Device for osteosynthesis
This application is a continuation of application Ser. No. 273,818, filed as PCT DE88/00017 on Jan. 14, 1988, published as WO88/05287 on Jul. 28, 1988, now abandoned. 
    
    
     The invention relates to a device for osteosynthesis. 
     Devices for osteosynthesis, particularly metallic devices, function to set a fracture. For bent, arched or curved bone segments, e.g., in jaw surgery, fixing of the fracture ends precisely in the desired and required position is very difficult, particularly when--as is currently conventional--the devices are to be completely covered, that is, applied internally. 
     An osteosynthesis device of this character is known from U.S. Pat. No. 1,789,060. With this device, setting of the fracture is effected outside of the body and such device consists essentially of two support plates which carry the setting members so that they are adjustable longitudinally of the support plate and so that their height relative to the support plate can be adjusted. Pivotal movement of the setting members on the support plates is not possible. The two support plates are joined to one another by a complicated hinge which consists, on the one hand, of two relatively adjustable hemispheres capable of being arrested relative to one another and, on the other hand, of an elongated guide slot in each support plate. The elongated slots of the two support plates are perpendicular to one another so that the height of one of the support plates and the transverse position of the other support plate can be regulated. This arrangement provides for alignment of the bone in a discontinuous manner only and, for fractures of complicated arched bones such as, for example, jawbones or dorsal vertebrae, only limited alignment of the fracture is possible due to the limited degrees of freedom of the osteosynthesis device. 
     It is an object of the invention to create an osteosynthesis device for the setting of fractures which makes it possible to achieve a large pivot angle of the two support plates relative to one another and allows alignment of the bone to be accomplished continuously so that the work of the surgeon is simplified. 
     An osteosynthesis device according to the invention makes it possible to achieve a large pivot angle of the two support plates relative to one another via a double-ball hinge and a spacer disposed between the two balls, and further makes it possible to adjust each individual support plate for itself in all directions. 
     The mounting of the setting members on the support plates for pivotal movement and height adjustment as additionally provided by the invention creates additional degrees of freedom for the overall arrangement which make it possible to carry out even the most complicated bone settings and alignments. 
     With the osteosynthesis device according to the invention, it is thus possible to first apply the setting members to the bone segments to be joined, to then connect the support plates, to then place the support plates at the desired angle, e.g., under an x-ray screen, and align the bone parts with respect to one another, and to then completely fix the entire osteosynthesis device as regards its adjustability. The design according to the invention takes account of the two possible setting errors which commonly occur, namely, rotation of the two separated bone parts and shifting of the two bone parts in two different planes. 
    
    
     An exemplary embodiment of the invention is described below with reference of the drawings in which: 
     FIG. 1 is a schematic overall view of the osteosynthesis device; and 
     FIG. 2 is an exploded view illustrating the individual components of the device shown in FIG. 1 in order to clarify the function of the individual elements. 
    
    
     In FIG. 1, 1 and 2 denote two support plates which are connected to one another by a double-ball hinge 3. The support plates carry setting members 4 and 5 with the setting members in the illustrated exemplary embodiment each consisting of two screws 6 and 7 which can be fixed to the support plates. 
     The setting members are fixed to the support plates by means of small fastening supports 8 and 9 and these small fastening supports are mounted on the support plates 1 and 2 for adjustment longitudinally thereof. Fixing of the small fastening supports 8 and 9 and their adjustment takes place via screw spindles 10 and 11, respectively. 
     The double-ball hinge 3 consists of two balls 14 and 15 which are connected to one another by a rigid spacer 12 and lie in ball sockets 16 and 17 .Iadd.which are concave portions of a sphere, said portions being shown .Iaddend.having the shape of a quarter of a sphere and located at the ends of the support plates 1 and 2. Fixing of the balls occurs via ball socket plates 18 and 19 which are likewise formed with recesses .Iadd.which are also concave portions of a sphere and are shown .Iaddend.in the shape of a quarter of a sphere. The recess 20 provided in the ball socket plate 19 and .Iadd.shown to be .Iaddend.shaped like a quarter of a sphere is visible in FIG. 2. Attachment of the ball socket plates 18 and 19 is effected by means of screws 21 which screw into corresponding bores 22 in the support plates. By tightening the screws 21 to a greater or lesser degree, it is possible for the double-ball hinge 3 to be movable to all sides or to be rigid. 
     Slide guides 23 and 24 are provided in the support plates 1 and 2 and respectively guide sliding blocks 25 and 26 on which a respective clamping member 27 or 28 can be screwed, e.g., via the screws 29. Each clamping member 27 and 28 has two receiving spaces 30 conforming to the shape of the nails 6 and 7. By appropriately tightening the screws 29, the positions of the nails 6 and 7 can be fixed. Upon loosening the screws 29, rotation of the clamping members 27 and 28 out of the positions shown in FIG. 1 is possible so that the orientations of the screws 6 and 7 can be regulated. 
     The sliding blocks 25 and 26 are received in the slide guides 23 and 24 and have--as is observable in the drawing--a bore provided with internal threads which mesh with the external threads of the screw spindles 10 and 11. Each screw spindle 10 and 11 is fixed in the slide guide 23 or 24 by guiding the shaft of the screw spindle 10 or 11 in a respective opening 31 or 32 and placing an elastic snap ring 33 or 34 on the shaft. The enlarged head 35 or 36 of the screw spindle 10 constitutes the abutment for the elastic snap ring 33 or 34.