Capped locking clamp for manipulation of surgical implants
The present invention relates to a forceps for handling surgical implants, in particular spinal osteosynthesis implants (screw or hook). 
     It is known that the various instruments for taking hold of and handling implants require the surgeon to exert sufficient force in the region of the noses of the instrument. Therefore, the instruments usually employed are in the form of forceps equipped with a rack. Now, around the gripping noses of these forceps and often over a great height, the overall size of the forceps is considerable. This overall size may constitute a hindrance which is all the more serious when the surgeon must use in turn several instruments close to one another and is unable, owing to their overall size, to dispose them within a radius of 3 or 4 centimetres on the vertebral segment of the patient. 
     Further, when the surgeon wishes to release the forceps, he must initially grip it still further so as to disengage the rack, which constitutes a further drawback. 
     An object of the invention is therefore to provide a forceps which is arranged in such a manner that these drawbacks are diminished or eliminated. 
     The forceps to which the invention relates comprises two branches articulated together and having terminal portions provided with gripping noses. 
     According to the invention, one end portion of one of the branches, opposed to the nose, is capped by a cap connected to an elastically yieldable device for retaining said cap on the branch while allowing said cap to tilt relative to the branch, and the corresponding end portion of the second branch is so shaped as to be insertable, by a transverse thrust, under the cap by causing it to tilt relative to the support branch therefor, said cap being thereafter automatically returned by the elastically yieldable device to a position in which it caps the two end portions of the branches and maintains the forceps in the closed position. 
     With this arrangement, the overall size of the forceps is markedly reduced relative to conventional rack-type forceps. 
    
    
     Further features and advantages of the invention will be apparent from the following description with reference to the accompanying drawings which illustrate two embodiments of the invention by way of non-limitative examples. 
     FIG. 1 is a perspective view to a slightly larger scale of a first embodiment of the forceps for gripping surgical implants according to the invention, in the open position. 
     FIG. 2 is a longitudinal half-sectional, half-elevational view of the end portion of the branch shown in FIG. 1 provided with its maintaining cap and the elastically yieldable cap-retaining and returning device. 
     FIG. 3 is an elevational view to a larger scale than that of FIG. 1 of the end portions of the forceps in an intermediate position between the open and closed positions of the forceps. 
     FIG. 4 is a view similar to FIG. 3 of the end portions of the forceps in the closed position of the latter, the two end portions of the branches being capped by the cap and the forceps being maintained in the closed position. 
     FIG. 5 is a partial side elevational view of the region of the articulation of the forceps shown in FIGS. 1 to 4, the forceps being in the closed position, this region being provided with means for limiting the angular opening of the forceps. 
     FIG. 6 is a view similar to FIG. 5 of the forceps in the open position. 
     FIGS. 7 and 8 are respectively a top plan view and a side elevational view to a smaller scale of the articulation region of one of the branches of the forceps shown in FIGS. 5 and 6. 
     FIGS. 9 and 10 are views similar to FIGS. 7 and 8 of the other branch of the forceps. 
     FIG. 11 is a partial top plan view of a branch of a second embodiment of the forceps according to the invention. 
     FIG. 12 is a partial side elevational view of the branch shown in FIG. 11 and the corresponding cap. 
     FIG. 13 is a top plan view of a removable wing member which is part of the branch shown in FIGS. 11 and 12. 
    
    
     The forceps 1 shown in the drawing is adapted to handle surgical implants, in particular spinal osteosynthesis implants such as screws and hooks having an open or closed body of various known types (not shown). 
     This forceps comprises two branches 2, 3 articulated together by a transverse pin 4 and having terminal portions 5, 6 provided with respective noses 7, 8 for taking hold of the implants. The noses 7, 8 are arranged in the known manner and comprise, in particular, on their confronting inner faces, two lugs 9, 11 for gripping the implant. 
     The portions of the branches 2, 3 remote from the noses 7, 8 beyond the articulation pin 4 have a substantially semi-circular cross-sectional shape with axial recesses 12, 13. Circular grooves 14 are provided on their outer surface so that the surgeon has a better grip on the forceps 1. 
     The end portion 15 of the branch 2 remote from the respective nose 7 terminates in a transverse eye 16 and is capped by a cap 17 made for example from a suitable plastics material. The cap 17 defines, adjacent the end portion 15, a cylindrical cavity 18 for receiving the eye 16 with, around the eye, a transverse clearance j on one side and a larger clearance J on the diametrically opposite side. The eye defines with the cavity 18 the clearance (J) between the edge 16a of the eye and the wall 18a of the cavity 18, the clearance (J) extending over a suitable angular sector around the eye 16, for example a semi-circumference. 
