Abstract:
An implantation system for a locking nail has an aiming device, wherein the locking nail is formed for detachable attachment to the aiming device at the one end thereof. The nail has two locking holes on the other end and has an exterior feature such as a groove connecting the locking holes which groove is parallel to the axis, or indentations or elevations running in the perimeter direction in the region of the locking holes. The aiming device has a rigid aiming arm with a free end portion having three aiming bores arranged in a plane generally parallel to the axis. The outer two of the aiming bores are located at a distance from each other which corresponds to the distance of the distal locking holes of the locking nail. The system further has a connecting piece universally movable on the aiming arm. The connecting piece has an accommodation aperture for selective detachable attachment to a rod-like nail adapter which, on its part, has a coupling for detachable attachment of the locking nail.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to an implantation system for locking nails used in fracture fixation.  
           [0002]    Locking nails for the operative repairs of fractures of tubular bones are widely used. For example, application is described in “The Journal of Trauma” of 1993, Vol. 35 No. 5, p. 772 to 775. Typical for such locking nails is the arrangement of two transverse bores, i.e. cross-bores at one end (the distal end, for instance) and at least one transversal bore on the other end (the proximal end, for instance). Bone screws are guided through the transverse bores, which are screwed in at opposing sides into the cortical substance of the bone. Through this, the locking nail is secured axially and against rotation.  
           [0003]    When using such locking nails, the position of the transverse bores or locking holes in the locking nail has to be identified, so that the cortical substance of the bone is drilled from the right place from the outside. To do this, a series of aiming or targeting devices has become known, which conveniently operate with X-rays in order to determine the position of the transverse bores with respect to the aiming device. In this case, the bone is drilled in the proper place with the aid of the aiming device and a so-called drilling or aiming sleeve, so that the bone screws can be screwed in. Known aiming devices are conveniently connected to one end (for example, the proximal end) of the nail. In this way, the correspondence of the locking holes to aiming bores in the aiming device is approximately determined. However, it has to be taken into account that by reason of the bone&#39;s curvature and possible rotation of the nail upon it being driven into the bone, the expected position of the locking holes does not coincide with the actual one.  
           [0004]    For this reason, it has been difficult to perform an accurate identification of the position of the locking holes only by mechanical procedures.  
           [0005]    From WO 01/60272 A1, published Aug. 23, 2001 (U.S. Ser. No. 10/203,492 filed Nov. 15, 2002, which is assigned to the Assignee of the present invention, the teachings of which are incorporated herein by reference), a locking nail is disclosed in which a groove parallel to the nail axis is formed in the nail shaft only in the distal portion in the region of the locking holes. The leading axis of the groove cuts the axis of the bore approximately perpendicularly. In the mentioned document, an aiming device is also described, the aiming arm of which is provided with two aiming bores. The aiming bores are formed in a portion of the aiming arm of the aiming device which is elastically yielding. With the aid of a thin rod-like feeler, the actual position of the nail in the bone is determined with the aid of the locking holes and the groove between them. By turning the nail and by axial displacement it can be detected when the feeler is in the region of a locking hole.  
           [0006]    It has been found that this purely mechanical method still poses problems for the surgeon, because he cannot always determine in a sufficiently accurate manner the actual position of the nail by actuating the feeler.  
         SUMMARY OF THE INVENTION  
         [0007]    The invention therefore has as one objective to provide an implantation system and an aiming device, respectively, by which the position of the locking holes can be determined in a simple manner and the bores in the bone can be seated at the proper place. This and other objects are provided by an implantation system which has at least one locking nail and an aiming or targeting device wherein the locking nail is attached to the aiming device at one end thereof. The nail has at least two locking holes on an opposite second end and has an exterior surface element, such as a groove, adjacent the locking holes. The aiming device has a rigid aiming arm with a free end aiming or guide portion having at least two and preferably at least three aiming bores arranged in a plane parallel to or in a plane including the longitudinal axis of the nail. In any case, the axes of the aiming bores can be aligned with the corresponding axes of the locking nail bores. The outer two aiming bores are spaced at a distance from each other which corresponds to the distance between the two locking holes of the locking nail. The aiming arm has a connecting piece movable on the aiming arm and being attachable thereto, wherein the connecting piece has an aperture for accommodating a detachable nail adapter which can be attached to one end, usually the exposed end, of the locking nail.  
