Abstract:
A method of implanting in a fibula a malleolar implant including a head and a shank. The method comprises the steps of creating a bore in the fibula extending from an inner face to an outer face and applying a traction force to the malleolar implant so that the shank is pulled into the bore.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation of U.S. patent application Ser. No. 10/254,984, filed Sep. 26, 2002; which is a divisional of U.S. patent application Ser. No. 09/631,938, filed Aug. 3, 2000; which claims priority from French Application Serial No. 99 10340, filed Aug. 5, 1999, all herein incorporated by reference in their entirety. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a malleolar implant for a partial or total prosthesis of the ankle and to an ancillary tool for placing such an implant.  
         [0004]     2. Description of the Related Art  
         [0005]     It is known, for example from EP-A-0 864 304, to fit an ankle prosthesis with a malleolar implant intended to bear against an articular surface at the level of the astragalus, whether it be question of a natural surface or of a surface of a prosthetic component. During an operation on an ankle, access to the internal articular surfaces is limited by the ligamentary system which does not necessarily allow a sufficient dislocation of the joint. In particular, access to the internal surface of the fibular malleolus may be insufficient, which induces difficulties in positioning the implant, particularly by impaction.  
         [0006]     With reference to the embodiments of  FIGS. 4 and 5 , it is envisaged in EP-A-0 864 304 to introduce an implant from the outer face of the fibula. However, this necessarily limits the surface of the head of this implant, which must be less than or equal to the surface of the orifice provided in the bone, so that it is necessarily of relatively small dimensions with the result of substantially fragilizing the malleolus.  
         [0007]     For the foregoing reasons, the positioning of the malleolar implants in the known prostheses is not entirely satisfactory.  
         [0008]     It is a particular object of the present invention to overcome these drawbacks by proposing a novel malleolar implant which may be positioned precisely, even though access to the internal surface of the fibular malleolus may be limited and whereas its articular head presents dimensions allowing it to perform its function efficiently.  
       SUMMARY  
       [0009]     In one embodiment, the invention is a method of implanting in a fibula a malleolar implant including a head and a shank. The method comprises the steps of creating a bore in the fibula extending from an inner face to an outer face and applying a traction force to the malleolar implant so that the shank is pulled into the bore.  
         [0010]     In one embodiment, the invention is a method of implanting in a fibula a malleolar implant including a shank coupled to a head. The method comprises the step of creating a bore in the fibula extending from an inner face to an outer face. The shank and the bore are aligned. A traction force is applied to the shank so that the shank is pulled into the bore.  
         [0011]     In another embodiment, the invention is a method of implanting in a fibula a malleolar implant including a shank coupled to a head. The method comprises the steps of creating a bore in the fibula extending from an inner face to an outer face and inserting a traction member through an orifice in the shank. A traction force is applied to the traction member in a direction parallel to a longitudinal axis of the bore so that the shank is pulled into the bore.  
         [0012]     In another embodiment, the invention is a method of implanting in a fibula a malleolar implant including a shank coupled to a head. The method comprises the steps of creating a bore in the fibula extending from an inner face to an outer face and inserting a traction member through an orifice in the shank. The traction member is extended through the bore from the inner face to the outer face. A traction force is applied to the traction member from a location external to the outer face of the fibula so that the shank is pulled into the bore.  
         [0013]     In another embodiment, the invention is a method of implanting a malleolar implant in a fibula. The method comprises the steps of creating a bore in the fibula extending from an inner face to an outer face and providing a malleolar implant having a shank coupled to a head. A traction force is applied to the implant from a location external to the outer face of the fibula so that the shank is pulled into the bore.  
         [0014]     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The invention will be more readily understood on reading the following description of an embodiment of a malleolar implant and its ancillary tool according to the invention, given solely by way of example and with reference to the accompanying drawings, in which:  
         [0016]      FIG. 1  is a view in perspective of an implant according to the invention.  
         [0017]      FIG. 2  is a view in perspective of the implant of  FIG. 1  during positioning in a fibular malleolus, shown with parts torn away.  
         [0018]      FIG. 3  schematically shows, with parts torn away, an ancillary tool for placing the implant of  FIG. 1 , in the course of use.  
         [0019]      FIG. 4  is a view in perspective of the tool of  FIG. 3 , from underneath. 
     
    
       [0020]     While the invention is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION  
       [0021]     Referring now to the drawings, the implant  1  shown in  FIGS. 1 and 2  is intended to be introduced in a bore  2  made in the lateral or fibular malleolus  3 . The implant  1  comprises a convex head  4 , substantially in the form of a spherical cap and of which the radius of curvature is substantially equal to that of the outer cheek of the astragalus of the ankle in question. The shank  5  of the implant  1  is provided with outer radial flanges  6  of which the outer diameter d.sub.6 is substantially equal to the inner diameter d.sub.2 of the bore  2 .  
