Abstract:
The instrument serves the application in particular of bone grafts in the space between two vertebrae and consists of a shank, of a handle and of a holder for the implant, which forms the distal instrument part. The holder is pivotably mounted relative to the shank and can be fixed in its position which in each case is reached by pivoting.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention proceeds from a surgical instrument for applying implants, in particular bone grafts in the region of the vertebral column, consisting of a shank, a handle and of a holder for the implant which forms the distal instrument part.  
           [0002]    With known instruments of this type, e.g. the holder for the implant, which is formed as a spike, is rigidly connected to the shank of the instrument, i.e. in an unchangeable alignment to the instrument longitudinal axis. This is also the case with the instrument which is disclosed in FR-A 2 764 795 and described as a key, with which a support body may be implanted between neighbouring vertebral bodies and with which the holder is formed as a threaded stem to which the implant is connected by screwing.  
           [0003]    With the use of these surgical instruments it is necessary for the location of the defect concerned and the access to this to lie in the axis direction of the instrument for the purpose of introducing the implant, which makes its application more difficult and demands an exact alignment of the instrument onto the location of operation.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    It is the object of the invention to specify a surgical instrument for applying implants which permits a variably adjustable aligment of the implant in relation to the instrument and operation location, and specifically where required also even during the operation procedure. Furthermore at the same time the instrument is to permit a simple and secure handling and with regard to the demands on hygiene able to be easily disassembled.  
           [0005]    Proceeding from an instrument of the initially mentioned type this object is achieved according to the invention in that the holder is pivotably mounted relative to the shank and is fixable in its position which is in each case achieved by pivoting.  
           [0006]    According to a preferred embodiment form of the invention on the holder there may be provided an essentially spherical bearing body which is mounted in the shank and which is pivotable about two axes intersecting perpendicularly and which by way of a rod which runs through the shank and which with its distal end is movable against the periphery of the bearing body, may be fixed by way of clamping.  
           [0007]    In order to achieve a rotational fit connection between a handle of the instrument and the bearing body, the bearing body may be provided with a groove running on a circular path of more than 180°, wherein into the groove engage pins which are fastened to the shank, which lie on the same axis and which form a first pivot axis for the bearing body, and the bearing body with the pins sliding in the groove is pivotable about a second pivot axis which stands perpendicular on the first pivot axis and the plane of the groove.  
           [0008]    The fixing of the bearing body by clamping may usefully be made possible in that the distal open end of the shank is drawn inwards and forms a spherically curved annular surface as a shoulder and bearing surface for the bearing body and that in the distal end region of the rod formed as a tube there is provided an insert whose end projecting out of the rod is formed as a spherically curved annular surface which by way of distal adjustment of the rod can be brought to bear against the periphery of the bearing body, in order to fix this bearing body and thus also the holder carrying the implant in the respective pivot position by way of a clamping effect.  
           [0009]    In the proximal end region of the handle rigidly connected to the shank there is provided an inner thread into which a threaded projection of a clamping head is screwed, said head being rigidly connected to the rod. By rotating the clamping head and thus the rod in a first direction this may be distally adjusted for fixing the bearing body and reversely by rotating in a second direction may be adjusted proximally in order thus to lift the clamping effect between the bearing body and the parts engaging it or only to reduce this clamping effect somewhat, by which means the holder becomes pivotable and subsequently after pivoting into a suitable position may again be fixed by rotating the clamping head in the first direction.  
           [0010]    The holder on the proximal side blends into an annular shoulder forming an abutment for the implant and via a cylinder projecting through the open end of the shank is rigidly connected to the bearing body. If with the instrument, bone parts or bone grafts are to be applied, it is useful to form the holder as a distally conically tapering threaded spike which may be simply screwed into the implant and which securely holds this. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The invention is hereinafter described in more detail by way of an embodiment example shown in the drawing. There are shown in:  
         [0012]    [0012]FIG. 1 a total view of the instrument according to the invention in a part longitudinal section,  
         [0013]    [0013]FIG. 2 an enlarged sectional representation of the distal end region of the instrument shown in FIG. 1,  
         [0014]    [0014]FIG. 3 the bearing body and holder of the instrument according to FIG. 2,  
         [0015]    [0015]FIG. 4 the bearing body and holder of the instrument according to FIG. 2 in a plan view.  