           [0008]    The free end aiming portion of the mounting arm is rotatably mounted around an axis perpendicular to the longitudinal axis of the aiming arm and includes a first locking element for locking the free end portion in a predetermined rotational position. The rotational axis may coincide with the axis of the interior aiming bore of the at least three bores. The aiming portion is divided in the region of the aiming bores into a narrower portion and a broader portion by a recess parallel to an axis perpendicular to the axis of the aiming bores.  
           [0009]    The nail adapter may be rotatably mounted in the connecting piece and include a locking element to set the rotational position of the nail adapter and the connecting piece in relation to each other. An adjustor may be provided between the connecting piece and the nail adapter to adjust the relative rotational position therebetween. The aiming arm may be formed as a bar with a noncircular cross-section, which bars extends through a complimentary aperture in the connecting piece and wherein one wall of the aperture is formed by a clamping element which can be actuated by a clamping screw.  
           [0010]    The invention also relates to a method for locating a pair of axially spaced cross-bores in the first end of a locking nail implanted in a bone canal using the apparatus of the present invention. The method includes mounting the aiming device on a second end of the nail, the aiming device having an arm portion extending generally parallel to the longitudinal axially extent of the nail and having a guide bore portion swivel mounted on a free end of the aiming arm for movement at least in a direction perpendicular to the axially extent of the arm. The guide bore portion has at least two axially spaced bores therein and preferably three axially spaced bores. The outer bores of said at least two bores and preferably three bores are spaced at a distance equal to the axial distance between the cross-bores and the first end of the locking nail. A bore in the bone adjacent one of the cross-bores is drilled by using one of the axially spaced bores on the aiming arm preferably the middle hole. After the bore is drilled, the guide bore portion is removed to allow access to the drilled hole. Alternatively, if the guide bore portion is coupled to the aiming arm, the entire aiming arm/guide bore portion can be removed. If the guide portion is modular, it, alone, may be removed. Using the hole drilled in the bone as an access port, one of the nail cross-bores is located by feel, if necessary, by manipulating the axial and rotational position of the nail. To facilitate this, the nail is either initially inserted a distance greater than its required distance or a distance less than its required distance to enable the surgeon to determine whether the cross-bore found is closer to the first or second ends of the nail. A location pin is then placed in the located nail cross-bore and the guide bore portion is remounted by aligning the corresponding bore and the guide bore portion with the location pin mounted in the cross-bore. The other nail cross-bore can then be drilled.  
           [0011]    A connecting element may be placed between the second end of the nail and the aiming arm, which connecting element allows for universal movement of the aiming arm and, therefore, the guide bore portion at its free end, with respect to the nail so that the bores in the guide bore portion may be accurately aligned in any desired position.  
           [0012]    The locking nail in the inventive implantation system is provided with an apparatus with the aid of which the position of the locking holes can be detected. For instance, one means consists in disposing a groove parallel to the axis between the locking holes. Another means consists in providing perimeter grooves in the region of the locking holes or alternatively suitable stops, which can be detected with the aid of a feeler.  
           [0013]    However, one feature of the present aiming system is that the aiming arm is rigid and has an aiming or guide bore portion, in which three aiming bores are preferably provided. The axes of the aiming bores are situated in a plane which runs in the longitudinal axis of the aiming arm or parallel to it. The distance of the outer aiming bores corresponds to the distance of the locking holes. The middle aiming bore may be placed anywhere between the outer aiming bores, for example, at half the distance of their separation. The locking nail is detachably connectable to a nail adapter, for example, by a suitable threaded joint. The nail adapter is detachably connectable with a connecting piece, which on its part is detachably connectable with the rigid aiming arm. The detachable connection of the nail adapter with the aiming arm makes the use of the inventive aiming device possible for a plurality of different locking nails, without requiring a separate aiming device for each type of locking nail. Through the adjustment between the adapter at the one side and aiming arm on the other side, the nail can be adjusted in relation to the aiming arm before implantation. This takes place in a simple manner by, for example, aligning the outer aiming bores of the aiming portion of the aiming arm with the locking holes of the nail with the aid of a calibrating pin. Consecutively, the nail can be implanted, the nail adapter being allowed to remain fixed on the nail.  
           [0014]    The locking nail is now either hammered in farther than its required end position or less far than the desired end position. Next, the aiming device is reassembled and the cortical substance of the bone on the near side is drilled via the middle of the three aiming bores. Thereafter, the aiming device is detached from the nail adapter again and a rod-like feeler is put through the bone bore. The feeler will impinge against the closed wall of the locking nail and in the most favorable case into the groove which connects the locking holes. By turning the nail the groove may be found, for example, and it can be confirmed that it is in fact engaged by the feeler. Then, the nail is drawn out or is driven in farther, until the feeler cooperates with the respective locking hole.  