         [0022]     According to the invention, two orifices  7  are provided in the shank  5  and are capable of receiving a suture thread  8  or other flexible tie. When such a thread is engaged in one of the orifices  7 , it is possible to exert on the thread  8  an effort of traction T which is transmitted by the thread  8  to the shank  5  as represented by arrow T′ in  FIG. 2 . In this way, by pulling on the thread  8 , the surgeon introduces the shank  5  in the bore  2  without having to exert an effort of thrust on the head  4  which may be difficult to access due to the surrounding ligamentary system.  
         [0023]     In other words, it suffices for the surgeon to place a thread in one of the orifices  7 , to pass the two strands of the thread  8  in the bore  2  via the inner face of the malleolus, then to pull the strands via the outer side of the malleolus. The traction on the thread  8  has the effect of introducing the shank  5  of the implant  1  in the bore  2  and of applying the head  4  on the bone. The effort of traction T exerted on the thread  8  may be intense and directed parallel to the longitudinal axis X.sub.2 of the bore  2 , with the result that the shank is efficiently drawn towards the inside of the bore  2 . In particular, taking into account the direction and intensity of the effort of traction T, the diameters d.sub.2 and d.sub.6 can be provided to be substantially equal, with the result that the shank  5  is firmly maintained in place after having been positioned.  
         [0024]     The shank  5  is provided with two bores  7  distributed along its axis X.sub.5, the bore  7  nearest the end  5   a  of the shank  5  being used. The fact that the shank  5  comprises a plurality of orifices  7  makes it possible to use an orifice  7  relatively close to the end  5   a  of the shank  5  and to avail of such an orifice including when the shank  5  is cut in order to adapt its length to the thickness e of the malleolus  3 . The number of bores  7  may, of course, be increased if necessary.  
         [0025]     The bore  2  is made via the outer face  3   a  of the malleolus  3  with the aid of the ancillary tool shown in  FIGS. 3 and 4 . This tool  10  comprises a spacer block  11  provided to be disposed between the tibia T and the astragalus A of an ankle to be fitted with the implant  1 . The block  11  comprises a substantially planar upper surface  12  intended to cooperate with a planar surface created by resection of the distal end of the tibia. The lower surface  13  of the block  11  is formed by two planar surfaces  13   a  and  13   b  inclined with respect to each other by an angle .alpha., the surfaces  13   a  and  13   b  being provided to bear respectively on corresponding surfaces created by resection of the upper face of the astragalus A.  
         [0026]     The surface  12  of the block  11  comprises a C-shaped housing  14  intended to receive a shim  15  of which the upper surface  16  is in contact with the lower surface of the tibia T. The thickness E of the shim  15  shown in  FIG. 3  is such that its upper surface  16  is flush with the upper surface  12  of the block  11 .  
         [0027]     However, thicker shims may be used when the distance E′ between the lower surface of the tibia and upper surface of the astragalus is greater than in the configuration shown in  FIG. 3 .  
         [0028]     The block  11  defines a housing  17  for receiving the end  20  of a substantially C-shaped lug  21 . The end  20  is provided with a bore (not shown) which, in the configuration of  FIGS. 3 and 4 , is aligned with a bore  18  made in the block  11  and passing downwardly through this block, i.e. connecting the surfaces  12  and  13 . A screw  19  may be introduced in this bore which is at least partially tapped, this making it possible to immobilize the end  20  of the lug  21  inside the housing  17 . In practice, the clearance made when the screw  19  is tightened allows a limited pivoting about axis X.sub.18 of the bore  18 .  
         [0029]     At its end  22  opposite the end  20 , the lug  21  supports a clamping system  23  adapted to be maneuvered thanks to a knurl  24  and making it possible to apply the malleolus  3  of the fibula P against a stop  25  formed on an extension  26  of the end  20  of the lug  21 . X.sub.23 denotes the longitudinal axis of these clamping means. The clamping means  23  are hollow, with the result that a drill  30  may be introduced up to the level of the outer face  3   a  of the malleolus  3  in order to make the bore  2  from the outside towards the inside of the malleolus  3 . In this way, the surgeon may easily aim at the suitable part of the malleolus  3  thanks to the clamping means  23  which also constitute a bore guide for the drill  30 .  
         [0030]     As the lug  21  is capable of pivoting about axis X.sub.18, the position of axis X.sub.23 is variable in pivoting about this axis X.sub.18, which makes it possible optimally to adjust the orientation of the bore  2  as a function of the exact geometry of the malleolus  3 . .beta. denotes the maximum angle of pivoting of the axis X.sub.23 about axis X.sub.18. In practice, the angle .beta. is of the order of 10.degree.  
         [0031]     Thanks to the tool  10 , a bore  2  may therefore be formed from the outside, allowing a rapid and efficient implantation of the implant  1 .  
         [0032]     When shims  15  of thickness greater than those shown in  FIG. 2  are used, they can be provided to overlap the bore  18 , as the screw  19  is placed in position before positioning of the shim  15  which is effected during operation as a function of the distance E′.  
         [0033]     The invention has been shown with a total ankle prosthesis, which corresponds to the geometry of the surfaces  12  and  13  of the block  11 . However, it is also applicable to a partial ankle prosthesis, without modification of the implant  1 , the ancillary tool in that case being adapted to the geometry of the anatomical articulation surfaces between the tibia and the astragalus.  
         [0034]     Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.