     Provided in the cap 17 is a tapped hole 20 extending axially relative to the branch 2 and adapted to receive a corresponding threaded end portion 19 of a screw 21 which extends with clearance through the central opening 22 of the eye 16. The screw 21 is partly disposed in the axial recess 12 and is provided with an elastically yieldable device constituted by a compression spring 23 coaxial with the shank of the screw 21. The spring 23 bears at one end against the eye 16 and at the opposite end against the head 24 of the screw 21. Consequently this spring exerts on the cap 17, through the screw 21, an axial force F for elastically returning the cap 17 to the position in which it bears against the surface of the eye 16 perpendicular to the axis of the recess 12. 
     Disposed in the vicinity of the articulation pin 4 between the two branches 2, 3 is a spring 25 whose opposite ends are respectively fixed to inner faces, planar in this region, of the branches 2 and 3. The spring 25 returns the latter to the spread-apart position, the forceps being open (position shown in FIG. 1). 
     Lastly, means are provided for limiting the angular opening of the branches 1, 2 when the forceps is in the open position. 
     In the embodiment shown in FIGS. 5 to 10, these means comprise, in the vicinity of the articulation pin 4, a lug 28 fixed to one of the branches, namely the branch 2 in the illustrated embodiment, and extending toward the confronting face of the other branch 3. Formed in this confronting face is a blind opening 29 whose section is larger than the section of the lug 28. 
     The latter therefore has a certain freedom of movement in the opening 29 when opening the forceps 1, depending on the respective dimensions of the lug and opening, which allows a correspondingly limited angular movement between the two branches 2, 3 when opening the forceps (FIG. 6). 
     The overall size of the forceps in the open position is consequently very small. 
     It should moreover be noted that the edge 26 of the cap 17 adjacent the ends of the branches 2, 3 is rounded in axial section and the end portion 27 of the branch 3 which is not provided with the cap 17 also has a rounded edge 28. 
     The handling forceps according to the invention is employed in the following manner: 
     In the open position, the branch 3 is maintained angularly spaced from the branch 2 by the spring 25, and the cap 17 solely caps the eye 16 and the end portion 15 of the branch 2, as shown in FIGS. 1 and 2. 
     In starting in the open position shown in FIGS. 1 and 2, to close the forceps 1 it is sufficient to move the two branches 2, 3 towards each other until the end portion with the rounded edge 28 comes into contact with the corresponding rounded edge 26 of the cap 17 and lifts the latter (FIG. 3). The cap 17, the screw 21 and the spring 23 therefore tilt under the effect of this thrust owing to the provision of the clearance between the cap 17 and the eye 16. In continuing to exert the thrust on the end portion 27, the latter is engaged under the cap 17 in the semi-circular gap or clearance J between the eye 16 and the wall 18a which is so dimensioned as to receive the extremity of the end portion 27 of the branch 3 (FIG. 4). This tilting of the cap 17 and screw 21 occurs in opposition to the return force exerted by the spring 23 and, as soon as the extremity of the end portion 27 has completely entered the clearance J, the spring 23 automatically returns the cap 17 and screw 21 to their initial position (FIG. 4). 
     In this position, the noses 7, 8 are brought closer together and are clamped on the implant to be handled, the forceps 1 being maintained in this closed position by the cap 17. 
     To open the forceps, the surgeon merely has to exert with the thumb a slight pressure in a direction roughly parallel to the axis of the forceps 1 on the base of the cap 17 adjacent the rounded edge 26, which permits easily disengaging the latter from the end portion 27. As soon as the rounded edge 28 starts to slide on the rounded edge 26, the spring 25 swings the branch 3 away from the branch 2 to the open position of the forceps (FIG. 1). The lug 28 and the hole 29 limit the opening of the branches 2 and 3 to a small angle so that the opened forceps does not take up a large amount of space. 
     The overall size of the forceps 1 according to the invention is consequently smaller than that of the rack-type forceps of the prior art, so that the surgeon can hold several instruments close to one another in a region of very small area in the course of his intervention. 
     Further, the forceps is easily and rapidly released, i.e. opened, since it is sufficient to exert a slight thrust with a thumb or finger on the cap 17. 
     In the embodiment shown in FIGS. 11 to 13, the cap 31 is pivotally mounted on the forceps branch 32 by a transverse pin 33 mounted at the end of the latter, no cap returning spring being employed here. The cap 31 is therefore pivotable on the pin 33 between an open forceps position and a closed forceps position in which it caps the ends of the two branches. 
     Further, one of the branches of the forceps, namely the branch 32 in the presently-described embodiment, has a longitudinal recess 34. The latter forms a housing for an elongate wing member 35 which is rotatively mounted on this branch by a pin 36 engaged in apertures 37 and 38 in the branch 32 and the wing member 35. 
     The wing member 35 may assume two extreme angular positions, namely a first position in which it is entirely contained within the recess 34, its surface being then flush with the surface of the branch 32 that it completes, and a second position in which it is substantially perpendicular to the branch 32 and permits using the forceps as a screw driver. 
     It must be understood that the scope of the invention is not intended to be limited to the described embodiments and may encompass variants. Thus, the elastically yieldable device (21, 23) for returning the cap 17 may be made in any other way equivalent to that shown and the lugs 9, 11 may be eliminated.