           [0015]    Next, the aiming device is mounted again, and one of the outer aiming bores is aligned with the detected locking hole. To do this, several possibilities may be contemplated. Preferably, an attachment sleeve is used, which is provided with a nearer portion with a diameter which corresponds to the diameter of the of the locking hole, and another portion, with a diameter corresponding to that of the aiming bore. The interior diameter of the attachment sleeve is dimensioned such that it can be pushed on the rod-like feeler, which is still present in the locking hole and the bone bore. Thus, a rather accurate alignment of an aiming bore with a locking hole can be achieved, by mounting the aiming arm again and pushing the one of its aiming bores onto the fixing sleeve. When this has been done, the second aiming bore in the aiming arm is also aligned with the second locking hole, and the cortical substance of the bone can be drilled above the second locking hole in the known manner, so that consecutively the seating of the locking screw can occur. When the first locking has been performed, the second locking can take place also, by drilling the cortical substance of the bone via that aiming bore, by which alignment had previously occurred, in order to seat the second locking screw.  
           [0016]    As already mentioned, the locking nail is provided with means, such as a groove, in the region of the locking holes by which the feeling and the detection of a locking hole is facilitated. It is also theoretically conceivable, however, to get along without such means, assuming only the locking nail has not been rotated around the diameter of the locking hole upon driving in. If this is the case, the surgeon knows the rotational position of the holes best, the surgeon does not know how far the nail has to be pulled out or driven in, until the axial position of the locking hole is reached.  
           [0017]    For calibration, in the spirit of the invention, it is preferred that the aiming portion be rotatably mounted around an axis perpendicular to the longitudinal axis of the aiming arm and be provided with first attachment means for fixing the aiming portion in a predetermined swiveling position. Preferably, the swiveling axis is situated on the axis of that aiming bore, which is nearest to the other end of the nail.  
           [0018]    According to another embodiment of the invention, the aiming portion is provided with a slit parallel to the axis in the region of the aiming bores, which extends perpendicular to the axes of the aiming bores and subdivides the aiming portion into a narrower and a broader portion. In this way, a clamping effect is achieved upon seating in of the calibrating pin, drilling sleeve or the like, so that these parts do not unintentionally slip or fall out.  
           [0019]    According to another embodiment of the invention, the calibration is further facilitated if the nail adapter is mounted rotabably around it longitudinal axis in the connecting piece and second attachment means is provided to fix the relative swiveling position. According to another form of the invention, an adjustor is provided between the connecting piece and the nail adapter for the adjustment of the relative swiveling position. The adjustor may contain an adjustment screw or the like for example.  
           [0020]    The rigid aiming arm of the inventive aiming device is preferably formed as an oblong bar with noncircular cross-section, which is inserted into a complementary aperture of the connecting piece, one wall of the aperture being formed by a clamping element, which can be actuated by a clamping screw. Thus, the connecting piece can be axially adjusted continuously on the aiming arm, the angular position remaining unchanged.  
           [0021]    These and other objects and advantages of the present invention will become apparent from the following description of the accompanying drawings, which disclose several embodiments of the invention. It is to be understood that the drawings are to be used for the purposes of illustration only and not as a definition of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 shows an aiming device according to the invention in a lateral view;  
         [0023]    [0023]FIG. 2 shows a lateral view rotated at 90° from the aiming device shown in FIG. 1;  
         [0024]    [0024]FIG. 3 shows the aiming device according to FIGS. 1 and 2 in a perspective representation;  
         [0025]    [0025]FIG. 4 shows the end of an aiming arm of the aiming device according to FIGS.  1  to  3 ;  
         [0026]    [0026]FIG. 5 shows an end view of an aiming portion of the aiming device according to FIGS.  1  to  3 ;  
         [0027]    [0027]FIG. 6 shows a section through the end view of FIG. 5, along the line  6 - 6 ;  
         [0028]    [0028]FIG. 7 shows the end view of the aiming portion according to FIG. 5 rotated at 90°;  
         [0029]    [0029]FIG. 8 shows in perspective the connecting and the calibrating piece of the aiming device according to FIGS.  1  to  3 ;  
         [0030]    [0030]FIG. 9 shows the connecting piece of the structure according to FIG. 8;  
         [0031]    [0031]FIG. 10 shows a section through the connecting piece according to FIG. 9;  
         [0032]    [0032]FIG. 11 shows a side view of the connecting and calibrating piece according to FIG. 8;  
         [0033]    [0033]FIG. 12 shows a detail of the arrangement according to FIG. 11;  
         [0034]    [0034]FIG. 13 shows the side view of a calibrating pin;  
         [0035]    [0035]FIG. 14 shows the side view of a feeler;  
         [0036]    [0036]FIG. 15 shows a side view, of the feeler according to FIG. 14 rotated 90°;  
         [0037]    [0037]FIG. 16 shows the lateral view of a fixing sleeve;  
         [0038]    [0038]FIG. 17 shows the lateral view of a locking nail, as well as a nail adapter attached thereto;  
         [0039]    [0039]FIG. 18 shows a second embodiment for the end of a nail;  
         [0040]    [0040]FIG. 19 shows yet another embodiment for the end of the locking nail; and  
         [0041]    [0041]FIG. 20 shows the lateral view of a nail adapter for the system according to the preceding figures. 
