screw  29  can be rotated about the longitudinal axis  3 , while rotation of the fixation element  56  about the longitudinal axis  3  is prevented by the rear ends of the pins  27 , which are guided in the two longitudinal grooves  26 , which extend parallel to the longitudinal axis  3  in the inner wall of the first expanded segment  31 . 
     The embodiment of the interacting means  5 ;  6 , shown in  FIG. 4   b,  differs from the embodiment of the interacting means  5 ;  6 , shown in  FIG. 4   a  only in that an out-of-round fixation element  56 , which preferably is oval when viewed in a cross section orthogonal to the longitudinal axis  3  and which is rotationally fixed in a complementarily equipped, first expanded segment  31  of the central borehole  18  in the shaft  2 , is provided. The fixation element  56  has an indentation  57 , orthogonal to the longitudinal axis  3 , so that the U-shaped fixation element  56 , before the installation of the screw  29 , can be shifted in the borehole  18  in the shaft  2  transversely to the longitudinal axis  3  over the screw  29 . At its rear end  58 , the indentation  57  has a constriction  59 , which can be pushed transversely to the longitudinal axis  3  into the second annular groove  28 . The fixation element  56  is connected axially firmly with the screw  29  by means of this constriction  59 , which is inserted into the second annular groove  28 , whereas the screw  29  can be rotated relatively to the fixation element  56  about the longitudinal axis  3 . 
       FIG. 4   c  shows an embodiment of the interacting means  5 ;  6 , which differs from the embodiment, shown in  FIG. 4   b  only in that the fixation element  56  is taken up in a terminally disposed, first expanded segment  81  of the central borehole  80  in the anchoring element  4 . Viewed in the cross-section orthogonal to the longitudinal axis  3 , the fixation element  56  as well as the first expanded segment  81  have an oval cross-sectional surface, so that the fixation element  56  is prevented from rotating about the longitudinal axis  3 , but is taken up axially displaceable in the first expanded segment  81 . Similarly to  FIG. 4   b,  the fixation element  56  has an indentation  57 , which is orthogonal to the longitudinal axis  3 , so that the fixation element  56 , which is constructed U-shaped, can be shifted transversely to the longitudinal axis  3  over the screw  29 . The indentation  57  also has a constriction  59  here, which can be shifted transversely to the longitudinal axis  3  into the annular groove  28 , so that the fixation element  56  is connected axially fast with the screw  29 , the rotation of the screw  29  not being hindered. The screw  29  can be screwed here into an internal threat  82 , which is disposed in a second, expanded segment  83  of the central borehole  80  in the anchoring element  4 . Furthermore, an oval annular element  84  is disposed in a complementary, oval recess  85  in the central borehole  18  in the shaft  2  and also secured against rotation about the longitudinal axis  3  by the oval configuration of the ring element  84  and the recess  85 . The two denticulations  23 ;  24 , which can be brought into engagement with one another, are mounted at the two adjacent front surfaces at the fixation element  56  and at the ring element  84 , so that the denticulations  23 ;  24  can be engaged or disengaged by the axial displacement of the fixation element  56  by means of the screw  29 . 
     The embodiment of the interacting means  5 ;  6 , shown in  FIG. 4   d,  differs from the embodiment of the interacting means  5 ;  6 , shown in  FIG. 4 , only in that an out-of-round fixation element  56 , which preferably is oval when viewed in a cross section orthogonal to the longitudinal axis  3 , is provided, which is rotationally fixed in a complementarily configured, first expanded segment  31  of the central borehole  18  in a shaft  2 . At the fixed in  10  of the anchoring element  4 , a circularly cylindrical connecting piece  91 , which is coaxial with the longitudinal axis  3 , is disposed and can be introduced into a complementarily constructed second expansion  32  of the central borehole, which is disposed at the fixed end  34  of the shaft  2 . At the front face, this connecting piece  91  has a first denticulation  23 , which can be brought into engagement with a second denticulation  24 , which is disposed at the opposite front face of the fixation element  56 . For this purpose, the coupling  37  comprises a screw  29 , which can be screwed into an internal threat  33  in the central borehole  18 . At its end facing the anchoring element  4 , the screw  29  has a screw head  25  of larger diameter, which can be pushed transversely to the longitudinal axis  3  into a guide  75 , which is radially open at one side, and can be fastened there so that it is axially fixed but free to move rotationally. When the screw  29  is tightened, on the one hand, the shaft  2  is pressed axially against the anchoring element  4 , as the result of which the function of the axially locking-in-position means  12  is assumed by the screw  29 , and, on the other, the two denticulations  23 ;  24  are brought into engagement, so that, in the embodiment shown here, the axial locking-in-position means  12  and the interacting means  5 ;  6  are not independent of one another. 
     Accordingly, for the embodiments of the interacting means  5 ;  6 , shown in  FIGS. 4   a  to  4   d,  when the denticulations  23 ;  24  engage one another, the shaft  2  and the anchoring element  4  are rotationally coupled positively and, when the denticulations  23 ;  24  are disengaged, the shaft  2  can be rotated relative to the anchoring element  4  about the longitudinal axis  3 . 
     As shown in  FIG. 5 , the sleeve tab  45  can be fastened by means of bone screws  47 , which are to be introduced into the boreholes  46  laterally to the femur  48 , whereas the guide sleeve  49  comes to lie laterally at the neck of the femur fracture or the trochanteric fracture. Accordingly, with the help of the bone fixation means  1 , the head fragment can be fixed rotationally stably with the rest of the femur  48 . 
     The surgical technique for implanting the bone fixation means consists therein that
         by means of an instrument and in one step, several boreholes of different diameter for bringing the bone fixation means  1  and the guide sleeve  49 , mounted at the sleeve tab  45 , into the center of the neck of the femur, can be produced in the lateromedial direction below the large trochanter;   subsequently, the bone fixation means  1  is rotated or hammered into the neck of the femur, the correct depths for hammering or screwing it in being determined by a targeting device,   after which the guide sleeve  49  of the sleeve tab  45  is pushed over the shaft of the bone fixation means and aligned at the femur shaft;   the sleeve tab  45  is fixed to the bone shaft with the help of bone fixation means  20  constructed as bone screws and   the rotational movement of the shaft  2  and the anchoring element  4  is blocked by means of an instrument.