         [0016]    [0016]FIG. 5 a sectional representation according to FIG. 2 with a holder formed as a screwdriver tip,  
         [0017]    [0017]FIG. 6 the instrument according to the invention in an application as a bone graft applicator and  
         [0018]    [0018]FIG. 7 the instrument according to the invention in an application as a screwdriver. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    The instrument consists according to FIG. 1 of a shank  1  with a handle  2  arranged proximally on the shank, of a holder  3  for the implant, which is arranged on the distal side, and of an actuation rod  4 .  
         [0020]    The shank  1  is formed tubular and comprises at its distal end an annular surface  5  whose contour is shaped spherically, but may also be shaped conically. The shank  1  and the handle  2  are unreleasably corrected to one another. In a channel  6  of the shank an actuation rod  4  is arranged in an axially displaceable manner. This is provided at its distal end with an insert  7  whose end-face region comprises a spherical recess  8 . On the proximal end of the actuation rod  4  there is seated a clamping head  9  with a threaded projection which is screwed into a corresponding inner thread  11  on the proximal-side end of the handle  2 . Thus by rotating the clamping head  9  in a first direction the actuation rod  4  with the insert  7  are moved distally and by rotating the clamping head in another second direction are moved proximally.  
         [0021]    At the distal-side end of the shank  1  there is mounted the holder  3 . This is provided with an essentially spherical bearing body  12  which via a cylindrical extension  13  blends into a distally tapering spherical threaded spike on whose foot there is provided an annular shoulder  15  as an abutment for the implant. The bearing body  12  is provided with a groove  16  which runs on a circular path of more than 180°, into which engage pins  17  fastened on the shank  1  and lying on the same axis.  
         [0022]    For preparing the instrument for an operation firstly the holder  3  is assembled. The holder may for this purpose be designed as two parts and comprise a threaded projection between the bearing body  12  and the threaded spike  14 , to which these two parts may be releasably connected. The application of the holder  3  is effected then such that firstly the bearing body  12  with the cylindrical extension  13  in front is introduced into the channel  6 . Then the actuation rod  4  from the proximal is pushed into the channel and by way of the mentioned threaded connection  10 / 11  of the insert  7  located at the end of the actuation rod  4 , by rotating the clamping head  9  in the first direction, comes to take its bearing and thus the bearing body  12  is clamped between the annular surface  5  and the recess  8 , so that subsequently the threaded spike  14  may be screwed to the bearing body  12 .  
         [0023]    The receiving of e.g. an implant  21  to be applied between two vertebral bodies  23  (FIG. 6) is effected such that the conical threaded spike  14  is screwed into the implant up to its bearing on the annular shoulder  15 . Thereafter by proximal adjustment of the actuation rod  4  the clamping force acting on the bearing body  12  may be reduced or lifted, so that the desired position of the holder and thus also of the implant relative to the instrument axis may be set. After fixing this position again by distal adjustment of the actuation rod  4  now the implant under endoscopic observation may be brought to the location of the defect and applied. With this there exists the possibility of a correction of the previously set position within the context of a self-alignment, and specifically by way of an intermediate release of the holder, and subsequent fixing of the holder as soon as this has automatically aligned into a position suitable for the application procedure.  
         [0024]    In order for example to connect and bridge neighbouring vertebral bodies by way of a bone plate  24  according to FIG. 7, which is to be screwed to these bodies, instead of the threaded spike  14  there is applied a holder  3  with a screwdriver tip  20  so that the instrument in total as a screwdriver, with the screws  22  as implant parts, may be screwed through the bone plate  24  into the respective vertebral bodies  23 .