     
    
     DETAILED DESCRIPTION  
       [0042]    Referring to FIGS.  1  to  3 , there is shown an aiming arm  10 , which, in the preferred embodiment, has a square cross-section. On the left end of aiming arm  10  in FIG. 1, a calibrating and connecting piece  12  is seated, and on the right end an aiming portion  14  is shown. Aiming portion  14  is rotatably mounted on a suitable bearing portion  16  on the right end of aiming arm  10 .  
         [0043]    Locking nails for which the aiming device according to FIGS.  1  to  3  is applicable are represented in FIGS.  17  to  19 . In FIG. 17 a locking nail  20  is shown, for instance a femoral nail. Nail  20  is provided with two axially spaced apart locking holes or cross-bores  22 ,  24  on the distal end, and a locking hole or cross-bore  26  on the proximal end. A groove  28  extends parallel to the nail axis and in the preferred embodiment has a U- or V-shaped cross-section between the locking holes  22 ,  24 . The outer diameter of locking nail  20  is connected to an oblong nail adapter  30 , preferably with the aid of a screw  32 , which is screwable into the proximal end of nail  20 . On the other end, nail adapter  30  is provided with flat portions  34  facing each other.  
         [0044]    In FIG. 18, a second embodiment of the end of a locking nail  43  is shown, with locking holes  40 ,  41  and diametric grooves  50 ,  52  in the region of the locking holes  40 ,  41 . In FIG. 19 locking holes  40   a,    41   a  are shown, which are formed in a distal end portion reduced in diameter of the locking nail  43   a.  On the left side of the locking holes  40   a,    41   a,  respectively, radial collars  56 ,  58  are formed, the collar  58  being chamfered towards the left end. The function of the nail forms shown can also be used in the process set forth below. Grooves  50 ,  52  and flanges  56 ,  58  can be used to detect the location of the cross-bores.  
         [0045]    As may especially be seen from the FIGS.  5  to  7 , the preferred aiming portion  14  is provided with at least two and preferably three aiming bores  60 ,  62 ,  64 , the axes of which are situated in a plane which goes through the longitudinal axis of aiming arm  10  or runs parallel to it. The axial separation of the outer aiming bores  60 ,  64  corresponds to the distance of the locking holes  22 ,  24  or  40 ,  41  or  40   a,    41   a,  respectively. As follows from FIGS. 6 and 7, the aiming portion  14  is provided with a first relatively broad recess  66 , with a width marginally larger than the width of bearing portion  16 . As follows from FIG. 4, bearing portion  16  is formed fork-like with arms  70 ,  71 , which have an extension  72  adjacent and between the ends of the arms  70 ,  71 , which have an extension  72  near to the ends of the arms  70 ,  71  and an arcuate slit  74  running transversely on the end of the arms  70 ,  71 . From FIGS. 6 and 7, it follows that the recess  66  is traversed by the shank of a fixing screw  76 , the diameter of the shank being somewhat smaller than the width of arcuate slit  74  of bearing portion  16 . On the inner end, the recess  66  is traversed by a bearing sleeve  68 . It is possible that recess  66  could be made solid such as by using a pivot pin leaving only the two outer bores  60 ,  64 . When bearing portion  16  is introduced into the slit, the shank of the fixing screw  76  is placed in the arcuate slit  74  and the sleeve  68  in the extension  72 . Thus, the aiming portion  14  is rotatably mounted around the axis of the sleeve  68  in the bearing portion  16 . The relative swiveling position is fixed by the fixing screw  76 .  
         [0046]    The aiming portion  14  is also subdivided by a relatively narrower slit  78 , which is introduced from the direction of the free end of the aiming portion  14 , into a relatively broad portion  80  which is provided with recess  66 , and a relatively narrower portion  82 . The latter is flexible in a limited degree in relation to the former and has bores, which are aligned with the aiming bores  60 ,  62  and  64 .  
         [0047]    In FIGS.  8  to  10 , a preferred connecting piece  84  is represented, with the aid of which the nail adapter can be maintained movable and detachable on the aiming arm  10 , for instance, according to FIG. 17. In the preferred embodiment, connecting piece  84  is provided with a square aperture  86  of a cross-section corresponding to the cross-section of the aiming arm  10 . A clamping portion  88  is movably mounted in the connecting piece  84  and forms a corner portion of the aperture  86 . The portion  88  is actuated by a clamping screw  90 , which acts upon a relatively thin portion  92  of the portion  88 , which is separated from the remaining portion  88  by a slit similar in form to portion  82  and slit  78  of portion  14 , in order to obtain a spring-like effect. A pin  94 , which seats in a groove of portion  88 , limits the adjustment of portion  88 .  
         [0048]    Connecting piece  84  additionally is provided with a bearing sleeve  96 , the axis of which runs perpendicular to the axis of the accommodation aperture  86 . A slot  98  is formed in the bearing sleeve  96  which slit has an extension in the diametral direction. Further, a pin  100  is press fit in bearing sleeve  96 , which pin protrudes somewhat from the interior of the bearing sleeve  96 .  
         [0049]    In FIG. 11, the other side of the calibrating and connecting piece as shown in FIG. 8 is represented in a lateral view. In FIG. 12, a preferred sleeve portion  102  is shown which is provided with a slot  104  partially extending into the diametral direction. The sleeve portion  102  is dimensioned such that it can be inserted into the bearing sleeve  96 , the slots  98  and  104  at least partially allowed to come into congruence. On one end of the sleeve portion is attached an arm  106  on which is pivotally mounted an adjustment screw  110  at point  108 . Screw  110  is provided with a cylindrical locking bolt  112  which is provided with an internal thread. The operation of the screw  110  takes place via a rotary knob  114 , which, upon rotation, acts to move bolt  112 . An arm  116  opposite the arm  106  is formed on the sleeve portion  102  at the same cylindrical end surface, which arm has a bent flange  118  open towards the one side. In the sleeve portion  102  there is situated an additional sleeve portion  120 , on which an arm  122  is formed. On the free end of the arm  122  a circular recess  124  is formed, which accommodates the cylindrical locking bolt  112 . Thus, upon a rotation of the knob  114  a relative swiveling between the arms  106  and  122  takes place. With a knob  126  a fixing screw  128  is actuated, which engages into a thread bore (not shown) of the sleeve portion  120 . The shank of the screw  128  extends through the slots  98  and  104  of bearing sleeve  96  and sleeve portion  102 . The sleeve portion  102  has a noncircular aperture  130  for the accommodation of the end portion of the nail adapter  30 . With the aid of fixing screw  128  the axial position of the nail adapter in the aperture  130  can be fixed. By swiveling the arm  122  in relation to the connecting piece  84 , the nail adapter can be turned around its axis and, by doing so, can perform a swiveling of the nail  20 . The relative swiveling position of the sleeve portion  102  and the arms  106  and  116 , respectively, with respect to the connecting piece  84  is effected by the fixing screw  90 , the shank of which extends through the bent flange  118 .  
         [0050]    In FIG. 13, a calibrating pin  132  is shown, with a left portion  134  of smaller diameter and a relatively long portion  136  of larger diameter. The diameter of the portion  134  corresponds to the diameter of locking holes  26 ,  24  and  40 ,  41  and  40   a,    41   a,  respectively. The diameter of portion  136  corresponds to the diameter of aiming bores  60 ,  62  and  64 , respectively.  
         [0051]    In FIGS. 14 and 15 a feeler or location  138  is shown, which has a circular cross-section of a relatively small diameter over its length, which is significantly smaller than the diameter of the locking holes. On one end the feeler  138  is chamfered, as shown at  140 , for the formation of a kind of cutting edge. On the other end, the feeler pin or location pin  138  has opposing flats  142 , for the purpose of clamping into a grip or handle portion (not shown).  
         [0052]    In FIG. 16 a fixing sleeve  144  is represented with a portion  146 , the exterior diameter of which corresponds to the diameter of the locking holes  22 ,  24  and  41 ,  40 ,  41   a,    40   a,  respectively. A portion  148  has a larger diameter, which corresponds to the diameter of the aiming bores  60  to  64 . On the right end, the aiming sleeve  144  is provided with a clamping portion  150  for the purposes of a detachable connection with a handle. The aiming sleeve  144  has a continuous axial bore with a diameter roughly matching that of pin  138  such that the feeler pin  138  can be pushed through it.  
         [0053]    The nail adapter  160  shown in FIG. 20 has a shaft  162 , the cross-section of which is complementary to the cross-section of the aperture  130  in the connecting piece  84  (see for example FIG. 8). On the left end of the shaft  162 , an adapter portion  164  is attached to shaft  162  with the aid of a screw connection (not shown). Adapter portion  164  has two protrusions  166  on the free end, which engage in corresponding recesses of the nail (not shown), in order to predetermine its angular position. The nail is then fixed on the adapter  160  with the aid of a screw connection which extends through the hollow portion  164  in a known manner.  
         [0054]    At  168  and  170 , respectively, bores through the shaft  162  are indicated, which can also be used as aiming or alignment bores.  
         [0055]    The described implantation system is employed as follows. Firstly, a calibration is performed. The nail to be implanted, for example, nail  20  in FIG. 17, is connected with the nail adapter  30 . Nail adapter  30  is inserted into aperture  130  of the connecting piece and is fixed with the aid of clamping screw  126 . By axially adjusting connecting piece  84  on aiming arm  10  and, as the case may be, by swiveling the nail by actuating the adjustment screw  114 , locking holes  22 ,  24  are aligned with aiming bores  60 ,  64 . At first, an alignment with respect to the aiming bore  60  takes place by inserting a calibrating pin according to FIG. 13. Optionally, a drill bit guiding sleeve and a drill may be used for this purpose. In that, the portion  134  of calibrating pin  132  arrives in the locking hole  22 . Subsequently, aiming portion  14  is swiveled so far until the aiming bore  64  is also aligned with the locking hole  24 , which can be detected with the aid of the calibration pin. Thereafter, a fixing of the aiming portion  14  in the actual swiveling position with the aid of the fixing screw  76  takes place. The position of the nail had been previously adjusted by the clamping screw  126 , fixing screw  90  and adjustment screw  114 . Subsequently, the nail adapter  30  is removed by disengaging clamping screw  126 , and locking nail  20  is driven into the bone in the conventional manner, for example, from the proximal position into the femur channel. The nail adapter  30  remains attached on locking nail  20 . Locking nail  20  is driven in for a certain distance somewhat farther than the desired end position. This oversize corresponds to a distance which is smaller than the separation of locking holes  22 ,  24 . After the nail has been driven in, a fixing of aiming arm  10  on nail adapter  30  takes place in the already described way. Now, a hole is drilled into the cortical substance on the near side of the bone through middle aiming bore  72  with the aid of a suitable drilling sleeve and, as the case may be, a tissue protection sleeve. In doing this, care must be taken to avoid the drill coming into contact with the nail  20 . After this hole is drilled, the aiming device is subsequently removed from the nail adapter, and an attempt is made to feel the groove  28  with the aid of the feeler  138 , which is pushed through the bone bore. If this fails, the groove  28  can be detected by feel by slightly turning the nail  20  in the bone channel. As soon as this occurs, the nail  20  is somewhat pulled out, until the feeler  22  detects the locking hole  24  by feel. When this is done, the fixing sleeve  144  is placed over the feeler  138 . In this, the portion  146  arrives in the locking hole  24  through the bone bore. The aiming device is subsequently mounted anew with the fixing sleeve  144  seated in this way, the aiming bore  64  being aligned to the fixing sleeve  144 . When the fixing of the aiming device has taken place, the inner aiming bore  60  is automatically aligned to the inner locking hole  22 . Now the bone can be drilled on opposing sides of the locking hole  22  with the aid of the conventional methods and a locking screw can be inserted, in order to fix the nail in the bone. When this has taken place, the cortical substance of the bone can be drilled also on the other side by also removing the fixing sleeve  144  and with the aid of the conventional methods, in order to incorporate a locking screw also into this region.  
         [0056]    As soon as the distal locking is ended, a locking in the region of the proximal locking hole  26  can also take place in known manner.  
         [0057]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.